Merge remote-tracking branch 'refs/remotes/grpc/master'

28 files changed, 960 insertions, 1134 deletions

diff --git a/BUILD b/BUILD
index e46356a81b..ba44e050ca 100644
--- a/BUILD
+++ b/BUILD
@@ -182,7 +182,6 @@ cc_library(
     "src/core/support/thd_internal.h",
     "src/core/support/time_precise.h",
     "src/core/census/aggregation.h",
-    "src/core/census/context.h",
     "src/core/census/rpc_metric_id.h",
     "src/core/httpcli/httpcli_security_connector.c",
     "src/core/security/base64.c",
@@ -379,7 +378,6 @@ cc_library(
     "src/core/census/initialize.c",
     "src/core/census/operation.c",
     "src/core/census/placeholders.c",
-    "src/core/census/tag_set.c",
     "src/core/census/tracing.c",
   ],
   hdrs = [
@@ -580,7 +578,6 @@ cc_library(
     "src/core/transport/transport.h",
     "src/core/transport/transport_impl.h",
     "src/core/census/aggregation.h",
-    "src/core/census/context.h",
     "src/core/census/rpc_metric_id.h",
     "src/core/surface/init_unsecure.c",
     "src/core/profiling/basic_timers.c",
@@ -757,7 +754,6 @@ cc_library(
     "src/core/census/initialize.c",
     "src/core/census/operation.c",
     "src/core/census/placeholders.c",
-    "src/core/census/tag_set.c",
     "src/core/census/tracing.c",
   ],
   hdrs = [
@@ -1405,7 +1401,6 @@ objc_library(
     "src/core/census/initialize.c",
     "src/core/census/operation.c",
     "src/core/census/placeholders.c",
-    "src/core/census/tag_set.c",
     "src/core/census/tracing.c",
   ],
   hdrs = [
@@ -1602,7 +1597,6 @@ objc_library(
     "src/core/support/thd_internal.h",
     "src/core/support/time_precise.h",
     "src/core/census/aggregation.h",
-    "src/core/census/context.h",
     "src/core/census/rpc_metric_id.h",
   ],
   includes = [
diff --git a/Makefile b/Makefile
index 40d360c67a..16e6b32eba 100644
--- a/Makefile
+++ b/Makefile
@@ -831,6 +831,7 @@ algorithm_test: $(BINDIR)/$(CONFIG)/algorithm_test
 alloc_test: $(BINDIR)/$(CONFIG)/alloc_test
 alpn_test: $(BINDIR)/$(CONFIG)/alpn_test
 bin_encoder_test: $(BINDIR)/$(CONFIG)/bin_encoder_test
+census_context_test: $(BINDIR)/$(CONFIG)/census_context_test
 channel_create_test: $(BINDIR)/$(CONFIG)/channel_create_test
 chttp2_hpack_encoder_test: $(BINDIR)/$(CONFIG)/chttp2_hpack_encoder_test
 chttp2_status_conversion_test: $(BINDIR)/$(CONFIG)/chttp2_status_conversion_test
@@ -908,7 +909,6 @@ set_initial_connect_string_test: $(BINDIR)/$(CONFIG)/set_initial_connect_string_
 sockaddr_resolver_test: $(BINDIR)/$(CONFIG)/sockaddr_resolver_test
 sockaddr_utils_test: $(BINDIR)/$(CONFIG)/sockaddr_utils_test
 socket_utils_test: $(BINDIR)/$(CONFIG)/socket_utils_test
-tag_set_test: $(BINDIR)/$(CONFIG)/tag_set_test
 tcp_client_posix_test: $(BINDIR)/$(CONFIG)/tcp_client_posix_test
 tcp_posix_test: $(BINDIR)/$(CONFIG)/tcp_posix_test
 tcp_server_posix_test: $(BINDIR)/$(CONFIG)/tcp_server_posix_test
@@ -1138,6 +1138,7 @@ buildtests_c: privatelibs_c \
   $(BINDIR)/$(CONFIG)/alloc_test \
   $(BINDIR)/$(CONFIG)/alpn_test \
   $(BINDIR)/$(CONFIG)/bin_encoder_test \
+  $(BINDIR)/$(CONFIG)/census_context_test \
   $(BINDIR)/$(CONFIG)/channel_create_test \
   $(BINDIR)/$(CONFIG)/chttp2_hpack_encoder_test \
   $(BINDIR)/$(CONFIG)/chttp2_status_conversion_test \
@@ -1208,7 +1209,6 @@ buildtests_c: privatelibs_c \
   $(BINDIR)/$(CONFIG)/sockaddr_resolver_test \
   $(BINDIR)/$(CONFIG)/sockaddr_utils_test \
   $(BINDIR)/$(CONFIG)/socket_utils_test \
-  $(BINDIR)/$(CONFIG)/tag_set_test \
   $(BINDIR)/$(CONFIG)/tcp_client_posix_test \
   $(BINDIR)/$(CONFIG)/tcp_posix_test \
   $(BINDIR)/$(CONFIG)/tcp_server_posix_test \
@@ -1371,6 +1371,8 @@ test_c: buildtests_c
 	$(Q) $(BINDIR)/$(CONFIG)/alpn_test || ( echo test alpn_test failed ; exit 1 )
 	$(E) "[RUN]     Testing bin_encoder_test"
 	$(Q) $(BINDIR)/$(CONFIG)/bin_encoder_test || ( echo test bin_encoder_test failed ; exit 1 )
+	$(E) "[RUN]     Testing census_context_test"
+	$(Q) $(BINDIR)/$(CONFIG)/census_context_test || ( echo test census_context_test failed ; exit 1 )
 	$(E) "[RUN]     Testing channel_create_test"
 	$(Q) $(BINDIR)/$(CONFIG)/channel_create_test || ( echo test channel_create_test failed ; exit 1 )
 	$(E) "[RUN]     Testing chttp2_hpack_encoder_test"
@@ -1505,8 +1507,6 @@ test_c: buildtests_c
 	$(Q) $(BINDIR)/$(CONFIG)/sockaddr_utils_test || ( echo test sockaddr_utils_test failed ; exit 1 )
 	$(E) "[RUN]     Testing socket_utils_test"
 	$(Q) $(BINDIR)/$(CONFIG)/socket_utils_test || ( echo test socket_utils_test failed ; exit 1 )
-	$(E) "[RUN]     Testing tag_set_test"
-	$(Q) $(BINDIR)/$(CONFIG)/tag_set_test || ( echo test tag_set_test failed ; exit 1 )
 	$(E) "[RUN]     Testing tcp_client_posix_test"
 	$(Q) $(BINDIR)/$(CONFIG)/tcp_client_posix_test || ( echo test tcp_client_posix_test failed ; exit 1 )
 	$(E) "[RUN]     Testing tcp_posix_test"
@@ -2343,7 +2343,6 @@ LIBGRPC_SRC = \
     src/core/census/initialize.c \
     src/core/census/operation.c \
     src/core/census/placeholders.c \
-    src/core/census/tag_set.c \
     src/core/census/tracing.c \
 
 PUBLIC_HEADERS_C += \
@@ -2715,7 +2714,6 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/census/initialize.c \
     src/core/census/operation.c \
     src/core/census/placeholders.c \
-    src/core/census/tag_set.c \
     src/core/census/tracing.c \
 
 PUBLIC_HEADERS_C += \
@@ -5803,6 +5801,38 @@ endif
 endif
 
 
+CENSUS_CONTEXT_TEST_SRC = \
+    test/core/census/context_test.c \
+
+CENSUS_CONTEXT_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(CENSUS_CONTEXT_TEST_SRC))))
+ifeq ($(NO_SECURE),true)
+
+# You can't build secure targets if you don't have OpenSSL.
+
+$(BINDIR)/$(CONFIG)/census_context_test: openssl_dep_error
+
+else
+
+
+
+$(BINDIR)/$(CONFIG)/census_context_test: $(CENSUS_CONTEXT_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a
+	$(E) "[LD]      Linking $@"
+	$(Q) mkdir -p `dirname $@`
+	$(Q) $(LD) $(LDFLAGS) $(CENSUS_CONTEXT_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/census_context_test
+
+endif
+
+$(OBJDIR)/$(CONFIG)/test/core/census/context_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a
+
+deps_census_context_test: $(CENSUS_CONTEXT_TEST_OBJS:.o=.dep)
+
+ifneq ($(NO_SECURE),true)
+ifneq ($(NO_DEPS),true)
+-include $(CENSUS_CONTEXT_TEST_OBJS:.o=.dep)
+endif
+endif
+
+
 CHANNEL_CREATE_TEST_SRC = \
     test/core/surface/channel_create_test.c \
 
@@ -8267,38 +8297,6 @@ endif
 endif
 
 
-TAG_SET_TEST_SRC = \
-    test/core/census/tag_set_test.c \
-
-TAG_SET_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(TAG_SET_TEST_SRC))))
-ifeq ($(NO_SECURE),true)
-
-# You can't build secure targets if you don't have OpenSSL.
-
-$(BINDIR)/$(CONFIG)/tag_set_test: openssl_dep_error
-
-else
-
-
-
-$(BINDIR)/$(CONFIG)/tag_set_test: $(TAG_SET_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a
-	$(E) "[LD]      Linking $@"
-	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) $(TAG_SET_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/tag_set_test
-
-endif
-
-$(OBJDIR)/$(CONFIG)/test/core/census/tag_set_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a
-
-deps_tag_set_test: $(TAG_SET_TEST_OBJS:.o=.dep)
-
-ifneq ($(NO_SECURE),true)
-ifneq ($(NO_DEPS),true)
--include $(TAG_SET_TEST_OBJS:.o=.dep)
-endif
-endif
-
-
 TCP_CLIENT_POSIX_TEST_SRC = \
     test/core/iomgr/tcp_client_posix_test.c \
 
diff --git a/binding.gyp b/binding.gyp
index e76ea54674..e4946135b0 100644
--- a/binding.gyp
+++ b/binding.gyp
@@ -685,7 +685,6 @@
         'src/core/census/initialize.c',
         'src/core/census/operation.c',
         'src/core/census/placeholders.c',
-        'src/core/census/tag_set.c',
         'src/core/census/tracing.c',
       ],
       "conditions": [
diff --git a/build.yaml b/build.yaml
index 8d19ed1958..b615945198 100644
--- a/build.yaml
+++ b/build.yaml
@@ -14,14 +14,12 @@ filegroups:
   - include/grpc/census.h
   headers:
   - src/core/census/aggregation.h
-  - src/core/census/context.h
   - src/core/census/rpc_metric_id.h
   src:
   - src/core/census/context.c
   - src/core/census/initialize.c
   - src/core/census/operation.c
   - src/core/census/placeholders.c
-  - src/core/census/tag_set.c
   - src/core/census/tracing.c
 - name: gpr
   public_headers:
@@ -896,6 +894,14 @@ targets:
   deps:
   - grpc_test_util
   - grpc
+- name: census_context_test
+  build: test
+  language: c
+  src:
+  - test/core/census/context_test.c
+  deps:
+  - grpc_test_util
+  - grpc
 - name: channel_create_test
   build: test
   language: c
@@ -1561,14 +1567,6 @@ targets:
   - mac
   - linux
   - posix
-- name: tag_set_test
-  build: test
-  language: c
-  src:
-  - test/core/census/tag_set_test.c
-  deps:
-  - grpc_test_util
-  - grpc
 - name: tcp_client_posix_test
   cpu_cost: 0.5
   build: test
diff --git a/gRPC.podspec b/gRPC.podspec
index ccfce5eaeb..4cafd8c3c0 100644
--- a/gRPC.podspec
+++ b/gRPC.podspec
@@ -201,7 +201,6 @@ Pod::Spec.new do |s|
                       'src/core/support/thd_internal.h',
                       'src/core/support/time_precise.h',
                       'src/core/census/aggregation.h',
-                      'src/core/census/context.h',
                       'src/core/census/rpc_metric_id.h',
                       'include/grpc/grpc_security.h',
                       'include/grpc/byte_buffer.h',
@@ -453,7 +452,6 @@ Pod::Spec.new do |s|
                       'src/core/census/initialize.c',
                       'src/core/census/operation.c',
                       'src/core/census/placeholders.c',
-                      'src/core/census/tag_set.c',
                       'src/core/census/tracing.c'
 
     ss.private_header_files = 'src/core/security/auth_filters.h',
@@ -594,7 +592,6 @@ Pod::Spec.new do |s|
                               'src/core/support/thd_internal.h',
                               'src/core/support/time_precise.h',
                               'src/core/census/aggregation.h',
-                              'src/core/census/context.h',
                               'src/core/census/rpc_metric_id.h'
 
     ss.header_mappings_dir = '.'
diff --git a/grpc.def b/grpc.def
index 4a1cc75cc9..d37e6879c5 100644
--- a/grpc.def
+++ b/grpc.def
@@ -3,7 +3,14 @@ EXPORTS
     census_shutdown
     census_supported
     census_enabled
-    census_context_serialize
+    census_context_create
+    census_context_destroy
+    census_context_get_status
+    census_context_initialize_iterator
+    census_context_next_tag
+    census_context_get_tag
+    census_context_encode
+    census_context_decode
     census_trace_mask
     census_set_trace_mask
     census_start_rpc_op_timestamp
@@ -16,15 +23,6 @@ EXPORTS
     census_trace_scan_start
     census_get_trace_record
     census_trace_scan_end
-    census_tag_set_create
-    census_tag_set_destroy
-    census_tag_set_get_create_status
-    census_tag_set_initialize_iterator
-    census_tag_set_next_tag
-    census_tag_set_get_tag_by_key
-    census_tag_set_encode
-    census_tag_set_decode
-    census_context_tag_set
     census_record_values
     census_view_create
     census_view_delete
diff --git a/grpc.gemspec b/grpc.gemspec
index 0b866db852..e305ea57ef 100755
--- a/grpc.gemspec
+++ b/grpc.gemspec
@@ -240,7 +240,6 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/support/thd_internal.h )
   s.files += %w( src/core/support/time_precise.h )
   s.files += %w( src/core/census/aggregation.h )
-  s.files += %w( src/core/census/context.h )
   s.files += %w( src/core/census/rpc_metric_id.h )
   s.files += %w( src/core/httpcli/httpcli_security_connector.c )
   s.files += %w( src/core/security/base64.c )
@@ -437,7 +436,6 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/census/initialize.c )
   s.files += %w( src/core/census/operation.c )
   s.files += %w( src/core/census/placeholders.c )
-  s.files += %w( src/core/census/tag_set.c )
   s.files += %w( src/core/census/tracing.c )
   s.files += %w( third_party/boringssl/crypto/aes/internal.h )
   s.files += %w( third_party/boringssl/crypto/asn1/asn1_locl.h )
diff --git a/include/grpc/census.h b/include/grpc/census.h
index 70d4f80efb..6313b196f2 100644
--- a/include/grpc/census.h
+++ b/include/grpc/census.h
@@ -70,28 +70,148 @@ CENSUS_API int census_supported(void);
 CENSUS_API int census_enabled(void);
 
 /**
-  Context is a handle used by census to represent the current tracing and
-  tagging information. Contexts should be propagated across RPC's. Contexts
-  are created by any of the census_start_*_op() functions. A context is
-  typically used as argument to most census functions. Conceptually, contexts
-  should be thought of as specific to single RPC/thread. The context can be
-  serialized for passing across the wire, via census_context_serialize().
-*/
+  A Census Context is a handle used by Census to represent the current tracing
+  and stats collection information. Contexts should be propagated across RPC's
+  (this is the responsibility of the local RPC system). A context is typically
+  used as the first argument to most census functions. Conceptually, they
+  should be thought of as specific to a single RPC/thread. The user visible
+  context representation is that of a collection of key:value string pairs,
+  each of which is termed a 'tag'; these form the basis against which Census
+  metrics will be recorded. Keys are unique within a context. */
 typedef struct census_context census_context;
 
-/* This function is called by the RPC subsystem whenever it needs to get a
- * serialized form of the current census context (presumably to pass across
- * the wire). Arguments:
- * 'buffer': pointer to memory into which serialized context will be placed
- * 'buf_size': size of 'buffer'
- *
- * Returns: the number of bytes used in buffer if successful, or 0 if the
- * buffer is of insufficient size.
- *
- * TODO(aveitch): determine how best to communicate required/max buffer size
- * so caller doesn't have to guess. */
-CENSUS_API size_t census_context_serialize(const census_context *context,
-                                           char *buffer, size_t buf_size);
+/* A tag is a key:value pair. The key is a non-empty, printable (UTF-8
+   encoded), nil-terminated string. The value is a binary string, that may be
+   printable. There are limits on the sizes of both keys and values (see
+   CENSUS_MAX_TAG_KB_LEN definition below), and the number of tags that can be
+   propagated (CENSUS_MAX_PROPAGATED_TAGS). Users should also remember that
+   some systems may have limits on, e.g., the number of bytes that can be
+   transmitted as metadata, and that larger tags means more memory consumed
+   and time in processing. */
+typedef struct {
+  const char *key;
+  const char *value;
+  size_t value_len;
+  uint8_t flags;
+} census_tag;
+
+/* Maximum length of a tag's key or value. */
+#define CENSUS_MAX_TAG_KV_LEN 255
+/* Maximum number of propagatable tags. */
+#define CENSUS_MAX_PROPAGATED_TAGS 255
+
+/* Tag flags. */
+#define CENSUS_TAG_PROPAGATE 1 /* Tag should be propagated over RPC */
+#define CENSUS_TAG_STATS 2     /* Tag will be used for statistics aggregation */
+#define CENSUS_TAG_BINARY 4    /* Tag value is not printable */
+#define CENSUS_TAG_RESERVED 8  /* Reserved for internal use. */
+/* Flag values 8,16,32,64,128 are reserved for future/internal use. Clients
+   should not use or rely on their values. */
+
+#define CENSUS_TAG_IS_PROPAGATED(flags) (flags & CENSUS_TAG_PROPAGATE)
+#define CENSUS_TAG_IS_STATS(flags) (flags & CENSUS_TAG_STATS)
+#define CENSUS_TAG_IS_BINARY(flags) (flags & CENSUS_TAG_BINARY)
+
+/* An instance of this structure is kept by every context, and records the
+   basic information associated with the creation of that context. */
+typedef struct {
+  int n_propagated_tags;        /* number of propagated printable tags */
+  int n_propagated_binary_tags; /* number of propagated binary tags */
+  int n_local_tags;             /* number of non-propagated (local) tags */
+  int n_deleted_tags;           /* number of tags that were deleted */
+  int n_added_tags;             /* number of tags that were added */
+  int n_modified_tags;          /* number of tags that were modified */
+  int n_invalid_tags;           /* number of tags with bad keys or values (e.g.
+                                   longer than CENSUS_MAX_TAG_KV_LEN) */
+  int n_ignored_tags;           /* number of tags ignored because of
+                                   CENSUS_MAX_PROPAGATED_TAGS limit. */
+} census_context_status;
+
+/* Create a new context, adding and removing tags from an existing context.
+   This will copy all tags from the 'tags' input, so it is recommended
+   to add as many tags in a single operation as is practical for the client.
+   @param base Base context to build upon. Can be NULL.
+   @param tags A set of tags to be added/changed/deleted. Tags with keys that
+   are in 'tags', but not 'base', are added to the tag set. Keys that are in
+   both 'tags' and 'base' will have their value/flags modified. Tags with keys
+   in both, but with NULL or zero-length values, will be deleted from the tag
+   set. Tags with invalid (too long or short) keys or values will be ignored.
+   If adding a tag will result in more than CENSUS_MAX_PROPAGATED_TAGS in either
+   binary or non-binary tags, they will be ignored, as will deletions of
+   tags that don't exist.
+   @param ntags number of tags in 'tags'
+   @param status If not NULL, will return a pointer to a census_context_status
+   structure containing information about the new context and status of the
+   tags used in its creation.
+   @return A new, valid census_context.
+*/
+CENSUS_API census_context *census_context_create(
+    const census_context *base, const census_tag *tags, int ntags,
+    census_context_status const **status);
+
+/* Destroy a context. Once this function has been called, the context cannot
+   be reused. */
+CENSUS_API void census_context_destroy(census_context *context);
+
+/* Get a pointer to the original status from the context creation. */
+CENSUS_API const census_context_status *census_context_get_status(
+    const census_context *context);
+
+/* Structure used for iterating over the tegs in a context. API clients should
+   not use or reference internal fields - neither their contents or
+   presence/absence are guaranteed. */
+typedef struct {
+  const census_context *context;
+  int base;
+  int index;
+  char *kvm;
+} census_context_iterator;
+
+/* Initialize a census_tag_iterator. Must be called before first use. */
+CENSUS_API void census_context_initialize_iterator(
+    const census_context *context, census_context_iterator *iterator);
+
+/* Get the contents of the "next" tag in the context. If there are no more
+   tags, returns 0 (and 'tag' contents will be unchanged), otherwise returns 1.
+   */
+CENSUS_API int census_context_next_tag(census_context_iterator *iterator,
+                                       census_tag *tag);
+
+/* Get a context tag by key. Returns 0 if the key is not present. */
+CENSUS_API int census_context_get_tag(const census_context *context,
+                                      const char *key, census_tag *tag);
+
+/* Tag set encode/decode functionality. These functionas are intended
+   for use by RPC systems only, for purposes of transmitting/receiving contexts.
+   */
+
+/* Encode a context into a buffer. The propagated tags are encoded into the
+   buffer in two regions: one for printable tags, and one for binary tags.
+   @param context context to be encoded
+   @param buffer pointer to buffer. This address will be used to encode the
+                 printable tags.
+   @param buf_size number of available bytes in buffer.
+   @param print_buf_size Will be set to the number of bytes consumed by
+                         printable tags.
+   @param bin_buf_size Will be set to the number of bytes used to encode the
+                       binary tags.
+   @return A pointer to the binary tag's encoded, or NULL if the buffer was
+           insufficiently large to hold the encoded tags. Thus, if successful,
+           printable tags are encoded into
+           [buffer, buffer + *print_buf_size) and binary tags into
+           [returned-ptr, returned-ptr + *bin_buf_size) (and the returned
+           pointer should be buffer + *print_buf_size) */
+CENSUS_API char *census_context_encode(const census_context *context,
+                                       char *buffer, size_t buf_size,
+                                       size_t *print_buf_size,
+                                       size_t *bin_buf_size);
+
+/* Decode context buffers encoded with census_context_encode(). Returns NULL
+   if there is an error in parsing either buffer. */
+CENSUS_API census_context *census_context_decode(const char *buffer,
+                                                 size_t size,
+                                                 const char *bin_buffer,
+                                                 size_t bin_size);
 
 /* Distributed traces can have a number of options. */
 enum census_trace_mask_values {
@@ -326,146 +446,6 @@ CENSUS_API int census_get_trace_record(census_trace_record *trace_record);
 /** End a scan previously started by census_trace_scan_start() */
 CENSUS_API void census_trace_scan_end();
 
-/* A Census tag set is a collection of key:value string pairs; these form the
-   basis against which Census metrics will be recorded. Keys are unique within
-   a tag set. All contexts have an associated tag set. */
-typedef struct census_tag_set census_tag_set;
-
-/* A tag is a key:value pair. The key is a non-empty, printable (UTF-8
-   encoded), nil-terminated string. The value is a binary string, that may be
-   printable. There are limits on the sizes of both keys and values (see
-   CENSUS_MAX_TAG_KB_LEN definition below), and the number of tags that can be
-   propagated (CENSUS_MAX_PROPAGATED_TAGS). Users should also remember that
-   some systems may have limits on, e.g., the number of bytes that can be
-   transmitted as metadata, and that larger tags means more memory consumed
-   and time in processing. */
-typedef struct {
-  const char *key;
-  const char *value;
-  size_t value_len;
-  uint8_t flags;
-} census_tag;
-
-/* Maximum length of a tag's key or value. */
-#define CENSUS_MAX_TAG_KV_LEN 255
-/* Maximum number of propagatable tags. */
-#define CENSUS_MAX_PROPAGATED_TAGS 255
-
-/* Tag flags. */
-#define CENSUS_TAG_PROPAGATE 1 /* Tag should be propagated over RPC */
-#define CENSUS_TAG_STATS 2     /* Tag will be used for statistics aggregation */
-#define CENSUS_TAG_BINARY 4    /* Tag value is not printable */
-#define CENSUS_TAG_RESERVED 8  /* Reserved for internal use. */
-/* Flag values 8,16,32,64,128 are reserved for future/internal use. Clients
-   should not use or rely on their values. */
-
-#define CENSUS_TAG_IS_PROPAGATED(flags) (flags & CENSUS_TAG_PROPAGATE)
-#define CENSUS_TAG_IS_STATS(flags) (flags & CENSUS_TAG_STATS)
-#define CENSUS_TAG_IS_BINARY(flags) (flags & CENSUS_TAG_BINARY)
-
-typedef struct {
-  int n_propagated_tags;        /* number of propagated printable tags */
-  int n_propagated_binary_tags; /* number of propagated binary tags */
-  int n_local_tags;             /* number of non-propagated (local) tags */
-  int n_deleted_tags;           /* number of tags that were deleted */
-  int n_added_tags;             /* number of tags that were added */
-  int n_modified_tags;          /* number of tags that were modified */
-  int n_invalid_tags;           /* number of tags with bad keys or values (e.g.
-                                   longer than CENSUS_MAX_TAG_KV_LEN) */
-  int n_ignored_tags;           /* number of tags ignored because of
-                                   CENSUS_MAX_PROPAGATED_TAGS limit. */
-} census_tag_set_create_status;
-
-/* Create a new tag set, adding and removing tags from an existing tag set.
-   This will copy all tags from it's input parameters, so it is recommended
-   to add as many tags in a single operation as is practical for the client.
-   @param base Base tag set to build upon. Can be NULL.
-   @param tags A set of tags to be added/changed/deleted. Tags with keys that
-   are in 'tags', but not 'base', are added to the tag set. Keys that are in
-   both 'tags' and 'base' will have their value/flags modified. Tags with keys
-   in both, but with NULL or zero-length values, will be deleted from the tag
-   set. Tags with invalid (too long or short) keys or values will be ignored.
-   If adding a tag will result in more than CENSUS_MAX_PROPAGATED_TAGS in either
-   binary or non-binary tags, they will be ignored, as will deletions of
-   tags that don't exist.
-   @param ntags number of tags in 'tags'
-   @param status If not NULL, will return a pointer to a
-   census_tag_set_create_status structure containing information about the new
-   tag set and status of the tags used in its creation.
-   @return A new, valid census_tag_set.
-*/
-CENSUS_API census_tag_set *census_tag_set_create(
-    const census_tag_set *base, const census_tag *tags, int ntags,
-    census_tag_set_create_status const **status);
-
-/* Destroy a tag set created by census_tag_set_create(). Once this function
-   has been called, the tag set cannot be reused. */
-CENSUS_API void census_tag_set_destroy(census_tag_set *tags);
-
-/* Get a pointer to the original status from the creation of this tag set. */
-CENSUS_API const census_tag_set_create_status *census_tag_set_get_create_status(
-    const census_tag_set *tags);
-
-/* Structure used for tag set iteration. API clients should not use or
-   reference internal fields - neither their contents or presence/absence are
-   guaranteed. */
-typedef struct {
-  const census_tag_set *tags;
-  int base;
-  int index;
-  char *kvm;
-} census_tag_set_iterator;
-
-/* Initialize a tag set iterator. Must be called before first use of the
-   iterator. */
-CENSUS_API void census_tag_set_initialize_iterator(
-    const census_tag_set *tags, census_tag_set_iterator *iterator);
-
-/* Get the contents of the "next" tag in the tag set. If there are no more
-   tags in the tag set, returns 0 (and 'tag' contents will be unchanged),
-   otherwise returns 1. */
-CENSUS_API int census_tag_set_next_tag(census_tag_set_iterator *iterator,
-                                       census_tag *tag);
-
-/* Get a tag by its key. Returns 0 if the key is not present in the tag
-   set. */
-CENSUS_API int census_tag_set_get_tag_by_key(const census_tag_set *tags,
-                                             const char *key, census_tag *tag);
-
-/* Tag set encode/decode functionality. These functionas are intended
-   for use by RPC systems only, for purposes of transmitting/receiving tag
-   sets. */
-
-/* Encode a tag set into a buffer. The propagated tags are encoded into the
-   buffer in two regions: one for printable tags, and one for binary tags.
-   @param tags tag set to be encoded
-   @param buffer pointer to buffer. This address will be used to encode the
-                 printable tags.
-   @param buf_size number of available bytes in buffer.
-   @param print_buf_size Will be set to the number of bytes consumed by
-                         printable tags.
-   @param bin_buf_size Will be set to the number of bytes used to encode the
-                       binary tags.
-   @return A pointer to the binary tag's encoded, or NULL if the buffer was
-           insufficiently large to hold the encoded tags. Thus, if successful,
-           printable tags are encoded into
-           [buffer, buffer + *print_buf_size) and binary tags into
-           [returned-ptr, returned-ptr + *bin_buf_size) (and the return value
-           should be buffer + *print_buf_size) */
-CENSUS_API char *census_tag_set_encode(const census_tag_set *tags, char *buffer,
-                                       size_t buf_size, size_t *print_buf_size,
-                                       size_t *bin_buf_size);
-
-/* Decode tag set buffers encoded with census_tag_set_encode_*(). Returns NULL
-   if there is an error in parsing either buffer. */
-CENSUS_API census_tag_set *census_tag_set_decode(const char *buffer,
-                                                 size_t size,
-                                                 const char *bin_buffer,
-                                                 size_t bin_size);
-
-/* Get a contexts tag set. */
-CENSUS_API census_tag_set *census_context_tag_set(census_context *context);
-
 /* Core stats collection API's. The following concepts are used:
    * Aggregation: A collection of values. Census supports the following
        aggregation types:
@@ -511,8 +491,7 @@ extern census_aggregation_ops census_agg_window;
     construction via census_define_view(). */
 typedef struct {
   const census_aggregation_ops *ops;
-  const void *
-      create_arg; /* Argument to be used for aggregation initialization. */
+  const void *create_arg; /* Aaggregation initialization argument. */
 } census_aggregation;
 
 /** A census view type. Opaque. */
@@ -520,14 +499,17 @@ typedef struct census_view census_view;
 
 /** Create a new view.
   @param metric_id Metric with which this view is associated.
-  @param tags tags that define the view
+  @param tags tags that define the view.
   @param aggregations aggregations to associate with the view
   @param naggregations number of aggregations
 
   @return A new census view
 */
+
+/* TODO(aveitch): consider if context is the right argument type to pass in
+   tags. */
 CENSUS_API census_view *census_view_create(
-    uint32_t metric_id, const census_tag_set *tags,
+    uint32_t metric_id, const census_context *tags,
     const census_aggregation *aggregations, size_t naggregations);
 
 /** Destroy a previously created view. */
@@ -540,7 +522,7 @@ CENSUS_API size_t census_view_metric(const census_view *view);
 CENSUS_API size_t census_view_naggregations(const census_view *view);
 
 /** Get tags associated with view. */
-CENSUS_API const census_tag_set *census_view_tags(const census_view *view);
+CENSUS_API const census_context *census_view_tags(const census_view *view);
 
 /** Get aggregation descriptors associated with a view. */
 CENSUS_API const census_aggregation *census_view_aggregrations(
@@ -549,7 +531,7 @@ CENSUS_API const census_aggregation *census_view_aggregrations(
 /** Holds all the aggregation data for a particular view instantiation. Forms
   part of the data returned by census_view_data(). */
 typedef struct {
-  const census_tag_set *tags; /* Tags for this set of aggregations. */
+  const census_context *tags; /* Tags for this set of aggregations. */
   const void **data; /* One data set for every aggregation in the view. */
 } census_view_aggregation_data;
 
diff --git a/package.json b/package.json
index f9e3384cb1..59e18128ee 100644
--- a/package.json
+++ b/package.json
@@ -280,7 +280,6 @@
     "src/core/support/thd_internal.h",
     "src/core/support/time_precise.h",
     "src/core/census/aggregation.h",
-    "src/core/census/context.h",
     "src/core/census/rpc_metric_id.h",
     "src/core/httpcli/httpcli_security_connector.c",
     "src/core/security/base64.c",
@@ -477,7 +476,6 @@
     "src/core/census/initialize.c",
     "src/core/census/operation.c",
     "src/core/census/placeholders.c",
-    "src/core/census/tag_set.c",
     "src/core/census/tracing.c",
     "third_party/zlib/crc32.h",
     "third_party/zlib/deflate.h",
diff --git a/src/core/census/context.c b/src/core/census/context.c
index cab58b653c..e60330de64 100644
--- a/src/core/census/context.c
+++ b/src/core/census/context.c
@@ -1,6 +1,6 @@
 /*
  *
- * Copyright 2015, Google Inc.
+ * Copyright 2015-2016, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -31,16 +31,500 @@
  *
  */
 
-#include "src/core/census/context.h"
-
-#include <string.h>
 #include <grpc/census.h>
 #include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/port_platform.h>
+#include <grpc/support/useful.h>
+#include <stdbool.h>
+#include <string.h>
+#include "src/core/support/string.h"
+
+// Functions in this file support the public context API, including
+// encoding/decoding as part of context propagation across RPC's. The overall
+// requirements (in approximate priority order) for the
+// context representation:
+// 1. Efficient conversion to/from wire format
+// 2. Minimal bytes used on-wire
+// 3. Efficient context creation
+// 4. Efficient lookup of tag value for a key
+// 5. Efficient iteration over tags
+// 6. Minimal memory footprint
+//
+// Notes on tradeoffs/decisions:
+// * tag includes 1 byte length of key, as well as nil-terminating byte. These
+//   are to aid in efficient parsing and the ability to directly return key
+//   strings. This is more important than saving a single byte/tag on the wire.
+// * The wire encoding uses only single byte values. This eliminates the need
+//   to handle endian-ness conversions. It also means there is a hard upper
+//   limit of 255 for both CENSUS_MAX_TAG_KV_LEN and CENSUS_MAX_PROPAGATED_TAGS.
+// * Keep all tag information (keys/values/flags) in a single memory buffer,
+//   that can be directly copied to the wire.
+// * Binary tags share the same structure as, but are encoded separately from,
+//   non-binary tags. This is primarily because non-binary tags are far more
+//   likely to be repeated across multiple RPC calls, so are more efficiently
+//   cached and compressed in any metadata schemes.
+
+// Structure representing a set of tags. Essentially a count of number of tags
+// present, and pointer to a chunk of memory that contains the per-tag details.
+struct tag_set {
+  int ntags;        // number of tags.
+  int ntags_alloc;  // ntags + number of deleted tags (total number of tags
+  // in all of kvm). This will always be == ntags, except during the process
+  // of building a new tag set.
+  size_t kvm_size;  // number of bytes allocated for key/value storage.
+  size_t kvm_used;  // number of bytes of used key/value memory
+  char *kvm;        // key/value memory. Consists of repeated entries of:
+  //   Offset  Size  Description
+  //     0      1    Key length, including trailing 0. (K)
+  //     1      1    Value length. (V)
+  //     2      1    Flags
+  //     3      K    Key bytes
+  //     3 + K  V    Value bytes
+  //
+  // We refer to the first 3 entries as the 'tag header'. If extra values are
+  // introduced in the header, you will need to modify the TAG_HEADER_SIZE
+  // constant, the raw_tag structure (and everything that uses it) and the
+  // encode/decode functions appropriately.
+};
+
+// Number of bytes in tag header.
+#define TAG_HEADER_SIZE 3  // key length (1) + value length (1) + flags (1)
+// Offsets to tag header entries.
+#define KEY_LEN_OFFSET 0
+#define VALUE_LEN_OFFSET 1
+#define FLAG_OFFSET 2
+
+// raw_tag represents the raw-storage form of a tag in the kvm of a tag_set.
+struct raw_tag {
+  uint8_t key_len;
+  uint8_t value_len;
+  uint8_t flags;
+  char *key;
+  char *value;
+};
+
+// Use a reserved flag bit for indication of deleted tag.
+#define CENSUS_TAG_DELETED CENSUS_TAG_RESERVED
+#define CENSUS_TAG_IS_DELETED(flags) (flags & CENSUS_TAG_DELETED)
+
+// Primary (external) representation of a context. Composed of 3 underlying
+// tag_set structs, one for each of the binary/printable propagated tags, and
+// one for everything else. This is to efficiently support tag
+// encoding/decoding.
+struct census_context {
+  struct tag_set tags[3];
+  census_context_status status;
+};
+
+// Indices into the tags member of census_context
+#define PROPAGATED_TAGS 0
+#define PROPAGATED_BINARY_TAGS 1
+#define LOCAL_TAGS 2
+
+// Extract a raw tag given a pointer (raw) to the tag header. Allow for some
+// extra bytes in the tag header (see encode/decode functions for usage: this
+// allows for future expansion of the tag header).
+static char *decode_tag(struct raw_tag *tag, char *header, int offset) {
+  tag->key_len = (uint8_t)(*header++);
+  tag->value_len = (uint8_t)(*header++);
+  tag->flags = (uint8_t)(*header++);
+  header += offset;
+  tag->key = header;
+  header += tag->key_len;
+  tag->value = header;
+  return header + tag->value_len;
+}
 
-/* Placeholder implementation only. */
+// Make a copy (in 'to') of an existing tag_set.
+static void tag_set_copy(struct tag_set *to, const struct tag_set *from) {
+  memcpy(to, from, sizeof(struct tag_set));
+  to->kvm = gpr_malloc(to->kvm_size);
+  memcpy(to->kvm, from->kvm, from->kvm_used);
+}
+
+// Delete a tag from a tag_set, if it exists (returns true if it did).
+static bool tag_set_delete_tag(struct tag_set *tags, const char *key,
+                               size_t key_len) {
+  char *kvp = tags->kvm;
+  for (int i = 0; i < tags->ntags_alloc; i++) {
+    uint8_t *flags = (uint8_t *)(kvp + FLAG_OFFSET);
+    struct raw_tag tag;
+    kvp = decode_tag(&tag, kvp, 0);
+    if (CENSUS_TAG_IS_DELETED(tag.flags)) continue;
+    if ((key_len == tag.key_len) && (memcmp(key, tag.key, key_len) == 0)) {
+      *flags |= CENSUS_TAG_DELETED;
+      tags->ntags--;
+      return true;
+    }
+  }
+  return false;
+}
+
+// Delete a tag from a context, return true if it existed.
+static bool context_delete_tag(census_context *context, const census_tag *tag,
+                               size_t key_len) {
+  return (
+      tag_set_delete_tag(&context->tags[LOCAL_TAGS], tag->key, key_len) ||
+      tag_set_delete_tag(&context->tags[PROPAGATED_TAGS], tag->key, key_len) ||
+      tag_set_delete_tag(&context->tags[PROPAGATED_BINARY_TAGS], tag->key,
+                         key_len));
+}
+
+// Add a tag to a tag_set. Return true on success, false if the tag could
+// not be added because of constraints on tag set size. This function should
+// not be called if the tag may already exist (in a non-deleted state) in
+// the tag_set, as that would result in two tags with the same key.
+static bool tag_set_add_tag(struct tag_set *tags, const census_tag *tag,
+                            size_t key_len) {
+  if (tags->ntags == CENSUS_MAX_PROPAGATED_TAGS) {
+    return false;
+  }
+  const size_t tag_size = key_len + tag->value_len + TAG_HEADER_SIZE;
+  if (tags->kvm_used + tag_size > tags->kvm_size) {
+    // allocate new memory if needed
+    tags->kvm_size += 2 * CENSUS_MAX_TAG_KV_LEN + TAG_HEADER_SIZE;
+    char *new_kvm = gpr_malloc(tags->kvm_size);
+    memcpy(new_kvm, tags->kvm, tags->kvm_used);
+    gpr_free(tags->kvm);
+    tags->kvm = new_kvm;
+  }
+  char *kvp = tags->kvm + tags->kvm_used;
+  *kvp++ = (char)key_len;
+  *kvp++ = (char)tag->value_len;
+  // ensure reserved flags are not used.
+  *kvp++ = (char)(tag->flags & (CENSUS_TAG_PROPAGATE | CENSUS_TAG_STATS |
+                                CENSUS_TAG_BINARY));
+  memcpy(kvp, tag->key, key_len);
+  kvp += key_len;
+  memcpy(kvp, tag->value, tag->value_len);
+  tags->kvm_used += tag_size;
+  tags->ntags++;
+  tags->ntags_alloc++;
+  return true;
+}
+
+// Add/modify/delete a tag to/in a context. Caller must validate that tag key
+// etc. are valid.
+static void context_modify_tag(census_context *context, const census_tag *tag,
+                               size_t key_len) {
+  // First delete the tag if it is already present.
+  bool deleted = context_delete_tag(context, tag, key_len);
+  // Determine if we need to add it back.
+  bool call_add = tag->value != NULL && tag->value_len != 0;
+  bool added = false;
+  if (call_add) {
+    if (CENSUS_TAG_IS_PROPAGATED(tag->flags)) {
+      if (CENSUS_TAG_IS_BINARY(tag->flags)) {
+        added = tag_set_add_tag(&context->tags[PROPAGATED_BINARY_TAGS], tag,
+                                key_len);
+      } else {
+        added = tag_set_add_tag(&context->tags[PROPAGATED_TAGS], tag, key_len);
+      }
+    } else {
+      added = tag_set_add_tag(&context->tags[LOCAL_TAGS], tag, key_len);
+    }
+  }
+  if (deleted) {
+    if (call_add) {
+      context->status.n_modified_tags++;
+    } else {
+      context->status.n_deleted_tags++;
+    }
+  } else {
+    if (added) {
+      context->status.n_added_tags++;
+    } else {
+      context->status.n_ignored_tags++;
+    }
+  }
+}
+
+// Remove memory used for deleted tags from a tag set. Basic algorithm:
+// 1) Walk through tag set to find first deleted tag. Record where it is.
+// 2) Find the next not-deleted tag. Copy all of kvm from there to the end
+//    "over" the deleted tags
+// 3) repeat #1 and #2 until we have seen all tags
+// 4) if we are still looking for a not-deleted tag, then all the end portion
+//    of the kvm is deleted. Just reduce the used amount of memory by the
+//    appropriate amount.
+static void tag_set_flatten(struct tag_set *tags) {
+  if (tags->ntags == tags->ntags_alloc) return;
+  bool found_deleted = false;  // found a deleted tag.
+  char *kvp = tags->kvm;
+  char *dbase = NULL;  // record location of deleted tag
+  for (int i = 0; i < tags->ntags_alloc; i++) {
+    struct raw_tag tag;
+    char *next_kvp = decode_tag(&tag, kvp, 0);
+    if (found_deleted) {
+      if (!CENSUS_TAG_IS_DELETED(tag.flags)) {
+        ptrdiff_t reduce = kvp - dbase;  // #bytes in deleted tags
+        GPR_ASSERT(reduce > 0);
+        ptrdiff_t copy_size = tags->kvm + tags->kvm_used - kvp;
+        GPR_ASSERT(copy_size > 0);
+        memmove(dbase, kvp, (size_t)copy_size);
+        tags->kvm_used -= (size_t)reduce;
+        next_kvp -= reduce;
+        found_deleted = false;
+      }
+    } else {
+      if (CENSUS_TAG_IS_DELETED(tag.flags)) {
+        dbase = kvp;
+        found_deleted = true;
+      }
+    }
+    kvp = next_kvp;
+  }
+  if (found_deleted) {
+    GPR_ASSERT(dbase > tags->kvm);
+    tags->kvm_used = (size_t)(dbase - tags->kvm);
+  }
+  tags->ntags_alloc = tags->ntags;
+}
 
-size_t census_context_serialize(const census_context *context, char *buffer,
-                                size_t buf_size) {
-  /* TODO(aveitch): implement serialization */
+census_context *census_context_create(const census_context *base,
+                                      const census_tag *tags, int ntags,
+                                      census_context_status const **status) {
+  census_context *context = gpr_malloc(sizeof(census_context));
+  // If we are given a base, copy it into our new tag set. Otherwise set it
+  // to zero/NULL everything.
+  if (base == NULL) {
+    memset(context, 0, sizeof(census_context));
+  } else {
+    tag_set_copy(&context->tags[PROPAGATED_TAGS], &base->tags[PROPAGATED_TAGS]);
+    tag_set_copy(&context->tags[PROPAGATED_BINARY_TAGS],
+                 &base->tags[PROPAGATED_BINARY_TAGS]);
+    tag_set_copy(&context->tags[LOCAL_TAGS], &base->tags[LOCAL_TAGS]);
+    memset(&context->status, 0, sizeof(context->status));
+  }
+  // Walk over the additional tags and, for those that aren't invalid, modify
+  // the context to add/replace/delete as required.
+  for (int i = 0; i < ntags; i++) {
+    const census_tag *tag = &tags[i];
+    size_t key_len = strlen(tag->key) + 1;
+    // ignore the tag if it is too long/short.
+    if (key_len != 1 && key_len <= CENSUS_MAX_TAG_KV_LEN &&
+        tag->value_len <= CENSUS_MAX_TAG_KV_LEN) {
+      context_modify_tag(context, tag, key_len);
+    } else {
+      context->status.n_invalid_tags++;
+    }
+  }
+  // Remove any deleted tags, update status if needed, and return.
+  tag_set_flatten(&context->tags[PROPAGATED_TAGS]);
+  tag_set_flatten(&context->tags[PROPAGATED_BINARY_TAGS]);
+  tag_set_flatten(&context->tags[LOCAL_TAGS]);
+  context->status.n_propagated_tags = context->tags[PROPAGATED_TAGS].ntags;
+  context->status.n_propagated_binary_tags =
+      context->tags[PROPAGATED_BINARY_TAGS].ntags;
+  context->status.n_local_tags = context->tags[LOCAL_TAGS].ntags;
+  if (status) {
+    *status = &context->status;
+  }
+  return context;
+}
+
+const census_context_status *census_context_get_status(
+    const census_context *context) {
+  return &context->status;
+}
+
+void census_context_destroy(census_context *context) {
+  gpr_free(context->tags[PROPAGATED_TAGS].kvm);
+  gpr_free(context->tags[PROPAGATED_BINARY_TAGS].kvm);
+  gpr_free(context->tags[LOCAL_TAGS].kvm);
+  gpr_free(context);
+}
+
+void census_context_initialize_iterator(const census_context *context,
+                                        census_context_iterator *iterator) {
+  iterator->context = context;
+  iterator->index = 0;
+  if (context->tags[PROPAGATED_TAGS].ntags != 0) {
+    iterator->base = PROPAGATED_TAGS;
+    iterator->kvm = context->tags[PROPAGATED_TAGS].kvm;
+  } else if (context->tags[PROPAGATED_BINARY_TAGS].ntags != 0) {
+    iterator->base = PROPAGATED_BINARY_TAGS;
+    iterator->kvm = context->tags[PROPAGATED_BINARY_TAGS].kvm;
+  } else if (context->tags[LOCAL_TAGS].ntags != 0) {
+    iterator->base = LOCAL_TAGS;
+    iterator->kvm = context->tags[LOCAL_TAGS].kvm;
+  } else {
+    iterator->base = -1;
+  }
+}
+
+int census_context_next_tag(census_context_iterator *iterator,
+                            census_tag *tag) {
+  if (iterator->base < 0) {
+    return 0;
+  }
+  struct raw_tag raw;
+  iterator->kvm = decode_tag(&raw, iterator->kvm, 0);
+  tag->key = raw.key;
+  tag->value = raw.value;
+  tag->value_len = raw.value_len;
+  tag->flags = raw.flags;
+  if (++iterator->index == iterator->context->tags[iterator->base].ntags) {
+    do {
+      if (iterator->base == LOCAL_TAGS) {
+        iterator->base = -1;
+        return 1;
+      }
+    } while (iterator->context->tags[++iterator->base].ntags == 0);
+    iterator->index = 0;
+    iterator->kvm = iterator->context->tags[iterator->base].kvm;
+  }
+  return 1;
+}
+
+// Find a tag in a tag_set by key. Return true if found, false otherwise.
+static bool tag_set_get_tag(const struct tag_set *tags, const char *key,
+                            size_t key_len, census_tag *tag) {
+  char *kvp = tags->kvm;
+  for (int i = 0; i < tags->ntags; i++) {
+    struct raw_tag raw;
+    kvp = decode_tag(&raw, kvp, 0);
+    if (key_len == raw.key_len && memcmp(raw.key, key, key_len) == 0) {
+      tag->key = raw.key;
+      tag->value = raw.value;
+      tag->value_len = raw.value_len;
+      tag->flags = raw.flags;
+      return true;
+    }
+  }
+  return false;
+}
+
+int census_context_get_tag(const census_context *context, const char *key,
+                           census_tag *tag) {
+  size_t key_len = strlen(key) + 1;
+  if (key_len == 1) {
+    return 0;
+  }
+  if (tag_set_get_tag(&context->tags[PROPAGATED_TAGS], key, key_len, tag) ||
+      tag_set_get_tag(&context->tags[PROPAGATED_BINARY_TAGS], key, key_len,
+                      tag) ||
+      tag_set_get_tag(&context->tags[LOCAL_TAGS], key, key_len, tag)) {
+    return 1;
+  }
   return 0;
 }
+
+// Context encoding and decoding functions.
+//
+// Wire format for tag_set's on the wire:
+//
+// First, a tag set header:
+//
+// offset   bytes  description
+//   0        1    version number
+//   1        1    number of bytes in this header. This allows for future
+//                 expansion.
+//   2        1    number of bytes in each tag header.
+//   3        1    ntags value from tag set.
+//
+//   This is followed by the key/value memory from struct tag_set.
+
+#define ENCODED_VERSION 0      // Version number
+#define ENCODED_HEADER_SIZE 4  // size of tag set header
+
+// Encode a tag set. Returns 0 if buffer is too small.
+static size_t tag_set_encode(const struct tag_set *tags, char *buffer,
+                             size_t buf_size) {
+  if (buf_size < ENCODED_HEADER_SIZE + tags->kvm_used) {
+    return 0;
+  }
+  buf_size -= ENCODED_HEADER_SIZE;
+  *buffer++ = (char)ENCODED_VERSION;
+  *buffer++ = (char)ENCODED_HEADER_SIZE;
+  *buffer++ = (char)TAG_HEADER_SIZE;
+  *buffer++ = (char)tags->ntags;
+  if (tags->ntags == 0) {
+    return ENCODED_HEADER_SIZE;
+  }
+  memcpy(buffer, tags->kvm, tags->kvm_used);
+  return ENCODED_HEADER_SIZE + tags->kvm_used;
+}
+
+char *census_context_encode(const census_context *context, char *buffer,
+                            size_t buf_size, size_t *print_buf_size,
+                            size_t *bin_buf_size) {
+  *print_buf_size =
+      tag_set_encode(&context->tags[PROPAGATED_TAGS], buffer, buf_size);
+  if (*print_buf_size == 0) {
+    return NULL;
+  }
+  char *b_buffer = buffer + *print_buf_size;
+  *bin_buf_size = tag_set_encode(&context->tags[PROPAGATED_BINARY_TAGS],
+                                 b_buffer, buf_size - *print_buf_size);
+  if (*bin_buf_size == 0) {
+    return NULL;
+  }
+  return b_buffer;
+}
+
+// Decode a tag set.
+static void tag_set_decode(struct tag_set *tags, const char *buffer,
+                           size_t size) {
+  uint8_t version = (uint8_t)(*buffer++);
+  uint8_t header_size = (uint8_t)(*buffer++);
+  uint8_t tag_header_size = (uint8_t)(*buffer++);
+  tags->ntags = tags->ntags_alloc = (int)(*buffer++);
+  if (tags->ntags == 0) {
+    tags->ntags_alloc = 0;
+    tags->kvm_size = 0;
+    tags->kvm_used = 0;
+    tags->kvm = NULL;
+    return;
+  }
+  if (header_size != ENCODED_HEADER_SIZE) {
+    GPR_ASSERT(version != ENCODED_VERSION);
+    GPR_ASSERT(ENCODED_HEADER_SIZE < header_size);
+    buffer += (header_size - ENCODED_HEADER_SIZE);
+  }
+  tags->kvm_used = size - header_size;
+  tags->kvm_size = tags->kvm_used + CENSUS_MAX_TAG_KV_LEN;
+  tags->kvm = gpr_malloc(tags->kvm_size);
+  if (tag_header_size != TAG_HEADER_SIZE) {
+    // something new in the tag information. I don't understand it, so
+    // don't copy it over.
+    GPR_ASSERT(version != ENCODED_VERSION);
+    GPR_ASSERT(tag_header_size > TAG_HEADER_SIZE);
+    char *kvp = tags->kvm;
+    for (int i = 0; i < tags->ntags; i++) {
+      memcpy(kvp, buffer, TAG_HEADER_SIZE);
+      kvp += header_size;
+      struct raw_tag raw;
+      buffer =
+          decode_tag(&raw, (char *)buffer, tag_header_size - TAG_HEADER_SIZE);
+      memcpy(kvp, raw.key, (size_t)raw.key_len + raw.value_len);
+      kvp += raw.key_len + raw.value_len;
+    }
+  } else {
+    memcpy(tags->kvm, buffer, tags->kvm_used);
+  }
+}
+
+census_context *census_context_decode(const char *buffer, size_t size,
+                                      const char *bin_buffer, size_t bin_size) {
+  census_context *context = gpr_malloc(sizeof(census_context));
+  memset(&context->tags[LOCAL_TAGS], 0, sizeof(struct tag_set));
+  if (buffer == NULL) {
+    memset(&context->tags[PROPAGATED_TAGS], 0, sizeof(struct tag_set));
+  } else {
+    tag_set_decode(&context->tags[PROPAGATED_TAGS], buffer, size);
+  }
+  if (bin_buffer == NULL) {
+    memset(&context->tags[PROPAGATED_BINARY_TAGS], 0, sizeof(struct tag_set));
+  } else {
+    tag_set_decode(&context->tags[PROPAGATED_BINARY_TAGS], bin_buffer,
+                   bin_size);
+  }
+  memset(&context->status, 0, sizeof(context->status));
+  context->status.n_propagated_tags = context->tags[PROPAGATED_TAGS].ntags;
+  context->status.n_propagated_binary_tags =
+      context->tags[PROPAGATED_BINARY_TAGS].ntags;
+  // TODO(aveitch): check that BINARY flag is correct for each type.
+  return context;
+}
diff --git a/src/core/census/context.h b/src/core/census/context.h
deleted file mode 100644
index 700bcf86cf..0000000000
--- a/src/core/census/context.h
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_INTERNAL_CORE_CENSUS_CONTEXT_H
-#define GRPC_INTERNAL_CORE_CENSUS_CONTEXT_H
-
-#include <grpc/census.h>
-
-#define GRPC_CENSUS_MAX_ON_THE_WIRE_TAG_BYTES 2048
-
-/* census_context is the in-memory representation of information needed to
- * maintain tracing, RPC statistics and resource usage information. */
-struct census_context {
-  census_tag_set *tags; /* Opaque data structure for census tags. */
-};
-
-#endif /* GRPC_INTERNAL_CORE_CENSUS_CONTEXT_H */
diff --git a/src/core/census/placeholders.c b/src/core/census/placeholders.c
index 5829cc9460..fe23d13971 100644
--- a/src/core/census/placeholders.c
+++ b/src/core/census/placeholders.c
@@ -37,11 +37,6 @@
 
 /* Placeholders for the pending APIs */
 
-census_tag_set *census_context_tag_set(census_context *context) {
-  (void)context;
-  abort();
-}
-
 int census_get_trace_record(census_trace_record *trace_record) {
   (void)trace_record;
   abort();
@@ -73,7 +68,7 @@ const census_aggregation *census_view_aggregrations(const census_view *view) {
   abort();
 }
 
-census_view *census_view_create(uint32_t metric_id, const census_tag_set *tags,
+census_view *census_view_create(uint32_t metric_id, const census_context *tags,
                                 const census_aggregation *aggregations,
                                 size_t naggregations) {
   (void)metric_id;
@@ -83,7 +78,7 @@ census_view *census_view_create(uint32_t metric_id, const census_tag_set *tags,
   abort();
 }
 
-const census_tag_set *census_view_tags(const census_view *view) {
+const census_context *census_view_tags(const census_view *view) {
   (void)view;
   abort();
 }
diff --git a/src/core/census/tag_set.c b/src/core/census/tag_set.c
deleted file mode 100644
index 9b65a1dfa1..0000000000
--- a/src/core/census/tag_set.c
+++ /dev/null
@@ -1,535 +0,0 @@
-/*
- *
- * Copyright 2015-2016, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/census.h>
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/port_platform.h>
-#include <grpc/support/useful.h>
-#include <stdbool.h>
-#include <string.h>
-#include "src/core/support/string.h"
-
-// Functions in this file support the public tag_set API, as well as
-// encoding/decoding tag_sets as part of context propagation across
-// RPC's. The overall requirements (in approximate priority order) for the
-// tag_set representations:
-// 1. Efficient conversion to/from wire format
-// 2. Minimal bytes used on-wire
-// 3. Efficient tag set creation
-// 4. Efficient lookup of value for a key
-// 5. Efficient lookup of value for an index (to support iteration)
-// 6. Minimal memory footprint
-//
-// Notes on tradeoffs/decisions:
-// * tag includes 1 byte length of key, as well as nil-terminating byte. These
-//   are to aid in efficient parsing and the ability to directly return key
-//   strings. This is more important than saving a single byte/tag on the wire.
-// * The wire encoding uses only single byte values. This eliminates the need
-//   to handle endian-ness conversions. It also means there is a hard upper
-//   limit of 255 for both CENSUS_MAX_TAG_KV_LEN and CENSUS_MAX_PROPAGATED_TAGS.
-// * Keep all tag information (keys/values/flags) in a single memory buffer,
-//   that can be directly copied to the wire.14
-// * Binary tags share the same structure as, but are encoded separately from,
-//   non-binary tags. This is primarily because non-binary tags are far more
-//   likely to be repeated across multiple RPC calls, so are more efficiently
-//   cached and compressed in any metadata schemes.
-// * all lengths etc. are restricted to one byte. This eliminates endian
-//   issues.
-
-// Structure representing a set of tags. Essentially a count of number of tags
-// present, and pointer to a chunk of memory that contains the per-tag details.
-struct tag_set {
-  int ntags;        // number of tags.
-  int ntags_alloc;  // ntags + number of deleted tags (total number of tags
-  // in all of kvm). This will always be == ntags, except during the process
-  // of building a new tag set.
-  size_t kvm_size;  // number of bytes allocated for key/value storage.
-  size_t kvm_used;  // number of bytes of used key/value memory
-  char *kvm;        // key/value memory. Consists of repeated entries of:
-  //   Offset  Size  Description
-  //     0      1    Key length, including trailing 0. (K)
-  //     1      1    Value length. (V)
-  //     2      1    Flags
-  //     3      K    Key bytes
-  //     3 + K  V    Value bytes
-  //
-  // We refer to the first 3 entries as the 'tag header'. If extra values are
-  // introduced in the header, you will need to modify the TAG_HEADER_SIZE
-  // constant, the raw_tag structure (and everything that uses it) and the
-  // encode/decode functions appropriately.
-};
-
-// Number of bytes in tag header.
-#define TAG_HEADER_SIZE 3  // key length (1) + value length (1) + flags (1)
-// Offsets to tag header entries.
-#define KEY_LEN_OFFSET 0
-#define VALUE_LEN_OFFSET 1
-#define FLAG_OFFSET 2
-
-// raw_tag represents the raw-storage form of a tag in the kvm of a tag_set.
-struct raw_tag {
-  uint8_t key_len;
-  uint8_t value_len;
-  uint8_t flags;
-  char *key;
-  char *value;
-};
-
-// Use a reserved flag bit for indication of deleted tag.
-#define CENSUS_TAG_DELETED CENSUS_TAG_RESERVED
-#define CENSUS_TAG_IS_DELETED(flags) (flags & CENSUS_TAG_DELETED)
-
-// Primary (external) representation of a tag set. Composed of 3 underlying
-// tag_set structs, one for each of the binary/printable propagated tags, and
-// one for everything else. This is to efficiently support tag
-// encoding/decoding.
-struct census_tag_set {
-  struct tag_set tags[3];
-  census_tag_set_create_status status;
-};
-
-// Indices into the tags member of census_tag_set
-#define PROPAGATED_TAGS 0
-#define PROPAGATED_BINARY_TAGS 1
-#define LOCAL_TAGS 2
-
-// Extract a raw tag given a pointer (raw) to the tag header. Allow for some
-// extra bytes in the tag header (see encode/decode functions for usage: this
-// allows for future expansion of the tag header).
-static char *decode_tag(struct raw_tag *tag, char *header, int offset) {
-  tag->key_len = (uint8_t)(*header++);
-  tag->value_len = (uint8_t)(*header++);
-  tag->flags = (uint8_t)(*header++);
-  header += offset;
-  tag->key = header;
-  header += tag->key_len;
-  tag->value = header;
-  return header + tag->value_len;
-}
-
-// Make a copy (in 'to') of an existing tag_set.
-static void tag_set_copy(struct tag_set *to, const struct tag_set *from) {
-  memcpy(to, from, sizeof(struct tag_set));
-  to->kvm = gpr_malloc(to->kvm_size);
-  memcpy(to->kvm, from->kvm, from->kvm_used);
-}
-
-// Delete a tag from a tag_set, if it exists (returns true if it did).
-static bool tag_set_delete_tag(struct tag_set *tags, const char *key,
-                               size_t key_len) {
-  char *kvp = tags->kvm;
-  for (int i = 0; i < tags->ntags_alloc; i++) {
-    uint8_t *flags = (uint8_t *)(kvp + FLAG_OFFSET);
-    struct raw_tag tag;
-    kvp = decode_tag(&tag, kvp, 0);
-    if (CENSUS_TAG_IS_DELETED(tag.flags)) continue;
-    if ((key_len == tag.key_len) && (memcmp(key, tag.key, key_len) == 0)) {
-      *flags |= CENSUS_TAG_DELETED;
-      tags->ntags--;
-      return true;
-    }
-  }
-  return false;
-}
-
-// Delete a tag from a census_tag_set, return true if it existed.
-static bool cts_delete_tag(census_tag_set *tags, const census_tag *tag,
-                           size_t key_len) {
-  return (tag_set_delete_tag(&tags->tags[LOCAL_TAGS], tag->key, key_len) ||
-          tag_set_delete_tag(&tags->tags[PROPAGATED_TAGS], tag->key, key_len) ||
-          tag_set_delete_tag(&tags->tags[PROPAGATED_BINARY_TAGS], tag->key,
-                             key_len));
-}
-
-// Add a tag to a tag_set. Return true on sucess, false if the tag could
-// not be added because of constraints on tag set size. This function should
-// not be called if the tag may already exist (in a non-deleted state) in
-// the tag_set, as that would result in two tags with the same key.
-static bool tag_set_add_tag(struct tag_set *tags, const census_tag *tag,
-                            size_t key_len) {
-  if (tags->ntags == CENSUS_MAX_PROPAGATED_TAGS) {
-    return false;
-  }
-  const size_t tag_size = key_len + tag->value_len + TAG_HEADER_SIZE;
-  if (tags->kvm_used + tag_size > tags->kvm_size) {
-    // allocate new memory if needed
-    tags->kvm_size += 2 * CENSUS_MAX_TAG_KV_LEN + TAG_HEADER_SIZE;
-    char *new_kvm = gpr_malloc(tags->kvm_size);
-    memcpy(new_kvm, tags->kvm, tags->kvm_used);
-    gpr_free(tags->kvm);
-    tags->kvm = new_kvm;
-  }
-  char *kvp = tags->kvm + tags->kvm_used;
-  *kvp++ = (char)key_len;
-  *kvp++ = (char)tag->value_len;
-  // ensure reserved flags are not used.
-  *kvp++ = (char)(tag->flags & (CENSUS_TAG_PROPAGATE | CENSUS_TAG_STATS |
-                                CENSUS_TAG_BINARY));
-  memcpy(kvp, tag->key, key_len);
-  kvp += key_len;
-  memcpy(kvp, tag->value, tag->value_len);
-  tags->kvm_used += tag_size;
-  tags->ntags++;
-  tags->ntags_alloc++;
-  return true;
-}
-
-// Add/modify/delete a tag to/in a census_tag_set. Caller must validate that
-// tag key etc. are valid.
-static void cts_modify_tag(census_tag_set *tags, const census_tag *tag,
-                           size_t key_len) {
-  // First delete the tag if it is already present.
-  bool deleted = cts_delete_tag(tags, tag, key_len);
-  // Determine if we need to add it back.
-  bool call_add = tag->value != NULL && tag->value_len != 0;
-  bool added = false;
-  if (call_add) {
-    if (CENSUS_TAG_IS_PROPAGATED(tag->flags)) {
-      if (CENSUS_TAG_IS_BINARY(tag->flags)) {
-        added =
-            tag_set_add_tag(&tags->tags[PROPAGATED_BINARY_TAGS], tag, key_len);
-      } else {
-        added = tag_set_add_tag(&tags->tags[PROPAGATED_TAGS], tag, key_len);
-      }
-    } else {
-      added = tag_set_add_tag(&tags->tags[LOCAL_TAGS], tag, key_len);
-    }
-  }
-  if (deleted) {
-    if (call_add) {
-      tags->status.n_modified_tags++;
-    } else {
-      tags->status.n_deleted_tags++;
-    }
-  } else {
-    if (added) {
-      tags->status.n_added_tags++;
-    } else {
-      tags->status.n_ignored_tags++;
-    }
-  }
-}
-
-// Remove memory used for deleted tags from the tag set. Basic algorithm:
-// 1) Walk through tag set to find first deleted tag. Record where it is.
-// 2) Find the next not-deleted tag. Copy all of kvm from there to the end
-//    "over" the deleted tags
-// 3) repeat #1 and #2 until we have seen all tags
-// 4) if we are still looking for a not-deleted tag, then all the end portion
-//    of the kvm is deleted. Just reduce the used amount of memory by the
-//    appropriate amount.
-static void tag_set_flatten(struct tag_set *tags) {
-  if (tags->ntags == tags->ntags_alloc) return;
-  bool found_deleted = false;  // found a deleted tag.
-  char *kvp = tags->kvm;
-  char *dbase = NULL;  // record location of deleted tag
-  for (int i = 0; i < tags->ntags_alloc; i++) {
-    struct raw_tag tag;
-    char *next_kvp = decode_tag(&tag, kvp, 0);
-    if (found_deleted) {
-      if (!CENSUS_TAG_IS_DELETED(tag.flags)) {
-        ptrdiff_t reduce = kvp - dbase;  // #bytes in deleted tags
-        GPR_ASSERT(reduce > 0);
-        ptrdiff_t copy_size = tags->kvm + tags->kvm_used - kvp;
-        GPR_ASSERT(copy_size > 0);
-        memmove(dbase, kvp, (size_t)copy_size);
-        tags->kvm_used -= (size_t)reduce;
-        next_kvp -= reduce;
-        found_deleted = false;
-      }
-    } else {
-      if (CENSUS_TAG_IS_DELETED(tag.flags)) {
-        dbase = kvp;
-        found_deleted = true;
-      }
-    }
-    kvp = next_kvp;
-  }
-  if (found_deleted) {
-    GPR_ASSERT(dbase > tags->kvm);
-    tags->kvm_used = (size_t)(dbase - tags->kvm);
-  }
-  tags->ntags_alloc = tags->ntags;
-}
-
-census_tag_set *census_tag_set_create(
-    const census_tag_set *base, const census_tag *tags, int ntags,
-    census_tag_set_create_status const **status) {
-  census_tag_set *new_ts = gpr_malloc(sizeof(census_tag_set));
-  // If we are given a base, copy it into our new tag set. Otherwise set it
-  // to zero/NULL everything.
-  if (base == NULL) {
-    memset(new_ts, 0, sizeof(census_tag_set));
-  } else {
-    tag_set_copy(&new_ts->tags[PROPAGATED_TAGS], &base->tags[PROPAGATED_TAGS]);
-    tag_set_copy(&new_ts->tags[PROPAGATED_BINARY_TAGS],
-                 &base->tags[PROPAGATED_BINARY_TAGS]);
-    tag_set_copy(&new_ts->tags[LOCAL_TAGS], &base->tags[LOCAL_TAGS]);
-    memset(&new_ts->status, 0, sizeof(new_ts->status));
-  }
-  // Walk over the additional tags and, for those that aren't invalid, modify
-  // the tag set to add/replace/delete as required.
-  for (int i = 0; i < ntags; i++) {
-    const census_tag *tag = &tags[i];
-    size_t key_len = strlen(tag->key) + 1;
-    // ignore the tag if it is too long/short.
-    if (key_len != 1 && key_len <= CENSUS_MAX_TAG_KV_LEN &&
-        tag->value_len <= CENSUS_MAX_TAG_KV_LEN) {
-      cts_modify_tag(new_ts, tag, key_len);
-    } else {
-      new_ts->status.n_invalid_tags++;
-    }
-  }
-  // Remove any deleted tags, update status if needed, and return.
-  tag_set_flatten(&new_ts->tags[PROPAGATED_TAGS]);
-  tag_set_flatten(&new_ts->tags[PROPAGATED_BINARY_TAGS]);
-  tag_set_flatten(&new_ts->tags[LOCAL_TAGS]);
-  new_ts->status.n_propagated_tags = new_ts->tags[PROPAGATED_TAGS].ntags;
-  new_ts->status.n_propagated_binary_tags =
-      new_ts->tags[PROPAGATED_BINARY_TAGS].ntags;
-  new_ts->status.n_local_tags = new_ts->tags[LOCAL_TAGS].ntags;
-  if (status) {
-    *status = &new_ts->status;
-  }
-  return new_ts;
-}
-
-const census_tag_set_create_status *census_tag_set_get_create_status(
-    const census_tag_set *tags) {
-  return &tags->status;
-}
-
-void census_tag_set_destroy(census_tag_set *tags) {
-  gpr_free(tags->tags[PROPAGATED_TAGS].kvm);
-  gpr_free(tags->tags[PROPAGATED_BINARY_TAGS].kvm);
-  gpr_free(tags->tags[LOCAL_TAGS].kvm);
-  gpr_free(tags);
-}
-
-// Initialize a tag set iterator. Must be called before first use of the
-// iterator.
-void census_tag_set_initialize_iterator(const census_tag_set *tags,
-                                        census_tag_set_iterator *iterator) {
-  iterator->tags = tags;
-  iterator->index = 0;
-  if (tags->tags[PROPAGATED_TAGS].ntags != 0) {
-    iterator->base = PROPAGATED_TAGS;
-    iterator->kvm = tags->tags[PROPAGATED_TAGS].kvm;
-  } else if (tags->tags[PROPAGATED_BINARY_TAGS].ntags != 0) {
-    iterator->base = PROPAGATED_BINARY_TAGS;
-    iterator->kvm = tags->tags[PROPAGATED_BINARY_TAGS].kvm;
-  } else if (tags->tags[LOCAL_TAGS].ntags != 0) {
-    iterator->base = LOCAL_TAGS;
-    iterator->kvm = tags->tags[LOCAL_TAGS].kvm;
-  } else {
-    iterator->base = -1;
-  }
-}
-
-// Get the contents of the "next" tag in the tag set. If there are no more
-// tags in the tag set, returns 0 (and 'tag' contents will be unchanged),
-// otherwise returns 1. */
-int census_tag_set_next_tag(census_tag_set_iterator *iterator,
-                            census_tag *tag) {
-  if (iterator->base < 0) {
-    return 0;
-  }
-  struct raw_tag raw;
-  iterator->kvm = decode_tag(&raw, iterator->kvm, 0);
-  tag->key = raw.key;
-  tag->value = raw.value;
-  tag->value_len = raw.value_len;
-  tag->flags = raw.flags;
-  if (++iterator->index == iterator->tags->tags[iterator->base].ntags) {
-    do {
-      if (iterator->base == LOCAL_TAGS) {
-        iterator->base = -1;
-        return 1;
-      }
-    } while (iterator->tags->tags[++iterator->base].ntags == 0);
-    iterator->index = 0;
-    iterator->kvm = iterator->tags->tags[iterator->base].kvm;
-  }
-  return 1;
-}
-
-// Find a tag in a tag_set by key. Return true if found, false otherwise.
-static bool tag_set_get_tag_by_key(const struct tag_set *tags, const char *key,
-                                   size_t key_len, census_tag *tag) {
-  char *kvp = tags->kvm;
-  for (int i = 0; i < tags->ntags; i++) {
-    struct raw_tag raw;
-    kvp = decode_tag(&raw, kvp, 0);
-    if (key_len == raw.key_len && memcmp(raw.key, key, key_len) == 0) {
-      tag->key = raw.key;
-      tag->value = raw.value;
-      tag->value_len = raw.value_len;
-      tag->flags = raw.flags;
-      return true;
-    }
-  }
-  return false;
-}
-
-int census_tag_set_get_tag_by_key(const census_tag_set *tags, const char *key,
-                                  census_tag *tag) {
-  size_t key_len = strlen(key) + 1;
-  if (key_len == 1) {
-    return 0;
-  }
-  if (tag_set_get_tag_by_key(&tags->tags[PROPAGATED_TAGS], key, key_len, tag) ||
-      tag_set_get_tag_by_key(&tags->tags[PROPAGATED_BINARY_TAGS], key, key_len,
-                             tag) ||
-      tag_set_get_tag_by_key(&tags->tags[LOCAL_TAGS], key, key_len, tag)) {
-    return 1;
-  }
-  return 0;
-}
-
-// tag_set encoding and decoding functions.
-//
-// Wire format for tag sets on the wire:
-//
-// First, a tag set header:
-//
-// offset   bytes  description
-//   0        1    version number
-//   1        1    number of bytes in this header. This allows for future
-//                 expansion.
-//   2        1    number of bytes in each tag header.
-//   3        1    ntags value from tag set.
-//
-//   This is followed by the key/value memory from struct tag_set.
-
-#define ENCODED_VERSION 0      // Version number
-#define ENCODED_HEADER_SIZE 4  // size of tag set header
-
-// Encode a tag set. Returns 0 if buffer is too small.
-static size_t tag_set_encode(const struct tag_set *tags, char *buffer,
-                             size_t buf_size) {
-  if (buf_size < ENCODED_HEADER_SIZE + tags->kvm_used) {
-    return 0;
-  }
-  buf_size -= ENCODED_HEADER_SIZE;
-  *buffer++ = (char)ENCODED_VERSION;
-  *buffer++ = (char)ENCODED_HEADER_SIZE;
-  *buffer++ = (char)TAG_HEADER_SIZE;
-  *buffer++ = (char)tags->ntags;
-  if (tags->ntags == 0) {
-    return ENCODED_HEADER_SIZE;
-  }
-  memcpy(buffer, tags->kvm, tags->kvm_used);
-  return ENCODED_HEADER_SIZE + tags->kvm_used;
-}
-
-char *census_tag_set_encode(const census_tag_set *tags, char *buffer,
-                            size_t buf_size, size_t *print_buf_size,
-                            size_t *bin_buf_size) {
-  *print_buf_size =
-      tag_set_encode(&tags->tags[PROPAGATED_TAGS], buffer, buf_size);
-  if (*print_buf_size == 0) {
-    return NULL;
-  }
-  char *b_buffer = buffer + *print_buf_size;
-  *bin_buf_size = tag_set_encode(&tags->tags[PROPAGATED_BINARY_TAGS], b_buffer,
-                                 buf_size - *print_buf_size);
-  if (*bin_buf_size == 0) {
-    return NULL;
-  }
-  return b_buffer;
-}
-
-// Decode a tag set.
-static void tag_set_decode(struct tag_set *tags, const char *buffer,
-                           size_t size) {
-  uint8_t version = (uint8_t)(*buffer++);
-  uint8_t header_size = (uint8_t)(*buffer++);
-  uint8_t tag_header_size = (uint8_t)(*buffer++);
-  tags->ntags = tags->ntags_alloc = (int)(*buffer++);
-  if (tags->ntags == 0) {
-    tags->ntags_alloc = 0;
-    tags->kvm_size = 0;
-    tags->kvm_used = 0;
-    tags->kvm = NULL;
-    return;
-  }
-  if (header_size != ENCODED_HEADER_SIZE) {
-    GPR_ASSERT(version != ENCODED_VERSION);
-    GPR_ASSERT(ENCODED_HEADER_SIZE < header_size);
-    buffer += (header_size - ENCODED_HEADER_SIZE);
-  }
-  tags->kvm_used = size - header_size;
-  tags->kvm_size = tags->kvm_used + CENSUS_MAX_TAG_KV_LEN;
-  tags->kvm = gpr_malloc(tags->kvm_size);
-  if (tag_header_size != TAG_HEADER_SIZE) {
-    // something new in the tag information. I don't understand it, so
-    // don't copy it over.
-    GPR_ASSERT(version != ENCODED_VERSION);
-    GPR_ASSERT(tag_header_size > TAG_HEADER_SIZE);
-    char *kvp = tags->kvm;
-    for (int i = 0; i < tags->ntags; i++) {
-      memcpy(kvp, buffer, TAG_HEADER_SIZE);
-      kvp += header_size;
-      struct raw_tag raw;
-      buffer =
-          decode_tag(&raw, (char *)buffer, tag_header_size - TAG_HEADER_SIZE);
-      memcpy(kvp, raw.key, (size_t)raw.key_len + raw.value_len);
-      kvp += raw.key_len + raw.value_len;
-    }
-  } else {
-    memcpy(tags->kvm, buffer, tags->kvm_used);
-  }
-}
-
-census_tag_set *census_tag_set_decode(const char *buffer, size_t size,
-                                      const char *bin_buffer, size_t bin_size) {
-  census_tag_set *new_ts = gpr_malloc(sizeof(census_tag_set));
-  memset(&new_ts->tags[LOCAL_TAGS], 0, sizeof(struct tag_set));
-  if (buffer == NULL) {
-    memset(&new_ts->tags[PROPAGATED_TAGS], 0, sizeof(struct tag_set));
-  } else {
-    tag_set_decode(&new_ts->tags[PROPAGATED_TAGS], buffer, size);
-  }
-  if (bin_buffer == NULL) {
-    memset(&new_ts->tags[PROPAGATED_BINARY_TAGS], 0, sizeof(struct tag_set));
-  } else {
-    tag_set_decode(&new_ts->tags[PROPAGATED_BINARY_TAGS], bin_buffer, bin_size);
-  }
-  memset(&new_ts->status, 0, sizeof(new_ts->status));
-  new_ts->status.n_propagated_tags = new_ts->tags[PROPAGATED_TAGS].ntags;
-  new_ts->status.n_propagated_binary_tags =
-      new_ts->tags[PROPAGATED_BINARY_TAGS].ntags;
-  // TODO(aveitch): check that BINARY flag is correct for each type.
-  return new_ts;
-}
diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py
index 1b2490e9ff..6e89c87436 100644
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@@ -225,7 +225,6 @@ CORE_SOURCE_FILES = [
   'src/core/census/initialize.c',
   'src/core/census/operation.c',
   'src/core/census/placeholders.c',
-  'src/core/census/tag_set.c',
   'src/core/census/tracing.c',
   'src/boringssl/err_data.c',
   'third_party/boringssl/crypto/aes/aes.c',
diff --git a/src/ruby/ext/grpc/rb_grpc_imports.generated.c b/src/ruby/ext/grpc/rb_grpc_imports.generated.c
index a278b2ba99..d4ddb734c0 100644
--- a/src/ruby/ext/grpc/rb_grpc_imports.generated.c
+++ b/src/ruby/ext/grpc/rb_grpc_imports.generated.c
@@ -41,7 +41,14 @@ census_initialize_type census_initialize_import;
 census_shutdown_type census_shutdown_import;
 census_supported_type census_supported_import;
 census_enabled_type census_enabled_import;
-census_context_serialize_type census_context_serialize_import;
+census_context_create_type census_context_create_import;
+census_context_destroy_type census_context_destroy_import;
+census_context_get_status_type census_context_get_status_import;
+census_context_initialize_iterator_type census_context_initialize_iterator_import;
+census_context_next_tag_type census_context_next_tag_import;
+census_context_get_tag_type census_context_get_tag_import;
+census_context_encode_type census_context_encode_import;
+census_context_decode_type census_context_decode_import;
 census_trace_mask_type census_trace_mask_import;
 census_set_trace_mask_type census_set_trace_mask_import;
 census_start_rpc_op_timestamp_type census_start_rpc_op_timestamp_import;
@@ -54,15 +61,6 @@ census_trace_print_type census_trace_print_import;
 census_trace_scan_start_type census_trace_scan_start_import;
 census_get_trace_record_type census_get_trace_record_import;
 census_trace_scan_end_type census_trace_scan_end_import;
-census_tag_set_create_type census_tag_set_create_import;
-census_tag_set_destroy_type census_tag_set_destroy_import;
-census_tag_set_get_create_status_type census_tag_set_get_create_status_import;
-census_tag_set_initialize_iterator_type census_tag_set_initialize_iterator_import;
-census_tag_set_next_tag_type census_tag_set_next_tag_import;
-census_tag_set_get_tag_by_key_type census_tag_set_get_tag_by_key_import;
-census_tag_set_encode_type census_tag_set_encode_import;
-census_tag_set_decode_type census_tag_set_decode_import;
-census_context_tag_set_type census_context_tag_set_import;
 census_record_values_type census_record_values_import;
 census_view_create_type census_view_create_import;
 census_view_delete_type census_view_delete_import;
@@ -303,7 +301,14 @@ void grpc_rb_load_imports(HMODULE library) {
   census_shutdown_import = (census_shutdown_type) GetProcAddress(library, "census_shutdown");
   census_supported_import = (census_supported_type) GetProcAddress(library, "census_supported");
   census_enabled_import = (census_enabled_type) GetProcAddress(library, "census_enabled");
-  census_context_serialize_import = (census_context_serialize_type) GetProcAddress(library, "census_context_serialize");
+  census_context_create_import = (census_context_create_type) GetProcAddress(library, "census_context_create");
+  census_context_destroy_import = (census_context_destroy_type) GetProcAddress(library, "census_context_destroy");
+  census_context_get_status_import = (census_context_get_status_type) GetProcAddress(library, "census_context_get_status");
+  census_context_initialize_iterator_import = (census_context_initialize_iterator_type) GetProcAddress(library, "census_context_initialize_iterator");
+  census_context_next_tag_import = (census_context_next_tag_type) GetProcAddress(library, "census_context_next_tag");
+  census_context_get_tag_import = (census_context_get_tag_type) GetProcAddress(library, "census_context_get_tag");
+  census_context_encode_import = (census_context_encode_type) GetProcAddress(library, "census_context_encode");
+  census_context_decode_import = (census_context_decode_type) GetProcAddress(library, "census_context_decode");
   census_trace_mask_import = (census_trace_mask_type) GetProcAddress(library, "census_trace_mask");
   census_set_trace_mask_import = (census_set_trace_mask_type) GetProcAddress(library, "census_set_trace_mask");
   census_start_rpc_op_timestamp_import = (census_start_rpc_op_timestamp_type) GetProcAddress(library, "census_start_rpc_op_timestamp");
@@ -316,15 +321,6 @@ void grpc_rb_load_imports(HMODULE library) {
   census_trace_scan_start_import = (census_trace_scan_start_type) GetProcAddress(library, "census_trace_scan_start");
   census_get_trace_record_import = (census_get_trace_record_type) GetProcAddress(library, "census_get_trace_record");
   census_trace_scan_end_import = (census_trace_scan_end_type) GetProcAddress(library, "census_trace_scan_end");
-  census_tag_set_create_import = (census_tag_set_create_type) GetProcAddress(library, "census_tag_set_create");
-  census_tag_set_destroy_import = (census_tag_set_destroy_type) GetProcAddress(library, "census_tag_set_destroy");
-  census_tag_set_get_create_status_import = (census_tag_set_get_create_status_type) GetProcAddress(library, "census_tag_set_get_create_status");
-  census_tag_set_initialize_iterator_import = (census_tag_set_initialize_iterator_type) GetProcAddress(library, "census_tag_set_initialize_iterator");
-  census_tag_set_next_tag_import = (census_tag_set_next_tag_type) GetProcAddress(library, "census_tag_set_next_tag");
-  census_tag_set_get_tag_by_key_import = (census_tag_set_get_tag_by_key_type) GetProcAddress(library, "census_tag_set_get_tag_by_key");
-  census_tag_set_encode_import = (census_tag_set_encode_type) GetProcAddress(library, "census_tag_set_encode");
-  census_tag_set_decode_import = (census_tag_set_decode_type) GetProcAddress(library, "census_tag_set_decode");
-  census_context_tag_set_import = (census_context_tag_set_type) GetProcAddress(library, "census_context_tag_set");
   census_record_values_import = (census_record_values_type) GetProcAddress(library, "census_record_values");
   census_view_create_import = (census_view_create_type) GetProcAddress(library, "census_view_create");
   census_view_delete_import = (census_view_delete_type) GetProcAddress(library, "census_view_delete");
diff --git a/src/ruby/ext/grpc/rb_grpc_imports.generated.h b/src/ruby/ext/grpc/rb_grpc_imports.generated.h
index 3e29496a43..45e9b47574 100644
--- a/src/ruby/ext/grpc/rb_grpc_imports.generated.h
+++ b/src/ruby/ext/grpc/rb_grpc_imports.generated.h
@@ -73,9 +73,30 @@ extern census_supported_type census_supported_import;
 typedef int(*census_enabled_type)(void);
 extern census_enabled_type census_enabled_import;
 #define census_enabled census_enabled_import
-typedef size_t(*census_context_serialize_type)(const census_context *context, char *buffer, size_t buf_size);
-extern census_context_serialize_type census_context_serialize_import;
-#define census_context_serialize census_context_serialize_import
+typedef census_context *(*census_context_create_type)(const census_context *base, const census_tag *tags, int ntags, census_context_status const **status);
+extern census_context_create_type census_context_create_import;
+#define census_context_create census_context_create_import
+typedef void(*census_context_destroy_type)(census_context *context);
+extern census_context_destroy_type census_context_destroy_import;
+#define census_context_destroy census_context_destroy_import
+typedef const census_context_status *(*census_context_get_status_type)(const census_context *context);
+extern census_context_get_status_type census_context_get_status_import;
+#define census_context_get_status census_context_get_status_import
+typedef void(*census_context_initialize_iterator_type)(const census_context *context, census_context_iterator *iterator);
+extern census_context_initialize_iterator_type census_context_initialize_iterator_import;
+#define census_context_initialize_iterator census_context_initialize_iterator_import
+typedef int(*census_context_next_tag_type)(census_context_iterator *iterator, census_tag *tag);
+extern census_context_next_tag_type census_context_next_tag_import;
+#define census_context_next_tag census_context_next_tag_import
+typedef int(*census_context_get_tag_type)(const census_context *context, const char *key, census_tag *tag);
+extern census_context_get_tag_type census_context_get_tag_import;
+#define census_context_get_tag census_context_get_tag_import
+typedef char *(*census_context_encode_type)(const census_context *context, char *buffer, size_t buf_size, size_t *print_buf_size, size_t *bin_buf_size);
+extern census_context_encode_type census_context_encode_import;
+#define census_context_encode census_context_encode_import
+typedef census_context *(*census_context_decode_type)(const char *buffer, size_t size, const char *bin_buffer, size_t bin_size);
+extern census_context_decode_type census_context_decode_import;
+#define census_context_decode census_context_decode_import
 typedef int(*census_trace_mask_type)(const census_context *context);
 extern census_trace_mask_type census_trace_mask_import;
 #define census_trace_mask census_trace_mask_import
@@ -112,37 +133,10 @@ extern census_get_trace_record_type census_get_trace_record_import;
 typedef void(*census_trace_scan_end_type)();
 extern census_trace_scan_end_type census_trace_scan_end_import;
 #define census_trace_scan_end census_trace_scan_end_import
-typedef census_tag_set *(*census_tag_set_create_type)(const census_tag_set *base, const census_tag *tags, int ntags, census_tag_set_create_status const **status);
-extern census_tag_set_create_type census_tag_set_create_import;
-#define census_tag_set_create census_tag_set_create_import
-typedef void(*census_tag_set_destroy_type)(census_tag_set *tags);
-extern census_tag_set_destroy_type census_tag_set_destroy_import;
-#define census_tag_set_destroy census_tag_set_destroy_import
-typedef const census_tag_set_create_status *(*census_tag_set_get_create_status_type)(const census_tag_set *tags);
-extern census_tag_set_get_create_status_type census_tag_set_get_create_status_import;
-#define census_tag_set_get_create_status census_tag_set_get_create_status_import
-typedef void(*census_tag_set_initialize_iterator_type)(const census_tag_set *tags, census_tag_set_iterator *iterator);
-extern census_tag_set_initialize_iterator_type census_tag_set_initialize_iterator_import;
-#define census_tag_set_initialize_iterator census_tag_set_initialize_iterator_import
-typedef int(*census_tag_set_next_tag_type)(census_tag_set_iterator *iterator, census_tag *tag);
-extern census_tag_set_next_tag_type census_tag_set_next_tag_import;
-#define census_tag_set_next_tag census_tag_set_next_tag_import
-typedef int(*census_tag_set_get_tag_by_key_type)(const census_tag_set *tags, const char *key, census_tag *tag);
-extern census_tag_set_get_tag_by_key_type census_tag_set_get_tag_by_key_import;
-#define census_tag_set_get_tag_by_key census_tag_set_get_tag_by_key_import
-typedef char *(*census_tag_set_encode_type)(const census_tag_set *tags, char *buffer, size_t buf_size, size_t *print_buf_size, size_t *bin_buf_size);
-extern census_tag_set_encode_type census_tag_set_encode_import;
-#define census_tag_set_encode census_tag_set_encode_import
-typedef census_tag_set *(*census_tag_set_decode_type)(const char *buffer, size_t size, const char *bin_buffer, size_t bin_size);
-extern census_tag_set_decode_type census_tag_set_decode_import;
-#define census_tag_set_decode census_tag_set_decode_import
-typedef census_tag_set *(*census_context_tag_set_type)(census_context *context);
-extern census_context_tag_set_type census_context_tag_set_import;
-#define census_context_tag_set census_context_tag_set_import
 typedef void(*census_record_values_type)(census_context *context, census_value *values, size_t nvalues);
 extern census_record_values_type census_record_values_import;
 #define census_record_values census_record_values_import
-typedef census_view *(*census_view_create_type)(uint32_t metric_id, const census_tag_set *tags, const census_aggregation *aggregations, size_t naggregations);
+typedef census_view *(*census_view_create_type)(uint32_t metric_id, const census_context *tags, const census_aggregation *aggregations, size_t naggregations);
 extern census_view_create_type census_view_create_import;
 #define census_view_create census_view_create_import
 typedef void(*census_view_delete_type)(census_view *view);
@@ -154,7 +148,7 @@ extern census_view_metric_type census_view_metric_import;
 typedef size_t(*census_view_naggregations_type)(const census_view *view);
 extern census_view_naggregations_type census_view_naggregations_import;
 #define census_view_naggregations census_view_naggregations_import
-typedef const census_tag_set *(*census_view_tags_type)(const census_view *view);
+typedef const census_context *(*census_view_tags_type)(const census_view *view);
 extern census_view_tags_type census_view_tags_import;
 #define census_view_tags census_view_tags_import
 typedef const census_aggregation *(*census_view_aggregrations_type)(const census_view *view);
diff --git a/test/core/census/tag_set_test.c b/test/core/census/context_test.c
index 1056e98d55..63e7103ddc 100644
--- a/test/core/census/tag_set_test.c
+++ b/test/core/census/context_test.c
@@ -31,7 +31,7 @@
  *
  */
 
-// Test census_tag_set functions, including encoding/decoding
+// Test census_context functions, including encoding/decoding
 
 #include <grpc/census.h>
 #include <grpc/support/log.h>
@@ -46,7 +46,7 @@ static uint8_t one_byte_val = 7;
 static uint32_t four_byte_val = 0x12345678;
 static uint64_t eight_byte_val = 0x1234567890abcdef;
 
-// A set of tags Used to create a basic tag_set for testing. Each tag has a
+// A set of tags Used to create a basic context for testing. Each tag has a
 // unique set of flags. Note that replace_add_delete_test() relies on specific
 // offsets into this array - if you add or delete entries, you will also need
 // to change the test.
@@ -65,7 +65,7 @@ static census_tag basic_tags[BASIC_TAG_COUNT] = {
     /* 7 */ {"k7", (char *)&four_byte_val, 4,
              CENSUS_TAG_PROPAGATE | CENSUS_TAG_STATS | CENSUS_TAG_BINARY}};
 
-// Set of tags used to modify the basic tag_set. Note that
+// Set of tags used to modify the basic context. Note that
 // replace_add_delete_test() relies on specific offsets into this array - if
 // you add or delete entries, you will also need to change the test. Other
 // tests that rely on specific instances have XXX_XXX_OFFSET definitions (also
@@ -99,35 +99,34 @@ static bool compare_tag(const census_tag *t1, const census_tag *t2) {
           t1->flags == t2->flags);
 }
 
-// Utility function to validate a tag exists in tag set.
-static bool validate_tag(const census_tag_set *cts, const census_tag *tag) {
+// Utility function to validate a tag exists in context.
+static bool validate_tag(const census_context *context, const census_tag *tag) {
   census_tag tag2;
-  if (census_tag_set_get_tag_by_key(cts, tag->key, &tag2) != 1) return false;
+  if (census_context_get_tag(context, tag->key, &tag2) != 1) return false;
   return compare_tag(tag, &tag2);
 }
 
-// Create an empty tag_set.
+// Create an empty context.
 static void empty_test(void) {
-  struct census_tag_set *cts = census_tag_set_create(NULL, NULL, 0, NULL);
-  GPR_ASSERT(cts != NULL);
-  const census_tag_set_create_status *status =
-      census_tag_set_get_create_status(cts);
-  census_tag_set_create_status expected = {0, 0, 0, 0, 0, 0, 0, 0};
+  struct census_context *context = census_context_create(NULL, NULL, 0, NULL);
+  GPR_ASSERT(context != NULL);
+  const census_context_status *status = census_context_get_status(context);
+  census_context_status expected = {0, 0, 0, 0, 0, 0, 0, 0};
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
-  census_tag_set_destroy(cts);
+  census_context_destroy(context);
 }
 
-// Test create and iteration over basic tag set.
+// Test create and iteration over basic context.
 static void basic_test(void) {
-  const census_tag_set_create_status *status;
-  struct census_tag_set *cts =
-      census_tag_set_create(NULL, basic_tags, BASIC_TAG_COUNT, &status);
-  census_tag_set_create_status expected = {2, 2, 4, 0, 8, 0, 0, 0};
+  const census_context_status *status;
+  struct census_context *context =
+      census_context_create(NULL, basic_tags, BASIC_TAG_COUNT, &status);
+  census_context_status expected = {2, 2, 4, 0, 8, 0, 0, 0};
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
-  census_tag_set_iterator it;
-  census_tag_set_initialize_iterator(cts, &it);
+  census_context_iterator it;
+  census_context_initialize_iterator(context, &it);
   census_tag tag;
-  while (census_tag_set_next_tag(&it, &tag)) {
+  while (census_context_next_tag(&it, &tag)) {
     // can't rely on tag return order: make sure it matches exactly one.
     int matches = 0;
     for (int i = 0; i < BASIC_TAG_COUNT; i++) {
@@ -135,29 +134,28 @@ static void basic_test(void) {
     }
     GPR_ASSERT(matches == 1);
   }
-  census_tag_set_destroy(cts);
+  census_context_destroy(context);
 }
 
-// Test that census_tag_set_get_tag_by_key().
+// Test census_context_get_tag().
 static void lookup_by_key_test(void) {
-  struct census_tag_set *cts =
-      census_tag_set_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
+  struct census_context *context =
+      census_context_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
   census_tag tag;
   for (int i = 0; i < BASIC_TAG_COUNT; i++) {
-    GPR_ASSERT(census_tag_set_get_tag_by_key(cts, basic_tags[i].key, &tag) ==
-               1);
+    GPR_ASSERT(census_context_get_tag(context, basic_tags[i].key, &tag) == 1);
     GPR_ASSERT(compare_tag(&tag, &basic_tags[i]));
   }
   // non-existent keys
-  GPR_ASSERT(census_tag_set_get_tag_by_key(cts, "key", &tag) == 0);
-  GPR_ASSERT(census_tag_set_get_tag_by_key(cts, "key01", &tag) == 0);
-  GPR_ASSERT(census_tag_set_get_tag_by_key(cts, "k9", &tag) == 0);
-  GPR_ASSERT(census_tag_set_get_tag_by_key(cts, "random", &tag) == 0);
-  GPR_ASSERT(census_tag_set_get_tag_by_key(cts, "", &tag) == 0);
-  census_tag_set_destroy(cts);
+  GPR_ASSERT(census_context_get_tag(context, "key", &tag) == 0);
+  GPR_ASSERT(census_context_get_tag(context, "key01", &tag) == 0);
+  GPR_ASSERT(census_context_get_tag(context, "k9", &tag) == 0);
+  GPR_ASSERT(census_context_get_tag(context, "random", &tag) == 0);
+  GPR_ASSERT(census_context_get_tag(context, "", &tag) == 0);
+  census_context_destroy(context);
 }
 
-// Try creating tag set with invalid entries.
+// Try creating context with invalid entries.
 static void invalid_test(void) {
   char key[300];
   memset(key, 'k', 299);
@@ -168,155 +166,156 @@ static void invalid_test(void) {
   // long keys, short value. Key lengths (including terminator) should be
   // <= 255 (CENSUS_MAX_TAG_KV_LEN)
   GPR_ASSERT(strlen(key) == 299);
-  const census_tag_set_create_status *status;
-  struct census_tag_set *cts = census_tag_set_create(NULL, &tag, 1, &status);
-  census_tag_set_create_status expected = {0, 0, 0, 0, 0, 0, 1, 0};
+  const census_context_status *status;
+  struct census_context *context =
+      census_context_create(NULL, &tag, 1, &status);
+  census_context_status expected = {0, 0, 0, 0, 0, 0, 1, 0};
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
-  census_tag_set_destroy(cts);
+  census_context_destroy(context);
   key[CENSUS_MAX_TAG_KV_LEN] = 0;
   GPR_ASSERT(strlen(key) == CENSUS_MAX_TAG_KV_LEN);
-  cts = census_tag_set_create(NULL, &tag, 1, &status);
+  context = census_context_create(NULL, &tag, 1, &status);
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
-  census_tag_set_destroy(cts);
+  census_context_destroy(context);
   key[CENSUS_MAX_TAG_KV_LEN - 1] = 0;
   GPR_ASSERT(strlen(key) == CENSUS_MAX_TAG_KV_LEN - 1);
-  cts = census_tag_set_create(NULL, &tag, 1, &status);
-  census_tag_set_create_status expected2 = {0, 0, 1, 0, 1, 0, 0, 0};
+  context = census_context_create(NULL, &tag, 1, &status);
+  census_context_status expected2 = {0, 0, 1, 0, 1, 0, 0, 0};
   GPR_ASSERT(memcmp(status, &expected2, sizeof(expected2)) == 0);
-  census_tag_set_destroy(cts);
+  census_context_destroy(context);
   // now try with long values
   tag.value_len = 300;
-  cts = census_tag_set_create(NULL, &tag, 1, &status);
+  context = census_context_create(NULL, &tag, 1, &status);
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
-  census_tag_set_destroy(cts);
+  census_context_destroy(context);
   tag.value_len = CENSUS_MAX_TAG_KV_LEN + 1;
-  cts = census_tag_set_create(NULL, &tag, 1, &status);
+  context = census_context_create(NULL, &tag, 1, &status);
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
-  census_tag_set_destroy(cts);
+  census_context_destroy(context);
   tag.value_len = CENSUS_MAX_TAG_KV_LEN;
-  cts = census_tag_set_create(NULL, &tag, 1, &status);
+  context = census_context_create(NULL, &tag, 1, &status);
   GPR_ASSERT(memcmp(status, &expected2, sizeof(expected2)) == 0);
-  census_tag_set_destroy(cts);
+  census_context_destroy(context);
   // 0 length key.
   key[0] = 0;
-  cts = census_tag_set_create(NULL, &tag, 1, &status);
+  context = census_context_create(NULL, &tag, 1, &status);
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
-  census_tag_set_destroy(cts);
+  census_context_destroy(context);
 }
 
-// Make a copy of a tag set
+// Make a copy of a context
 static void copy_test(void) {
-  struct census_tag_set *cts =
-      census_tag_set_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
-  const census_tag_set_create_status *status;
-  struct census_tag_set *cts2 = census_tag_set_create(cts, NULL, 0, &status);
-  census_tag_set_create_status expected = {2, 2, 4, 0, 0, 0, 0, 0};
+  struct census_context *context =
+      census_context_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
+  const census_context_status *status;
+  struct census_context *context2 =
+      census_context_create(context, NULL, 0, &status);
+  census_context_status expected = {2, 2, 4, 0, 0, 0, 0, 0};
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
   for (int i = 0; i < BASIC_TAG_COUNT; i++) {
     census_tag tag;
-    GPR_ASSERT(census_tag_set_get_tag_by_key(cts2, basic_tags[i].key, &tag) ==
-               1);
+    GPR_ASSERT(census_context_get_tag(context2, basic_tags[i].key, &tag) == 1);
     GPR_ASSERT(compare_tag(&tag, &basic_tags[i]));
   }
-  census_tag_set_destroy(cts);
-  census_tag_set_destroy(cts2);
+  census_context_destroy(context);
+  census_context_destroy(context2);
 }
 
 // replace a single tag value
 static void replace_value_test(void) {
-  struct census_tag_set *cts =
-      census_tag_set_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
-  const census_tag_set_create_status *status;
-  struct census_tag_set *cts2 = census_tag_set_create(
-      cts, modify_tags + REPLACE_VALUE_OFFSET, 1, &status);
-  census_tag_set_create_status expected = {2, 2, 4, 0, 0, 1, 0, 0};
+  struct census_context *context =
+      census_context_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
+  const census_context_status *status;
+  struct census_context *context2 = census_context_create(
+      context, modify_tags + REPLACE_VALUE_OFFSET, 1, &status);
+  census_context_status expected = {2, 2, 4, 0, 0, 1, 0, 0};
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
   census_tag tag;
-  GPR_ASSERT(census_tag_set_get_tag_by_key(
-                 cts2, modify_tags[REPLACE_VALUE_OFFSET].key, &tag) == 1);
+  GPR_ASSERT(census_context_get_tag(
+                 context2, modify_tags[REPLACE_VALUE_OFFSET].key, &tag) == 1);
   GPR_ASSERT(compare_tag(&tag, &modify_tags[REPLACE_VALUE_OFFSET]));
-  census_tag_set_destroy(cts);
-  census_tag_set_destroy(cts2);
+  census_context_destroy(context);
+  census_context_destroy(context2);
 }
 
 // replace a single tags flags
 static void replace_flags_test(void) {
-  struct census_tag_set *cts =
-      census_tag_set_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
-  const census_tag_set_create_status *status;
-  struct census_tag_set *cts2 =
-      census_tag_set_create(cts, modify_tags + REPLACE_FLAG_OFFSET, 1, &status);
-  census_tag_set_create_status expected = {1, 2, 5, 0, 0, 1, 0, 0};
+  struct census_context *context =
+      census_context_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
+  const census_context_status *status;
+  struct census_context *context2 = census_context_create(
+      context, modify_tags + REPLACE_FLAG_OFFSET, 1, &status);
+  census_context_status expected = {1, 2, 5, 0, 0, 1, 0, 0};
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
   census_tag tag;
-  GPR_ASSERT(census_tag_set_get_tag_by_key(
-                 cts2, modify_tags[REPLACE_FLAG_OFFSET].key, &tag) == 1);
+  GPR_ASSERT(census_context_get_tag(
+                 context2, modify_tags[REPLACE_FLAG_OFFSET].key, &tag) == 1);
   GPR_ASSERT(compare_tag(&tag, &modify_tags[REPLACE_FLAG_OFFSET]));
-  census_tag_set_destroy(cts);
-  census_tag_set_destroy(cts2);
+  census_context_destroy(context);
+  census_context_destroy(context2);
 }
 
 // delete a single tag.
 static void delete_tag_test(void) {
-  struct census_tag_set *cts =
-      census_tag_set_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
-  const census_tag_set_create_status *status;
-  struct census_tag_set *cts2 =
-      census_tag_set_create(cts, modify_tags + DELETE_TAG_OFFSET, 1, &status);
-  census_tag_set_create_status expected = {2, 1, 4, 1, 0, 0, 0, 0};
+  struct census_context *context =
+      census_context_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
+  const census_context_status *status;
+  struct census_context *context2 = census_context_create(
+      context, modify_tags + DELETE_TAG_OFFSET, 1, &status);
+  census_context_status expected = {2, 1, 4, 1, 0, 0, 0, 0};
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
   census_tag tag;
-  GPR_ASSERT(census_tag_set_get_tag_by_key(
-                 cts2, modify_tags[DELETE_TAG_OFFSET].key, &tag) == 0);
-  census_tag_set_destroy(cts);
-  census_tag_set_destroy(cts2);
+  GPR_ASSERT(census_context_get_tag(
+                 context2, modify_tags[DELETE_TAG_OFFSET].key, &tag) == 0);
+  census_context_destroy(context);
+  census_context_destroy(context2);
 }
 
 // add a single new tag.
 static void add_tag_test(void) {
-  struct census_tag_set *cts =
-      census_tag_set_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
-  const census_tag_set_create_status *status;
-  struct census_tag_set *cts2 =
-      census_tag_set_create(cts, modify_tags + ADD_TAG_OFFSET, 1, &status);
-  census_tag_set_create_status expected = {2, 2, 5, 0, 1, 0, 0, 0};
+  struct census_context *context =
+      census_context_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
+  const census_context_status *status;
+  struct census_context *context2 =
+      census_context_create(context, modify_tags + ADD_TAG_OFFSET, 1, &status);
+  census_context_status expected = {2, 2, 5, 0, 1, 0, 0, 0};
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
   census_tag tag;
-  GPR_ASSERT(census_tag_set_get_tag_by_key(
-                 cts2, modify_tags[ADD_TAG_OFFSET].key, &tag) == 1);
+  GPR_ASSERT(census_context_get_tag(context2, modify_tags[ADD_TAG_OFFSET].key,
+                                    &tag) == 1);
   GPR_ASSERT(compare_tag(&tag, &modify_tags[ADD_TAG_OFFSET]));
-  census_tag_set_destroy(cts);
-  census_tag_set_destroy(cts2);
+  census_context_destroy(context);
+  census_context_destroy(context2);
 }
 
 // test many changes at once.
 static void replace_add_delete_test(void) {
-  struct census_tag_set *cts =
-      census_tag_set_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
-  const census_tag_set_create_status *status;
-  struct census_tag_set *cts2 =
-      census_tag_set_create(cts, modify_tags, MODIFY_TAG_COUNT, &status);
-  census_tag_set_create_status expected = {2, 1, 6, 2, 3, 4, 0, 2};
+  struct census_context *context =
+      census_context_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
+  const census_context_status *status;
+  struct census_context *context2 =
+      census_context_create(context, modify_tags, MODIFY_TAG_COUNT, &status);
+  census_context_status expected = {2, 1, 6, 2, 3, 4, 0, 2};
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
-  // validate tag set contents. Use specific indices into the two arrays
+  // validate context contents. Use specific indices into the two arrays
   // holding tag values.
-  GPR_ASSERT(validate_tag(cts2, &basic_tags[3]));
-  GPR_ASSERT(validate_tag(cts2, &basic_tags[4]));
-  GPR_ASSERT(validate_tag(cts2, &modify_tags[0]));
-  GPR_ASSERT(validate_tag(cts2, &modify_tags[1]));
-  GPR_ASSERT(validate_tag(cts2, &modify_tags[6]));
-  GPR_ASSERT(validate_tag(cts2, &modify_tags[7]));
-  GPR_ASSERT(validate_tag(cts2, &modify_tags[8]));
-  GPR_ASSERT(validate_tag(cts2, &modify_tags[9]));
-  GPR_ASSERT(validate_tag(cts2, &modify_tags[10]));
-  GPR_ASSERT(!validate_tag(cts2, &basic_tags[0]));
-  GPR_ASSERT(!validate_tag(cts2, &basic_tags[1]));
-  GPR_ASSERT(!validate_tag(cts2, &basic_tags[2]));
-  GPR_ASSERT(!validate_tag(cts2, &basic_tags[5]));
-  GPR_ASSERT(!validate_tag(cts2, &basic_tags[6]));
-  GPR_ASSERT(!validate_tag(cts2, &basic_tags[7]));
-  census_tag_set_destroy(cts);
-  census_tag_set_destroy(cts2);
+  GPR_ASSERT(validate_tag(context2, &basic_tags[3]));
+  GPR_ASSERT(validate_tag(context2, &basic_tags[4]));
+  GPR_ASSERT(validate_tag(context2, &modify_tags[0]));
+  GPR_ASSERT(validate_tag(context2, &modify_tags[1]));
+  GPR_ASSERT(validate_tag(context2, &modify_tags[6]));
+  GPR_ASSERT(validate_tag(context2, &modify_tags[7]));
+  GPR_ASSERT(validate_tag(context2, &modify_tags[8]));
+  GPR_ASSERT(validate_tag(context2, &modify_tags[9]));
+  GPR_ASSERT(validate_tag(context2, &modify_tags[10]));
+  GPR_ASSERT(!validate_tag(context2, &basic_tags[0]));
+  GPR_ASSERT(!validate_tag(context2, &basic_tags[1]));
+  GPR_ASSERT(!validate_tag(context2, &basic_tags[2]));
+  GPR_ASSERT(!validate_tag(context2, &basic_tags[5]));
+  GPR_ASSERT(!validate_tag(context2, &basic_tags[6]));
+  GPR_ASSERT(!validate_tag(context2, &basic_tags[7]));
+  census_context_destroy(context);
+  census_context_destroy(context2);
 }
 
 #define BUF_SIZE 200
@@ -324,38 +323,37 @@ static void replace_add_delete_test(void) {
 // test encode/decode.
 static void encode_decode_test(void) {
   char buffer[BUF_SIZE];
-  struct census_tag_set *cts =
-      census_tag_set_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
+  struct census_context *context =
+      census_context_create(NULL, basic_tags, BASIC_TAG_COUNT, NULL);
   size_t print_bsize;
   size_t bin_bsize;
   // Test with too small a buffer
-  GPR_ASSERT(census_tag_set_encode(cts, buffer, 2, &print_bsize, &bin_bsize) ==
-             NULL);
-  char *b_buffer =
-      census_tag_set_encode(cts, buffer, BUF_SIZE, &print_bsize, &bin_bsize);
+  GPR_ASSERT(census_context_encode(context, buffer, 2, &print_bsize,
+                                   &bin_bsize) == NULL);
+  char *b_buffer = census_context_encode(context, buffer, BUF_SIZE,
+                                         &print_bsize, &bin_bsize);
   GPR_ASSERT(b_buffer != NULL && print_bsize > 0 && bin_bsize > 0 &&
              print_bsize + bin_bsize <= BUF_SIZE &&
              b_buffer == buffer + print_bsize);
-  census_tag_set *cts2 =
-      census_tag_set_decode(buffer, print_bsize, b_buffer, bin_bsize);
-  GPR_ASSERT(cts2 != NULL);
-  const census_tag_set_create_status *status =
-      census_tag_set_get_create_status(cts2);
-  census_tag_set_create_status expected = {2, 2, 0, 0, 0, 0, 0, 0};
+  census_context *context2 =
+      census_context_decode(buffer, print_bsize, b_buffer, bin_bsize);
+  GPR_ASSERT(context2 != NULL);
+  const census_context_status *status = census_context_get_status(context2);
+  census_context_status expected = {2, 2, 0, 0, 0, 0, 0, 0};
   GPR_ASSERT(memcmp(status, &expected, sizeof(expected)) == 0);
   for (int i = 0; i < BASIC_TAG_COUNT; i++) {
     census_tag tag;
     if (CENSUS_TAG_IS_PROPAGATED(basic_tags[i].flags)) {
-      GPR_ASSERT(census_tag_set_get_tag_by_key(cts2, basic_tags[i].key, &tag) ==
+      GPR_ASSERT(census_context_get_tag(context2, basic_tags[i].key, &tag) ==
                  1);
       GPR_ASSERT(compare_tag(&tag, &basic_tags[i]));
     } else {
-      GPR_ASSERT(census_tag_set_get_tag_by_key(cts2, basic_tags[i].key, &tag) ==
+      GPR_ASSERT(census_context_get_tag(context2, basic_tags[i].key, &tag) ==
                  0);
     }
   }
-  census_tag_set_destroy(cts2);
-  census_tag_set_destroy(cts);
+  census_context_destroy(context2);
+  census_context_destroy(context);
 }
 
 int main(int argc, char *argv[]) {
diff --git a/test/cpp/qps/client_async.cc b/test/cpp/qps/client_async.cc
index f3f8f37051..6b6294ba51 100644
--- a/test/cpp/qps/client_async.cc
+++ b/test/cpp/qps/client_async.cc
@@ -96,7 +96,8 @@ class ClientRpcContextUnaryImpl : public ClientRpcContext {
       std::function<
           std::unique_ptr<grpc::ClientAsyncResponseReader<ResponseType>>(
               BenchmarkService::Stub*, grpc::ClientContext*, const RequestType&,
-              CompletionQueue*)> start_req,
+              CompletionQueue*)>
+          start_req,
       std::function<void(grpc::Status, ResponseType*)> on_done)
       : ClientRpcContext(channel_id),
         context_(),
@@ -142,7 +143,8 @@ class ClientRpcContextUnaryImpl : public ClientRpcContext {
   std::function<void(grpc::Status, ResponseType*)> callback_;
   std::function<std::unique_ptr<grpc::ClientAsyncResponseReader<ResponseType>>(
       BenchmarkService::Stub*, grpc::ClientContext*, const RequestType&,
-      CompletionQueue*)> start_req_;
+      CompletionQueue*)>
+      start_req_;
   grpc::Status status_;
   double start_;
   std::unique_ptr<grpc::ClientAsyncResponseReader<ResponseType>>
@@ -162,11 +164,12 @@ class AsyncClient : public ClientImpl<StubType, RequestType> {
   using ClientImpl<StubType, RequestType>::cores_;
   using ClientImpl<StubType, RequestType>::channels_;
   using ClientImpl<StubType, RequestType>::request_;
-  AsyncClient(const ClientConfig& config,
-              std::function<ClientRpcContext*(int, StubType*,
-                                              const RequestType&)> setup_ctx,
-              std::function<std::unique_ptr<StubType>(std::shared_ptr<Channel>)>
-                  create_stub)
+  AsyncClient(
+      const ClientConfig& config,
+      std::function<ClientRpcContext*(int, StubType*, const RequestType&)>
+          setup_ctx,
+      std::function<std::unique_ptr<StubType>(std::shared_ptr<Channel>)>
+          create_stub)
       : ClientImpl<StubType, RequestType>(config, create_stub),
         num_async_threads_(NumThreads(config)),
         channel_lock_(new std::mutex[config.client_channels()]),
@@ -408,7 +411,8 @@ class ClientRpcContextStreamingImpl : public ClientRpcContext {
       std::function<std::unique_ptr<
           grpc::ClientAsyncReaderWriter<RequestType, ResponseType>>(
           BenchmarkService::Stub*, grpc::ClientContext*, CompletionQueue*,
-          void*)> start_req,
+          void*)>
+          start_req,
       std::function<void(grpc::Status, ResponseType*)> on_done)
       : ClientRpcContext(channel_id),
         context_(),
@@ -460,10 +464,10 @@ class ClientRpcContextStreamingImpl : public ClientRpcContext {
   ResponseType response_;
   bool (ClientRpcContextStreamingImpl::*next_state_)(bool, Histogram*);
   std::function<void(grpc::Status, ResponseType*)> callback_;
-  std::function<
-      std::unique_ptr<grpc::ClientAsyncReaderWriter<RequestType, ResponseType>>(
-          BenchmarkService::Stub*, grpc::ClientContext*, CompletionQueue*,
-          void*)> start_req_;
+  std::function<std::unique_ptr<
+      grpc::ClientAsyncReaderWriter<RequestType, ResponseType>>(
+      BenchmarkService::Stub*, grpc::ClientContext*, CompletionQueue*, void*)>
+      start_req_;
   grpc::Status status_;
   double start_;
   std::unique_ptr<grpc::ClientAsyncReaderWriter<RequestType, ResponseType>>
@@ -507,7 +511,8 @@ class ClientRpcContextGenericStreamingImpl : public ClientRpcContext {
       int channel_id, grpc::GenericStub* stub, const ByteBuffer& req,
       std::function<std::unique_ptr<grpc::GenericClientAsyncReaderWriter>(
           grpc::GenericStub*, grpc::ClientContext*,
-          const grpc::string& method_name, CompletionQueue*, void*)> start_req,
+          const grpc::string& method_name, CompletionQueue*, void*)>
+          start_req,
       std::function<void(grpc::Status, ByteBuffer*)> on_done)
       : ClientRpcContext(channel_id),
         context_(),
@@ -564,7 +569,8 @@ class ClientRpcContextGenericStreamingImpl : public ClientRpcContext {
   std::function<void(grpc::Status, ByteBuffer*)> callback_;
   std::function<std::unique_ptr<grpc::GenericClientAsyncReaderWriter>(
       grpc::GenericStub*, grpc::ClientContext*, const grpc::string&,
-      CompletionQueue*, void*)> start_req_;
+      CompletionQueue*, void*)>
+      start_req_;
   grpc::Status status_;
   double start_;
   std::unique_ptr<grpc::GenericClientAsyncReaderWriter> stream_;
diff --git a/tools/doxygen/Doxyfile.core.internal b/tools/doxygen/Doxyfile.core.internal
index 337d628942..e91b47c6f4 100644
--- a/tools/doxygen/Doxyfile.core.internal
+++ b/tools/doxygen/Doxyfile.core.internal
@@ -953,7 +953,6 @@ src/core/support/string_win32.h \
 src/core/support/thd_internal.h \
 src/core/support/time_precise.h \
 src/core/census/aggregation.h \
-src/core/census/context.h \
 src/core/census/rpc_metric_id.h \
 src/core/httpcli/httpcli_security_connector.c \
 src/core/security/base64.c \
@@ -1150,7 +1149,6 @@ src/core/census/context.c \
 src/core/census/initialize.c \
 src/core/census/operation.c \
 src/core/census/placeholders.c \
-src/core/census/tag_set.c \
 src/core/census/tracing.c
 
 # This tag can be used to specify the character encoding of the source files
diff --git a/tools/run_tests/sources_and_headers.json b/tools/run_tests/sources_and_headers.json
index 76065e99c7..d2938ae3ca 100644
--- a/tools/run_tests/sources_and_headers.json
+++ b/tools/run_tests/sources_and_headers.json
@@ -68,6 +68,18 @@
     ], 
     "headers": [], 
     "language": "c", 
+    "name": "census_context_test", 
+    "src": [
+      "test/core/census/context_test.c"
+    ]
+  }, 
+  {
+    "deps": [
+      "grpc", 
+      "grpc_test_util"
+    ], 
+    "headers": [], 
+    "language": "c", 
     "name": "channel_create_test", 
     "src": [
       "test/core/surface/channel_create_test.c"
@@ -988,18 +1000,6 @@
     ], 
     "headers": [], 
     "language": "c", 
-    "name": "tag_set_test", 
-    "src": [
-      "test/core/census/tag_set_test.c"
-    ]
-  }, 
-  {
-    "deps": [
-      "grpc", 
-      "grpc_test_util"
-    ], 
-    "headers": [], 
-    "language": "c", 
     "name": "tcp_client_posix_test", 
     "src": [
       "test/core/iomgr/tcp_client_posix_test.c"
@@ -2506,7 +2506,6 @@
       "include/grpc/support/tls_pthread.h", 
       "include/grpc/support/useful.h", 
       "src/core/census/aggregation.h", 
-      "src/core/census/context.h", 
       "src/core/census/grpc_filter.h", 
       "src/core/census/rpc_metric_id.h", 
       "src/core/channel/channel_args.h", 
@@ -2706,7 +2705,6 @@
       "include/grpc/support/useful.h", 
       "src/core/census/aggregation.h", 
       "src/core/census/context.c", 
-      "src/core/census/context.h", 
       "src/core/census/grpc_context.c", 
       "src/core/census/grpc_filter.c", 
       "src/core/census/grpc_filter.h", 
@@ -2714,7 +2712,6 @@
       "src/core/census/operation.c", 
       "src/core/census/placeholders.c", 
       "src/core/census/rpc_metric_id.h", 
-      "src/core/census/tag_set.c", 
       "src/core/census/tracing.c", 
       "src/core/channel/channel_args.c", 
       "src/core/channel/channel_args.h", 
@@ -3181,7 +3178,6 @@
       "include/grpc/support/tls_pthread.h", 
       "include/grpc/support/useful.h", 
       "src/core/census/aggregation.h", 
-      "src/core/census/context.h", 
       "src/core/census/grpc_filter.h", 
       "src/core/census/rpc_metric_id.h", 
       "src/core/channel/channel_args.h", 
@@ -3366,7 +3362,6 @@
       "include/grpc/support/useful.h", 
       "src/core/census/aggregation.h", 
       "src/core/census/context.c", 
-      "src/core/census/context.h", 
       "src/core/census/grpc_context.c", 
       "src/core/census/grpc_filter.c", 
       "src/core/census/grpc_filter.h", 
@@ -3374,7 +3369,6 @@
       "src/core/census/operation.c", 
       "src/core/census/placeholders.c", 
       "src/core/census/rpc_metric_id.h", 
-      "src/core/census/tag_set.c", 
       "src/core/census/tracing.c", 
       "src/core/channel/channel_args.c", 
       "src/core/channel/channel_args.h", 
diff --git a/tools/run_tests/tests.json b/tools/run_tests/tests.json
index a23a340b6c..4669d37bb1 100644
--- a/tools/run_tests/tests.json
+++ b/tools/run_tests/tests.json
@@ -113,6 +113,26 @@
     "exclude_configs": [], 
     "flaky": false, 
     "language": "c", 
+    "name": "census_context_test", 
+    "platforms": [
+      "linux", 
+      "mac", 
+      "posix", 
+      "windows"
+    ]
+  }, 
+  {
+    "args": [], 
+    "ci_platforms": [
+      "linux", 
+      "mac", 
+      "posix", 
+      "windows"
+    ], 
+    "cpu_cost": 1.0, 
+    "exclude_configs": [], 
+    "flaky": false, 
+    "language": "c", 
     "name": "channel_create_test", 
     "platforms": [
       "linux", 
@@ -1424,26 +1444,6 @@
     "ci_platforms": [
       "linux", 
       "mac", 
-      "posix", 
-      "windows"
-    ], 
-    "cpu_cost": 1.0, 
-    "exclude_configs": [], 
-    "flaky": false, 
-    "language": "c", 
-    "name": "tag_set_test", 
-    "platforms": [
-      "linux", 
-      "mac", 
-      "posix", 
-      "windows"
-    ]
-  }, 
-  {
-    "args": [], 
-    "ci_platforms": [
-      "linux", 
-      "mac", 
       "posix"
     ], 
     "cpu_cost": 0.5, 
diff --git a/vsprojects/buildtests_c.sln b/vsprojects/buildtests_c.sln
index 1b7261d3a9..f56a69f1ae 100644
--- a/vsprojects/buildtests_c.sln
+++ b/vsprojects/buildtests_c.sln
@@ -126,6 +126,15 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "bin_encoder_test", "vcxproj
 		{29D16885-7228-4C31-81ED-5F9187C7F2A9} = {29D16885-7228-4C31-81ED-5F9187C7F2A9}
 	EndProjectSection
 EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "census_context_test", "vcxproj\test\census_context_test\census_context_test.vcxproj", "{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}"
+	ProjectSection(myProperties) = preProject
+        	lib = "False"
+	EndProjectSection
+	ProjectSection(ProjectDependencies) = postProject
+		{17BCAFC0-5FDC-4C94-AEB9-95F3E220614B} = {17BCAFC0-5FDC-4C94-AEB9-95F3E220614B}
+		{29D16885-7228-4C31-81ED-5F9187C7F2A9} = {29D16885-7228-4C31-81ED-5F9187C7F2A9}
+	EndProjectSection
+EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "channel_create_test", "vcxproj\test\channel_create_test\channel_create_test.vcxproj", "{AFC88484-3A2E-32BC-25B2-23DF741D4F3D}"
 	ProjectSection(myProperties) = preProject
         	lib = "False"
@@ -724,15 +733,6 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "sockaddr_utils_test", "vcxp
 		{29D16885-7228-4C31-81ED-5F9187C7F2A9} = {29D16885-7228-4C31-81ED-5F9187C7F2A9}
 	EndProjectSection
 EndProject
-Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "tag_set_test", "vcxproj\test\tag_set_test\tag_set_test.vcxproj", "{430F8F07-6AAD-0150-B35B-DB9E2E21941A}"
-	ProjectSection(myProperties) = preProject
-        	lib = "False"
-	EndProjectSection
-	ProjectSection(ProjectDependencies) = postProject
-		{17BCAFC0-5FDC-4C94-AEB9-95F3E220614B} = {17BCAFC0-5FDC-4C94-AEB9-95F3E220614B}
-		{29D16885-7228-4C31-81ED-5F9187C7F2A9} = {29D16885-7228-4C31-81ED-5F9187C7F2A9}
-	EndProjectSection
-EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "time_averaged_stats_test", "vcxproj\test\time_averaged_stats_test\time_averaged_stats_test.vcxproj", "{D1EB2A9B-8508-62D7-8FC4-11A11B1CBFD3}"
 	ProjectSection(myProperties) = preProject
         	lib = "False"
@@ -1349,6 +1349,22 @@ Global
 		{D5C70922-D68E-0E9D-9988-995E0F9A79AE}.Release-DLL|Win32.Build.0 = Release|Win32
 		{D5C70922-D68E-0E9D-9988-995E0F9A79AE}.Release-DLL|x64.ActiveCfg = Release|x64
 		{D5C70922-D68E-0E9D-9988-995E0F9A79AE}.Release-DLL|x64.Build.0 = Release|x64
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Debug|Win32.ActiveCfg = Debug|Win32
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Debug|x64.ActiveCfg = Debug|x64
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Release|Win32.ActiveCfg = Release|Win32
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Release|x64.ActiveCfg = Release|x64
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Debug|Win32.Build.0 = Debug|Win32
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Debug|x64.Build.0 = Debug|x64
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Release|Win32.Build.0 = Release|Win32
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Release|x64.Build.0 = Release|x64
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Debug-DLL|Win32.ActiveCfg = Debug|Win32
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Debug-DLL|Win32.Build.0 = Debug|Win32
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Debug-DLL|x64.ActiveCfg = Debug|x64
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Debug-DLL|x64.Build.0 = Debug|x64
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Release-DLL|Win32.ActiveCfg = Release|Win32
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Release-DLL|Win32.Build.0 = Release|Win32
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Release-DLL|x64.ActiveCfg = Release|x64
+		{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}.Release-DLL|x64.Build.0 = Release|x64
 		{AFC88484-3A2E-32BC-25B2-23DF741D4F3D}.Debug|Win32.ActiveCfg = Debug|Win32
 		{AFC88484-3A2E-32BC-25B2-23DF741D4F3D}.Debug|x64.ActiveCfg = Debug|x64
 		{AFC88484-3A2E-32BC-25B2-23DF741D4F3D}.Release|Win32.ActiveCfg = Release|Win32
@@ -2421,22 +2437,6 @@ Global
 		{529771F0-10B0-9B1A-1E7E-8A8E01870348}.Release-DLL|Win32.Build.0 = Release|Win32
 		{529771F0-10B0-9B1A-1E7E-8A8E01870348}.Release-DLL|x64.ActiveCfg = Release|x64
 		{529771F0-10B0-9B1A-1E7E-8A8E01870348}.Release-DLL|x64.Build.0 = Release|x64
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Debug|Win32.ActiveCfg = Debug|Win32
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Debug|x64.ActiveCfg = Debug|x64
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Release|Win32.ActiveCfg = Release|Win32
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Release|x64.ActiveCfg = Release|x64
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Debug|Win32.Build.0 = Debug|Win32
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Debug|x64.Build.0 = Debug|x64
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Release|Win32.Build.0 = Release|Win32
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Release|x64.Build.0 = Release|x64
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Debug-DLL|Win32.ActiveCfg = Debug|Win32
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Debug-DLL|Win32.Build.0 = Debug|Win32
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Debug-DLL|x64.ActiveCfg = Debug|x64
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Debug-DLL|x64.Build.0 = Debug|x64
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Release-DLL|Win32.ActiveCfg = Release|Win32
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Release-DLL|Win32.Build.0 = Release|Win32
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Release-DLL|x64.ActiveCfg = Release|x64
-		{430F8F07-6AAD-0150-B35B-DB9E2E21941A}.Release-DLL|x64.Build.0 = Release|x64
 		{D1EB2A9B-8508-62D7-8FC4-11A11B1CBFD3}.Debug|Win32.ActiveCfg = Debug|Win32
 		{D1EB2A9B-8508-62D7-8FC4-11A11B1CBFD3}.Debug|x64.ActiveCfg = Debug|x64
 		{D1EB2A9B-8508-62D7-8FC4-11A11B1CBFD3}.Release|Win32.ActiveCfg = Release|Win32
diff --git a/vsprojects/vcxproj/grpc/grpc.vcxproj b/vsprojects/vcxproj/grpc/grpc.vcxproj
index 02c5936f2a..f7a19de4a7 100644
--- a/vsprojects/vcxproj/grpc/grpc.vcxproj
+++ b/vsprojects/vcxproj/grpc/grpc.vcxproj
@@ -462,7 +462,6 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\support\thd_internal.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\support\time_precise.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\census\aggregation.h" />
-    <ClInclude Include="$(SolutionDir)\..\src\core\census\context.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\census\rpc_metric_id.h" />
   </ItemGroup>
   <ItemGroup>
@@ -856,8 +855,6 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\census\placeholders.c">
     </ClCompile>
-    <ClCompile Include="$(SolutionDir)\..\src\core\census\tag_set.c">
-    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\census\tracing.c">
     </ClCompile>
   </ItemGroup>
diff --git a/vsprojects/vcxproj/grpc/grpc.vcxproj.filters b/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
index d6c9ebbc50..b9fa984390 100644
--- a/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
+++ b/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
@@ -586,9 +586,6 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\census\placeholders.c">
       <Filter>src\core\census</Filter>
     </ClCompile>
-    <ClCompile Include="$(SolutionDir)\..\src\core\census\tag_set.c">
-      <Filter>src\core\census</Filter>
-    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\census\tracing.c">
       <Filter>src\core\census</Filter>
     </ClCompile>
@@ -1175,9 +1172,6 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\census\aggregation.h">
       <Filter>src\core\census</Filter>
     </ClInclude>
-    <ClInclude Include="$(SolutionDir)\..\src\core\census\context.h">
-      <Filter>src\core\census</Filter>
-    </ClInclude>
     <ClInclude Include="$(SolutionDir)\..\src\core\census\rpc_metric_id.h">
       <Filter>src\core\census</Filter>
     </ClInclude>
diff --git a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
index 98cf423e2b..3220dbdc70 100644
--- a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
+++ b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
@@ -438,7 +438,6 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\transport\transport.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\transport\transport_impl.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\census\aggregation.h" />
-    <ClInclude Include="$(SolutionDir)\..\src\core\census\context.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\census\rpc_metric_id.h" />
   </ItemGroup>
   <ItemGroup>
@@ -792,8 +791,6 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\census\placeholders.c">
     </ClCompile>
-    <ClCompile Include="$(SolutionDir)\..\src\core\census\tag_set.c">
-    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\census\tracing.c">
     </ClCompile>
   </ItemGroup>
diff --git a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
index 31e2157b02..a9cdf19c66 100644
--- a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
+++ b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
@@ -526,9 +526,6 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\census\placeholders.c">
       <Filter>src\core\census</Filter>
     </ClCompile>
-    <ClCompile Include="$(SolutionDir)\..\src\core\census\tag_set.c">
-      <Filter>src\core\census</Filter>
-    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\census\tracing.c">
       <Filter>src\core\census</Filter>
     </ClCompile>
@@ -1070,9 +1067,6 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\census\aggregation.h">
       <Filter>src\core\census</Filter>
     </ClInclude>
-    <ClInclude Include="$(SolutionDir)\..\src\core\census\context.h">
-      <Filter>src\core\census</Filter>
-    </ClInclude>
     <ClInclude Include="$(SolutionDir)\..\src\core\census\rpc_metric_id.h">
       <Filter>src\core\census</Filter>
     </ClInclude>
diff --git a/vsprojects/vcxproj/test/tag_set_test/tag_set_test.vcxproj b/vsprojects/vcxproj/test/census_context_test/census_context_test.vcxproj
index 26ddfe13ef..c29f3db7d8 100644
--- a/vsprojects/vcxproj/test/tag_set_test/tag_set_test.vcxproj
+++ b/vsprojects/vcxproj/test/census_context_test/census_context_test.vcxproj
@@ -20,7 +20,7 @@
     </ProjectConfiguration>
   </ItemGroup>
   <PropertyGroup Label="Globals">
-    <ProjectGuid>{430F8F07-6AAD-0150-B35B-DB9E2E21941A}</ProjectGuid>
+    <ProjectGuid>{5C1CFC2D-AF3C-D7CB-BA74-D267E91CBC73}</ProjectGuid>
     <IgnoreWarnIntDirInTempDetected>true</IgnoreWarnIntDirInTempDetected>
     <IntDir>$(SolutionDir)IntDir\$(MSBuildProjectName)\</IntDir>
   </PropertyGroup>
@@ -60,14 +60,14 @@
   </ImportGroup>
   <PropertyGroup Label="UserMacros" />
   <PropertyGroup Condition="'$(Configuration)'=='Debug'">
-    <TargetName>tag_set_test</TargetName>
+    <TargetName>census_context_test</TargetName>
     <Linkage-grpc_dependencies_zlib>static</Linkage-grpc_dependencies_zlib>
     <Configuration-grpc_dependencies_zlib>Debug</Configuration-grpc_dependencies_zlib>
     <Linkage-grpc_dependencies_openssl>static</Linkage-grpc_dependencies_openssl>
     <Configuration-grpc_dependencies_openssl>Debug</Configuration-grpc_dependencies_openssl>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)'=='Release'">
-    <TargetName>tag_set_test</TargetName>
+    <TargetName>census_context_test</TargetName>
     <Linkage-grpc_dependencies_zlib>static</Linkage-grpc_dependencies_zlib>
     <Configuration-grpc_dependencies_zlib>Release</Configuration-grpc_dependencies_zlib>
     <Linkage-grpc_dependencies_openssl>static</Linkage-grpc_dependencies_openssl>
@@ -158,7 +158,7 @@
   </ItemDefinitionGroup>
 
   <ItemGroup>
-    <ClCompile Include="$(SolutionDir)\..\test\core\census\tag_set_test.c">
+    <ClCompile Include="$(SolutionDir)\..\test\core\census\context_test.c">
     </ClCompile>
   </ItemGroup>
   <ItemGroup>
diff --git a/vsprojects/vcxproj/test/tag_set_test/tag_set_test.vcxproj.filters b/vsprojects/vcxproj/test/census_context_test/census_context_test.vcxproj.filters
index 6b31532251..53a7a66e2e 100644
--- a/vsprojects/vcxproj/test/tag_set_test/tag_set_test.vcxproj.filters
+++ b/vsprojects/vcxproj/test/census_context_test/census_context_test.vcxproj.filters
@@ -1,20 +1,20 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <ItemGroup>
-    <ClCompile Include="$(SolutionDir)\..\test\core\census\tag_set_test.c">
+    <ClCompile Include="$(SolutionDir)\..\test\core\census\context_test.c">
       <Filter>test\core\census</Filter>
     </ClCompile>
   </ItemGroup>
 
   <ItemGroup>
     <Filter Include="test">
-      <UniqueIdentifier>{500aa440-5924-8047-996a-4c5096d1ef96}</UniqueIdentifier>
+      <UniqueIdentifier>{bc15bb31-7dbe-17f2-fb1c-4bc140ce1707}</UniqueIdentifier>
     </Filter>
     <Filter Include="test\core">
-      <UniqueIdentifier>{a3bf80f0-5b13-f623-277b-05f0231dd933}</UniqueIdentifier>
+      <UniqueIdentifier>{806f9b58-6a48-ae09-3cc6-bb36e3126f27}</UniqueIdentifier>
     </Filter>
     <Filter Include="test\core\census">
-      <UniqueIdentifier>{b6ed1b86-7795-4da9-a169-9eccf836852c}</UniqueIdentifier>
+      <UniqueIdentifier>{85e37a47-e797-dcd1-b1e0-df553a454d8f}</UniqueIdentifier>
     </Filter>
   </ItemGroup>
 </Project>