Merge branch 'master' of https://github.com/grpc/grpc into go_advanced_interop

54 files changed, 588 insertions, 144 deletions

diff --git a/BUILD b/BUILD
index 894c7b2c6d..e73b32ded7 100644
--- a/BUILD
+++ b/BUILD
@@ -203,6 +203,7 @@ cc_library(
     "src/core/lib/iomgr/sockaddr_posix.h",
     "src/core/lib/iomgr/sockaddr_utils.h",
     "src/core/lib/iomgr/sockaddr_windows.h",
+    "src/core/lib/iomgr/socket_mutator.h",
     "src/core/lib/iomgr/socket_utils.h",
     "src/core/lib/iomgr/socket_utils_posix.h",
     "src/core/lib/iomgr/socket_windows.h",
@@ -376,6 +377,7 @@ cc_library(
     "src/core/lib/iomgr/resolve_address_windows.c",
     "src/core/lib/iomgr/resource_quota.c",
     "src/core/lib/iomgr/sockaddr_utils.c",
+    "src/core/lib/iomgr/socket_mutator.c",
     "src/core/lib/iomgr/socket_utils_common_posix.c",
     "src/core/lib/iomgr/socket_utils_linux.c",
     "src/core/lib/iomgr/socket_utils_posix.c",
@@ -637,6 +639,7 @@ cc_library(
     "src/core/lib/iomgr/sockaddr_posix.h",
     "src/core/lib/iomgr/sockaddr_utils.h",
     "src/core/lib/iomgr/sockaddr_windows.h",
+    "src/core/lib/iomgr/socket_mutator.h",
     "src/core/lib/iomgr/socket_utils.h",
     "src/core/lib/iomgr/socket_utils_posix.h",
     "src/core/lib/iomgr/socket_windows.h",
@@ -795,6 +798,7 @@ cc_library(
     "src/core/lib/iomgr/resolve_address_windows.c",
     "src/core/lib/iomgr/resource_quota.c",
     "src/core/lib/iomgr/sockaddr_utils.c",
+    "src/core/lib/iomgr/socket_mutator.c",
     "src/core/lib/iomgr/socket_utils_common_posix.c",
     "src/core/lib/iomgr/socket_utils_linux.c",
     "src/core/lib/iomgr/socket_utils_posix.c",
@@ -1026,6 +1030,7 @@ cc_library(
     "src/core/lib/iomgr/sockaddr_posix.h",
     "src/core/lib/iomgr/sockaddr_utils.h",
     "src/core/lib/iomgr/sockaddr_windows.h",
+    "src/core/lib/iomgr/socket_mutator.h",
     "src/core/lib/iomgr/socket_utils.h",
     "src/core/lib/iomgr/socket_utils_posix.h",
     "src/core/lib/iomgr/socket_windows.h",
@@ -1176,6 +1181,7 @@ cc_library(
     "src/core/lib/iomgr/resolve_address_windows.c",
     "src/core/lib/iomgr/resource_quota.c",
     "src/core/lib/iomgr/sockaddr_utils.c",
+    "src/core/lib/iomgr/socket_mutator.c",
     "src/core/lib/iomgr/socket_utils_common_posix.c",
     "src/core/lib/iomgr/socket_utils_linux.c",
     "src/core/lib/iomgr/socket_utils_posix.c",
@@ -2037,6 +2043,7 @@ objc_library(
     "src/core/lib/iomgr/resolve_address_windows.c",
     "src/core/lib/iomgr/resource_quota.c",
     "src/core/lib/iomgr/sockaddr_utils.c",
+    "src/core/lib/iomgr/socket_mutator.c",
     "src/core/lib/iomgr/socket_utils_common_posix.c",
     "src/core/lib/iomgr/socket_utils_linux.c",
     "src/core/lib/iomgr/socket_utils_posix.c",
@@ -2277,6 +2284,7 @@ objc_library(
     "src/core/lib/iomgr/sockaddr_posix.h",
     "src/core/lib/iomgr/sockaddr_utils.h",
     "src/core/lib/iomgr/sockaddr_windows.h",
+    "src/core/lib/iomgr/socket_mutator.h",
     "src/core/lib/iomgr/socket_utils.h",
     "src/core/lib/iomgr/socket_utils_posix.h",
     "src/core/lib/iomgr/socket_windows.h",
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 98d54f2198..3ea9998341 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -331,6 +331,7 @@ add_library(grpc
   src/core/lib/iomgr/resolve_address_windows.c
   src/core/lib/iomgr/resource_quota.c
   src/core/lib/iomgr/sockaddr_utils.c
+  src/core/lib/iomgr/socket_mutator.c
   src/core/lib/iomgr/socket_utils_common_posix.c
   src/core/lib/iomgr/socket_utils_linux.c
   src/core/lib/iomgr/socket_utils_posix.c
@@ -610,6 +611,7 @@ add_library(grpc_cronet
   src/core/lib/iomgr/resolve_address_windows.c
   src/core/lib/iomgr/resource_quota.c
   src/core/lib/iomgr/sockaddr_utils.c
+  src/core/lib/iomgr/socket_mutator.c
   src/core/lib/iomgr/socket_utils_common_posix.c
   src/core/lib/iomgr/socket_utils_linux.c
   src/core/lib/iomgr/socket_utils_posix.c
@@ -861,6 +863,7 @@ add_library(grpc_unsecure
   src/core/lib/iomgr/resolve_address_windows.c
   src/core/lib/iomgr/resource_quota.c
   src/core/lib/iomgr/sockaddr_utils.c
+  src/core/lib/iomgr/socket_mutator.c
   src/core/lib/iomgr/socket_utils_common_posix.c
   src/core/lib/iomgr/socket_utils_linux.c
   src/core/lib/iomgr/socket_utils_posix.c
diff --git a/Makefile b/Makefile
index 56c05f1585..351abdaada 100644
--- a/Makefile
+++ b/Makefile
@@ -2665,6 +2665,7 @@ LIBGRPC_SRC = \
     src/core/lib/iomgr/resolve_address_windows.c \
     src/core/lib/iomgr/resource_quota.c \
     src/core/lib/iomgr/sockaddr_utils.c \
+    src/core/lib/iomgr/socket_mutator.c \
     src/core/lib/iomgr/socket_utils_common_posix.c \
     src/core/lib/iomgr/socket_utils_linux.c \
     src/core/lib/iomgr/socket_utils_posix.c \
@@ -2962,6 +2963,7 @@ LIBGRPC_CRONET_SRC = \
     src/core/lib/iomgr/resolve_address_windows.c \
     src/core/lib/iomgr/resource_quota.c \
     src/core/lib/iomgr/sockaddr_utils.c \
+    src/core/lib/iomgr/socket_mutator.c \
     src/core/lib/iomgr/socket_utils_common_posix.c \
     src/core/lib/iomgr/socket_utils_linux.c \
     src/core/lib/iomgr/socket_utils_posix.c \
@@ -3250,6 +3252,7 @@ LIBGRPC_TEST_UTIL_SRC = \
     src/core/lib/iomgr/resolve_address_windows.c \
     src/core/lib/iomgr/resource_quota.c \
     src/core/lib/iomgr/sockaddr_utils.c \
+    src/core/lib/iomgr/socket_mutator.c \
     src/core/lib/iomgr/socket_utils_common_posix.c \
     src/core/lib/iomgr/socket_utils_linux.c \
     src/core/lib/iomgr/socket_utils_posix.c \
@@ -3467,6 +3470,7 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/lib/iomgr/resolve_address_windows.c \
     src/core/lib/iomgr/resource_quota.c \
     src/core/lib/iomgr/sockaddr_utils.c \
+    src/core/lib/iomgr/socket_mutator.c \
     src/core/lib/iomgr/socket_utils_common_posix.c \
     src/core/lib/iomgr/socket_utils_linux.c \
     src/core/lib/iomgr/socket_utils_posix.c \
diff --git a/binding.gyp b/binding.gyp
index ba90fcaa10..11a2e2884e 100644
--- a/binding.gyp
+++ b/binding.gyp
@@ -611,6 +611,7 @@
         'src/core/lib/iomgr/resolve_address_windows.c',
         'src/core/lib/iomgr/resource_quota.c',
         'src/core/lib/iomgr/sockaddr_utils.c',
+        'src/core/lib/iomgr/socket_mutator.c',
         'src/core/lib/iomgr/socket_utils_common_posix.c',
         'src/core/lib/iomgr/socket_utils_linux.c',
         'src/core/lib/iomgr/socket_utils_posix.c',
diff --git a/build.yaml b/build.yaml
index 41c0f9a086..518484134b 100644
--- a/build.yaml
+++ b/build.yaml
@@ -210,6 +210,7 @@ filegroups:
   - src/core/lib/iomgr/sockaddr_posix.h
   - src/core/lib/iomgr/sockaddr_utils.h
   - src/core/lib/iomgr/sockaddr_windows.h
+  - src/core/lib/iomgr/socket_mutator.h
   - src/core/lib/iomgr/socket_utils.h
   - src/core/lib/iomgr/socket_utils_posix.h
   - src/core/lib/iomgr/socket_windows.h
@@ -307,6 +308,7 @@ filegroups:
   - src/core/lib/iomgr/resolve_address_windows.c
   - src/core/lib/iomgr/resource_quota.c
   - src/core/lib/iomgr/sockaddr_utils.c
+  - src/core/lib/iomgr/socket_mutator.c
   - src/core/lib/iomgr/socket_utils_common_posix.c
   - src/core/lib/iomgr/socket_utils_linux.c
   - src/core/lib/iomgr/socket_utils_posix.c
diff --git a/config.m4 b/config.m4
index 988cc5b003..9d1c2268c7 100644
--- a/config.m4
+++ b/config.m4
@@ -127,6 +127,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/lib/iomgr/resolve_address_windows.c \
     src/core/lib/iomgr/resource_quota.c \
     src/core/lib/iomgr/sockaddr_utils.c \
+    src/core/lib/iomgr/socket_mutator.c \
     src/core/lib/iomgr/socket_utils_common_posix.c \
     src/core/lib/iomgr/socket_utils_linux.c \
     src/core/lib/iomgr/socket_utils_posix.c \
diff --git a/doc/PROTOCOL-WEB.md b/doc/PROTOCOL-WEB.md
index 7d9b9f069a..562d5999cf 100644
--- a/doc/PROTOCOL-WEB.md
+++ b/doc/PROTOCOL-WEB.md
@@ -60,8 +60,7 @@ HTTP/2 related behavior (specified in [gRPC over HTTP2](http://www.grpc.io/docs/
 Message framing (vs. [http2-transport-mapping](http://www.grpc.io/docs/guides/wire.html#http2-transport-mapping))
 
 1. Response status encoded as part of the response body
-  * Key-value pairs formatted as HTTP/1.1 headers block (without the empty
-  newline \r\n to terminate the block)
+  * Key-value pairs encoded in the HTTP/2 [literal header format](https://tools.ietf.org/html/rfc7541#section-6.2) as a single header block.
 2. 8th (MSB) bit of the 1st gRPC frame byte
   * 0: data
   * 1: trailers
diff --git a/gRPC-Core.podspec b/gRPC-Core.podspec
index 8869bec32e..bba1aeab53 100644
--- a/gRPC-Core.podspec
+++ b/gRPC-Core.podspec
@@ -292,6 +292,7 @@ Pod::Spec.new do |s|
                       'src/core/lib/iomgr/sockaddr_posix.h',
                       'src/core/lib/iomgr/sockaddr_utils.h',
                       'src/core/lib/iomgr/sockaddr_windows.h',
+                      'src/core/lib/iomgr/socket_mutator.h',
                       'src/core/lib/iomgr/socket_utils.h',
                       'src/core/lib/iomgr/socket_utils_posix.h',
                       'src/core/lib/iomgr/socket_windows.h',
@@ -469,6 +470,7 @@ Pod::Spec.new do |s|
                       'src/core/lib/iomgr/resolve_address_windows.c',
                       'src/core/lib/iomgr/resource_quota.c',
                       'src/core/lib/iomgr/sockaddr_utils.c',
+                      'src/core/lib/iomgr/socket_mutator.c',
                       'src/core/lib/iomgr/socket_utils_common_posix.c',
                       'src/core/lib/iomgr/socket_utils_linux.c',
                       'src/core/lib/iomgr/socket_utils_posix.c',
@@ -695,6 +697,7 @@ Pod::Spec.new do |s|
                               'src/core/lib/iomgr/sockaddr_posix.h',
                               'src/core/lib/iomgr/sockaddr_utils.h',
                               'src/core/lib/iomgr/sockaddr_windows.h',
+                              'src/core/lib/iomgr/socket_mutator.h',
                               'src/core/lib/iomgr/socket_utils.h',
                               'src/core/lib/iomgr/socket_utils_posix.h',
                               'src/core/lib/iomgr/socket_windows.h',
diff --git a/grpc.gemspec b/grpc.gemspec
index b071fccb82..aac12c4824 100755
--- a/grpc.gemspec
+++ b/grpc.gemspec
@@ -212,6 +212,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/iomgr/sockaddr_posix.h )
   s.files += %w( src/core/lib/iomgr/sockaddr_utils.h )
   s.files += %w( src/core/lib/iomgr/sockaddr_windows.h )
+  s.files += %w( src/core/lib/iomgr/socket_mutator.h )
   s.files += %w( src/core/lib/iomgr/socket_utils.h )
   s.files += %w( src/core/lib/iomgr/socket_utils_posix.h )
   s.files += %w( src/core/lib/iomgr/socket_windows.h )
@@ -389,6 +390,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/iomgr/resolve_address_windows.c )
   s.files += %w( src/core/lib/iomgr/resource_quota.c )
   s.files += %w( src/core/lib/iomgr/sockaddr_utils.c )
+  s.files += %w( src/core/lib/iomgr/socket_mutator.c )
   s.files += %w( src/core/lib/iomgr/socket_utils_common_posix.c )
   s.files += %w( src/core/lib/iomgr/socket_utils_linux.c )
   s.files += %w( src/core/lib/iomgr/socket_utils_posix.c )
diff --git a/include/grpc++/impl/codegen/completion_queue.h b/include/grpc++/impl/codegen/completion_queue.h
index 29bc97fdf7..ef00163b7e 100644
--- a/include/grpc++/impl/codegen/completion_queue.h
+++ b/include/grpc++/impl/codegen/completion_queue.h
@@ -240,7 +240,7 @@ class ServerCompletionQueue : public CompletionQueue {
  private:
   bool is_frequently_polled_;
   friend class ServerBuilder;
-  /// \param is_frequently_polled Informs the GPRC library about whether the
+  /// \param is_frequently_polled Informs the GRPC library about whether the
   /// server completion queue would be actively polled (by calling Next() or
   /// AsyncNext()). By default all server completion queues are assumed to be
   /// frequently polled.
diff --git a/include/grpc++/support/channel_arguments.h b/include/grpc++/support/channel_arguments.h
index 49a3e9461c..8d975f5214 100644
--- a/include/grpc++/support/channel_arguments.h
+++ b/include/grpc++/support/channel_arguments.h
@@ -79,6 +79,9 @@ class ChannelArguments {
   /// Set the compression algorithm for the channel.
   void SetCompressionAlgorithm(grpc_compression_algorithm algorithm);
 
+  /// Set the socket mutator for the channel.
+  void SetSocketMutator(grpc_socket_mutator* mutator);
+
   /// The given string will be sent at the front of the user agent string.
   void SetUserAgentPrefix(const grpc::string& user_agent_prefix);
 
diff --git a/include/grpc/impl/codegen/grpc_types.h b/include/grpc/impl/codegen/grpc_types.h
index 1bf78e4e69..8c5215faee 100644
--- a/include/grpc/impl/codegen/grpc_types.h
+++ b/include/grpc/impl/codegen/grpc_types.h
@@ -84,6 +84,9 @@ typedef struct grpc_server grpc_server;
     can have messages written to it and read from it. */
 typedef struct grpc_call grpc_call;
 
+/** The Socket Mutator interface allows changes on socket options */
+typedef struct grpc_socket_mutator grpc_socket_mutator;
+
 /** Type specifier for grpc_arg */
 typedef enum {
   GRPC_ARG_STRING,
@@ -215,6 +218,8 @@ typedef struct {
 /** Resolved addresses in a form used by the LB policy.
     Not intended for external use. */
 #define GRPC_ARG_LB_ADDRESSES "grpc.lb_addresses"
+/** The grpc_socket_mutator instance that set the socket options. A pointer. */
+#define GRPC_ARG_SOCKET_MUTATOR "grpc.socket_mutator"
 /** \} */
 
 /** Result of a grpc call. If the caller satisfies the prerequisites of a
diff --git a/include/grpc/impl/codegen/port_platform.h b/include/grpc/impl/codegen/port_platform.h
index 34df89700d..cd989d664c 100644
--- a/include/grpc/impl/codegen/port_platform.h
+++ b/include/grpc/impl/codegen/port_platform.h
@@ -368,14 +368,14 @@ typedef unsigned __int64 uint64_t;
 #endif
 #endif
 
-#ifndef GPRC_PRINT_FORMAT_CHECK
+#ifndef GPR_PRINT_FORMAT_CHECK
 #ifdef __GNUC__
-#define GPRC_PRINT_FORMAT_CHECK(FORMAT_STR, ARGS) \
+#define GPR_PRINT_FORMAT_CHECK(FORMAT_STR, ARGS) \
   __attribute__((format(printf, FORMAT_STR, ARGS)))
 #else
-#define GPRC_PRINT_FORMAT_CHECK(FORMAT_STR, ARGS)
+#define GPR_PRINT_FORMAT_CHECK(FORMAT_STR, ARGS)
 #endif
-#endif /* GPRC_PRINT_FORMAT_CHECK */
+#endif /* GPR_PRINT_FORMAT_CHECK */
 
 #if GPR_FORBID_UNREACHABLE_CODE
 #define GPR_UNREACHABLE_CODE(STATEMENT)
diff --git a/include/grpc/support/log.h b/include/grpc/support/log.h
index 5acf17fc2c..88346cc9f4 100644
--- a/include/grpc/support/log.h
+++ b/include/grpc/support/log.h
@@ -75,7 +75,7 @@ const char *gpr_log_severity_string(gpr_log_severity severity);
 /* Log a message. It's advised to use GPR_xxx above to generate the context
  * for each message */
 GPRAPI void gpr_log(const char *file, int line, gpr_log_severity severity,
-                    const char *format, ...) GPRC_PRINT_FORMAT_CHECK(4, 5);
+                    const char *format, ...) GPR_PRINT_FORMAT_CHECK(4, 5);
 
 GPRAPI void gpr_log_message(const char *file, int line,
                             gpr_log_severity severity, const char *message);
diff --git a/include/grpc/support/string_util.h b/include/grpc/support/string_util.h
index 952cbfc26b..5ab983d15d 100644
--- a/include/grpc/support/string_util.h
+++ b/include/grpc/support/string_util.h
@@ -55,7 +55,7 @@ GPRAPI char *gpr_strdup(const char *src);
    On error, returns -1 and sets *strp to NULL. If the format string is bad,
    the result is undefined. */
 GPRAPI int gpr_asprintf(char **strp, const char *format, ...)
-    GPRC_PRINT_FORMAT_CHECK(2, 3);
+    GPR_PRINT_FORMAT_CHECK(2, 3);
 
 #ifdef __cplusplus
 }
diff --git a/package.xml b/package.xml
index 348ad5f23c..1d2a443858 100644
--- a/package.xml
+++ b/package.xml
@@ -219,6 +219,7 @@
     <file baseinstalldir="/" name="src/core/lib/iomgr/sockaddr_posix.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/sockaddr_utils.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/sockaddr_windows.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/iomgr/socket_mutator.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/socket_utils.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/socket_utils_posix.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/socket_windows.h" role="src" />
@@ -396,6 +397,7 @@
     <file baseinstalldir="/" name="src/core/lib/iomgr/resolve_address_windows.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/resource_quota.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/sockaddr_utils.c" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/iomgr/socket_mutator.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/socket_utils_common_posix.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/socket_utils_linux.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/socket_utils_posix.c" role="src" />
diff --git a/src/core/ext/census/census_log.h b/src/core/ext/census/census_log.h
index 534ecc5705..1b185a53b9 100644
--- a/src/core/ext/census/census_log.h
+++ b/src/core/ext/census/census_log.h
@@ -84,7 +84,7 @@ const void *census_log_read_next(size_t *bytes_available);
 */
 size_t census_log_remaining_space(void);
 
-/* Returns the number of times gprc_stats_log_start_write() failed due to
+/* Returns the number of times grpc_stats_log_start_write() failed due to
    out-of-space. */
 int census_log_out_of_space_count(void);
 
diff --git a/src/core/ext/census/mlog.h b/src/core/ext/census/mlog.h
index a256426f91..18805ad994 100644
--- a/src/core/ext/census/mlog.h
+++ b/src/core/ext/census/mlog.h
@@ -88,7 +88,7 @@ const void* census_log_read_next(size_t* bytes_available);
 */
 size_t census_log_remaining_space(void);
 
-/* Returns the number of times gprc_stats_log_start_write() failed due to
+/* Returns the number of times grpc_stats_log_start_write() failed due to
    out-of-space. */
 int64_t census_log_out_of_space_count(void);
 
diff --git a/src/core/ext/lb_policy/grpclb/grpclb.c b/src/core/ext/lb_policy/grpclb/grpclb.c
index d68fbb3dfb..44ac9a017e 100644
--- a/src/core/ext/lb_policy/grpclb/grpclb.c
+++ b/src/core/ext/lb_policy/grpclb/grpclb.c
@@ -1155,8 +1155,8 @@ static void lb_on_response_received(grpc_exec_ctx *exec_ctx, void *arg,
     }
     gpr_mu_unlock(&glb_policy->mu);
   } else { /* empty payload: call cancelled. */
-    /* dispose of the "lb_on_response_received" weak ref taken in
-     * query_for_backends_locked() and reused in every reception loop */
+           /* dispose of the "lb_on_response_received" weak ref taken in
+            * query_for_backends_locked() and reused in every reception loop */
     gpr_mu_unlock(&glb_policy->mu);
     GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
                               "lb_on_response_received_empty_payload");
diff --git a/src/core/lib/channel/channel_args.c b/src/core/lib/channel/channel_args.c
index cfc072c0b5..401a2ad4fe 100644
--- a/src/core/lib/channel/channel_args.c
+++ b/src/core/lib/channel/channel_args.c
@@ -298,6 +298,12 @@ uint32_t grpc_channel_args_compression_algorithm_get_states(
   }
 }
 
+grpc_channel_args *grpc_channel_args_set_socket_mutator(
+    grpc_channel_args *a, grpc_socket_mutator *mutator) {
+  grpc_arg tmp = grpc_socket_mutator_to_arg(mutator);
+  return grpc_channel_args_copy_and_add(a, &tmp, 1);
+}
+
 int grpc_channel_args_compare(const grpc_channel_args *a,
                               const grpc_channel_args *b) {
   int c = GPR_ICMP(a->num_args, b->num_args);
diff --git a/src/core/lib/channel/channel_args.h b/src/core/lib/channel/channel_args.h
index 1e05303471..88fc0e37a3 100644
--- a/src/core/lib/channel/channel_args.h
+++ b/src/core/lib/channel/channel_args.h
@@ -36,6 +36,7 @@
 
 #include <grpc/compression.h>
 #include <grpc/grpc.h>
+#include "src/core/lib/iomgr/socket_mutator.h"
 
 // Channel args are intentionally immutable, to avoid the need for locking.
 
@@ -100,6 +101,13 @@ uint32_t grpc_channel_args_compression_algorithm_get_states(
 int grpc_channel_args_compare(const grpc_channel_args *a,
                               const grpc_channel_args *b);
 
+/** Returns a channel arg instance with socket mutator added. The socket mutator
+ * will perform its mutate_fd method on all file descriptors used by the
+ * channel.
+ * If \a a is non-MULL, its args are copied. */
+grpc_channel_args *grpc_channel_args_set_socket_mutator(
+    grpc_channel_args *a, grpc_socket_mutator *mutator);
+
 /** Returns the value of argument \a name from \a args, or NULL if not found. */
 const grpc_arg *grpc_channel_args_find(const grpc_channel_args *args,
                                        const char *name);
diff --git a/src/core/lib/iomgr/ev_epoll_linux.c b/src/core/lib/iomgr/ev_epoll_linux.c
index db51ec4939..91041a7c28 100644
--- a/src/core/lib/iomgr/ev_epoll_linux.c
+++ b/src/core/lib/iomgr/ev_epoll_linux.c
@@ -163,7 +163,7 @@ static void fd_global_shutdown(void);
 #define PI_ADD_REF(p, r) pi_add_ref((p))
 #define PI_UNREF(exec_ctx, p, r) pi_unref((exec_ctx), (p))
 
-#endif /* !defined(GPRC_PI_REF_COUNT_DEBUG) */
+#endif /* !defined(GRPC_PI_REF_COUNT_DEBUG) */
 
 /* This is also used as grpc_workqueue (by directly casing it) */
 typedef struct polling_island {
diff --git a/src/core/lib/iomgr/socket_mutator.c b/src/core/lib/iomgr/socket_mutator.c
new file mode 100644
index 0000000000..8b1efb6bab
--- /dev/null
+++ b/src/core/lib/iomgr/socket_mutator.c
@@ -0,0 +1,98 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/lib/iomgr/socket_mutator.h"
+
+#include <grpc/impl/codegen/grpc_types.h>
+#include <grpc/support/sync.h>
+#include <grpc/support/useful.h>
+
+void grpc_socket_mutator_init(grpc_socket_mutator *mutator,
+                              const grpc_socket_mutator_vtable *vtable) {
+  mutator->vtable = vtable;
+  gpr_ref_init(&mutator->refcount, 1);
+}
+
+grpc_socket_mutator *grpc_socket_mutator_ref(grpc_socket_mutator *mutator) {
+  gpr_ref(&mutator->refcount);
+  return mutator;
+}
+
+bool grpc_socket_mutator_mutate_fd(grpc_socket_mutator *mutator, int fd) {
+  return mutator->vtable->mutate_fd(fd, mutator);
+}
+
+int grpc_socket_mutator_compare(grpc_socket_mutator *a,
+                                grpc_socket_mutator *b) {
+  int c = GPR_ICMP(a, b);
+  if (c != 0) {
+    grpc_socket_mutator *sma = a;
+    grpc_socket_mutator *smb = b;
+    c = GPR_ICMP(sma->vtable, smb->vtable);
+    if (c == 0) {
+      c = sma->vtable->compare(sma, smb);
+    }
+  }
+  return c;
+}
+
+void grpc_socket_mutator_unref(grpc_socket_mutator *mutator) {
+  if (gpr_unref(&mutator->refcount)) {
+    mutator->vtable->destory(mutator);
+  }
+}
+
+static void *socket_mutator_arg_copy(void *p) {
+  return grpc_socket_mutator_ref(p);
+}
+
+static void socket_mutator_arg_destroy(void *p) {
+  grpc_socket_mutator_unref(p);
+}
+
+static int socket_mutator_cmp(void *a, void *b) {
+  return grpc_socket_mutator_compare((grpc_socket_mutator *)a,
+                                     (grpc_socket_mutator *)b);
+}
+
+static const grpc_arg_pointer_vtable socket_mutator_arg_vtable = {
+    socket_mutator_arg_copy, socket_mutator_arg_destroy, socket_mutator_cmp};
+
+grpc_arg grpc_socket_mutator_to_arg(grpc_socket_mutator *mutator) {
+  grpc_arg arg;
+  arg.type = GRPC_ARG_POINTER;
+  arg.key = GRPC_ARG_SOCKET_MUTATOR;
+  arg.value.pointer.vtable = &socket_mutator_arg_vtable;
+  arg.value.pointer.p = mutator;
+  return arg;
+}
diff --git a/src/core/lib/iomgr/socket_mutator.h b/src/core/lib/iomgr/socket_mutator.h
new file mode 100644
index 0000000000..2f5b6c248e
--- /dev/null
+++ b/src/core/lib/iomgr/socket_mutator.h
@@ -0,0 +1,80 @@
+/*
+ *
+ * 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_CORE_LIB_IOMGR_SOCKET_MUTATOR_H
+#define GRPC_CORE_LIB_IOMGR_SOCKET_MUTATOR_H
+
+#include <grpc/impl/codegen/grpc_types.h>
+#include <grpc/support/sync.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** The virtual table of grpc_socket_mutator */
+typedef struct {
+  /** Mutates the socket opitons of \a fd */
+  bool (*mutate_fd)(int fd, grpc_socket_mutator *mutator);
+  /** Compare socket mutator \a a and \a b */
+  int (*compare)(grpc_socket_mutator *a, grpc_socket_mutator *b);
+  /** Destroys the socket mutator instance */
+  void (*destory)(grpc_socket_mutator *mutator);
+} grpc_socket_mutator_vtable;
+
+/** The Socket Mutator interface allows changes on socket options */
+struct grpc_socket_mutator {
+  const grpc_socket_mutator_vtable *vtable;
+  gpr_refcount refcount;
+};
+
+/** called by concrete implementations to initialize the base struct */
+void grpc_socket_mutator_init(grpc_socket_mutator *mutator,
+                              const grpc_socket_mutator_vtable *vtable);
+
+/** Wrap \a mutator as a grpc_arg */
+grpc_arg grpc_socket_mutator_to_arg(grpc_socket_mutator *mutator);
+
+/** Perform the file descriptor mutation operation of \a mutator on \a fd */
+bool grpc_socket_mutator_mutate_fd(grpc_socket_mutator *mutator, int fd);
+
+/** Compare if \a a and \a b are the same mutator or have same settings */
+int grpc_socket_mutator_compare(grpc_socket_mutator *a, grpc_socket_mutator *b);
+
+grpc_socket_mutator *grpc_socket_mutator_ref(grpc_socket_mutator *mutator);
+void grpc_socket_mutator_unref(grpc_socket_mutator *mutator);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_LIB_IOMGR_SOCKET_MUTATOR_H */
diff --git a/src/core/lib/iomgr/socket_utils_common_posix.c b/src/core/lib/iomgr/socket_utils_common_posix.c
index bc28bbe316..88e9ade253 100644
--- a/src/core/lib/iomgr/socket_utils_common_posix.c
+++ b/src/core/lib/iomgr/socket_utils_common_posix.c
@@ -209,6 +209,15 @@ grpc_error *grpc_set_socket_low_latency(int fd, int low_latency) {
   return GRPC_ERROR_NONE;
 }
 
+/* set a socket using a grpc_socket_mutator */
+grpc_error *grpc_set_socket_with_mutator(int fd, grpc_socket_mutator *mutator) {
+  GPR_ASSERT(mutator);
+  if (!grpc_socket_mutator_mutate_fd(mutator, fd)) {
+    return GRPC_ERROR_CREATE("grpc_socket_mutator failed.");
+  }
+  return GRPC_ERROR_NONE;
+}
+
 static gpr_once g_probe_ipv6_once = GPR_ONCE_INIT;
 static int g_ipv6_loopback_available;
 
diff --git a/src/core/lib/iomgr/socket_utils_posix.h b/src/core/lib/iomgr/socket_utils_posix.h
index 175fb2b717..e84d3781a1 100644
--- a/src/core/lib/iomgr/socket_utils_posix.h
+++ b/src/core/lib/iomgr/socket_utils_posix.h
@@ -39,7 +39,9 @@
 #include <sys/socket.h>
 #include <unistd.h>
 
+#include <grpc/impl/codegen/grpc_types.h>
 #include "src/core/lib/iomgr/error.h"
+#include "src/core/lib/iomgr/socket_mutator.h"
 
 /* a wrapper for accept or accept4 */
 int grpc_accept4(int sockfd, grpc_resolved_address *resolved_addr, int nonblock,
@@ -88,6 +90,9 @@ grpc_error *grpc_set_socket_sndbuf(int fd, int buffer_size_bytes);
 /* Tries to set the socket's receive buffer to given size. */
 grpc_error *grpc_set_socket_rcvbuf(int fd, int buffer_size_bytes);
 
+/* Tries to set the socket using a grpc_socket_mutator */
+grpc_error *grpc_set_socket_with_mutator(int fd, grpc_socket_mutator *mutator);
+
 /* An enum to keep track of IPv4/IPv6 socket modes.
 
    Currently, this information is only used when a socket is first created, but
diff --git a/src/core/lib/iomgr/tcp_client.h b/src/core/lib/iomgr/tcp_client.h
index 18e6e60ebc..0485661316 100644
--- a/src/core/lib/iomgr/tcp_client.h
+++ b/src/core/lib/iomgr/tcp_client.h
@@ -34,6 +34,7 @@
 #ifndef GRPC_CORE_LIB_IOMGR_TCP_CLIENT_H
 #define GRPC_CORE_LIB_IOMGR_TCP_CLIENT_H
 
+#include <grpc/impl/codegen/grpc_types.h>
 #include <grpc/support/time.h>
 #include "src/core/lib/iomgr/endpoint.h"
 #include "src/core/lib/iomgr/pollset_set.h"
diff --git a/src/core/lib/iomgr/tcp_client_posix.c b/src/core/lib/iomgr/tcp_client_posix.c
index bc08c94ee0..13347735df 100644
--- a/src/core/lib/iomgr/tcp_client_posix.c
+++ b/src/core/lib/iomgr/tcp_client_posix.c
@@ -51,6 +51,7 @@
 #include "src/core/lib/iomgr/ev_posix.h"
 #include "src/core/lib/iomgr/iomgr_posix.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
+#include "src/core/lib/iomgr/socket_mutator.h"
 #include "src/core/lib/iomgr/socket_utils_posix.h"
 #include "src/core/lib/iomgr/tcp_posix.h"
 #include "src/core/lib/iomgr/timer.h"
@@ -73,7 +74,8 @@ typedef struct {
   grpc_channel_args *channel_args;
 } async_connect;
 
-static grpc_error *prepare_socket(const grpc_resolved_address *addr, int fd) {
+static grpc_error *prepare_socket(const grpc_resolved_address *addr, int fd,
+                                  const grpc_channel_args *channel_args) {
   grpc_error *err = GRPC_ERROR_NONE;
 
   GPR_ASSERT(fd >= 0);
@@ -88,6 +90,16 @@ static grpc_error *prepare_socket(const grpc_resolved_address *addr, int fd) {
   }
   err = grpc_set_socket_no_sigpipe_if_possible(fd);
   if (err != GRPC_ERROR_NONE) goto error;
+  if (channel_args) {
+    for (size_t i = 0; i < channel_args->num_args; i++) {
+      if (0 == strcmp(channel_args->args[i].key, GRPC_ARG_SOCKET_MUTATOR)) {
+        GPR_ASSERT(channel_args->args[i].type == GRPC_ARG_POINTER);
+        grpc_socket_mutator *mutator = channel_args->args[i].value.pointer.p;
+        err = grpc_set_socket_with_mutator(fd, mutator);
+        if (err != GRPC_ERROR_NONE) goto error;
+      }
+    }
+  }
   goto done;
 
 error:
@@ -287,7 +299,7 @@ static void tcp_client_connect_impl(grpc_exec_ctx *exec_ctx,
     GPR_ASSERT(grpc_sockaddr_is_v4mapped(addr, &addr4_copy));
     addr = &addr4_copy;
   }
-  if ((error = prepare_socket(addr, fd)) != GRPC_ERROR_NONE) {
+  if ((error = prepare_socket(addr, fd, channel_args)) != GRPC_ERROR_NONE) {
     grpc_exec_ctx_sched(exec_ctx, closure, error, NULL);
     return;
   }
diff --git a/src/core/lib/iomgr/tcp_uv.c b/src/core/lib/iomgr/tcp_uv.c
index e690b18f20..6e2ad1dbe9 100644
--- a/src/core/lib/iomgr/tcp_uv.c
+++ b/src/core/lib/iomgr/tcp_uv.c
@@ -87,10 +87,12 @@ static void tcp_free(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp) {
 
 /*#define GRPC_TCP_REFCOUNT_DEBUG*/
 #ifdef GRPC_TCP_REFCOUNT_DEBUG
-#define TCP_UNREF(exec_ctx, tcp, reason) tcp_unref((exec_ctx), (tcp), (reason), __FILE__, __LINE__)
-#define TCP_REF(tcp, reason) tcp_ref((exec_ctx), (tcp), (reason), __FILE__, __LINE__)
-static void tcp_unref(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp, const char *reason, const char *file,
-                      int line) {
+#define TCP_UNREF(exec_ctx, tcp, reason) \
+  tcp_unref((exec_ctx), (tcp), (reason), __FILE__, __LINE__)
+#define TCP_REF(tcp, reason) \
+  tcp_ref((exec_ctx), (tcp), (reason), __FILE__, __LINE__)
+static void tcp_unref(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp,
+                      const char *reason, const char *file, int line) {
   gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "TCP unref %p : %s %d -> %d", tcp,
           reason, tcp->refcount.count, tcp->refcount.count - 1);
   if (gpr_unref(&tcp->refcount)) {
@@ -157,7 +159,7 @@ static void read_callback(uv_stream_t *stream, ssize_t nread,
       grpc_error_free_string(str);
       for (i = 0; i < tcp->read_slices->count; i++) {
         char *dump = grpc_dump_slice(tcp->read_slices->slices[i],
-                                    GPR_DUMP_HEX | GPR_DUMP_ASCII);
+                                     GPR_DUMP_HEX | GPR_DUMP_ASCII);
         gpr_log(GPR_DEBUG, "READ %p (peer=%s): %s", tcp, tcp->peer_string,
                 dump);
         gpr_free(dump);
@@ -234,7 +236,7 @@ static void uv_endpoint_write(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
 
     for (j = 0; j < write_slices->count; j++) {
       char *data = grpc_dump_slice(write_slices->slices[j],
-                                  GPR_DUMP_HEX | GPR_DUMP_ASCII);
+                                   GPR_DUMP_HEX | GPR_DUMP_ASCII);
       gpr_log(GPR_DEBUG, "WRITE %p (peer=%s): %s", tcp, tcp->peer_string, data);
       gpr_free(data);
     }
@@ -323,10 +325,13 @@ static grpc_resource_user *uv_get_resource_user(grpc_endpoint *ep) {
 
 static grpc_workqueue *uv_get_workqueue(grpc_endpoint *ep) { return NULL; }
 
+static int uv_get_fd(grpc_endpoint *ep) { return -1; }
+
 static grpc_endpoint_vtable vtable = {
     uv_endpoint_read,  uv_endpoint_write,     uv_get_workqueue,
     uv_add_to_pollset, uv_add_to_pollset_set, uv_endpoint_shutdown,
-    uv_destroy,        uv_get_resource_user,  uv_get_peer};
+    uv_destroy,        uv_get_resource_user,  uv_get_peer,
+    uv_get_fd};
 
 grpc_endpoint *grpc_tcp_create(uv_tcp_t *handle,
                                grpc_resource_quota *resource_quota,
diff --git a/src/core/lib/iomgr/tcp_windows.c b/src/core/lib/iomgr/tcp_windows.c
index 1fb7edc2b1..62afbcef51 100644
--- a/src/core/lib/iomgr/tcp_windows.c
+++ b/src/core/lib/iomgr/tcp_windows.c
@@ -402,6 +402,8 @@ static grpc_resource_user *win_get_resource_user(grpc_endpoint *ep) {
   return tcp->resource_user;
 }
 
+static int win_get_fd(grpc_endpoint *ep) { return -1; }
+
 static grpc_endpoint_vtable vtable = {win_read,
                                       win_write,
                                       win_get_workqueue,
@@ -410,7 +412,8 @@ static grpc_endpoint_vtable vtable = {win_read,
                                       win_shutdown,
                                       win_destroy,
                                       win_get_resource_user,
-                                      win_get_peer};
+                                      win_get_peer,
+                                      win_get_fd};
 
 grpc_endpoint *grpc_tcp_create(grpc_winsocket *socket,
                                grpc_resource_quota *resource_quota,
diff --git a/src/core/lib/security/transport/secure_endpoint.c b/src/core/lib/security/transport/secure_endpoint.c
index 2d32fae8a1..1b278410e8 100644
--- a/src/core/lib/security/transport/secure_endpoint.c
+++ b/src/core/lib/security/transport/secure_endpoint.c
@@ -31,15 +31,20 @@
  *
  */
 
-#include "src/core/lib/security/transport/secure_endpoint.h"
+/* With the addition of a libuv endpoint, sockaddr.h now includes uv.h when
+   using that endpoint. Because of various transitive includes in uv.h,
+   including windows.h on Windows, uv.h must be included before other system
+   headers. Therefore, sockaddr.h must always be included first */
+#include "src/core/lib/iomgr/sockaddr.h"
+
 #include <grpc/slice.h>
 #include <grpc/slice_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/sync.h>
 #include "src/core/lib/debug/trace.h"
-#include "src/core/lib/iomgr/sockaddr.h"
 #include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/security/transport/secure_endpoint.h"
 #include "src/core/lib/security/transport/tsi_error.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"
diff --git a/src/cpp/common/channel_arguments.cc b/src/cpp/common/channel_arguments.cc
index d86ba9dd4e..0067d6c5e1 100644
--- a/src/cpp/common/channel_arguments.cc
+++ b/src/cpp/common/channel_arguments.cc
@@ -39,7 +39,7 @@
 #include <grpc/impl/codegen/grpc_types.h>
 #include <grpc/support/log.h>
 #include "src/core/lib/channel/channel_args.h"
-
+#include "src/core/lib/iomgr/socket_mutator.h"
 namespace grpc {
 
 ChannelArguments::ChannelArguments() {
@@ -88,6 +88,24 @@ void ChannelArguments::SetCompressionAlgorithm(
   SetInt(GRPC_COMPRESSION_CHANNEL_DEFAULT_ALGORITHM, algorithm);
 }
 
+void ChannelArguments::SetSocketMutator(grpc_socket_mutator* mutator) {
+  if (!mutator) {
+    return;
+  }
+  grpc_arg mutator_arg = grpc_socket_mutator_to_arg(mutator);
+  bool replaced = false;
+  for (auto it = args_.begin(); it != args_.end(); ++it) {
+    if (it->type == mutator_arg.type &&
+        grpc::string(it->key) == grpc::string(mutator_arg.key)) {
+      it->value.pointer.vtable->destroy(it->value.pointer.p);
+      it->value.pointer = mutator_arg.value.pointer;
+    }
+  }
+  if (!replaced) {
+    args_.push_back(mutator_arg);
+  }
+}
+
 // Note: a second call to this will add in front the result of the first call.
 // An example is calling this on a copy of ChannelArguments which already has a
 // prefix. The user can build up a prefix string by calling this multiple times,
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCall.cs b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
index 5e61e9ec12..da45c4829d 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCall.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
@@ -388,35 +388,29 @@ namespace Grpc.Core.Internal
 
         private void Initialize(CompletionQueueSafeHandle cq)
         {
-            using (Profilers.ForCurrentThread().NewScope("AsyncCall.Initialize"))
-            { 
-                var call = CreateNativeCall(cq);
+            var call = CreateNativeCall(cq);
 
-                details.Channel.AddCallReference(this);
-                InitializeInternal(call);
-                RegisterCancellationCallback();
-            }
+            details.Channel.AddCallReference(this);
+            InitializeInternal(call);
+            RegisterCancellationCallback();
         }
 
         private INativeCall CreateNativeCall(CompletionQueueSafeHandle cq)
         {
-            using (Profilers.ForCurrentThread().NewScope("AsyncCall.CreateNativeCall"))
-            { 
-                if (injectedNativeCall != null)
-                {
-                    return injectedNativeCall;  // allows injecting a mock INativeCall in tests.
-                }
+            if (injectedNativeCall != null)
+            {
+                return injectedNativeCall;  // allows injecting a mock INativeCall in tests.
+            }
 
-                var parentCall = details.Options.PropagationToken != null ? details.Options.PropagationToken.ParentCall : CallSafeHandle.NullInstance;
+            var parentCall = details.Options.PropagationToken != null ? details.Options.PropagationToken.ParentCall : CallSafeHandle.NullInstance;
 
-                var credentials = details.Options.Credentials;
-                using (var nativeCredentials = credentials != null ? credentials.ToNativeCredentials() : null)
-                {
-                    var result = details.Channel.Handle.CreateCall(
-                                 parentCall, ContextPropagationToken.DefaultMask, cq,
-                                 details.Method, details.Host, Timespec.FromDateTime(details.Options.Deadline.Value), nativeCredentials);
-                    return result;
-                }
+            var credentials = details.Options.Credentials;
+            using (var nativeCredentials = credentials != null ? credentials.ToNativeCredentials() : null)
+            {
+                var result = details.Channel.Handle.CreateCall(
+                             parentCall, ContextPropagationToken.DefaultMask, cq,
+                             details.Method, details.Host, Timespec.FromDateTime(details.Options.Deadline.Value), nativeCredentials);
+                return result;
             }
         }
 
@@ -456,47 +450,44 @@ namespace Grpc.Core.Internal
             // NOTE: because this event is a result of batch containing GRPC_OP_RECV_STATUS_ON_CLIENT,
             // success will be always set to true.
 
-            using (Profilers.ForCurrentThread().NewScope("AsyncCall.HandleUnaryResponse"))
+            TaskCompletionSource<object> delayedStreamingWriteTcs = null;
+            TResponse msg = default(TResponse);
+            var deserializeException = TryDeserialize(receivedMessage, out msg);
+
+            lock (myLock)
             {
-                TaskCompletionSource<object> delayedStreamingWriteTcs = null;
-                TResponse msg = default(TResponse);
-                var deserializeException = TryDeserialize(receivedMessage, out msg);
+                finished = true;
 
-                lock (myLock)
+                if (deserializeException != null && receivedStatus.Status.StatusCode == StatusCode.OK)
                 {
-                    finished = true;
-
-                    if (deserializeException != null && receivedStatus.Status.StatusCode == StatusCode.OK)
-                    {
-                        receivedStatus = new ClientSideStatus(DeserializeResponseFailureStatus, receivedStatus.Trailers);
-                    }
-                    finishedStatus = receivedStatus;
-
-                    if (isStreamingWriteCompletionDelayed)
-                    {
-                        delayedStreamingWriteTcs = streamingWriteTcs;
-                        streamingWriteTcs = null;
-                    }
-
-                    ReleaseResourcesIfPossible();
+                    receivedStatus = new ClientSideStatus(DeserializeResponseFailureStatus, receivedStatus.Trailers);
                 }
+                finishedStatus = receivedStatus;
 
-                responseHeadersTcs.SetResult(responseHeaders);
-
-                if (delayedStreamingWriteTcs != null)
+                if (isStreamingWriteCompletionDelayed)
                 {
-                    delayedStreamingWriteTcs.SetException(GetRpcExceptionClientOnly());
+                    delayedStreamingWriteTcs = streamingWriteTcs;
+                    streamingWriteTcs = null;
                 }
 
-                var status = receivedStatus.Status;
-                if (status.StatusCode != StatusCode.OK)
-                {
-                    unaryResponseTcs.SetException(new RpcException(status));
-                    return;
-                }
+                ReleaseResourcesIfPossible();
+            }
+
+            responseHeadersTcs.SetResult(responseHeaders);
 
-                unaryResponseTcs.SetResult(msg);
+            if (delayedStreamingWriteTcs != null)
+            {
+                delayedStreamingWriteTcs.SetException(GetRpcExceptionClientOnly());
+            }
+
+            var status = receivedStatus.Status;
+            if (status.StatusCode != StatusCode.OK)
+            {
+                unaryResponseTcs.SetException(new RpcException(status));
+                return;
             }
+
+            unaryResponseTcs.SetResult(msg);
         }
 
         /// <summary>
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs b/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
index 9f9d260e7e..8668903f6e 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
@@ -181,19 +181,16 @@ namespace Grpc.Core.Internal
         /// </summary>
         protected bool ReleaseResourcesIfPossible()
         {
-            using (Profilers.ForCurrentThread().NewScope("AsyncCallBase.ReleaseResourcesIfPossible"))
+            if (!disposed && call != null)
             {
-                if (!disposed && call != null)
+                bool noMoreSendCompletions = streamingWriteTcs == null && (halfcloseRequested || cancelRequested || finished);
+                if (noMoreSendCompletions && readingDone && finished)
                 {
-                    bool noMoreSendCompletions = streamingWriteTcs == null && (halfcloseRequested || cancelRequested || finished);
-                    if (noMoreSendCompletions && readingDone && finished)
-                    {
-                        ReleaseResources();
-                        return true;
-                    }
+                    ReleaseResources();
+                    return true;
                 }
-                return false;
             }
+            return false;
         }
 
         protected abstract bool IsClient
@@ -229,28 +226,20 @@ namespace Grpc.Core.Internal
 
         protected byte[] UnsafeSerialize(TWrite msg)
         {
-            using (Profilers.ForCurrentThread().NewScope("AsyncCallBase.UnsafeSerialize"))
-            {
-                return serializer(msg);
-            }
+            return serializer(msg);
         }
 
         protected Exception TryDeserialize(byte[] payload, out TRead msg)
         {
-            using (Profilers.ForCurrentThread().NewScope("AsyncCallBase.TryDeserialize"))
+            try
             {
-                try
-                {
-                
-                    msg = deserializer(payload);
-                    return null;
-             
-                }
-                catch (Exception e)
-                {
-                    msg = default(TRead);
-                    return e;
-                }
+                msg = deserializer(payload);
+                return null;
+            }
+            catch (Exception e)
+            {
+                msg = default(TRead);
+                return e;
             }
         }
 
diff --git a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
index 82361f5797..f817a61bce 100644
--- a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
@@ -76,11 +76,8 @@ namespace Grpc.Core.Internal
 
         public void StartUnary(BatchContextSafeHandle ctx, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
         {
-            using (Profilers.ForCurrentThread().NewScope("CallSafeHandle.StartUnary"))
-            {
-                Native.grpcsharp_call_start_unary(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray, writeFlags)
-                    .CheckOk();
-            }
+            Native.grpcsharp_call_start_unary(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray, writeFlags)
+                .CheckOk();
         }
 
         public void StartClientStreaming(UnaryResponseClientHandler callback, MetadataArraySafeHandle metadataArray)
diff --git a/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
index 62864dff0c..0fb6360a23 100644
--- a/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
@@ -65,16 +65,13 @@ namespace Grpc.Core.Internal
 
         public CallSafeHandle CreateCall(CallSafeHandle parentCall, ContextPropagationFlags propagationMask, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline, CallCredentialsSafeHandle credentials)
         {
-            using (Profilers.ForCurrentThread().NewScope("ChannelSafeHandle.CreateCall"))
+            var result = Native.grpcsharp_channel_create_call(this, parentCall, propagationMask, cq, method, host, deadline);
+            if (credentials != null)
             {
-                var result = Native.grpcsharp_channel_create_call(this, parentCall, propagationMask, cq, method, host, deadline);
-                if (credentials != null)
-                {
-                    result.SetCredentials(credentials);
-                }
-                result.Initialize(cq);
-                return result;
+                result.SetCredentials(credentials);
             }
+            result.Initialize(cq);
+            return result;
         }
 
         public ChannelState CheckConnectivityState(bool tryToConnect)
diff --git a/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
index 46f5624223..6c9a31921e 100644
--- a/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
@@ -70,10 +70,7 @@ namespace Grpc.Core.Internal
 
         public CompletionQueueEvent Pluck(IntPtr tag)
         {
-            using (Profilers.ForCurrentThread().NewScope("CompletionQueueSafeHandle.Pluck"))
-            {
-                return Native.grpcsharp_completion_queue_pluck(this, tag);
-            }
+            return Native.grpcsharp_completion_queue_pluck(this, tag);
         }
 
         /// <summary>
diff --git a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
index a446c1f99f..25a6589f11 100644
--- a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
+++ b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
@@ -37,6 +37,7 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Grpc.Core.Logging;
+using Grpc.Core.Profiling;
 using Grpc.Core.Utils;
 
 namespace Grpc.Core.Internal
@@ -54,6 +55,8 @@ namespace Grpc.Core.Internal
         readonly int poolSize;
         readonly int completionQueueCount;
 
+        readonly List<BasicProfiler> threadProfilers = new List<BasicProfiler>();  // profilers assigned to threadpool threads
+
         bool stopRequested;
 
         IReadOnlyCollection<CompletionQueueSafeHandle> completionQueues;
@@ -82,7 +85,8 @@ namespace Grpc.Core.Internal
 
                 for (int i = 0; i < poolSize; i++)
                 {
-                    threads.Add(CreateAndStartThread(i));
+                    var optionalProfiler = i < threadProfilers.Count ? threadProfilers[i] : null;
+                    threads.Add(CreateAndStartThread(i, optionalProfiler));
                 }
             }
         }
@@ -111,6 +115,11 @@ namespace Grpc.Core.Internal
                 {
                     cq.Dispose();
                 }
+
+                for (int i = 0; i < threadProfilers.Count; i++)
+                {
+                    threadProfilers[i].Dump(string.Format("grpc_trace_thread_{0}.txt", i));
+                }
             });
         }
 
@@ -137,12 +146,12 @@ namespace Grpc.Core.Internal
             }
         }
 
-        private Thread CreateAndStartThread(int threadIndex)
+        private Thread CreateAndStartThread(int threadIndex, IProfiler optionalProfiler)
         {
             var cqIndex = threadIndex % completionQueues.Count;
             var cq = completionQueues.ElementAt(cqIndex);
 
-            var thread = new Thread(new ThreadStart(() => RunHandlerLoop(cq)));
+            var thread = new Thread(new ThreadStart(() => RunHandlerLoop(cq, optionalProfiler)));
             thread.IsBackground = true;
             thread.Name = string.Format("grpc {0} (cq {1})", threadIndex, cqIndex);
             thread.Start();
@@ -153,8 +162,13 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Body of the polling thread.
         /// </summary>
-        private void RunHandlerLoop(CompletionQueueSafeHandle cq)
+        private void RunHandlerLoop(CompletionQueueSafeHandle cq, IProfiler optionalProfiler)
         {
+            if (optionalProfiler != null)
+            {
+                Profilers.SetForCurrentThread(optionalProfiler);
+            }
+
             CompletionQueueEvent ev;
             do
             {
diff --git a/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs b/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs
index dc9f62fdab..05dda5b148 100644
--- a/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs
@@ -48,22 +48,19 @@ namespace Grpc.Core.Internal
             
         public static MetadataArraySafeHandle Create(Metadata metadata)
         {
-            using (Profilers.ForCurrentThread().NewScope("MetadataArraySafeHandle.Create"))
+            if (metadata.Count == 0)
             {
-                if (metadata.Count == 0)
-                {
-                    return new MetadataArraySafeHandle();
-                }
+                return new MetadataArraySafeHandle();
+            }
 
-                // TODO(jtattermusch): we might wanna check that the metadata is readonly 
-                var metadataArray = Native.grpcsharp_metadata_array_create(new UIntPtr((ulong)metadata.Count));
-                for (int i = 0; i < metadata.Count; i++)
-                {
-                    var valueBytes = metadata[i].GetSerializedValueUnsafe();
-                    Native.grpcsharp_metadata_array_add(metadataArray, metadata[i].Key, valueBytes, new UIntPtr((ulong)valueBytes.Length));
-                }
-                return metadataArray;
+            // TODO(jtattermusch): we might wanna check that the metadata is readonly
+            var metadataArray = Native.grpcsharp_metadata_array_create(new UIntPtr((ulong)metadata.Count));
+            for (int i = 0; i < metadata.Count; i++)
+            {
+                var valueBytes = metadata[i].GetSerializedValueUnsafe();
+                Native.grpcsharp_metadata_array_add(metadataArray, metadata[i].Key, valueBytes, new UIntPtr((ulong)valueBytes.Length));
             }
+            return metadataArray;
         }
 
         /// <summary>
diff --git a/src/csharp/Grpc.Core/Profiling/Profilers.cs b/src/csharp/Grpc.Core/Profiling/Profilers.cs
index aa0d96c0e0..6afabff6a7 100644
--- a/src/csharp/Grpc.Core/Profiling/Profilers.cs
+++ b/src/csharp/Grpc.Core/Profiling/Profilers.cs
@@ -80,7 +80,7 @@ namespace Grpc.Core.Profiling
         ProfilerEntry[] entries;
         int count;
 
-        public BasicProfiler() : this(1024*1024)
+        public BasicProfiler() : this(20*1024*1024)
         {
         }
 
diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py
index b0041871d4..8fe36d98a3 100644
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@@ -121,6 +121,7 @@ CORE_SOURCE_FILES = [
   'src/core/lib/iomgr/resolve_address_windows.c',
   'src/core/lib/iomgr/resource_quota.c',
   'src/core/lib/iomgr/sockaddr_utils.c',
+  'src/core/lib/iomgr/socket_mutator.c',
   'src/core/lib/iomgr/socket_utils_common_posix.c',
   'src/core/lib/iomgr/socket_utils_linux.c',
   'src/core/lib/iomgr/socket_utils_posix.c',
diff --git a/src/ruby/ext/grpc/rb_grpc_imports.generated.h b/src/ruby/ext/grpc/rb_grpc_imports.generated.h
index 7a64c1431d..b137700aa6 100644
--- a/src/ruby/ext/grpc/rb_grpc_imports.generated.h
+++ b/src/ruby/ext/grpc/rb_grpc_imports.generated.h
@@ -686,7 +686,7 @@ extern gpr_join_host_port_type gpr_join_host_port_import;
 typedef int(*gpr_split_host_port_type)(const char *name, char **host, char **port);
 extern gpr_split_host_port_type gpr_split_host_port_import;
 #define gpr_split_host_port gpr_split_host_port_import
-typedef void(*gpr_log_type)(const char *file, int line, gpr_log_severity severity, const char *format, ...) GPRC_PRINT_FORMAT_CHECK(4, 5);
+typedef void(*gpr_log_type)(const char *file, int line, gpr_log_severity severity, const char *format, ...) GPR_PRINT_FORMAT_CHECK(4, 5);
 extern gpr_log_type gpr_log_import;
 #define gpr_log gpr_log_import
 typedef void(*gpr_log_message_type)(const char *file, int line, gpr_log_severity severity, const char *message);
@@ -707,7 +707,7 @@ extern gpr_format_message_type gpr_format_message_import;
 typedef char *(*gpr_strdup_type)(const char *src);
 extern gpr_strdup_type gpr_strdup_import;
 #define gpr_strdup gpr_strdup_import
-typedef int(*gpr_asprintf_type)(char **strp, const char *format, ...) GPRC_PRINT_FORMAT_CHECK(2, 3);
+typedef int(*gpr_asprintf_type)(char **strp, const char *format, ...) GPR_PRINT_FORMAT_CHECK(2, 3);
 extern gpr_asprintf_type gpr_asprintf_import;
 #define gpr_asprintf gpr_asprintf_import
 typedef const char *(*gpr_subprocess_binary_extension_type)();
diff --git a/test/core/channel/channel_args_test.c b/test/core/channel/channel_args_test.c
index 8ef1bff22e..d3eb969f09 100644
--- a/test/core/channel/channel_args_test.c
+++ b/test/core/channel/channel_args_test.c
@@ -134,12 +134,26 @@ static void test_compression_algorithm_states(void) {
   grpc_channel_args_destroy(ch_args);
 }
 
+static void test_set_socket_mutator(void) {
+  grpc_channel_args *ch_args;
+  grpc_socket_mutator mutator;
+  grpc_socket_mutator_init(&mutator, NULL);
+
+  ch_args = grpc_channel_args_set_socket_mutator(NULL, &mutator);
+  GPR_ASSERT(ch_args->num_args == 1);
+  GPR_ASSERT(strcmp(ch_args->args[0].key, GRPC_ARG_SOCKET_MUTATOR) == 0);
+  GPR_ASSERT(ch_args->args[0].type == GRPC_ARG_POINTER);
+
+  grpc_channel_args_destroy(ch_args);
+}
+
 int main(int argc, char **argv) {
   grpc_test_init(argc, argv);
   grpc_init();
   test_create();
   test_set_compression_algorithm();
   test_compression_algorithm_states();
+  test_set_socket_mutator();
   grpc_shutdown();
   return 0;
 }
diff --git a/test/core/iomgr/socket_utils_test.c b/test/core/iomgr/socket_utils_test.c
index 67bc914c15..7eee2d1d10 100644
--- a/test/core/iomgr/socket_utils_test.c
+++ b/test/core/iomgr/socket_utils_test.c
@@ -39,13 +39,57 @@
 #include "src/core/lib/iomgr/socket_utils_posix.h"
 
 #include <errno.h>
+#include <netinet/ip.h>
 #include <string.h>
 
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <grpc/support/sync.h>
+#include <grpc/support/useful.h>
+#include "src/core/lib/iomgr/socket_mutator.h"
 #include "test/core/util/test_config.h"
 
+struct test_socket_mutator {
+  grpc_socket_mutator base;
+  int option_value;
+};
+
+static bool mutate_fd(int fd, grpc_socket_mutator *mutator) {
+  int newval;
+  socklen_t intlen = sizeof(newval);
+  struct test_socket_mutator *m = (struct test_socket_mutator *)mutator;
+
+  if (0 != setsockopt(fd, IPPROTO_IP, IP_TOS, &m->option_value,
+                      sizeof(m->option_value))) {
+    return false;
+  }
+  if (0 != getsockopt(fd, IPPROTO_IP, IP_TOS, &newval, &intlen)) {
+    return false;
+  }
+  if (newval != m->option_value) {
+    return false;
+  }
+  return true;
+}
+
+static void destroy_test_mutator(grpc_socket_mutator *mutator) {
+  struct test_socket_mutator *m = (struct test_socket_mutator *)mutator;
+  gpr_free(m);
+}
+
+static int compare_test_mutator(grpc_socket_mutator *a,
+                                grpc_socket_mutator *b) {
+  struct test_socket_mutator *ma = (struct test_socket_mutator *)a;
+  struct test_socket_mutator *mb = (struct test_socket_mutator *)b;
+  return GPR_ICMP(ma->option_value, mb->option_value);
+}
+
+static const grpc_socket_mutator_vtable mutator_vtable = {
+    mutate_fd, compare_test_mutator, destroy_test_mutator};
+
 int main(int argc, char **argv) {
   int sock;
+  grpc_error *err;
   grpc_test_init(argc, argv);
 
   sock = socket(PF_INET, SOCK_STREAM, 0);
@@ -68,6 +112,29 @@ int main(int argc, char **argv) {
   GPR_ASSERT(GRPC_LOG_IF_ERROR("set_socket_low_latency",
                                grpc_set_socket_low_latency(sock, 0)));
 
+  struct test_socket_mutator mutator;
+  grpc_socket_mutator_init(&mutator.base, &mutator_vtable);
+
+  mutator.option_value = IPTOS_LOWDELAY;
+  GPR_ASSERT(GRPC_LOG_IF_ERROR(
+      "set_socket_with_mutator",
+      grpc_set_socket_with_mutator(sock, (grpc_socket_mutator *)&mutator)));
+
+  mutator.option_value = IPTOS_THROUGHPUT;
+  GPR_ASSERT(GRPC_LOG_IF_ERROR(
+      "set_socket_with_mutator",
+      grpc_set_socket_with_mutator(sock, (grpc_socket_mutator *)&mutator)));
+
+  mutator.option_value = IPTOS_RELIABILITY;
+  GPR_ASSERT(GRPC_LOG_IF_ERROR(
+      "set_socket_with_mutator",
+      grpc_set_socket_with_mutator(sock, (grpc_socket_mutator *)&mutator)));
+
+  mutator.option_value = -1;
+  err = grpc_set_socket_with_mutator(sock, (grpc_socket_mutator *)&mutator);
+  GPR_ASSERT(err != GRPC_ERROR_NONE);
+  GRPC_ERROR_UNREF(err);
+
   close(sock);
 
   return 0;
diff --git a/test/core/profiling/mark_timings.stp b/test/core/profiling/mark_timings.stp
index 0c0a417faf..e96edbc149 100644
--- a/test/core/profiling/mark_timings.stp
+++ b/test/core/profiling/mark_timings.stp
@@ -2,7 +2,7 @@
  * probe definition.
  *
  * For a statically build binary, that'd be the name of the binary itself.
- * For dinamically built ones, point to the location of the libgprc.so being
+ * For dynamically built ones, point to the location of the libgrpc.so being
  * used. */
 
 global starts, times, times_per_tag
diff --git a/test/cpp/common/channel_arguments_test.cc b/test/cpp/common/channel_arguments_test.cc
index 342f6a5339..60d3215265 100644
--- a/test/cpp/common/channel_arguments_test.cc
+++ b/test/cpp/common/channel_arguments_test.cc
@@ -35,11 +35,56 @@
 
 #include <grpc++/grpc++.h>
 #include <grpc/grpc.h>
+#include <grpc/support/useful.h>
 #include <gtest/gtest.h>
+#include "src/core/lib/iomgr/socket_mutator.h"
 
 namespace grpc {
 namespace testing {
 
+namespace {
+
+// A simple grpc_socket_mutator to be used to test SetSocketMutator
+class TestSocketMutator : public grpc_socket_mutator {
+ public:
+  TestSocketMutator();
+
+  bool MutateFd(int fd) {
+    // Do nothing on the fd
+    return true;
+  }
+};
+
+//
+// C API for TestSocketMutator
+//
+
+bool test_mutator_mutate_fd(int fd, grpc_socket_mutator* mutator) {
+  TestSocketMutator* tsm = (TestSocketMutator*)mutator;
+  return tsm->MutateFd(fd);
+}
+
+int test_mutator_compare(grpc_socket_mutator* a, grpc_socket_mutator* b) {
+  return GPR_ICMP(a, b);
+}
+
+void test_mutator_destroy(grpc_socket_mutator* mutator) {
+  TestSocketMutator* tsm = (TestSocketMutator*)mutator;
+  delete tsm;
+}
+
+grpc_socket_mutator_vtable test_mutator_vtable = {
+    test_mutator_mutate_fd, test_mutator_compare, test_mutator_destroy};
+
+//
+// TestSocketMutator implementation
+//
+
+TestSocketMutator::TestSocketMutator() {
+  grpc_socket_mutator_init(this, &test_mutator_vtable);
+}
+}
+
 class ChannelArgumentsTest : public ::testing::Test {
  protected:
   ChannelArgumentsTest()
@@ -166,6 +211,26 @@ TEST_F(ChannelArgumentsTest, SetPointer) {
   EXPECT_TRUE(HasArg(arg0));
 }
 
+TEST_F(ChannelArgumentsTest, SetSocketMutator) {
+  VerifyDefaultChannelArgs();
+  grpc_arg arg0, arg1;
+  TestSocketMutator* mutator0 = new TestSocketMutator();
+  TestSocketMutator* mutator1 = new TestSocketMutator();
+  arg0 = grpc_socket_mutator_to_arg(mutator0);
+  arg1 = grpc_socket_mutator_to_arg(mutator1);
+
+  channel_args_.SetSocketMutator(mutator0);
+  EXPECT_TRUE(HasArg(arg0));
+
+  channel_args_.SetSocketMutator(mutator1);
+  EXPECT_TRUE(HasArg(arg1));
+  // arg0 is replaced by arg1
+  EXPECT_FALSE(HasArg(arg0));
+
+  // arg0 is destroyed by grpc_socket_mutator_to_arg(mutator1)
+  arg1.value.pointer.vtable->destroy(arg1.value.pointer.p);
+}
+
 TEST_F(ChannelArgumentsTest, SetUserAgentPrefix) {
   VerifyDefaultChannelArgs();
   grpc::string prefix("prefix");
diff --git a/tools/doxygen/Doxyfile.core.internal b/tools/doxygen/Doxyfile.core.internal
index 55b8d40aca..2acedbfc6a 100644
--- a/tools/doxygen/Doxyfile.core.internal
+++ b/tools/doxygen/Doxyfile.core.internal
@@ -835,6 +835,7 @@ src/core/lib/iomgr/sockaddr.h \
 src/core/lib/iomgr/sockaddr_posix.h \
 src/core/lib/iomgr/sockaddr_utils.h \
 src/core/lib/iomgr/sockaddr_windows.h \
+src/core/lib/iomgr/socket_mutator.h \
 src/core/lib/iomgr/socket_utils.h \
 src/core/lib/iomgr/socket_utils_posix.h \
 src/core/lib/iomgr/socket_windows.h \
@@ -1012,6 +1013,7 @@ src/core/lib/iomgr/resolve_address_uv.c \
 src/core/lib/iomgr/resolve_address_windows.c \
 src/core/lib/iomgr/resource_quota.c \
 src/core/lib/iomgr/sockaddr_utils.c \
+src/core/lib/iomgr/socket_mutator.c \
 src/core/lib/iomgr/socket_utils_common_posix.c \
 src/core/lib/iomgr/socket_utils_linux.c \
 src/core/lib/iomgr/socket_utils_posix.c \
diff --git a/tools/run_tests/sources_and_headers.json b/tools/run_tests/sources_and_headers.json
index 104eaa7475..05c2e52a3d 100644
--- a/tools/run_tests/sources_and_headers.json
+++ b/tools/run_tests/sources_and_headers.json
@@ -6695,6 +6695,7 @@
       "src/core/lib/iomgr/sockaddr_posix.h", 
       "src/core/lib/iomgr/sockaddr_utils.h", 
       "src/core/lib/iomgr/sockaddr_windows.h", 
+      "src/core/lib/iomgr/socket_mutator.h", 
       "src/core/lib/iomgr/socket_utils.h", 
       "src/core/lib/iomgr/socket_utils_posix.h", 
       "src/core/lib/iomgr/socket_windows.h", 
@@ -6852,6 +6853,8 @@
       "src/core/lib/iomgr/sockaddr_utils.c", 
       "src/core/lib/iomgr/sockaddr_utils.h", 
       "src/core/lib/iomgr/sockaddr_windows.h", 
+      "src/core/lib/iomgr/socket_mutator.c", 
+      "src/core/lib/iomgr/socket_mutator.h", 
       "src/core/lib/iomgr/socket_utils.h", 
       "src/core/lib/iomgr/socket_utils_common_posix.c", 
       "src/core/lib/iomgr/socket_utils_linux.c", 
diff --git a/vsprojects/vcxproj/grpc/grpc.vcxproj b/vsprojects/vcxproj/grpc/grpc.vcxproj
index c608cb8943..b3e5cd0267 100644
--- a/vsprojects/vcxproj/grpc/grpc.vcxproj
+++ b/vsprojects/vcxproj/grpc/grpc.vcxproj
@@ -344,6 +344,7 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_posix.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_utils.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_windows.h" />
+    <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_posix.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_windows.h" />
@@ -570,6 +571,8 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_utils.c">
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.c">
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_common_posix.c">
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_linux.c">
diff --git a/vsprojects/vcxproj/grpc/grpc.vcxproj.filters b/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
index c6ca85cab6..2b45e4629e 100644
--- a/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
+++ b/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
@@ -142,6 +142,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_utils.c">
       <Filter>src\core\lib\iomgr</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.c">
+      <Filter>src\core\lib\iomgr</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_common_posix.c">
       <Filter>src\core\lib\iomgr</Filter>
     </ClCompile>
@@ -869,6 +872,9 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_windows.h">
       <Filter>src\core\lib\iomgr</Filter>
     </ClInclude>
+    <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.h">
+      <Filter>src\core\lib\iomgr</Filter>
+    </ClInclude>
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils.h">
       <Filter>src\core\lib\iomgr</Filter>
     </ClInclude>
diff --git a/vsprojects/vcxproj/grpc_test_util/grpc_test_util.vcxproj b/vsprojects/vcxproj/grpc_test_util/grpc_test_util.vcxproj
index 764f4615b6..1cb474785a 100644
--- a/vsprojects/vcxproj/grpc_test_util/grpc_test_util.vcxproj
+++ b/vsprojects/vcxproj/grpc_test_util/grpc_test_util.vcxproj
@@ -237,6 +237,7 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_posix.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_utils.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_windows.h" />
+    <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_posix.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_windows.h" />
@@ -421,6 +422,8 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_utils.c">
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.c">
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_common_posix.c">
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_linux.c">
diff --git a/vsprojects/vcxproj/grpc_test_util/grpc_test_util.vcxproj.filters b/vsprojects/vcxproj/grpc_test_util/grpc_test_util.vcxproj.filters
index 2b72043001..0b3cbc2624 100644
--- a/vsprojects/vcxproj/grpc_test_util/grpc_test_util.vcxproj.filters
+++ b/vsprojects/vcxproj/grpc_test_util/grpc_test_util.vcxproj.filters
@@ -199,6 +199,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_utils.c">
       <Filter>src\core\lib\iomgr</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.c">
+      <Filter>src\core\lib\iomgr</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_common_posix.c">
       <Filter>src\core\lib\iomgr</Filter>
     </ClCompile>
@@ -665,6 +668,9 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_windows.h">
       <Filter>src\core\lib\iomgr</Filter>
     </ClInclude>
+    <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.h">
+      <Filter>src\core\lib\iomgr</Filter>
+    </ClInclude>
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils.h">
       <Filter>src\core\lib\iomgr</Filter>
     </ClInclude>
diff --git a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
index ed68f03ad5..f2d6ff9384 100644
--- a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
+++ b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
@@ -334,6 +334,7 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_posix.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_utils.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_windows.h" />
+    <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_posix.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_windows.h" />
@@ -538,6 +539,8 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_utils.c">
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.c">
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_common_posix.c">
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_linux.c">
diff --git a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
index e8c16e531f..1f83cd3ce9 100644
--- a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
+++ b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
@@ -145,6 +145,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_utils.c">
       <Filter>src\core\lib\iomgr</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.c">
+      <Filter>src\core\lib\iomgr</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils_common_posix.c">
       <Filter>src\core\lib\iomgr</Filter>
     </ClCompile>
@@ -782,6 +785,9 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\sockaddr_windows.h">
       <Filter>src\core\lib\iomgr</Filter>
     </ClInclude>
+    <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_mutator.h">
+      <Filter>src\core\lib\iomgr</Filter>
+    </ClInclude>
     <ClInclude Include="$(SolutionDir)\..\src\core\lib\iomgr\socket_utils.h">
       <Filter>src\core\lib\iomgr</Filter>
     </ClInclude>