Revert "Revert "Metadata handling rewrite""

This reverts commit 5e01e2ac977655aa074faf7fde0a74298f5e4c55.

14 files changed, 268 insertions, 105 deletions

diff --git a/include/grpc++/impl/codegen/call.h b/include/grpc++/impl/codegen/call.h
index 6ab00612f6..dd6c83a14a 100644
--- a/include/grpc++/impl/codegen/call.h
+++ b/include/grpc++/impl/codegen/call.h
@@ -45,6 +45,7 @@
 #include <grpc++/impl/codegen/config.h>
 #include <grpc++/impl/codegen/core_codegen_interface.h>
 #include <grpc++/impl/codegen/serialization_traits.h>
+#include <grpc++/impl/codegen/slice.h>
 #include <grpc++/impl/codegen/status.h>
 #include <grpc++/impl/codegen/status_helper.h>
 #include <grpc++/impl/codegen/string_ref.h>
@@ -62,19 +63,6 @@ class CallHook;
 class CompletionQueue;
 extern CoreCodegenInterface* g_core_codegen_interface;
 
-inline void FillMetadataMap(
-    grpc_metadata_array* arr,
-    std::multimap<grpc::string_ref, grpc::string_ref>* metadata) {
-  for (size_t i = 0; i < arr->count; i++) {
-    // TODO(yangg) handle duplicates?
-    metadata->insert(std::pair<grpc::string_ref, grpc::string_ref>(
-        arr->metadata[i].key, grpc::string_ref(arr->metadata[i].value,
-                                               arr->metadata[i].value_length)));
-  }
-  g_core_codegen_interface->grpc_metadata_array_destroy(arr);
-  g_core_codegen_interface->grpc_metadata_array_init(arr);
-}
-
 // TODO(yangg) if the map is changed before we send, the pointers will be a
 // mess. Make sure it does not happen.
 inline grpc_metadata* FillMetadataArray(
@@ -87,9 +75,8 @@ inline grpc_metadata* FillMetadataArray(
           metadata.size() * sizeof(grpc_metadata)));
   size_t i = 0;
   for (auto iter = metadata.cbegin(); iter != metadata.cend(); ++iter, ++i) {
-    metadata_array[i].key = iter->first.c_str();
-    metadata_array[i].value = iter->second.c_str();
-    metadata_array[i].value_length = iter->second.size();
+    metadata_array[i].key = SliceReferencingString(iter->first);
+    metadata_array[i].value = SliceReferencingString(iter->second);
   }
   return metadata_array;
 }
@@ -451,8 +438,9 @@ class CallOpServerSendStatus {
         trailing_metadata_count_;
     op->data.send_status_from_server.trailing_metadata = trailing_metadata_;
     op->data.send_status_from_server.status = send_status_code_;
+    status_details_slice_ = SliceReferencingString(send_status_details_);
     op->data.send_status_from_server.status_details =
-        send_status_details_.empty() ? nullptr : send_status_details_.c_str();
+        send_status_details_.empty() ? nullptr : &status_details_slice_;
     op->flags = 0;
     op->reserved = NULL;
   }
@@ -469,36 +457,35 @@ class CallOpServerSendStatus {
   grpc::string send_status_details_;
   size_t trailing_metadata_count_;
   grpc_metadata* trailing_metadata_;
+  grpc_slice status_details_slice_;
 };
 
 class CallOpRecvInitialMetadata {
  public:
-  CallOpRecvInitialMetadata() : recv_initial_metadata_(nullptr) {}
+  CallOpRecvInitialMetadata() : metadata_map_(nullptr) {}
 
   void RecvInitialMetadata(ClientContext* context) {
     context->initial_metadata_received_ = true;
-    recv_initial_metadata_ = &context->recv_initial_metadata_;
+    metadata_map_ = &context->recv_initial_metadata_;
   }
 
  protected:
   void AddOp(grpc_op* ops, size_t* nops) {
-    if (!recv_initial_metadata_) return;
-    memset(&recv_initial_metadata_arr_, 0, sizeof(recv_initial_metadata_arr_));
+    if (metadata_map_ == nullptr) return;
     grpc_op* op = &ops[(*nops)++];
     op->op = GRPC_OP_RECV_INITIAL_METADATA;
-    op->data.recv_initial_metadata = &recv_initial_metadata_arr_;
+    op->data.recv_initial_metadata = metadata_map_->arr();
     op->flags = 0;
     op->reserved = NULL;
   }
   void FinishOp(bool* status, int max_receive_message_size) {
-    if (recv_initial_metadata_ == nullptr) return;
-    FillMetadataMap(&recv_initial_metadata_arr_, recv_initial_metadata_);
-    recv_initial_metadata_ = nullptr;
+    if (metadata_map_ == nullptr) return;
+    metadata_map_->FillMap();
+    metadata_map_ = nullptr;
   }
 
  private:
-  std::multimap<grpc::string_ref, grpc::string_ref>* recv_initial_metadata_;
-  grpc_metadata_array recv_initial_metadata_arr_;
+  MetadataMap* metadata_map_;
 };
 
 class CallOpClientRecvStatus {
@@ -506,46 +493,37 @@ class CallOpClientRecvStatus {
   CallOpClientRecvStatus() : recv_status_(nullptr) {}
 
   void ClientRecvStatus(ClientContext* context, Status* status) {
-    recv_trailing_metadata_ = &context->trailing_metadata_;
+    metadata_map_ = &context->trailing_metadata_;
     recv_status_ = status;
   }
 
  protected:
   void AddOp(grpc_op* ops, size_t* nops) {
     if (recv_status_ == nullptr) return;
-    memset(&recv_trailing_metadata_arr_, 0,
-           sizeof(recv_trailing_metadata_arr_));
-    status_details_ = nullptr;
-    status_details_capacity_ = 0;
     grpc_op* op = &ops[(*nops)++];
     op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
-    op->data.recv_status_on_client.trailing_metadata =
-        &recv_trailing_metadata_arr_;
+    op->data.recv_status_on_client.trailing_metadata = metadata_map_->arr();
     op->data.recv_status_on_client.status = &status_code_;
     op->data.recv_status_on_client.status_details = &status_details_;
-    op->data.recv_status_on_client.status_details_capacity =
-        &status_details_capacity_;
     op->flags = 0;
     op->reserved = NULL;
   }
 
   void FinishOp(bool* status, int max_receive_message_size) {
     if (recv_status_ == nullptr) return;
-    FillMetadataMap(&recv_trailing_metadata_arr_, recv_trailing_metadata_);
-    *recv_status_ = Status(
-        static_cast<StatusCode>(status_code_),
-        status_details_ ? grpc::string(status_details_) : grpc::string());
-    g_core_codegen_interface->gpr_free(status_details_);
+    metadata_map_->FillMap();
+    *recv_status_ = Status(static_cast<StatusCode>(status_code_),
+                           grpc::string(GRPC_SLICE_START_PTR(status_details_),
+                                        GRPC_SLICE_END_PTR(status_details_)));
+    g_core_codegen_interface->grpc_slice_unref(status_details_);
     recv_status_ = nullptr;
   }
 
  private:
-  std::multimap<grpc::string_ref, grpc::string_ref>* recv_trailing_metadata_;
+  MetadataMap* metadata_map_;
   Status* recv_status_;
-  grpc_metadata_array recv_trailing_metadata_arr_;
   grpc_status_code status_code_;
-  char* status_details_;
-  size_t status_details_capacity_;
+  grpc_slice status_details_;
 };
 
 /// An abstract collection of CallOpSet's, to be used whenever
diff --git a/include/grpc++/impl/codegen/client_context.h b/include/grpc++/impl/codegen/client_context.h
index 777b2f8847..b91c7f65d4 100644
--- a/include/grpc++/impl/codegen/client_context.h
+++ b/include/grpc++/impl/codegen/client_context.h
@@ -57,7 +57,9 @@
 #include <grpc++/impl/codegen/config.h>
 #include <grpc++/impl/codegen/core_codegen_interface.h>
 #include <grpc++/impl/codegen/create_auth_context.h>
+#include <grpc++/impl/codegen/metadata_map.h>
 #include <grpc++/impl/codegen/security/auth_context.h>
+#include <grpc++/impl/codegen/slice.h>
 #include <grpc++/impl/codegen/status.h>
 #include <grpc++/impl/codegen/string_ref.h>
 #include <grpc++/impl/codegen/time.h>
@@ -193,7 +195,7 @@ class ClientContext {
   const std::multimap<grpc::string_ref, grpc::string_ref>&
   GetServerInitialMetadata() const {
     GPR_CODEGEN_ASSERT(initial_metadata_received_);
-    return recv_initial_metadata_;
+    return *recv_initial_metadata_.map();
   }
 
   /// Return a collection of trailing metadata key-value pairs. Note that keys
@@ -205,7 +207,7 @@ class ClientContext {
   const std::multimap<grpc::string_ref, grpc::string_ref>&
   GetServerTrailingMetadata() const {
     // TODO(yangg) check finished
-    return trailing_metadata_;
+    return *trailing_metadata_.map();
   }
 
   /// Set the deadline for the client call.
@@ -375,8 +377,8 @@ class ClientContext {
   mutable std::shared_ptr<const AuthContext> auth_context_;
   struct census_context* census_context_;
   std::multimap<grpc::string, grpc::string> send_initial_metadata_;
-  std::multimap<grpc::string_ref, grpc::string_ref> recv_initial_metadata_;
-  std::multimap<grpc::string_ref, grpc::string_ref> trailing_metadata_;
+  MetadataMap recv_initial_metadata_;
+  MetadataMap trailing_metadata_;
 
   grpc_call* propagate_from_call_;
   PropagationOptions propagation_options_;
diff --git a/include/grpc++/impl/codegen/client_unary_call.h b/include/grpc++/impl/codegen/client_unary_call.h
index 70d65549c8..201e52ae07 100644
--- a/include/grpc++/impl/codegen/client_unary_call.h
+++ b/include/grpc++/impl/codegen/client_unary_call.h
@@ -69,7 +69,14 @@ Status BlockingUnaryCall(ChannelInterface* channel, const RpcMethod& method,
   ops.ClientSendClose();
   ops.ClientRecvStatus(context, &status);
   call.PerformOps(&ops);
-  GPR_CODEGEN_ASSERT((cq.Pluck(&ops) && ops.got_message) || !status.ok());
+  if (cq.Pluck(&ops)) {
+    if (!ops.got_message && status.ok()) {
+      return Status(StatusCode::UNIMPLEMENTED,
+                    "No message returned for unary request");
+    }
+  } else {
+    GPR_CODEGEN_ASSERT(!status.ok());
+  }
   return status;
 }
 
diff --git a/include/grpc++/impl/codegen/core_codegen.h b/include/grpc++/impl/codegen/core_codegen.h
index 6b5e637e4e..754bf14b25 100644
--- a/include/grpc++/impl/codegen/core_codegen.h
+++ b/include/grpc++/impl/codegen/core_codegen.h
@@ -81,7 +81,10 @@ class CoreCodegen : public CoreCodegenInterface {
   grpc_slice grpc_slice_split_tail(grpc_slice* s, size_t split) override;
   void grpc_slice_buffer_add(grpc_slice_buffer* sb, grpc_slice slice) override;
   void grpc_slice_buffer_pop(grpc_slice_buffer* sb) override;
-
+  grpc_slice grpc_slice_from_static_buffer(const void* buffer,
+                                           size_t length) override;
+  grpc_slice grpc_slice_from_copied_buffer(const void* buffer,
+                                           size_t length) override;
   void grpc_metadata_array_init(grpc_metadata_array* array) override;
   void grpc_metadata_array_destroy(grpc_metadata_array* array) override;
 
@@ -91,7 +94,8 @@ class CoreCodegen : public CoreCodegenInterface {
   virtual const Status& ok() override;
   virtual const Status& cancelled() override;
 
-  void assert_fail(const char* failed_assertion) override;
+  void assert_fail(const char* failed_assertion, const char* file,
+                   int line) override;
 };
 
 }  // namespace grpc
diff --git a/include/grpc++/impl/codegen/core_codegen_interface.h b/include/grpc++/impl/codegen/core_codegen_interface.h
index 4783a43454..45ea040303 100644
--- a/include/grpc++/impl/codegen/core_codegen_interface.h
+++ b/include/grpc++/impl/codegen/core_codegen_interface.h
@@ -56,7 +56,8 @@ namespace grpc {
 class CoreCodegenInterface {
  public:
   /// Upon a failed assertion, log the error.
-  virtual void assert_fail(const char* failed_assertion) = 0;
+  virtual void assert_fail(const char* failed_assertion, const char* file,
+                           int line) = 0;
 
   virtual grpc_completion_queue* grpc_completion_queue_create(
       void* reserved) = 0;
@@ -99,6 +100,10 @@ class CoreCodegenInterface {
   virtual void grpc_slice_buffer_add(grpc_slice_buffer* sb,
                                      grpc_slice slice) = 0;
   virtual void grpc_slice_buffer_pop(grpc_slice_buffer* sb) = 0;
+  virtual grpc_slice grpc_slice_from_static_buffer(const void* buffer,
+                                                   size_t length) = 0;
+  virtual grpc_slice grpc_slice_from_copied_buffer(const void* buffer,
+                                                   size_t length) = 0;
 
   virtual void grpc_metadata_array_init(grpc_metadata_array* array) = 0;
   virtual void grpc_metadata_array_destroy(grpc_metadata_array* array) = 0;
@@ -113,11 +118,11 @@ class CoreCodegenInterface {
 extern CoreCodegenInterface* g_core_codegen_interface;
 
 /// Codegen specific version of \a GPR_ASSERT.
-#define GPR_CODEGEN_ASSERT(x)                          \
-  do {                                                 \
-    if (!(x)) {                                        \
-      grpc::g_core_codegen_interface->assert_fail(#x); \
-    }                                                  \
+#define GPR_CODEGEN_ASSERT(x)                                              \
+  do {                                                                     \
+    if (!(x)) {                                                            \
+      grpc::g_core_codegen_interface->assert_fail(#x, __FILE__, __LINE__); \
+    }                                                                      \
   } while (0)
 
 }  // namespace grpc
diff --git a/include/grpc++/impl/codegen/metadata_map.h b/include/grpc++/impl/codegen/metadata_map.h
new file mode 100644
index 0000000000..53b9d62f9f
--- /dev/null
+++ b/include/grpc++/impl/codegen/metadata_map.h
@@ -0,0 +1,71 @@
+/*
+*
+* 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 GRPCXX_IMPL_CODEGEN_METADATA_MAP_H
+#define GRPCXX_IMPL_CODEGEN_METADATA_MAP_H
+
+#include <grpc++/impl/codegen/slice.h>
+
+namespace grpc {
+
+class MetadataMap {
+ public:
+  MetadataMap() { memset(&arr_, 0, sizeof(arr_)); }
+
+  ~MetadataMap() {
+    g_core_codegen_interface->grpc_metadata_array_destroy(&arr_);
+  }
+
+  void FillMap() {
+    for (size_t i = 0; i < arr_.count; i++) {
+      // TODO(yangg) handle duplicates?
+      map_.insert(std::pair<grpc::string_ref, grpc::string_ref>(
+          StringRefFromSlice(&arr_.metadata[i].key),
+          StringRefFromSlice(&arr_.metadata[i].value)));
+    }
+  }
+
+  std::multimap<grpc::string_ref, grpc::string_ref> *map() { return &map_; }
+  const std::multimap<grpc::string_ref, grpc::string_ref> *map() const {
+    return &map_;
+  }
+  grpc_metadata_array *arr() { return &arr_; }
+
+ private:
+  grpc_metadata_array arr_;
+  std::multimap<grpc::string_ref, grpc::string_ref> map_;
+};
+
+}  // namespace grpc
+
+#endif  // GRPCXX_IMPL_CODEGEN_METADATA_MAP_H
diff --git a/include/grpc++/impl/codegen/server_context.h b/include/grpc++/impl/codegen/server_context.h
index dd30576379..8c7fe0809e 100644
--- a/include/grpc++/impl/codegen/server_context.h
+++ b/include/grpc++/impl/codegen/server_context.h
@@ -39,6 +39,7 @@
 
 #include <grpc++/impl/codegen/config.h>
 #include <grpc++/impl/codegen/create_auth_context.h>
+#include <grpc++/impl/codegen/metadata_map.h>
 #include <grpc++/impl/codegen/security/auth_context.h>
 #include <grpc++/impl/codegen/string_ref.h>
 #include <grpc++/impl/codegen/time.h>
@@ -123,7 +124,7 @@ class ServerContext {
 
   const std::multimap<grpc::string_ref, grpc::string_ref>& client_metadata()
       const {
-    return client_metadata_;
+    return *client_metadata_.map();
   }
 
   grpc_compression_level compression_level() const {
@@ -223,7 +224,7 @@ class ServerContext {
   CompletionQueue* cq_;
   bool sent_initial_metadata_;
   mutable std::shared_ptr<const AuthContext> auth_context_;
-  std::multimap<grpc::string_ref, grpc::string_ref> client_metadata_;
+  MetadataMap client_metadata_;
   std::multimap<grpc::string, grpc::string> initial_metadata_;
   std::multimap<grpc::string, grpc::string> trailing_metadata_;
 
diff --git a/include/grpc++/impl/codegen/server_interface.h b/include/grpc++/impl/codegen/server_interface.h
index 666b9ff66e..af1bf6fa6f 100644
--- a/include/grpc++/impl/codegen/server_interface.h
+++ b/include/grpc++/impl/codegen/server_interface.h
@@ -152,7 +152,6 @@ class ServerInterface : public CallHook {
     void* const tag_;
     const bool delete_on_finalize_;
     grpc_call* call_;
-    grpc_metadata_array initial_metadata_array_;
   };
 
   class RegisteredAsyncRequest : public BaseAsyncRequest {
diff --git a/include/grpc++/impl/codegen/slice.h b/include/grpc++/impl/codegen/slice.h
new file mode 100644
index 0000000000..04b2f9af01
--- /dev/null
+++ b/include/grpc++/impl/codegen/slice.h
@@ -0,0 +1,65 @@
+/*
+ *
+ * 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 GRPCXX_IMPL_CODEGEN_SLICE_H
+#define GRPCXX_IMPL_CODEGEN_SLICE_H
+
+#include <grpc++/impl/codegen/core_codegen_interface.h>
+#include <grpc++/impl/codegen/string_ref.h>
+
+namespace grpc {
+
+inline grpc::string_ref StringRefFromSlice(const grpc_slice* slice) {
+  return grpc::string_ref(
+      reinterpret_cast<const char*>(GRPC_SLICE_START_PTR(*slice)),
+      GRPC_SLICE_LENGTH(*slice));
+}
+
+inline grpc::string StringFromCopiedSlice(grpc_slice slice) {
+  return grpc::string(reinterpret_cast<char*>(GRPC_SLICE_START_PTR(slice)),
+                      GRPC_SLICE_LENGTH(slice));
+}
+
+inline grpc_slice SliceReferencingString(const grpc::string& str) {
+  return g_core_codegen_interface->grpc_slice_from_static_buffer(str.data(),
+                                                                 str.length());
+}
+
+inline grpc_slice SliceFromCopiedString(const grpc::string& str) {
+  return g_core_codegen_interface->grpc_slice_from_copied_buffer(str.data(),
+                                                                 str.length());
+}
+
+}  // namespace grpc
+
+#endif  // GRPCXX_IMPL_CODEGEN_SLICE_H
diff --git a/include/grpc/compression.h b/include/grpc/compression.h
index 5f285cdcdf..659d6fe758 100644
--- a/include/grpc/compression.h
+++ b/include/grpc/compression.h
@@ -34,11 +34,12 @@
 #ifndef GRPC_COMPRESSION_H
 #define GRPC_COMPRESSION_H
 
-#include <stdlib.h>
-
 #include <grpc/impl/codegen/port_platform.h>
 
+#include <stdlib.h>
+
 #include <grpc/impl/codegen/compression_types.h>
+#include <grpc/slice.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -48,8 +49,7 @@ extern "C" {
  * grpc_compression_algorithm instance, updating \a algorithm. Returns 1 upon
  * success, 0 otherwise. */
 GRPCAPI int grpc_compression_algorithm_parse(
-    const char *name, size_t name_length,
-    grpc_compression_algorithm *algorithm);
+    grpc_slice value, grpc_compression_algorithm *algorithm);
 
 /** Updates \a name with the encoding name corresponding to a valid \a
  * algorithm. Note that \a name is statically allocated and must *not* be freed.
diff --git a/include/grpc/grpc.h b/include/grpc/grpc.h
index 898f4d533b..37b823ae1e 100644
--- a/include/grpc/grpc.h
+++ b/include/grpc/grpc.h
@@ -178,8 +178,8 @@ GRPCAPI void grpc_channel_watch_connectivity_state(
     possible values). */
 GRPCAPI grpc_call *grpc_channel_create_call(
     grpc_channel *channel, grpc_call *parent_call, uint32_t propagation_mask,
-    grpc_completion_queue *completion_queue, const char *method,
-    const char *host, gpr_timespec deadline, void *reserved);
+    grpc_completion_queue *completion_queue, grpc_slice method,
+    const grpc_slice *host, gpr_timespec deadline, void *reserved);
 
 /** Ping the channels peer (load balanced channels will select one sub-channel
     to ping); if the channel is not connected, posts a failed. */
@@ -402,14 +402,14 @@ GRPCAPI void grpc_server_destroy(grpc_server *server);
 GRPCAPI int grpc_tracer_set_enabled(const char *name, int enabled);
 
 /** Check whether a metadata key is legal (will be accepted by core) */
-GRPCAPI int grpc_header_key_is_legal(const char *key, size_t length);
+GRPCAPI int grpc_header_key_is_legal(grpc_slice slice);
 
 /** Check whether a non-binary metadata value is legal (will be accepted by
     core) */
-GRPCAPI int grpc_header_nonbin_value_is_legal(const char *value, size_t length);
+GRPCAPI int grpc_header_nonbin_value_is_legal(grpc_slice slice);
 
 /** Check whether a metadata key corresponds to a binary value */
-GRPCAPI int grpc_is_binary_header(const char *key, size_t length);
+GRPCAPI int grpc_is_binary_header(grpc_slice slice);
 
 /** Convert grpc_call_error values to a string */
 GRPCAPI const char *grpc_call_error_to_string(grpc_call_error error);
diff --git a/include/grpc/impl/codegen/grpc_types.h b/include/grpc/impl/codegen/grpc_types.h
index ee8101aab8..8efd570bad 100644
--- a/include/grpc/impl/codegen/grpc_types.h
+++ b/include/grpc/impl/codegen/grpc_types.h
@@ -294,9 +294,11 @@ typedef enum grpc_call_error {
 
 /** A single metadata element */
 typedef struct grpc_metadata {
-  const char *key;
-  const char *value;
-  size_t value_length;
+  /* the key, value values are expected to line up with grpc_mdelem: if changing
+     them, update metadata.h at the same time. */
+  grpc_slice key;
+  grpc_slice value;
+
   uint32_t flags;
 
   /** The following fields are reserved for grpc internal use.
@@ -338,10 +340,8 @@ typedef struct {
 } grpc_metadata_array;
 
 typedef struct {
-  char *method;
-  size_t method_capacity;
-  char *host;
-  size_t host_capacity;
+  grpc_slice method;
+  grpc_slice host;
   gpr_timespec deadline;
   uint32_t flags;
   void *reserved;
@@ -423,7 +423,10 @@ typedef struct grpc_op {
       size_t trailing_metadata_count;
       grpc_metadata *trailing_metadata;
       grpc_status_code status;
-      const char *status_details;
+      /* optional: set to NULL if no details need sending, non-NULL if they do
+       * pointer will not be retained past the start_batch call
+       */
+      grpc_slice *status_details;
     } send_status_from_server;
     /** ownership of the array is with the caller, but ownership of the elements
         stays with the call object (ie key, value members are owned by the call
@@ -444,28 +447,7 @@ typedef struct grpc_op {
           value, or reuse it in a future op. */
       grpc_metadata_array *trailing_metadata;
       grpc_status_code *status;
-      /** status_details is a buffer owned by the application before the op
-          completes and after the op has completed. During the operation
-          status_details may be reallocated to a size larger than
-          *status_details_capacity, in which case *status_details_capacity will
-          be updated with the new array capacity.
-
-          Pre-allocating space:
-          size_t my_capacity = 8;
-          char *my_details = gpr_malloc(my_capacity);
-          x.status_details = &my_details;
-          x.status_details_capacity = &my_capacity;
-
-          Not pre-allocating space:
-          size_t my_capacity = 0;
-          char *my_details = NULL;
-          x.status_details = &my_details;
-          x.status_details_capacity = &my_capacity;
-
-          After the call:
-          gpr_free(my_details); */
-      char **status_details;
-      size_t *status_details_capacity;
+      grpc_slice *status_details;
     } recv_status_on_client;
     struct {
       /** out argument, set to 1 if the call failed in any way (seen as a
diff --git a/include/grpc/impl/codegen/slice.h b/include/grpc/impl/codegen/slice.h
index 00781bb76b..3c9c7b0285 100644
--- a/include/grpc/impl/codegen/slice.h
+++ b/include/grpc/impl/codegen/slice.h
@@ -40,6 +40,8 @@
 #include <grpc/impl/codegen/exec_ctx_fwd.h>
 #include <grpc/impl/codegen/gpr_slice.h>
 
+typedef struct grpc_slice grpc_slice;
+
 /* Slice API
 
    A slice represents a contiguous reference counted array of bytes.
@@ -53,14 +55,25 @@
    reference ownership semantics (who should call unref?) and mutability
    constraints (is the callee allowed to modify the slice?) */
 
+typedef struct grpc_slice_refcount_vtable {
+  void (*ref)(void *);
+  void (*unref)(grpc_exec_ctx *exec_ctx, void *);
+  int (*eq)(grpc_slice a, grpc_slice b);
+  uint32_t (*hash)(grpc_slice slice);
+} grpc_slice_refcount_vtable;
+
 /* Reference count container for grpc_slice. Contains function pointers to
    increment and decrement reference counts. Implementations should cleanup
    when the reference count drops to zero.
    Typically client code should not touch this, and use grpc_slice_malloc,
    grpc_slice_new, or grpc_slice_new_with_len instead. */
 typedef struct grpc_slice_refcount {
-  void (*ref)(void *);
-  void (*unref)(grpc_exec_ctx *exec_ctx, void *);
+  const grpc_slice_refcount_vtable *vtable;
+  /* If a subset of this slice is taken, use this pointer for the refcount.
+     Typically points back to the refcount itself, however iterning
+     implementations can use this to avoid a verification step on each hash
+     or equality check */
+  struct grpc_slice_refcount *sub_refcount;
 } grpc_slice_refcount;
 
 #define GRPC_SLICE_INLINED_SIZE (sizeof(size_t) + sizeof(uint8_t *) - 1)
@@ -74,7 +87,7 @@ typedef struct grpc_slice_refcount {
 
    If the slice does not have a refcount, it represents an inlined small piece
    of data that is copied by value. */
-typedef struct grpc_slice {
+struct grpc_slice {
   struct grpc_slice_refcount *refcount;
   union {
     struct {
@@ -86,7 +99,7 @@ typedef struct grpc_slice {
       uint8_t bytes[GRPC_SLICE_INLINED_SIZE];
     } inlined;
   } data;
-} grpc_slice;
+};
 
 #define GRPC_SLICE_BUFFER_INLINE_ELEMENTS 8
 
diff --git a/include/grpc/slice.h b/include/grpc/slice.h
index 1f181aae16..ea66e094e9 100644
--- a/include/grpc/slice.h
+++ b/include/grpc/slice.h
@@ -76,6 +76,12 @@ GPRAPI grpc_slice grpc_slice_new_with_len(void *p, size_t len,
    Aborts if malloc() fails. */
 GPRAPI grpc_slice grpc_slice_malloc(size_t length);
 
+/* Intern a slice:
+
+   The return value for two invocations of this function with  the same sequence
+   of bytes is a slice which points to the same memory. */
+GPRAPI grpc_slice grpc_slice_intern(grpc_slice slice);
+
 /* Create a slice by copying a string.
    Does not preserve null terminators.
    Equivalent to:
@@ -93,6 +99,9 @@ GPRAPI grpc_slice grpc_slice_from_copied_buffer(const char *source, size_t len);
 /* Create a slice pointing to constant memory */
 GPRAPI grpc_slice grpc_slice_from_static_string(const char *source);
 
+/* Create a slice pointing to constant memory */
+GPRAPI grpc_slice grpc_slice_from_static_buffer(const void *source, size_t len);
+
 /* Return a result slice derived from s, which shares a ref count with s, where
    result.data==s.data+begin, and result.length==end-begin.
    The ref count of s is increased by one.
@@ -113,18 +122,45 @@ GPRAPI grpc_slice grpc_slice_split_tail(grpc_slice *s, size_t split);
    Requires s intialized, split <= s.length */
 GPRAPI grpc_slice grpc_slice_split_head(grpc_slice *s, size_t split);
 
-GPRAPI grpc_slice gpr_empty_slice(void);
+GPRAPI grpc_slice grpc_empty_slice(void);
+
+GPRAPI uint32_t grpc_slice_default_hash_impl(grpc_slice s);
+GPRAPI int grpc_slice_default_eq_impl(grpc_slice a, grpc_slice b);
+
+GPRAPI int grpc_slice_eq(grpc_slice a, grpc_slice b);
 
 /* Returns <0 if a < b, ==0 if a == b, >0 if a > b
    The order is arbitrary, and is not guaranteed to be stable across different
    versions of the API. */
 GPRAPI int grpc_slice_cmp(grpc_slice a, grpc_slice b);
 GPRAPI int grpc_slice_str_cmp(grpc_slice a, const char *b);
+GPRAPI int grpc_slice_buf_cmp(grpc_slice a, const void *b, size_t blen);
+
+/* return non-zero if the first blen bytes of a are equal to b */
+GPRAPI int grpc_slice_buf_start_eq(grpc_slice a, const void *b, size_t blen);
+
+/* return the index of the last instance of \a c in \a s, or -1 if not found */
+GPRAPI int grpc_slice_rchr(grpc_slice s, char c);
+GPRAPI int grpc_slice_chr(grpc_slice s, char c);
+
+/* return the index of the first occurance of \a needle in \a haystack, or -1 if
+ * it's not found */
+GPRAPI int grpc_slice_slice(grpc_slice haystack, grpc_slice needle);
+
+GPRAPI uint32_t grpc_slice_hash(grpc_slice s);
 
 /* Do two slices point at the same memory, with the same length
    If a or b is inlined, actually compares data */
 GPRAPI int grpc_slice_is_equivalent(grpc_slice a, grpc_slice b);
 
+/* Return a slice pointing to newly allocated memory that has the same contents
+ * as \a s */
+GPRAPI grpc_slice grpc_slice_dup(grpc_slice a);
+
+/* Return a copy of slice as a C string. Offers no protection against embedded
+   NULL's. Returned string must be freed with gpr_free. */
+GPRAPI char *grpc_slice_to_c_string(grpc_slice s);
+
 #ifdef __cplusplus
 }
 #endif