Revert "Metadata handling rewrite"
diff --git a/src/cpp/client/channel_cc.cc b/src/cpp/client/channel_cc.cc
index c985183..357d831 100644
--- a/src/cpp/client/channel_cc.cc
+++ b/src/cpp/client/channel_cc.cc
@@ -107,20 +107,10 @@
     } else if (!host_.empty()) {
       host_str = host_.c_str();
     }
-    grpc_slice method_slice = SliceFromCopiedString(method.name());
-    grpc_slice host_slice;
-    if (host_str != nullptr) {
-      host_slice = SliceFromCopiedString(host_str);
-    }
-    c_call = grpc_channel_create_call(
-        c_channel_, context->propagate_from_call_,
-        context->propagation_options_.c_bitmask(), cq->cq(), method_slice,
-        host_str == nullptr ? nullptr : &host_slice, context->raw_deadline(),
-        nullptr);
-    grpc_slice_unref(method_slice);
-    if (host_str != nullptr) {
-      grpc_slice_unref(host_slice);
-    }
+    c_call = grpc_channel_create_call(c_channel_, context->propagate_from_call_,
+                                      context->propagation_options_.c_bitmask(),
+                                      cq->cq(), method.name(), host_str,
+                                      context->raw_deadline(), nullptr);
   }
   grpc_census_call_set_context(c_call, context->census_context());
   context->set_call(c_call, shared_from_this());
diff --git a/src/cpp/client/secure_credentials.cc b/src/cpp/client/secure_credentials.cc
index 25f6bab..269c523 100644
--- a/src/cpp/client/secure_credentials.cc
+++ b/src/cpp/client/secure_credentials.cc
@@ -206,18 +206,15 @@
   std::vector<grpc_metadata> md;
   for (auto it = metadata.begin(); it != metadata.end(); ++it) {
     grpc_metadata md_entry;
-    md_entry.key = SliceFromCopiedString(it->first);
-    md_entry.value = SliceFromCopiedString(it->second);
+    md_entry.key = it->first.c_str();
+    md_entry.value = it->second.data();
+    md_entry.value_length = it->second.size();
     md_entry.flags = 0;
     md.push_back(md_entry);
   }
   cb(user_data, md.empty() ? nullptr : &md[0], md.size(),
      static_cast<grpc_status_code>(status.error_code()),
      status.error_message().c_str());
-  for (auto it = md.begin(); it != md.end(); ++it) {
-    grpc_slice_unref(it->key);
-    grpc_slice_unref(it->value);
-  }
 }
 
 MetadataCredentialsPluginWrapper::MetadataCredentialsPluginWrapper(
diff --git a/src/cpp/client/secure_credentials.h b/src/cpp/client/secure_credentials.h
index 713654a..281db17 100644
--- a/src/cpp/client/secure_credentials.h
+++ b/src/cpp/client/secure_credentials.h
@@ -70,7 +70,7 @@
   grpc_call_credentials* const c_creds_;
 };
 
-class MetadataCredentialsPluginWrapper final : private GrpcLibraryCodegen {
+class MetadataCredentialsPluginWrapper final {
  public:
   static void Destroy(void* wrapper);
   static void GetMetadata(void* wrapper, grpc_auth_metadata_context context,
diff --git a/src/cpp/common/channel_filter.cc b/src/cpp/common/channel_filter.cc
index 253614c..c0dc9dd 100644
--- a/src/cpp/common/channel_filter.cc
+++ b/src/cpp/common/channel_filter.cc
@@ -36,8 +36,6 @@
 #include "src/core/lib/channel/channel_stack.h"
 #include "src/cpp/common/channel_filter.h"
 
-#include <grpc++/impl/codegen/slice.h>
-
 namespace grpc {
 
 // MetadataBatch
@@ -47,10 +45,8 @@
                                                const string &value) {
   grpc_linked_mdelem *storage = new grpc_linked_mdelem;
   memset(storage, 0, sizeof(grpc_linked_mdelem));
-  storage->md = grpc_mdelem_from_slices(exec_ctx, SliceFromCopiedString(key),
-                                        SliceFromCopiedString(value));
-  GRPC_LOG_IF_ERROR("MetadataBatch::AddMetadata",
-                    grpc_metadata_batch_link_head(exec_ctx, batch_, storage));
+  storage->md = grpc_mdelem_from_strings(exec_ctx, key.c_str(), value.c_str());
+  grpc_metadata_batch_link_head(batch_, storage);
   return storage;
 }
 
diff --git a/src/cpp/common/channel_filter.h b/src/cpp/common/channel_filter.h
index 5f9fd87..5de8f5e 100644
--- a/src/cpp/common/channel_filter.h
+++ b/src/cpp/common/channel_filter.h
@@ -76,8 +76,8 @@
   class const_iterator : public std::iterator<std::bidirectional_iterator_tag,
                                               const grpc_mdelem> {
    public:
-    const grpc_mdelem &operator*() const { return elem_->md; }
-    const grpc_mdelem operator->() const { return elem_->md; }
+    const grpc_mdelem &operator*() const { return *elem_->md; }
+    const grpc_mdelem *operator->() const { return elem_->md; }
 
     const_iterator &operator++() {
       elem_ = elem_->next;
@@ -133,7 +133,7 @@
   grpc_error *disconnect_with_error() const {
     return op_->disconnect_with_error;
   }
-  bool send_goaway() const { return op_->goaway_error != GRPC_ERROR_NONE; }
+  bool send_goaway() const { return op_->send_goaway; }
 
   // TODO(roth): Add methods for additional fields as needed.
 
diff --git a/src/cpp/common/core_codegen.cc b/src/cpp/common/core_codegen.cc
index 36e4c89..a07ad54 100644
--- a/src/cpp/common/core_codegen.cc
+++ b/src/cpp/common/core_codegen.cc
@@ -123,17 +123,6 @@
   return ::grpc_slice_split_tail(s, split);
 }
 
-grpc_slice CoreCodegen::grpc_slice_from_static_buffer(const void* buffer,
-                                                      size_t length) {
-  return ::grpc_slice_from_static_buffer(buffer, length);
-}
-
-grpc_slice CoreCodegen::grpc_slice_from_copied_buffer(const void* buffer,
-                                                      size_t length) {
-  return ::grpc_slice_from_copied_buffer(static_cast<const char*>(buffer),
-                                         length);
-}
-
 void CoreCodegen::grpc_slice_buffer_add(grpc_slice_buffer* sb,
                                         grpc_slice slice) {
   ::grpc_slice_buffer_add(sb, slice);
@@ -163,10 +152,8 @@
   return ::gpr_time_0(type);
 }
 
-void CoreCodegen::assert_fail(const char* failed_assertion, const char* file,
-                              int line) {
-  gpr_log(file, line, GPR_LOG_SEVERITY_ERROR, "assertion failed: %s",
-          failed_assertion);
+void CoreCodegen::assert_fail(const char* failed_assertion) {
+  gpr_log(GPR_ERROR, "assertion failed: %s", failed_assertion);
   abort();
 }
 
diff --git a/src/cpp/server/dynamic_thread_pool.cc b/src/cpp/server/dynamic_thread_pool.cc
index afb5bea..1fdc2ed 100644
--- a/src/cpp/server/dynamic_thread_pool.cc
+++ b/src/cpp/server/dynamic_thread_pool.cc
@@ -31,15 +31,12 @@
  *
  */
 
-#include "src/cpp/server/dynamic_thread_pool.h"
-
 #include <mutex>
 #include <thread>
 
-#include <grpc/support/log.h>
+#include "src/cpp/server/dynamic_thread_pool.h"
 
 namespace grpc {
-
 DynamicThreadPool::DynamicThread::DynamicThread(DynamicThreadPool* pool)
     : pool_(pool),
       thd_(new std::thread(&DynamicThreadPool::DynamicThread::ThreadFunc,
diff --git a/src/cpp/server/secure_server_credentials.cc b/src/cpp/server/secure_server_credentials.cc
index 10f662c..33bdc2a 100644
--- a/src/cpp/server/secure_server_credentials.cc
+++ b/src/cpp/server/secure_server_credentials.cc
@@ -35,12 +35,11 @@
 #include <map>
 #include <memory>
 
-#include <grpc++/impl/codegen/slice.h>
-#include <grpc++/security/auth_metadata_processor.h>
-
 #include "src/cpp/common/secure_auth_context.h"
 #include "src/cpp/server/secure_server_credentials.h"
 
+#include <grpc++/security/auth_metadata_processor.h>
+
 namespace grpc {
 
 void AuthMetadataProcessorAyncWrapper::Destroy(void* wrapper) {
@@ -72,8 +71,8 @@
     grpc_process_auth_metadata_done_cb cb, void* user_data) {
   AuthMetadataProcessor::InputMetadata metadata;
   for (size_t i = 0; i < num_md; i++) {
-    metadata.insert(std::make_pair(StringRefFromSlice(&md[i].key),
-                                   StringRefFromSlice(&md[i].value)));
+    metadata.insert(std::make_pair(
+        md[i].key, grpc::string_ref(md[i].value, md[i].value_length)));
   }
   SecureAuthContext context(ctx, false);
   AuthMetadataProcessor::OutputMetadata consumed_metadata;
@@ -86,8 +85,9 @@
   for (auto it = consumed_metadata.begin(); it != consumed_metadata.end();
        ++it) {
     grpc_metadata md_entry;
-    md_entry.key = SliceReferencingString(it->first);
-    md_entry.value = SliceReferencingString(it->second);
+    md_entry.key = it->first.c_str();
+    md_entry.value = it->second.data();
+    md_entry.value_length = it->second.size();
     md_entry.flags = 0;
     consumed_md.push_back(md_entry);
   }
@@ -95,8 +95,9 @@
   for (auto it = response_metadata.begin(); it != response_metadata.end();
        ++it) {
     grpc_metadata md_entry;
-    md_entry.key = SliceReferencingString(it->first);
-    md_entry.value = SliceReferencingString(it->second);
+    md_entry.key = it->first.c_str();
+    md_entry.value = it->second.data();
+    md_entry.value_length = it->second.size();
     md_entry.flags = 0;
     response_md.push_back(md_entry);
   }
diff --git a/src/cpp/server/server_cc.cc b/src/cpp/server/server_cc.cc
index dcc56ee..817d85a 100644
--- a/src/cpp/server/server_cc.cc
+++ b/src/cpp/server/server_cc.cc
@@ -576,6 +576,7 @@
       delete_on_finalize_(delete_on_finalize),
       call_(nullptr) {
   call_cq_->RegisterAvalanching();  // This op will trigger more ops
+  memset(&initial_metadata_array_, 0, sizeof(initial_metadata_array_));
 }
 
 ServerInterface::BaseAsyncRequest::~BaseAsyncRequest() {
@@ -585,8 +586,16 @@
 bool ServerInterface::BaseAsyncRequest::FinalizeResult(void** tag,
                                                        bool* status) {
   if (*status) {
-    context_->client_metadata_.FillMap();
+    for (size_t i = 0; i < initial_metadata_array_.count; i++) {
+      context_->client_metadata_.insert(
+          std::pair<grpc::string_ref, grpc::string_ref>(
+              initial_metadata_array_.metadata[i].key,
+              grpc::string_ref(
+                  initial_metadata_array_.metadata[i].value,
+                  initial_metadata_array_.metadata[i].value_length)));
+    }
   }
+  grpc_metadata_array_destroy(&initial_metadata_array_);
   context_->set_call(call_);
   context_->cq_ = call_cq_;
   Call call(call_, server_, call_cq_, server_->max_receive_message_size());
@@ -612,8 +621,8 @@
     ServerCompletionQueue* notification_cq) {
   grpc_server_request_registered_call(
       server_->server(), registered_method, &call_, &context_->deadline_,
-      context_->client_metadata_.arr(), payload, call_cq_->cq(),
-      notification_cq->cq(), this);
+      &initial_metadata_array_, payload, call_cq_->cq(), notification_cq->cq(),
+      this);
 }
 
 ServerInterface::GenericAsyncRequest::GenericAsyncRequest(
@@ -626,7 +635,7 @@
   GPR_ASSERT(notification_cq);
   GPR_ASSERT(call_cq);
   grpc_server_request_call(server->server(), &call_, &call_details_,
-                           context->client_metadata_.arr(), call_cq->cq(),
+                           &initial_metadata_array_, call_cq->cq(),
                            notification_cq->cq(), this);
 }
 
@@ -635,12 +644,11 @@
   // TODO(yangg) remove the copy here.
   if (*status) {
     static_cast<GenericServerContext*>(context_)->method_ =
-        StringFromCopiedSlice(call_details_.method);
-    static_cast<GenericServerContext*>(context_)->host_ =
-        StringFromCopiedSlice(call_details_.host);
+        call_details_.method;
+    static_cast<GenericServerContext*>(context_)->host_ = call_details_.host;
   }
-  grpc_slice_unref(call_details_.method);
-  grpc_slice_unref(call_details_.host);
+  gpr_free(call_details_.method);
+  gpr_free(call_details_.host);
   return BaseAsyncRequest::FinalizeResult(tag, status);
 }
 
diff --git a/src/cpp/server/server_context.cc b/src/cpp/server/server_context.cc
index a7aaa25..a66ec4a 100644
--- a/src/cpp/server/server_context.cc
+++ b/src/cpp/server/server_context.cc
@@ -144,10 +144,9 @@
       sent_initial_metadata_(false),
       compression_level_set_(false) {
   for (size_t i = 0; i < metadata_count; i++) {
-    client_metadata_.map()->insert(
-        std::pair<grpc::string_ref, grpc::string_ref>(
-            StringRefFromSlice(&metadata[i].key),
-            StringRefFromSlice(&metadata[i].value)));
+    client_metadata_.insert(std::pair<grpc::string_ref, grpc::string_ref>(
+        metadata[i].key,
+        grpc::string_ref(metadata[i].value, metadata[i].value_length)));
   }
 }
 
diff --git a/src/cpp/test/server_context_test_spouse.cc b/src/cpp/test/server_context_test_spouse.cc
index b812d16..b93152e 100644
--- a/src/cpp/test/server_context_test_spouse.cc
+++ b/src/cpp/test/server_context_test_spouse.cc
@@ -40,12 +40,11 @@
                                                 const grpc::string& value) {
   client_metadata_storage_.insert(
       std::pair<grpc::string, grpc::string>(key, value));
-  ctx_->client_metadata_.map()->clear();
+  ctx_->client_metadata_.clear();
   for (auto iter = client_metadata_storage_.begin();
        iter != client_metadata_storage_.end(); ++iter) {
-    ctx_->client_metadata_.map()->insert(
-        std::pair<grpc::string_ref, grpc::string_ref>(iter->first.c_str(),
-                                                      iter->second.c_str()));
+    ctx_->client_metadata_.insert(std::pair<grpc::string_ref, grpc::string_ref>(
+        iter->first.c_str(), iter->second.c_str()));
   }
 }
 
diff --git a/src/cpp/util/slice_cc.cc b/src/cpp/util/slice_cc.cc
index 6efb68e..c05f1cf 100644
--- a/src/cpp/util/slice_cc.cc
+++ b/src/cpp/util/slice_cc.cc
@@ -35,7 +35,7 @@
 
 namespace grpc {
 
-Slice::Slice() : slice_(grpc_empty_slice()) {}
+Slice::Slice() : slice_(gpr_empty_slice()) {}
 
 Slice::~Slice() { grpc_slice_unref(slice_); }