Merge pull request #17797 from nicolasnoble/channel

Folding the Channel class into the grpc_impl namespace.

BUILD

@@ -221,6 +221,7 @@ GRPCXX_PUBLIC_HDRS = [
     "include/grpcpp/alarm.h",
     "include/grpcpp/alarm_impl.h",
     "include/grpcpp/channel.h",
+    "include/grpcpp/channel_impl.h",
     "include/grpcpp/client_context.h",
     "include/grpcpp/completion_queue.h",
     "include/grpcpp/create_channel.h",

CMakeLists.txt

@@ -2991,6 +2991,7 @@ foreach(_hdr
   include/grpcpp/alarm.h
   include/grpcpp/alarm_impl.h
   include/grpcpp/channel.h
+  include/grpcpp/channel_impl.h
   include/grpcpp/client_context.h
   include/grpcpp/completion_queue.h
   include/grpcpp/create_channel.h
@@ -3582,6 +3583,7 @@ foreach(_hdr
   include/grpcpp/alarm.h
   include/grpcpp/alarm_impl.h
   include/grpcpp/channel.h
+  include/grpcpp/channel_impl.h
   include/grpcpp/client_context.h
   include/grpcpp/completion_queue.h
   include/grpcpp/create_channel.h
@@ -4537,6 +4539,7 @@ foreach(_hdr
   include/grpcpp/alarm.h
   include/grpcpp/alarm_impl.h
   include/grpcpp/channel.h
+  include/grpcpp/channel_impl.h
   include/grpcpp/client_context.h
   include/grpcpp/completion_queue.h
   include/grpcpp/create_channel.h

Makefile

@@ -5397,6 +5397,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/alarm.h \
     include/grpcpp/alarm_impl.h \
     include/grpcpp/channel.h \
+    include/grpcpp/channel_impl.h \
     include/grpcpp/client_context.h \
     include/grpcpp/completion_queue.h \
     include/grpcpp/create_channel.h \
@@ -5997,6 +5998,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/alarm.h \
     include/grpcpp/alarm_impl.h \
     include/grpcpp/channel.h \
+    include/grpcpp/channel_impl.h \
     include/grpcpp/client_context.h \
     include/grpcpp/completion_queue.h \
     include/grpcpp/create_channel.h \
@@ -6909,6 +6911,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/alarm.h \
     include/grpcpp/alarm_impl.h \
     include/grpcpp/channel.h \
+    include/grpcpp/channel_impl.h \
     include/grpcpp/client_context.h \
     include/grpcpp/completion_queue.h \
     include/grpcpp/create_channel.h \

build.yaml

@@ -1341,6 +1341,7 @@ filegroups:
   - include/grpcpp/alarm.h
   - include/grpcpp/alarm_impl.h
   - include/grpcpp/channel.h
+  - include/grpcpp/channel_impl.h
   - include/grpcpp/client_context.h
   - include/grpcpp/completion_queue.h
   - include/grpcpp/create_channel.h

gRPC-C++.podspec

@@ -82,6 +82,7 @@ Pod::Spec.new do |s|
     ss.source_files = 'include/grpcpp/alarm.h',
                       'include/grpcpp/alarm_impl.h',
                       'include/grpcpp/channel.h',
+                      'include/grpcpp/channel_impl.h',
                       'include/grpcpp/client_context.h',
                       'include/grpcpp/completion_queue.h',
                       'include/grpcpp/create_channel.h',

include/grpcpp/channel.h

@@ -19,96 +19,16 @@
 #ifndef GRPCPP_CHANNEL_H
 #define GRPCPP_CHANNEL_H
 
-#include <memory>
-#include <mutex>
-
-#include <grpc/grpc.h>
-#include <grpcpp/impl/call.h>
-#include <grpcpp/impl/codegen/channel_interface.h>
-#include <grpcpp/impl/codegen/client_interceptor.h>
-#include <grpcpp/impl/codegen/config.h>
-#include <grpcpp/impl/codegen/grpc_library.h>
-
-struct grpc_channel;
+#include <grpcpp/channel_impl.h>
 
 namespace grpc {
 
+typedef ::grpc_impl::Channel Channel;
+
 namespace experimental {
-/// Resets the channel's connection backoff.
-/// TODO(roth): Once we see whether this proves useful, either create a gRFC
-/// and change this to be a method of the Channel class, or remove it.
 void ChannelResetConnectionBackoff(Channel* channel);
 }  // namespace experimental
 
-/// Channels represent a connection to an endpoint. Created by \a CreateChannel.
-class Channel final : public ChannelInterface,
-                      public internal::CallHook,
-                      public std::enable_shared_from_this<Channel>,
-                      private GrpcLibraryCodegen {
- public:
-  ~Channel();
-
-  /// Get the current channel state. If the channel is in IDLE and
-  /// \a try_to_connect is set to true, try to connect.
-  grpc_connectivity_state GetState(bool try_to_connect) override;
-
-  /// Returns the LB policy name, or the empty string if not yet available.
-  grpc::string GetLoadBalancingPolicyName() const;
-
-  /// Returns the service config in JSON form, or the empty string if
-  /// not available.
-  grpc::string GetServiceConfigJSON() const;
-
- private:
-  template <class InputMessage, class OutputMessage>
-  friend class internal::BlockingUnaryCallImpl;
-  friend void experimental::ChannelResetConnectionBackoff(Channel* channel);
-  friend std::shared_ptr<Channel> CreateChannelInternal(
-      const grpc::string& host, grpc_channel* c_channel,
-      std::vector<
-          std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
-          interceptor_creators);
-  friend class internal::InterceptedChannel;
-  Channel(const grpc::string& host, grpc_channel* c_channel,
-          std::vector<
-              std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
-              interceptor_creators);
-
-  internal::Call CreateCall(const internal::RpcMethod& method,
-                            ClientContext* context,
-                            CompletionQueue* cq) override;
-  void PerformOpsOnCall(internal::CallOpSetInterface* ops,
-                        internal::Call* call) override;
-  void* RegisterMethod(const char* method) override;
-
-  void NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
-                               gpr_timespec deadline, CompletionQueue* cq,
-                               void* tag) override;
-  bool WaitForStateChangeImpl(grpc_connectivity_state last_observed,
-                              gpr_timespec deadline) override;
-
-  CompletionQueue* CallbackCQ() override;
-
-  internal::Call CreateCallInternal(const internal::RpcMethod& method,
-                                    ClientContext* context, CompletionQueue* cq,
-                                    size_t interceptor_pos) override;
-
-  const grpc::string host_;
-  grpc_channel* const c_channel_;  // owned
-
-  // mu_ protects callback_cq_ (the per-channel callbackable completion queue)
-  std::mutex mu_;
-
-  // callback_cq_ references the callbackable completion queue associated
-  // with this channel (if any). It is set on the first call to CallbackCQ().
-  // It is _not owned_ by the channel; ownership belongs with its internal
-  // shutdown callback tag (invoked when the CQ is fully shutdown).
-  CompletionQueue* callback_cq_ = nullptr;
-
-  std::vector<std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
-      interceptor_creators_;
-};
-
 }  // namespace grpc
 
 #endif  // GRPCPP_CHANNEL_H

include/grpcpp/channel_impl.h

@@ -0,0 +1,115 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_CHANNEL_IMPL_H
+#define GRPCPP_CHANNEL_IMPL_H
+
+#include <memory>
+#include <mutex>
+
+#include <grpc/grpc.h>
+#include <grpcpp/impl/call.h>
+#include <grpcpp/impl/codegen/channel_interface.h>
+#include <grpcpp/impl/codegen/client_interceptor.h>
+#include <grpcpp/impl/codegen/config.h>
+#include <grpcpp/impl/codegen/grpc_library.h>
+
+struct grpc_channel;
+
+namespace grpc_impl {
+
+namespace experimental {
+/// Resets the channel's connection backoff.
+/// TODO(roth): Once we see whether this proves useful, either create a gRFC
+/// and change this to be a method of the Channel class, or remove it.
+void ChannelResetConnectionBackoff(Channel* channel);
+}  // namespace experimental
+
+/// Channels represent a connection to an endpoint. Created by \a CreateChannel.
+class Channel final : public ::grpc::ChannelInterface,
+                      public ::grpc::internal::CallHook,
+                      public std::enable_shared_from_this<Channel>,
+                      private ::grpc::GrpcLibraryCodegen {
+ public:
+  ~Channel();
+
+  /// Get the current channel state. If the channel is in IDLE and
+  /// \a try_to_connect is set to true, try to connect.
+  grpc_connectivity_state GetState(bool try_to_connect) override;
+
+  /// Returns the LB policy name, or the empty string if not yet available.
+  grpc::string GetLoadBalancingPolicyName() const;
+
+  /// Returns the service config in JSON form, or the empty string if
+  /// not available.
+  grpc::string GetServiceConfigJSON() const;
+
+ private:
+  template <class InputMessage, class OutputMessage>
+  friend class ::grpc::internal::BlockingUnaryCallImpl;
+  friend void experimental::ChannelResetConnectionBackoff(Channel* channel);
+  friend std::shared_ptr<Channel> CreateChannelInternal(
+      const grpc::string& host, grpc_channel* c_channel,
+      std::vector<std::unique_ptr<
+          ::grpc::experimental::ClientInterceptorFactoryInterface>>
+          interceptor_creators);
+  friend class ::grpc::internal::InterceptedChannel;
+  Channel(const grpc::string& host, grpc_channel* c_channel,
+          std::vector<std::unique_ptr<
+              ::grpc::experimental::ClientInterceptorFactoryInterface>>
+              interceptor_creators);
+
+  ::grpc::internal::Call CreateCall(const ::grpc::internal::RpcMethod& method,
+                                    ::grpc::ClientContext* context,
+                                    ::grpc::CompletionQueue* cq) override;
+  void PerformOpsOnCall(::grpc::internal::CallOpSetInterface* ops,
+                        ::grpc::internal::Call* call) override;
+  void* RegisterMethod(const char* method) override;
+
+  void NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
+                               gpr_timespec deadline,
+                               ::grpc::CompletionQueue* cq, void* tag) override;
+  bool WaitForStateChangeImpl(grpc_connectivity_state last_observed,
+                              gpr_timespec deadline) override;
+
+  ::grpc::CompletionQueue* CallbackCQ() override;
+
+  ::grpc::internal::Call CreateCallInternal(
+      const ::grpc::internal::RpcMethod& method, ::grpc::ClientContext* context,
+      ::grpc::CompletionQueue* cq, size_t interceptor_pos) override;
+
+  const grpc::string host_;
+  grpc_channel* const c_channel_;  // owned
+
+  // mu_ protects callback_cq_ (the per-channel callbackable completion queue)
+  std::mutex mu_;
+
+  // callback_cq_ references the callbackable completion queue associated
+  // with this channel (if any). It is set on the first call to CallbackCQ().
+  // It is _not owned_ by the channel; ownership belongs with its internal
+  // shutdown callback tag (invoked when the CQ is fully shutdown).
+  ::grpc::CompletionQueue* callback_cq_ = nullptr;
+
+  std::vector<
+      std::unique_ptr<::grpc::experimental::ClientInterceptorFactoryInterface>>
+      interceptor_creators_;
+};
+
+}  // namespace grpc_impl
+
+#endif  // GRPCPP_CHANNEL_IMPL_H

include/grpcpp/impl/codegen/client_callback.h

@@ -29,9 +29,12 @@
 #include <grpcpp/impl/codegen/core_codegen_interface.h>
 #include <grpcpp/impl/codegen/status.h>
 
+namespace grpc_impl {
+class Channel;
+}
+
 namespace grpc {
 
-class Channel;
 class ClientContext;
 class CompletionQueue;
 

include/grpcpp/impl/codegen/client_context.h

@@ -56,9 +56,13 @@
 struct census_context;
 struct grpc_call;
 
-namespace grpc {
+namespace grpc_impl {
 
 class Channel;
+}
+
+namespace grpc {
+
 class ChannelInterface;
 class CompletionQueue;
 class CallCredentials;
@@ -391,7 +395,7 @@ class ClientContext {
   friend class ::grpc::testing::InteropClientContextInspector;
   friend class ::grpc::internal::CallOpClientRecvStatus;
   friend class ::grpc::internal::CallOpRecvInitialMetadata;
-  friend class Channel;
+  friend class ::grpc_impl::Channel;
   template <class R>
   friend class ::grpc::ClientReader;
   template <class W>
@@ -423,7 +427,8 @@ class ClientContext {
   }
 
   grpc_call* call() const { return call_; }
-  void set_call(grpc_call* call, const std::shared_ptr<Channel>& channel);
+  void set_call(grpc_call* call,
+                const std::shared_ptr<::grpc_impl::Channel>& channel);
 
   experimental::ClientRpcInfo* set_client_rpc_info(
       const char* method, internal::RpcMethod::RpcType type,
@@ -456,7 +461,7 @@ class ClientContext {
   bool wait_for_ready_explicitly_set_;
   bool idempotent_;
   bool cacheable_;
-  std::shared_ptr<Channel> channel_;
+  std::shared_ptr<::grpc_impl::Channel> channel_;
   std::mutex mu_;
   grpc_call* call_;
   bool call_canceled_;

include/grpcpp/impl/codegen/client_interceptor.h

@@ -26,10 +26,14 @@
 #include <grpcpp/impl/codegen/rpc_method.h>
 #include <grpcpp/impl/codegen/string_ref.h>
 
+namespace grpc_impl {
+
+class Channel;
+}
+
 namespace grpc {
 
 class ClientContext;
-class Channel;
 
 namespace internal {
 class InterceptorBatchMethodsImpl;

include/grpcpp/impl/codegen/completion_queue.h

@@ -41,6 +41,11 @@
 
 struct grpc_completion_queue;
 
+namespace grpc_impl {
+
+class Channel;
+}
+
 namespace grpc {
 
 template <class R>
@@ -58,7 +63,6 @@ template <class W, class R>
 class ServerReaderWriterBody;
 }  // namespace internal
 
-class Channel;
 class ChannelInterface;
 class ClientContext;
 class CompletionQueue;
@@ -278,7 +282,7 @@ class CompletionQueue : private GrpcLibraryCodegen {
   friend class ::grpc::internal::BlockingUnaryCallImpl;
 
   // Friends that need access to constructor for callback CQ
-  friend class ::grpc::Channel;
+  friend class ::grpc_impl::Channel;
 
   // For access to Register/CompleteAvalanching
   template <class Op1, class Op2, class Op3, class Op4, class Op5, class Op6>

include/grpcpp/impl/codegen/server_interface.h

@@ -28,10 +28,13 @@
 #include <grpcpp/impl/codegen/rpc_service_method.h>
 #include <grpcpp/impl/codegen/server_context.h>
 
+namespace grpc_impl {
+class Channel;
+}
+
 namespace grpc {
 
 class AsyncGenericService;
-class Channel;
 class GenericServerContext;
 class ServerCompletionQueue;
 class ServerContext;

include/grpcpp/security/credentials.h

@@ -32,9 +32,13 @@
 
 struct grpc_call;
 
+namespace grpc_impl {
+
+class Channel;
+}
+
 namespace grpc {
 class ChannelArguments;
-class Channel;
 class SecureChannelCredentials;
 class CallCredentials;
 class SecureCallCredentials;
@@ -42,7 +46,7 @@ class SecureCallCredentials;
 class ChannelCredentials;
 
 namespace experimental {
-std::shared_ptr<Channel> CreateCustomChannelWithInterceptors(
+std::shared_ptr<::grpc_impl::Channel> CreateCustomChannelWithInterceptors(
     const grpc::string& target,
     const std::shared_ptr<ChannelCredentials>& creds,
     const ChannelArguments& args,
@@ -70,12 +74,12 @@ class ChannelCredentials : private GrpcLibraryCodegen {
   virtual SecureChannelCredentials* AsSecureCredentials() = 0;
 
  private:
-  friend std::shared_ptr<Channel> CreateCustomChannel(
+  friend std::shared_ptr<::grpc_impl::Channel> CreateCustomChannel(
       const grpc::string& target,
       const std::shared_ptr<ChannelCredentials>& creds,
       const ChannelArguments& args);
 
-  friend std::shared_ptr<Channel>
+  friend std::shared_ptr<::grpc_impl::Channel>
   experimental::CreateCustomChannelWithInterceptors(
       const grpc::string& target,
       const std::shared_ptr<ChannelCredentials>& creds,
@@ -84,12 +88,12 @@ class ChannelCredentials : private GrpcLibraryCodegen {
           std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
           interceptor_creators);
 
-  virtual std::shared_ptr<Channel> CreateChannel(
+  virtual std::shared_ptr<::grpc_impl::Channel> CreateChannel(
       const grpc::string& target, const ChannelArguments& args) = 0;
 
   // This function should have been a pure virtual function, but it is
   // implemented as a virtual function so that it does not break API.
-  virtual std::shared_ptr<Channel> CreateChannelWithInterceptors(
+  virtual std::shared_ptr<::grpc_impl::Channel> CreateChannelWithInterceptors(
       const grpc::string& target, const ChannelArguments& args,
       std::vector<
           std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>

include/grpcpp/server.h

@@ -27,6 +27,7 @@
 
 #include <grpc/compression.h>
 #include <grpc/support/atm.h>
+#include <grpcpp/channel.h>
 #include <grpcpp/completion_queue.h>
 #include <grpcpp/impl/call.h>
 #include <grpcpp/impl/codegen/client_interceptor.h>

src/compiler/cpp_generator.cc

@@ -145,9 +145,11 @@ grpc::string GetHeaderIncludes(grpc_generator::File* file,
     PrintIncludes(printer.get(), headers, params.use_system_headers,
                   params.grpc_search_path);
     printer->Print(vars, "\n");
+    printer->Print(vars, "namespace grpc_impl {\n");
+    printer->Print(vars, "class Channel;\n");
+    printer->Print(vars, "}  // namespace grpc_impl\n\n");
     printer->Print(vars, "namespace grpc {\n");
     printer->Print(vars, "class CompletionQueue;\n");
-    printer->Print(vars, "class Channel;\n");
     printer->Print(vars, "class ServerCompletionQueue;\n");
     printer->Print(vars, "class ServerContext;\n");
     printer->Print(vars, "}  // namespace grpc\n\n");

src/cpp/client/channel_cc.cc

@@ -49,14 +49,18 @@
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/surface/completion_queue.h"
 
-namespace grpc {
-
-static internal::GrpcLibraryInitializer g_gli_initializer;
-Channel::Channel(
-    const grpc::string& host, grpc_channel* channel,
-    std::vector<
-        std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
-        interceptor_creators)
+void grpc::experimental::ChannelResetConnectionBackoff(
+    ::grpc::Channel* channel) {
+  grpc_impl::experimental::ChannelResetConnectionBackoff(channel);
+}
+
+namespace grpc_impl {
+
+static ::grpc::internal::GrpcLibraryInitializer g_gli_initializer;
+Channel::Channel(const grpc::string& host, grpc_channel* channel,
+                 std::vector<std::unique_ptr<
+                     ::grpc::experimental::ClientInterceptorFactoryInterface>>
+                     interceptor_creators)
     : host_(host), c_channel_(channel) {
   interceptor_creators_ = std::move(interceptor_creators);
   g_gli_initializer.summon();
@@ -72,7 +76,8 @@ Channel::~Channel() {
 namespace {
 
 inline grpc_slice SliceFromArray(const char* arr, size_t len) {
-  return g_core_codegen_interface->grpc_slice_from_copied_buffer(arr, len);
+  return ::grpc::g_core_codegen_interface->grpc_slice_from_copied_buffer(arr,
+                                                                         len);
 }
 
 grpc::string GetChannelInfoField(grpc_channel* channel,
@@ -110,10 +115,9 @@ void ChannelResetConnectionBackoff(Channel* channel) {
 
 }  // namespace experimental
 
-internal::Call Channel::CreateCallInternal(const internal::RpcMethod& method,
-                                           ClientContext* context,
-                                           CompletionQueue* cq,
-                                           size_t interceptor_pos) {
+::grpc::internal::Call Channel::CreateCallInternal(
+    const ::grpc::internal::RpcMethod& method, ::grpc::ClientContext* context,
+    ::grpc::CompletionQueue* cq, size_t interceptor_pos) {
   const bool kRegistered = method.channel_tag() && context->authority().empty();
   grpc_call* c_call = nullptr;
   if (kRegistered) {
@@ -122,7 +126,7 @@ internal::Call Channel::CreateCallInternal(const internal::RpcMethod& method,
         context->propagation_options_.c_bitmask(), cq->cq(),
         method.channel_tag(), context->raw_deadline(), nullptr);
   } else {
-    const string* host_str = nullptr;
+    const ::grpc::string* host_str = nullptr;
     if (!context->authority_.empty()) {
       host_str = &context->authority_;
     } else if (!host_.empty()) {
@@ -132,7 +136,7 @@ internal::Call Channel::CreateCallInternal(const internal::RpcMethod& method,
         SliceFromArray(method.name(), strlen(method.name()));
     grpc_slice host_slice;
     if (host_str != nullptr) {
-      host_slice = SliceFromCopiedString(*host_str);
+      host_slice = ::grpc::SliceFromCopiedString(*host_str);
     }
     c_call = grpc_channel_create_call(
         c_channel_, context->propagate_from_call_,
@@ -154,17 +158,17 @@ internal::Call Channel::CreateCallInternal(const internal::RpcMethod& method,
                                    interceptor_creators_, interceptor_pos);
   context->set_call(c_call, shared_from_this());
 
-  return internal::Call(c_call, this, cq, info);
+  return ::grpc::internal::Call(c_call, this, cq, info);
 }
 
-internal::Call Channel::CreateCall(const internal::RpcMethod& method,
-                                   ClientContext* context,
-                                   CompletionQueue* cq) {
+::grpc::internal::Call Channel::CreateCall(
+    const ::grpc::internal::RpcMethod& method, ::grpc::ClientContext* context,
+    ::grpc::CompletionQueue* cq) {
   return CreateCallInternal(method, context, cq, 0);
 }
 
-void Channel::PerformOpsOnCall(internal::CallOpSetInterface* ops,
-                               internal::Call* call) {
+void Channel::PerformOpsOnCall(::grpc::internal::CallOpSetInterface* ops,
+                               ::grpc::internal::Call* call) {
   ops->FillOps(
       call);  // Make a copy of call. It's fine since Call just has pointers
 }
@@ -180,7 +184,7 @@ grpc_connectivity_state Channel::GetState(bool try_to_connect) {
 
 namespace {
 
-class TagSaver final : public internal::CompletionQueueTag {
+class TagSaver final : public ::grpc::internal::CompletionQueueTag {
  public:
   explicit TagSaver(void* tag) : tag_(tag) {}
   ~TagSaver() override {}
@@ -198,7 +202,7 @@ class TagSaver final : public internal::CompletionQueueTag {
 
 void Channel::NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
                                       gpr_timespec deadline,
-                                      CompletionQueue* cq, void* tag) {
+                                      ::grpc::CompletionQueue* cq, void* tag) {
   TagSaver* tag_saver = new TagSaver(tag);
   grpc_channel_watch_connectivity_state(c_channel_, last_observed, deadline,
                                         cq->cq(), tag_saver);
@@ -206,7 +210,7 @@ void Channel::NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
 
 bool Channel::WaitForStateChangeImpl(grpc_connectivity_state last_observed,
                                      gpr_timespec deadline) {
-  CompletionQueue cq;
+  ::grpc::CompletionQueue cq;
   bool ok = false;
   void* tag = nullptr;
   NotifyOnStateChangeImpl(last_observed, deadline, &cq, nullptr);
@@ -221,7 +225,7 @@ class ShutdownCallback : public grpc_experimental_completion_queue_functor {
   ShutdownCallback() { functor_run = &ShutdownCallback::Run; }
   // TakeCQ takes ownership of the cq into the shutdown callback
   // so that the shutdown callback will be responsible for destroying it
-  void TakeCQ(CompletionQueue* cq) { cq_ = cq; }
+  void TakeCQ(::grpc::CompletionQueue* cq) { cq_ = cq; }
 
   // The Run function will get invoked by the completion queue library
   // when the shutdown is actually complete
@@ -232,17 +236,17 @@ class ShutdownCallback : public grpc_experimental_completion_queue_functor {
   }
 
  private:
-  CompletionQueue* cq_ = nullptr;
+  ::grpc::CompletionQueue* cq_ = nullptr;
 };
 }  // namespace
 
-CompletionQueue* Channel::CallbackCQ() {
+::grpc::CompletionQueue* Channel::CallbackCQ() {
   // TODO(vjpai): Consider using a single global CQ for the default CQ
   // if there is no explicit per-channel CQ registered
   std::lock_guard<std::mutex> l(mu_);
   if (callback_cq_ == nullptr) {
     auto* shutdown_callback = new ShutdownCallback;
-    callback_cq_ = new CompletionQueue(grpc_completion_queue_attributes{
+    callback_cq_ = new ::grpc::CompletionQueue(grpc_completion_queue_attributes{
         GRPC_CQ_CURRENT_VERSION, GRPC_CQ_CALLBACK, GRPC_CQ_DEFAULT_POLLING,
         shutdown_callback});
 
@@ -252,4 +256,4 @@ CompletionQueue* Channel::CallbackCQ() {
   return callback_cq_;
 }
 
-}  // namespace grpc
+}  // namespace grpc_impl

src/cpp/client/client_context.cc

@@ -30,6 +30,11 @@
 #include <grpcpp/server_context.h>
 #include <grpcpp/support/time.h>
 
+namespace grpc_impl {
+
+class Channel;
+}
+
 namespace grpc {
 
 class DefaultGlobalClientCallbacks final
@@ -82,8 +87,8 @@ void ClientContext::AddMetadata(const grpc::string& meta_key,
   send_initial_metadata_.insert(std::make_pair(meta_key, meta_value));
 }
 
-void ClientContext::set_call(grpc_call* call,
-                             const std::shared_ptr<Channel>& channel) {
+void ClientContext::set_call(
+    grpc_call* call, const std::shared_ptr<::grpc_impl::Channel>& channel) {
   std::unique_lock<std::mutex> lock(mu_);
   GPR_ASSERT(call_ == nullptr);
   call_ = call;

src/cpp/client/create_channel.cc

@@ -40,7 +40,7 @@ std::shared_ptr<Channel> CreateCustomChannel(
     const ChannelArguments& args) {
   GrpcLibraryCodegen init_lib;  // We need to call init in case of a bad creds.
   return creds ? creds->CreateChannel(target, args)
-               : CreateChannelInternal(
+               : ::grpc_impl::CreateChannelInternal(
                      "",
                      grpc_lame_client_channel_create(
                          nullptr, GRPC_STATUS_INVALID_ARGUMENT,
@@ -70,7 +70,7 @@ std::shared_ptr<Channel> CreateCustomChannelWithInterceptors(
         interceptor_creators) {
   return creds ? creds->CreateChannelWithInterceptors(
                      target, args, std::move(interceptor_creators))
-               : CreateChannelInternal(
+               : ::grpc_impl::CreateChannelInternal(
                      "",
                      grpc_lame_client_channel_create(
                          nullptr, GRPC_STATUS_INVALID_ARGUMENT,

src/cpp/client/create_channel_internal.cc

@@ -22,14 +22,15 @@
 
 struct grpc_channel;
 
-namespace grpc {
+namespace grpc_impl {
 
 std::shared_ptr<Channel> CreateChannelInternal(
     const grpc::string& host, grpc_channel* c_channel,
-    std::vector<
-        std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
+    std::vector<std::unique_ptr<
+        ::grpc::experimental::ClientInterceptorFactoryInterface>>
         interceptor_creators) {
   return std::shared_ptr<Channel>(
       new Channel(host, c_channel, std::move(interceptor_creators)));
 }
-}  // namespace grpc
+
+}  // namespace grpc_impl

src/cpp/client/create_channel_internal.h

@@ -26,15 +26,16 @@
 
 struct grpc_channel;
 
-namespace grpc {
+namespace grpc_impl {
+
 class Channel;
 
 std::shared_ptr<Channel> CreateChannelInternal(
     const grpc::string& host, grpc_channel* c_channel,
-    std::vector<
-        std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
+    std::vector<std::unique_ptr<
+        ::grpc::experimental::ClientInterceptorFactoryInterface>>
         interceptor_creators);
 
-}  // namespace grpc
+}  // namespace grpc_impl
 
 #endif  // GRPC_INTERNAL_CPP_CLIENT_CREATE_CHANNEL_INTERNAL_H

src/cpp/client/create_channel_posix.cc

@@ -32,7 +32,7 @@ std::shared_ptr<Channel> CreateInsecureChannelFromFd(const grpc::string& target,
                                                      int fd) {
   internal::GrpcLibrary init_lib;
   init_lib.init();
-  return CreateChannelInternal(
+  return ::grpc_impl::CreateChannelInternal(
       "", grpc_insecure_channel_create_from_fd(target.c_str(), fd, nullptr),
       std::vector<
           std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>());
@@ -44,7 +44,7 @@ std::shared_ptr<Channel> CreateCustomInsecureChannelFromFd(
   init_lib.init();
   grpc_channel_args channel_args;
   args.SetChannelArgs(&channel_args);
-  return CreateChannelInternal(
+  return ::grpc_impl::CreateChannelInternal(
       "",
       grpc_insecure_channel_create_from_fd(target.c_str(), fd, &channel_args),
       std::vector<
@@ -62,7 +62,7 @@ std::shared_ptr<Channel> CreateCustomInsecureChannelWithInterceptorsFromFd(
   init_lib.init();
   grpc_channel_args channel_args;
   args.SetChannelArgs(&channel_args);
-  return CreateChannelInternal(
+  return ::grpc_impl::CreateChannelInternal(
       "",
       grpc_insecure_channel_create_from_fd(target.c_str(), fd, &channel_args),
       std::move(interceptor_creators));

src/cpp/client/cronet_credentials.cc

@@ -47,7 +47,7 @@ class CronetChannelCredentialsImpl final : public ChannelCredentials {
           interceptor_creators) override {
     grpc_channel_args channel_args;
     args.SetChannelArgs(&channel_args);
-    return CreateChannelInternal(
+    return ::grpc_impl::CreateChannelInternal(
         "",
         grpc_cronet_secure_channel_create(engine_, target.c_str(),
                                           &channel_args, nullptr),

src/cpp/client/insecure_credentials.cc

@@ -45,7 +45,7 @@ class InsecureChannelCredentialsImpl final : public ChannelCredentials {
           interceptor_creators) override {
     grpc_channel_args channel_args;
     args.SetChannelArgs(&channel_args);
-    return CreateChannelInternal(
+    return ::grpc_impl::CreateChannelInternal(
         "",
         grpc_insecure_channel_create(target.c_str(), &channel_args, nullptr),
         std::move(interceptor_creators));

src/cpp/client/secure_credentials.cc

@@ -50,7 +50,7 @@ SecureChannelCredentials::CreateChannelWithInterceptors(
         interceptor_creators) {
   grpc_channel_args channel_args;
   args.SetChannelArgs(&channel_args);
-  return CreateChannelInternal(
+  return ::grpc_impl::CreateChannelInternal(
       args.GetSslTargetNameOverride(),
       grpc_secure_channel_create(c_creds_, target.c_str(), &channel_args,
                                  nullptr),

src/cpp/client/secure_credentials.h

@@ -27,6 +27,11 @@
 #include "src/core/lib/security/credentials/credentials.h"
 #include "src/cpp/server/thread_pool_interface.h"
 
+namespace grpc_impl {
+
+class Channel;
+}
+
 namespace grpc {
 
 class SecureChannelCredentials final : public ChannelCredentials {
@@ -37,13 +42,13 @@ class SecureChannelCredentials final : public ChannelCredentials {
   }
   grpc_channel_credentials* GetRawCreds() { return c_creds_; }
 
-  std::shared_ptr<grpc::Channel> CreateChannel(
+  std::shared_ptr<::grpc_impl::Channel> CreateChannel(
       const string& target, const grpc::ChannelArguments& args) override;
 
   SecureChannelCredentials* AsSecureCredentials() override { return this; }
 
  private:
-  std::shared_ptr<grpc::Channel> CreateChannelWithInterceptors(
+  std::shared_ptr<::grpc_impl::Channel> CreateChannelWithInterceptors(
       const string& target, const grpc::ChannelArguments& args,
       std::vector<
           std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>

src/cpp/server/server_cc.cc

@@ -794,7 +794,7 @@ grpc_server* Server::c_server() { return server_; }
 std::shared_ptr<Channel> Server::InProcessChannel(
     const ChannelArguments& args) {
   grpc_channel_args channel_args = args.c_channel_args();
-  return CreateChannelInternal(
+  return ::grpc_impl::CreateChannelInternal(
       "inproc", grpc_inproc_channel_create(server_, &channel_args, nullptr),
       std::vector<
           std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>());
@@ -807,7 +807,7 @@ Server::experimental_type::InProcessChannelWithInterceptors(
         std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
         interceptor_creators) {
   grpc_channel_args channel_args = args.c_channel_args();
-  return CreateChannelInternal(
+  return ::grpc_impl::CreateChannelInternal(
       "inproc",
       grpc_inproc_channel_create(server_->server_, &channel_args, nullptr),
       std::move(interceptor_creators));

test/cpp/codegen/compiler_test_golden

@@ -40,9 +40,12 @@
 #include <grpcpp/impl/codegen/stub_options.h>
 #include <grpcpp/impl/codegen/sync_stream.h>
 
+namespace grpc_impl {
+class Channel;
+}  // namespace grpc_impl
+
 namespace grpc {
 class CompletionQueue;
-class Channel;
 class ServerCompletionQueue;
 class ServerContext;
 }  // namespace grpc

test/cpp/codegen/golden_file_test.cc

@@ -31,7 +31,7 @@ using namespace gflags;
 
 DEFINE_string(
     generated_file_path, "",
-    "path to the directory containing generated files compiler_test.grpc.pb.h"
+    "path to the directory containing generated files compiler_test.grpc.pb.h "
     "and compiler_test_mock.grpc.pb.h");
 
 const char kGoldenFilePath[] = "test/cpp/codegen/compiler_test_golden";

test/cpp/microbenchmarks/bm_call_create.cc

@@ -131,7 +131,7 @@ static void* tag(int i) {
 static void BM_LameChannelCallCreateCpp(benchmark::State& state) {
   TrackCounters track_counters;
   auto stub =
-      grpc::testing::EchoTestService::NewStub(grpc::CreateChannelInternal(
+      grpc::testing::EchoTestService::NewStub(grpc_impl::CreateChannelInternal(
           "",
           grpc_lame_client_channel_create("localhost:1234",
                                           GRPC_STATUS_UNAUTHENTICATED, "blah"),

test/cpp/microbenchmarks/fullstack_fixtures.h

@@ -218,7 +218,7 @@ class EndpointPairFixture : public BaseFixture {
           "target", &c_args, GRPC_CLIENT_DIRECT_CHANNEL, client_transport_);
       grpc_chttp2_transport_start_reading(client_transport_, nullptr, nullptr);
 
-      channel_ = CreateChannelInternal(
+      channel_ = ::grpc_impl::CreateChannelInternal(
           "", channel,
           std::vector<std::unique_ptr<
               experimental::ClientInterceptorFactoryInterface>>());

test/cpp/performance/writes_per_rpc_test.cc

@@ -118,7 +118,7 @@ class EndpointPairFixture {
           "target", &c_args, GRPC_CLIENT_DIRECT_CHANNEL, transport);
       grpc_chttp2_transport_start_reading(transport, nullptr, nullptr);
 
-      channel_ = CreateChannelInternal(
+      channel_ = ::grpc_impl::CreateChannelInternal(
           "", channel,
           std::vector<std::unique_ptr<
               experimental::ClientInterceptorFactoryInterface>>());

test/cpp/util/create_test_channel.h

@@ -23,8 +23,12 @@
 
 #include <grpcpp/security/credentials.h>
 
-namespace grpc {
+namespace grpc_impl {
+
 class Channel;
+}
+
+namespace grpc {
 
 namespace testing {
 
@@ -32,31 +36,31 @@ typedef enum { INSECURE = 0, TLS, ALTS } transport_security;
 
 }  // namespace testing
 
-std::shared_ptr<Channel> CreateTestChannel(
+std::shared_ptr<::grpc_impl::Channel> CreateTestChannel(
     const grpc::string& server, testing::transport_security security_type);
 
-std::shared_ptr<Channel> CreateTestChannel(
+std::shared_ptr<::grpc_impl::Channel> CreateTestChannel(
     const grpc::string& server, const grpc::string& override_hostname,
     testing::transport_security security_type, bool use_prod_roots);
 
-std::shared_ptr<Channel> CreateTestChannel(
+std::shared_ptr<::grpc_impl::Channel> CreateTestChannel(
     const grpc::string& server, const grpc::string& override_hostname,
     testing::transport_security security_type, bool use_prod_roots,
     const std::shared_ptr<CallCredentials>& creds);
 
-std::shared_ptr<Channel> CreateTestChannel(
+std::shared_ptr<::grpc_impl::Channel> CreateTestChannel(
     const grpc::string& server, const grpc::string& override_hostname,
     testing::transport_security security_type, bool use_prod_roots,
     const std::shared_ptr<CallCredentials>& creds,
     const ChannelArguments& args);
 
-std::shared_ptr<Channel> CreateTestChannel(
+std::shared_ptr<::grpc_impl::Channel> CreateTestChannel(
     const grpc::string& server, const grpc::string& cred_type,
     const grpc::string& override_hostname, bool use_prod_roots,
     const std::shared_ptr<CallCredentials>& creds,
     const ChannelArguments& args);
 
-std::shared_ptr<Channel> CreateTestChannel(
+std::shared_ptr<::grpc_impl::Channel> CreateTestChannel(
     const grpc::string& server, const grpc::string& credential_type,
     const std::shared_ptr<CallCredentials>& creds);
 

tools/doxygen/Doxyfile.c++

@@ -927,6 +927,7 @@ include/grpc/support/workaround_list.h \
 include/grpcpp/alarm.h \
 include/grpcpp/alarm_impl.h \
 include/grpcpp/channel.h \
+include/grpcpp/channel_impl.h \
 include/grpcpp/client_context.h \
 include/grpcpp/completion_queue.h \
 include/grpcpp/create_channel.h \

tools/doxygen/Doxyfile.c++.internal

@@ -928,6 +928,7 @@ include/grpc/support/workaround_list.h \
 include/grpcpp/alarm.h \
 include/grpcpp/alarm_impl.h \
 include/grpcpp/channel.h \
+include/grpcpp/channel_impl.h \
 include/grpcpp/client_context.h \
 include/grpcpp/completion_queue.h \
 include/grpcpp/create_channel.h \

tools/run_tests/generated/sources_and_headers.json

@@ -11366,6 +11366,7 @@
       "include/grpcpp/alarm.h", 
       "include/grpcpp/alarm_impl.h", 
       "include/grpcpp/channel.h", 
+      "include/grpcpp/channel_impl.h", 
       "include/grpcpp/client_context.h", 
       "include/grpcpp/completion_queue.h", 
       "include/grpcpp/create_channel.h", 
@@ -11475,6 +11476,7 @@
       "include/grpcpp/alarm.h", 
       "include/grpcpp/alarm_impl.h", 
       "include/grpcpp/channel.h", 
+      "include/grpcpp/channel_impl.h", 
       "include/grpcpp/client_context.h", 
       "include/grpcpp/completion_queue.h", 
       "include/grpcpp/create_channel.h",