Revert "Folding the Channel class into the grpc_impl namespace."

BUILD

@@ -206,7 +206,6 @@ 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

@@ -2991,7 +2991,6 @@ 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
@@ -3583,7 +3582,6 @@ 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
@@ -4539,7 +4537,6 @@ 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

@@ -5397,7 +5397,6 @@ 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 \
@@ -5998,7 +5997,6 @@ 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 \
@@ -6911,7 +6909,6 @@ 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

@@ -1341,7 +1341,6 @@ 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

@@ -82,7 +82,6 @@ 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

@@ -19,16 +19,96 @@
 #ifndef GRPCPP_CHANNEL_H
 #define GRPCPP_CHANNEL_H
 
-#include <grpcpp/channel_impl.h>
+#include <memory>
+#include <mutex>
 
-namespace grpc {
+#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;
 
-typedef ::grpc_impl::Channel Channel;
+namespace grpc {
 
 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/impl/codegen/client_callback.h

@@ -29,12 +29,9 @@
 #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

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

include/grpcpp/impl/codegen/client_interceptor.h

@@ -26,14 +26,10 @@
 #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

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