text: /*
   *
   * 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 GRPC_CORE_LIB_SURFACE_CHANNEL_H
  #define GRPC_CORE_LIB_SURFACE_CHANNEL_H
  
  #include <grpc/support/port_platform.h>
  
  #include <map>
  
  #include "src/core/lib/channel/channel_stack.h"
  #include "src/core/lib/channel/channel_stack_builder.h"
  #include "src/core/lib/channel/channelz.h"
  #include "src/core/lib/gprpp/manual_constructor.h"
  #include "src/core/lib/surface/channel_stack_type.h"
  #include "src/core/lib/transport/metadata.h"
  
  /// Creates a grpc_channel.
  ///
  /// If the \a resource_user is not null, \a preallocated_bytes may have been
  /// allocated on that resource_user for use by the channel. These bytes will be
  /// freed from the resource_user upon channel destruction.
  ///
  /// Takes ownership of a \a resource_user ref.
  grpc_channel* grpc_channel_create(const char* target,
                                    const grpc_channel_args* args,
                                    grpc_channel_stack_type channel_stack_type,
                                    grpc_transport* optional_transport,
                                    grpc_resource_user* resource_user,
                                    size_t preallocated_bytes,
                                    grpc_error_handle* error);
  
  /** The same as grpc_channel_destroy, but doesn't create an ExecCtx, and so
   * is safe to use from within core. */
  void grpc_channel_destroy_internal(grpc_channel* channel);
  
  /// Creates a grpc_channel with a builder. See the description of
  /// \a grpc_channel_create for variable definitions.
  grpc_channel* grpc_channel_create_with_builder(
      grpc_channel_stack_builder* builder,
      grpc_channel_stack_type channel_stack_type,
      grpc_resource_user* resource_user, size_t preallocated_bytes,
      grpc_error_handle* error = nullptr);
  
  /** Create a call given a grpc_channel, in order to call \a method.
      Progress is tied to activity on \a pollset_set. The returned call object is
      meant to be used with \a grpc_call_start_batch_and_execute, which relies on
      callbacks to signal completions. \a method and \a host need
      only live through the invocation of this function. If \a parent_call is
      non-NULL, it must be a server-side call. It will be used to propagate
      properties from the server call to this new client call, depending on the
      value of \a propagation_mask (see propagation_bits.h for possible values) */
  grpc_call* grpc_channel_create_pollset_set_call(
      grpc_channel* channel, grpc_call* parent_call, uint32_t propagation_mask,
      grpc_pollset_set* pollset_set, const grpc_slice& method,
      const grpc_slice* host, grpc_millis deadline, void* reserved);
  
  /** Get a (borrowed) pointer to this channels underlying channel stack */
  grpc_channel_stack* grpc_channel_get_channel_stack(grpc_channel* channel);
  
  grpc_core::channelz::ChannelNode* grpc_channel_get_channelz_node(
      grpc_channel* channel);
  
  size_t grpc_channel_get_call_size_estimate(grpc_channel* channel);
  void grpc_channel_update_call_size_estimate(grpc_channel* channel, size_t size);
  
  namespace grpc_core {
  
  struct RegisteredCall {
    grpc_mdelem path;
    grpc_mdelem authority;
  
    explicit RegisteredCall(const char* method_arg, const char* host_arg);
    RegisteredCall(const RegisteredCall& other);
    RegisteredCall& operator=(const RegisteredCall&) = delete;
  
    ~RegisteredCall();
  };
  
  struct CallRegistrationTable {
    grpc_core::Mutex mu;
    // The map key should be owned strings rather than unowned char*'s to
    // guarantee that it outlives calls on the core channel (which may outlast the
    // C++ or other wrapped language Channel that registered these calls).
    std::map<std::pair<std::string, std::string>, RegisteredCall> map
        ABSL_GUARDED_BY(mu);
    int method_registration_attempts ABSL_GUARDED_BY(mu) = 0;
  };
  
  }  // namespace grpc_core
  
  struct grpc_channel {
    int is_client;
    grpc_compression_options compression_options;
  
    gpr_atm call_size_estimate;
    grpc_resource_user* resource_user;
    size_t preallocated_bytes;
  
    // TODO(vjpai): Once the grpc_channel is allocated via new rather than malloc,
    //              expand the members of the CallRegistrationTable directly into
    //              the grpc_channel. For now it is kept separate so that all the
    //              manual constructing can be done with a single call rather than
    //              a separate manual construction for each field.
    grpc_core::ManualConstructor<grpc_core::CallRegistrationTable>
        registration_table;
    grpc_core::RefCountedPtr<grpc_core::channelz::ChannelNode> channelz_node;
  
    char* target;
  };
  #define CHANNEL_STACK_FROM_CHANNEL(c) ((grpc_channel_stack*)((c) + 1))
  
  inline grpc_compression_options grpc_channel_compression_options(
      const grpc_channel* channel) {
    return channel->compression_options;
  }
  
  inline grpc_channel_stack* grpc_channel_get_channel_stack(
      grpc_channel* channel) {
    return CHANNEL_STACK_FROM_CHANNEL(channel);
  }
  
  inline grpc_core::channelz::ChannelNode* grpc_channel_get_channelz_node(
      grpc_channel* channel) {
    return channel->channelz_node.get();
  }
  
  #ifndef NDEBUG
  inline void grpc_channel_internal_ref(grpc_channel* channel,
                                        const char* reason) {
    GRPC_CHANNEL_STACK_REF(CHANNEL_STACK_FROM_CHANNEL(channel), reason);
  }
  inline void grpc_channel_internal_unref(grpc_channel* channel,
                                          const char* reason) {
    GRPC_CHANNEL_STACK_UNREF(CHANNEL_STACK_FROM_CHANNEL(channel), reason);
  }
  #define GRPC_CHANNEL_INTERNAL_REF(channel, reason) \
    grpc_channel_internal_ref(channel, reason)
  #define GRPC_CHANNEL_INTERNAL_UNREF(channel, reason) \
    grpc_channel_internal_unref(channel, reason)
  #else
  inline void grpc_channel_internal_ref(grpc_channel* channel) {
    GRPC_CHANNEL_STACK_REF(CHANNEL_STACK_FROM_CHANNEL(channel), "unused");
  }
  inline void grpc_channel_internal_unref(grpc_channel* channel) {
    GRPC_CHANNEL_STACK_UNREF(CHANNEL_STACK_FROM_CHANNEL(channel), "unused");
  }
  #define GRPC_CHANNEL_INTERNAL_REF(channel, reason) \
    grpc_channel_internal_ref(channel)
  #define GRPC_CHANNEL_INTERNAL_UNREF(channel, reason) \
    grpc_channel_internal_unref(channel)
  #endif
  
  // Return the channel's compression options.
  grpc_compression_options grpc_channel_compression_options(
      const grpc_channel* channel);
  
  // Ping the channels peer (load balanced channels will select one sub-channel to
  // ping); if the channel is not connected, posts a failed.
  void grpc_channel_ping(grpc_channel* channel, grpc_completion_queue* cq,
                         void* tag, void* reserved);
  
  #endif /* GRPC_CORE_LIB_SURFACE_CHANNEL_H */
  