grpc/include/grpc++/channel.h

/*
 *
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 *
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 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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#ifndef GRPCXX_CHANNEL_H
#define GRPCXX_CHANNEL_H

#include <memory>

#include <grpc/grpc.h>
#include <grpc++/impl/call.h>
#include <grpc++/impl/grpc_library.h>
#include <grpc++/support/config.h>

struct grpc_channel;

namespace grpc {
class CallOpSetInterface;
class ChannelArguments;
class CompletionQueue;
class ChannelCredentials;
class SecureChannelCredentials;

template <class R>
class ClientReader;
template <class W>
class ClientWriter;
template <class W, class R>
class ClientReaderWriter;
template <class R>
class ClientAsyncReader;
template <class W>
class ClientAsyncWriter;
template <class W, class R>
class ClientAsyncReaderWriter;
template <class R>
class ClientAsyncResponseReader;

/// Channels represent a connection to an endpoint. Created by \a CreateChannel.
class Channel GRPC_FINAL : public GrpcLibrary,
                           public CallHook,
                           public std::enable_shared_from_this<Channel> {
 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);

  /// Return the \a tag on \a cq when the channel state is changed or \a
  /// deadline expires. \a GetState needs to called to get the current state.
  template <typename T>
  void NotifyOnStateChange(grpc_connectivity_state last_observed, T deadline,
                           CompletionQueue* cq, void* tag) {
    TimePoint<T> deadline_tp(deadline);
    NotifyOnStateChangeImpl(last_observed, deadline_tp.raw_time(), cq, tag);
  }

  /// Blocking wait for channel state change or \a deadline expiration.
  /// \a GetState needs to called to get the current state.
  template <typename T>
  bool WaitForStateChange(grpc_connectivity_state last_observed, T deadline) {
    TimePoint<T> deadline_tp(deadline);
    return WaitForStateChangeImpl(last_observed, deadline_tp.raw_time());
  }

 private:
  template <class R>
  friend class ::grpc::ClientReader;
  template <class W>
  friend class ::grpc::ClientWriter;
  template <class W, class R>
  friend class ::grpc::ClientReaderWriter;
  template <class R>
  friend class ::grpc::ClientAsyncReader;
  template <class W>
  friend class ::grpc::ClientAsyncWriter;
  template <class W, class R>
  friend class ::grpc::ClientAsyncReaderWriter;
  template <class R>
  friend class ::grpc::ClientAsyncResponseReader;
  template <class InputMessage, class OutputMessage>
  friend Status BlockingUnaryCall(Channel* channel, const RpcMethod& method,
                                  ClientContext* context,
                                  const InputMessage& request,
                                  OutputMessage* result);
  friend class ::grpc::RpcMethod;
  friend std::shared_ptr<Channel> CreateChannelInternal(
      const grpc::string& host, grpc_channel* c_channel);

  Channel(const grpc::string& host, grpc_channel* c_channel);

  Call CreateCall(const RpcMethod& method, ClientContext* context,
                  CompletionQueue* cq);
  void PerformOpsOnCall(CallOpSetInterface* ops, Call* call);
  void* RegisterMethod(const char* method);

  void NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
                               gpr_timespec deadline, CompletionQueue* cq,
                               void* tag);
  bool WaitForStateChangeImpl(grpc_connectivity_state last_observed,
                              gpr_timespec deadline);

  const grpc::string host_;
  grpc_channel* const c_channel_;  // owned
};

}  // namespace grpc

#endif  // GRPCXX_CHANNEL_H