grpc/include/grpc++/completion_queue.h

/*
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#ifndef __GRPCPP_COMPLETION_QUEUE_H__
#define __GRPCPP_COMPLETION_QUEUE_H__

#include <grpc++/impl/client_unary_call.h>

struct grpc_completion_queue;

namespace grpc {

template <class R>
class ClientReader;
template <class W>
class ClientWriter;
template <class R, class W>
class ClientReaderWriter;
template <class R>
class ServerReader;
template <class W>
class ServerWriter;
template <class R, class W>
class ServerReaderWriter;

class CompletionQueue;
class Server;

class CompletionQueueTag {
 public:
  // Called prior to returning from Next(), return value
  // is the status of the operation (return status is the default thing
  // to do)
  virtual void FinalizeResult(void **tag, bool *status) = 0;
};

// grpc_completion_queue wrapper class
class CompletionQueue {
 public:
  CompletionQueue();
  explicit CompletionQueue(grpc_completion_queue *take);
  ~CompletionQueue();

  // Blocking read from queue.
  // Returns true if an event was received, false if the queue is ready
  // for destruction.
  bool Next(void **tag, bool *ok);

  // Shutdown has to be called, and the CompletionQueue can only be
  // destructed when false is returned from Next().
  void Shutdown();

  grpc_completion_queue* cq() { return cq_; }

 private:
  template <class R> friend class ::grpc::ClientReader;
  template <class W> friend class ::grpc::ClientWriter;
  template <class R, class W> friend class ::grpc::ClientReaderWriter;
  template <class R> friend class ::grpc::ServerReader;
  template <class W> friend class ::grpc::ServerWriter;
  template <class R, class W> friend class ::grpc::ServerReaderWriter;
  friend class ::grpc::Server;
  friend Status BlockingUnaryCall(ChannelInterface *channel, const RpcMethod &method,
      ClientContext *context,
      const google::protobuf::Message &request,
      google::protobuf::Message *result);

  bool Pluck(CompletionQueueTag *tag);

  grpc_completion_queue* cq_;  // owned
};

}  // namespace grpc

#endif  // __GRPCPP_COMPLETION_QUEUE_H__