/*
 *
 * Copyright 2014, Google Inc.
 * All rights reserved.
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 * modification, are permitted provided that the following conditions are
 * met:
 *
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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
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#ifndef __GRPCPP_COMPLETION_QUEUE_H__
#define __GRPCPP_COMPLETION_QUEUE_H__

struct grpc_completion_queue;

namespace grpc {

class CompletionQueue;

class CompletionQueueTag {
 public:
  virtual void FinalizeResult() = 0;

 private:
  friend class CompletionQueue;
  void *user_tag_;
};

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

  bool Pluck(void *tag);

  // Prepare a tag for the C api
  // Given a tag we'd like to receive from Next, what tag should we pass
  // down to the C api?
  // Usage example:
  //   grpc_call_start_batch(..., cq.PrepareTagForC(tag));
  // Allows attaching some work to be executed before the original tag
  // is returned.
  // MUST be used for all events that could be surfaced through this
  // wrapping API
  void *PrepareTagForC(CompletionQueueTag *cq_tag, void *user_tag) {
    cq_tag->user_tag_ = user_tag;
    return cq_tag;
  }

  // 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:
  grpc_completion_queue* cq_;  // owned
};

}  // namespace grpc

#endif  // __GRPCPP_COMPLETION_QUEUE_H__