rocksdb/thrift/lib/cpp/async/TFramedAsyncChannel.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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 THRIFT_ASYNC_TFRAMEDASYNCCHANNEL_H_
#define THRIFT_ASYNC_TFRAMEDASYNCCHANNEL_H_ 1

#include "thrift/lib/cpp/async/TStreamAsyncChannel.h"

namespace apache { namespace thrift { namespace async {

namespace detail {

/**
 * Encapsulation of one outstanding write request on a TFramedAsyncChannel.
 */
class TFramedACWriteRequest :
      public TAsyncChannelWriteRequestBase<TFramedACWriteRequest> {
 public:
  TFramedACWriteRequest(const VoidCallback& callback,
                        const VoidCallback& errorCallback,
                        transport::TMemoryBuffer* message,
                        TAsyncEventChannel* channel);

  void write(TAsyncTransport* transport,
             TAsyncTransport::WriteCallback* callback) THRIFT_NOEXCEPT;

  void writeSuccess() THRIFT_NOEXCEPT;
  void writeError(size_t bytesWritten,
                  const transport::TTransportException& ex) THRIFT_NOEXCEPT;

 private:
  union {
    uint32_t frameSize_;
    char frameSizeBuf_[sizeof(uint32_t)];
  };
};

/**
 * Read state for TFramedAsyncChannel
 */
class TFramedACReadState {
 public:
  typedef std::tr1::function<void()> VoidCallback;

  TFramedACReadState();

  // Methods required by TStreamAsyncChannel

  void setCallbackBuffer(transport::TMemoryBuffer* buffer) {
    buffer_ = buffer;
    bytesRead_ = 0;
  }
  void unsetCallbackBuffer() {
    buffer_ = NULL;
  }

  bool hasReadAheadData() {
    assert(bytesRead_ == 0);
    return false;
  }
  bool hasPartialMessage() {
    return (bytesRead_ > 0);
  }

  void getReadBuffer(void** bufReturn, size_t* lenReturn);
  bool readDataAvailable(size_t len);

  // Other methods specifict to TFramedAsyncChannel

  void setMaxFrameSize(uint32_t size) {
    maxFrameSize_ = size;
  }

  uint32_t getMaxFrameSize() const {
    return maxFrameSize_;
  }

 private:
  /// maximum frame size accepted
  uint32_t maxFrameSize_;

  union {
    uint32_t frameSize_;
    char frameSizeBuf_[sizeof(uint32_t)];
  };

  /**
   * The number of bytes read.
   *
   * This includes the bytes in the frame size.  When bytesRead_ is less than
   * sizeof(uint32_t), we are still reading the frame size.  Otherwise, we have
   * read bytesRead_ - sizeof(uint32_t) bytes of the body.
   */
  uint32_t bytesRead_;
  apache::thrift::transport::TMemoryBuffer* buffer_;
};

} // namespace detail

/**
 * TFramedAsyncChannel
 *
 * This is a TAsyncChannel implementation that reads and writes messages
 * prefixed with a 4-byte frame length.
 *
 * Its messages are compatible with TFramedTransport.
 */
class TFramedAsyncChannel :
  public TStreamAsyncChannel<detail::TFramedACWriteRequest,
                             detail::TFramedACReadState> {
 private:
  typedef TStreamAsyncChannel<detail::TFramedACWriteRequest,
                              detail::TFramedACReadState> Parent;

 public:
  explicit TFramedAsyncChannel(
    const boost::shared_ptr<TAsyncTransport>& transport
    )
    : Parent(transport) {}

  /**
   * Helper function to create a shared_ptr<TFramedAsyncChannel>.
   *
   * This passes in the correct destructor object, since TFramedAsyncChannel's
   * destructor is protected and cannot be invoked directly.
   */
  static boost::shared_ptr<TFramedAsyncChannel> newChannel(
      const boost::shared_ptr<TAsyncTransport>& transport) {
    return boost::shared_ptr<TFramedAsyncChannel>(
        new TFramedAsyncChannel(transport), Destructor());
  }

  /// size in bytes beyond which we'll reject a given frame size.
  void setMaxFrameSize(uint32_t size) {
    readState_.setMaxFrameSize(size);
  }

  uint32_t getMaxFrameSize() const {
    return readState_.getMaxFrameSize();
  }

 protected:
  /**
   * Protected destructor.
   *
   * Users of TFramedAsyncChannel must never delete it directly.  Instead,
   * invoke destroy().
   */
  virtual ~TFramedAsyncChannel() { }
};

class TFramedAsyncChannelFactory : public TStreamAsyncChannelFactory {
 public:
  TFramedAsyncChannelFactory()
    : maxFrameSize_(0x7fffffff)
    , recvTimeout_(0)
    , sendTimeout_(0) {}

  void setMaxFrameSize(uint32_t bytes) {
    maxFrameSize_ = bytes;
  }

  void setRecvTimeout(uint32_t milliseconds) {
    recvTimeout_ = milliseconds;
  }

  void setSendTimeout(uint32_t milliseconds) {
    sendTimeout_ = milliseconds;
  }

  virtual boost::shared_ptr<TAsyncEventChannel> newChannel(
      const boost::shared_ptr<TAsyncTransport>& transport) {
    boost::shared_ptr<TFramedAsyncChannel> channel(
        TFramedAsyncChannel::newChannel(transport));
    transport->setSendTimeout(sendTimeout_);
    channel->setMaxFrameSize(maxFrameSize_);
    channel->setRecvTimeout(recvTimeout_);
    return channel;
  }

 private:
  uint32_t maxFrameSize_;
  uint32_t recvTimeout_;
  uint32_t sendTimeout_;
};

}}} // apache::thrift::async

#endif // THRIFT_ASYNC_TFRAMEDASYNCCHANNEL_H_