click_hdfs/contirb/libhdfspp/lib/common/continuation/asio.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 LIB_COMMON_COROUTINES_ASIO_H_
#define LIB_COMMON_COROUTINES_ASIO_H_

#include "continuation.h"
#include "common/util.h"

#include "libhdfs++/status.h"

#include <asio/connect.hpp>
#include <asio/read.hpp>
#include <asio/write.hpp>
#include <asio/ip/tcp.hpp>

namespace hdfs {
namespace continuation {

template<class Stream, class MutableBufferSequence>
class ReadContinuation : public Continuation {
 public:
  ReadContinuation(Stream *stream, const MutableBufferSequence &buffer)
      : stream_(stream)
      , buffer_(buffer)
  {}
  virtual void Run(const Next& next) override {
    auto handler = [next](const asio::error_code &ec, size_t)
                   { next(ToStatus(ec)); };
    asio::async_read(*stream_, buffer_, handler);
  }

 private:
  Stream *stream_;
  MutableBufferSequence buffer_;
};

template<class Stream, class ConstBufferSequence>
class WriteContinuation : public Continuation {
 public:
  WriteContinuation(Stream *stream, const ConstBufferSequence& buffer)
      : stream_(stream)
      , buffer_(buffer)
  {}
  
  virtual void Run(const Next& next) override {
    auto handler = [next](const asio::error_code &ec, size_t)
                   { next(ToStatus(ec)); };
    asio::async_write(*stream_, buffer_, handler);
  }

 private:
  Stream *stream_;
  ConstBufferSequence buffer_;
};

template<class Socket, class Iterator>
class ConnectContinuation : public Continuation {
 public:
  ConnectContinuation(Socket *socket, Iterator begin, Iterator end,
                   Iterator *connected_endpoint)
      : socket_(socket)
      , begin_(begin)
      , end_(end)
      , connected_endpoint_(connected_endpoint)
  {}

  virtual void Run(const Next& next) override {
    auto handler = [this,next](const asio::error_code &ec, Iterator it) {
      if (connected_endpoint_) {
        *connected_endpoint_ = it;
      }
      next(ToStatus(ec));
    };
    asio::async_connect(*socket_, begin_, end_, handler);
  }
 private:
  Socket *socket_;
  Iterator begin_;
  Iterator end_;
  Iterator *connected_endpoint_;
};

template<class Stream, class ConstBufferSequence>
static inline Continuation* Write(Stream *stream, const ConstBufferSequence &buffer) {
  return new WriteContinuation<Stream, ConstBufferSequence>(stream, buffer);
}

template<class Stream, class MutableBufferSequence>
static inline Continuation* Read(Stream *stream, const MutableBufferSequence &buffer) {
  return new ReadContinuation<Stream, MutableBufferSequence>(stream, buffer);
}

template<class Socket, class Iterator>
static inline Continuation* Connect(Socket *socket, Iterator begin, Iterator end) {
  return new ConnectContinuation<Socket, Iterator>(socket, begin, end, nullptr);
}

}
}

#endif