select_reactor.hpp

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//
// select_reactor.hpp
// ~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef BOOST_ASIO_DETAIL_SELECT_REACTOR_HPP
#define BOOST_ASIO_DETAIL_SELECT_REACTOR_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include <boost/asio/detail/push_options.hpp>

#include <boost/asio/detail/socket_types.hpp> // Must come before posix_time.

#include <boost/asio/detail/push_options.hpp>
#include <cstddef>
#include <boost/config.hpp>
#include <boost/date_time/posix_time/posix_time_types.hpp>
#include <boost/shared_ptr.hpp>
#include <vector>
#include <boost/asio/detail/pop_options.hpp>

#include <boost/asio/io_service.hpp>
#include <boost/asio/detail/bind_handler.hpp>
#include <boost/asio/detail/fd_set_adapter.hpp>
#include <boost/asio/detail/mutex.hpp>
#include <boost/asio/detail/noncopyable.hpp>
#include <boost/asio/detail/reactor_op_queue.hpp>
#include <boost/asio/detail/select_interrupter.hpp>
#include <boost/asio/detail/select_reactor_fwd.hpp>
#include <boost/asio/detail/service_base.hpp>
#include <boost/asio/detail/signal_blocker.hpp>
#include <boost/asio/detail/socket_ops.hpp>
#include <boost/asio/detail/socket_types.hpp>
#include <boost/asio/detail/task_io_service.hpp>
#include <boost/asio/detail/thread.hpp>
#include <boost/asio/detail/timer_queue.hpp>

namespace boost {
namespace asio {
namespace detail {

template <bool Own_Thread>
class select_reactor
  : public boost::asio::detail::service_base<select_reactor<Own_Thread> >
{
public:
  // Per-descriptor data.
  struct per_descriptor_data
  {
  };

  // Constructor.
  select_reactor(boost::asio::io_service& io_service)
    : boost::asio::detail::service_base<
        select_reactor<Own_Thread> >(io_service),
      mutex_(),
      select_in_progress_(false),
      interrupter_(),
      read_op_queue_(),
      write_op_queue_(),
      except_op_queue_(),
      pending_cancellations_(),
      stop_thread_(false),
      thread_(0),
      shutdown_(false)
  {
    if (Own_Thread)
    {
      boost::asio::detail::signal_blocker sb;
      thread_ = new boost::asio::detail::thread(
          bind_handler(&select_reactor::call_run_thread, this));
    }
  }

  // Destructor.
  ~select_reactor()
  {
    shutdown_service();
  }

  // Destroy all user-defined handler objects owned by the service.
  void shutdown_service()
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    shutdown_ = true;
    stop_thread_ = true;
    lock.unlock();

    if (thread_)
    {
      interrupter_.interrupt();
      thread_->join();
      delete thread_;
      thread_ = 0;
    }

    read_op_queue_.destroy_operations();
    write_op_queue_.destroy_operations();
    except_op_queue_.destroy_operations();

    for (std::size_t i = 0; i < timer_queues_.size(); ++i)
      timer_queues_[i]->destroy_timers();
    timer_queues_.clear();
  }

  // Initialise the task, but only if the reactor is not in its own thread.
  void init_task()
  {
    if (!Own_Thread)
    {
      typedef task_io_service<select_reactor<Own_Thread> > task_io_service_type;
      use_service<task_io_service_type>(this->get_io_service()).init_task();
    }
  }

  // Register a socket with the reactor. Returns 0 on success, system error
  // code on failure.
  int register_descriptor(socket_type, per_descriptor_data&)
  {
    return 0;
  }

  // Start a new read operation. The handler object will be invoked when the
  // given descriptor is ready to be read, or an error has occurred.
  template <typename Handler>
  void start_read_op(socket_type descriptor, per_descriptor_data&,
      Handler handler, bool /*allow_speculative_read*/ = true)
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    if (!shutdown_)
      if (read_op_queue_.enqueue_operation(descriptor, handler))
        interrupter_.interrupt();
  }

  // Start a new write operation. The handler object will be invoked when the
  // given descriptor is ready to be written, or an error has occurred.
  template <typename Handler>
  void start_write_op(socket_type descriptor, per_descriptor_data&,
      Handler handler, bool /*allow_speculative_write*/ = true)
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    if (!shutdown_)
      if (write_op_queue_.enqueue_operation(descriptor, handler))
        interrupter_.interrupt();
  }

  // Start a new exception operation. The handler object will be invoked when
  // the given descriptor has exception information, or an error has occurred.
  template <typename Handler>
  void start_except_op(socket_type descriptor,
      per_descriptor_data&, Handler handler)
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    if (!shutdown_)
      if (except_op_queue_.enqueue_operation(descriptor, handler))
        interrupter_.interrupt();
  }

  // Wrapper for connect handlers to enable the handler object to be placed
  // in both the write and the except operation queues, but ensure that only
  // one of the handlers is called.
  template <typename Handler>
  class connect_handler_wrapper
  {
  public:
    connect_handler_wrapper(socket_type descriptor,
        boost::shared_ptr<bool> completed,
        select_reactor<Own_Thread>& reactor, Handler handler)
      : descriptor_(descriptor),
        completed_(completed),
        reactor_(reactor),
        handler_(handler)
    {
    }

    bool perform(boost::system::error_code& ec,
        std::size_t& bytes_transferred)
    {
      // Check whether one of the handlers has already been called. If it has,
      // then we don't want to do anything in this handler.
      if (*completed_)
      {
        completed_.reset(); // Indicate that this handler should not complete.
        return true;
      }

      // Cancel the other reactor operation for the connection.
      *completed_ = true;
      reactor_.enqueue_cancel_ops_unlocked(descriptor_);

      // Call the contained handler.
      return handler_.perform(ec, bytes_transferred);
    }

    void complete(const boost::system::error_code& ec,
        std::size_t bytes_transferred)
    {
      if (completed_.get())
        handler_.complete(ec, bytes_transferred);
    }

  private:
    socket_type descriptor_;
    boost::shared_ptr<bool> completed_;
    select_reactor<Own_Thread>& reactor_;
    Handler handler_;
  };

  // Start new write and exception operations. The handler object will be
  // invoked when the given descriptor is ready for writing or has exception
  // information available, or an error has occurred. The handler will be called
  // only once.
  template <typename Handler>
  void start_connect_op(socket_type descriptor,
      per_descriptor_data&, Handler handler)
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    if (!shutdown_)
    {
      boost::shared_ptr<bool> completed(new bool(false));
      connect_handler_wrapper<Handler> wrapped_handler(
          descriptor, completed, *this, handler);
      bool interrupt = write_op_queue_.enqueue_operation(
          descriptor, wrapped_handler);
      interrupt = except_op_queue_.enqueue_operation(
          descriptor, wrapped_handler) || interrupt;
      if (interrupt)
        interrupter_.interrupt();
    }
  }

  // Cancel all operations associated with the given descriptor. The
  // handlers associated with the descriptor will be invoked with the
  // operation_aborted error.
  void cancel_ops(socket_type descriptor, per_descriptor_data&)
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    cancel_ops_unlocked(descriptor);
  }

  // Enqueue cancellation of all operations associated with the given
  // descriptor. The handlers associated with the descriptor will be invoked
  // with the operation_aborted error. This function does not acquire the
  // select_reactor's mutex, and so should only be used when the reactor lock is
  // already held.
  void enqueue_cancel_ops_unlocked(socket_type descriptor)
  {
    pending_cancellations_.push_back(descriptor);
  }

  // Cancel any operations that are running against the descriptor and remove
  // its registration from the reactor.
  void close_descriptor(socket_type descriptor, per_descriptor_data&)
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    cancel_ops_unlocked(descriptor);
  }

  // Add a new timer queue to the reactor.
  template <typename Time_Traits>
  void add_timer_queue(timer_queue<Time_Traits>& timer_queue)
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    timer_queues_.push_back(&timer_queue);
  }