dev_poll_reactor.hpp

Boost provides free peer-reviewed portable C++ source libraries. We emphasize libraries that work

//
// dev_poll_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_DEV_POLL_REACTOR_HPP
#define BOOST_ASIO_DETAIL_DEV_POLL_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/dev_poll_reactor_fwd.hpp>

#if defined(BOOST_ASIO_HAS_DEV_POLL)

#include <boost/asio/detail/push_options.hpp>
#include <cstddef>
#include <vector>
#include <boost/config.hpp>
#include <boost/date_time/posix_time/posix_time_types.hpp>
#include <boost/throw_exception.hpp>
#include <sys/devpoll.h>
#include <boost/system/system_error.hpp>
#include <boost/asio/detail/pop_options.hpp>

#include <boost/asio/error.hpp>
#include <boost/asio/io_service.hpp>
#include <boost/asio/detail/bind_handler.hpp>
#include <boost/asio/detail/hash_map.hpp>
#include <boost/asio/detail/mutex.hpp>
#include <boost/asio/detail/task_io_service.hpp>
#include <boost/asio/detail/thread.hpp>
#include <boost/asio/detail/reactor_op_queue.hpp>
#include <boost/asio/detail/select_interrupter.hpp>
#include <boost/asio/detail/service_base.hpp>
#include <boost/asio/detail/signal_blocker.hpp>
#include <boost/asio/detail/socket_types.hpp>
#include <boost/asio/detail/timer_queue.hpp>

namespace boost {
namespace asio {
namespace detail {

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

  // Constructor.
  dev_poll_reactor(boost::asio::io_service& io_service)
    : boost::asio::detail::service_base<
        dev_poll_reactor<Own_Thread> >(io_service),
      mutex_(),
      dev_poll_fd_(do_dev_poll_create()),
      wait_in_progress_(false),
      interrupter_(),
      read_op_queue_(),
      write_op_queue_(),
      except_op_queue_(),
      pending_cancellations_(),
      stop_thread_(false),
      thread_(0),
      shutdown_(false)
  {
    // Start the reactor's internal thread only if needed.
    if (Own_Thread)
    {
      boost::asio::detail::signal_blocker sb;
      thread_ = new boost::asio::detail::thread(
          bind_handler(&dev_poll_reactor::call_run_thread, this));
    }

    // Add the interrupter's descriptor to /dev/poll.
    ::pollfd ev = { 0 };
    ev.fd = interrupter_.read_descriptor();
    ev.events = POLLIN | POLLERR;
    ev.revents = 0;
    ::write(dev_poll_fd_, &ev, sizeof(ev));
  }

  // Destructor.
  ~dev_poll_reactor()
  {
    shutdown_service();
    ::close(dev_poll_fd_);
  }

  // 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<dev_poll_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_)
      return;

    if (allow_speculative_read)
    {
      if (!read_op_queue_.has_operation(descriptor))
      {
        boost::system::error_code ec;
        std::size_t bytes_transferred = 0;
        if (handler.perform(ec, bytes_transferred))
        {
          handler.complete(ec, bytes_transferred);
          return;
        }
      }
    }

    if (read_op_queue_.enqueue_operation(descriptor, handler))
    {
      ::pollfd& ev = add_pending_event_change(descriptor);
      ev.events = POLLIN | POLLERR | POLLHUP;
      if (write_op_queue_.has_operation(descriptor))
        ev.events |= POLLOUT;
      if (except_op_queue_.has_operation(descriptor))
        ev.events |= POLLPRI;
      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_)
      return;

    if (allow_speculative_write)
    {
      if (!write_op_queue_.has_operation(descriptor))
      {
        boost::system::error_code ec;
        std::size_t bytes_transferred = 0;
        if (handler.perform(ec, bytes_transferred))
        {
          handler.complete(ec, bytes_transferred);
          return;
        }
      }
    }

    if (write_op_queue_.enqueue_operation(descriptor, handler))
    {
      ::pollfd& ev = add_pending_event_change(descriptor);
      ev.events = POLLOUT | POLLERR | POLLHUP;
      if (read_op_queue_.has_operation(descriptor))
        ev.events |= POLLIN;
      if (except_op_queue_.has_operation(descriptor))
        ev.events |= POLLPRI;
      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_)
      return;

    if (except_op_queue_.enqueue_operation(descriptor, handler))
    {
      ::pollfd& ev = add_pending_event_change(descriptor);
      ev.events = POLLPRI | POLLERR | POLLHUP;
      if (read_op_queue_.has_operation(descriptor))
        ev.events |= POLLIN;
      if (write_op_queue_.has_operation(descriptor))
        ev.events |= POLLOUT;
      interrupter_.interrupt();
    }
  }

  // Start a new write operation. The handler object will be invoked when the
  // information available, or an error has occurred.
  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_)
      return;

    if (write_op_queue_.enqueue_operation(descriptor, handler))
    {
      ::pollfd& ev = add_pending_event_change(descriptor);
      ev.events = POLLOUT | POLLERR | POLLHUP;
      if (read_op_queue_.has_operation(descriptor))
        ev.events |= POLLIN;
      if (except_op_queue_.has_operation(descriptor))
        ev.events |= POLLPRI;
      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);
  }

  // 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_);

    // Remove the descriptor from /dev/poll.
    ::pollfd& ev = add_pending_event_change(descriptor);
    ev.events = POLLREMOVE;
    interrupter_.interrupt();

    // Cancel any outstanding operations associated with the descriptor.
    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);
  }

  // Remove a timer queue from the reactor.
  template <typename Time_Traits>
  void remove_timer_queue(timer_queue<Time_Traits>& timer_queue)
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    for (std::size_t i = 0; i < timer_queues_.size(); ++i)
    {
      if (timer_queues_[i] == &timer_queue)
      {
        timer_queues_.erase(timer_queues_.begin() + i);
        return;
      }
    }
  }

  // Schedule a timer in the given timer queue to expire at the specified
  // absolute time. The handler object will be invoked when the timer expires.
  template <typename Time_Traits, typename Handler>
  void schedule_timer(timer_queue<Time_Traits>& timer_queue,
      const typename Time_Traits::time_type& time, Handler handler, void* token)
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    if (!shutdown_)
      if (timer_queue.enqueue_timer(time, handler, token))
        interrupter_.interrupt();
  }

  // Cancel the timer associated with the given token. Returns the number of
  // handlers that have been posted or dispatched.
  template <typename Time_Traits>
  std::size_t cancel_timer(timer_queue<Time_Traits>& timer_queue, void* token)
  {
    boost::asio::detail::mutex::scoped_lock lock(mutex_);
    std::size_t n = timer_queue.cancel_timer(token);
    if (n > 0)
      interrupter_.interrupt();
    return n;
  }

private:
  friend class task_io_service<dev_poll_reactor<Own_Thread> >;

  // Run /dev/poll once until interrupted or events are ready to be dispatched.
  void run(bool block)
  {