kqueue_reactor.hpp

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  // 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)
  {
    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<kqueue_reactor<Own_Thread> >;

  // Run the kqueue loop.
  void run(bool block)
  {
    asio::detail::mutex::scoped_lock lock(mutex_);

    // Dispatch any operation cancellations that were made while the select
    // loop was not running.
    read_op_queue_.dispatch_cancellations();
    write_op_queue_.dispatch_cancellations();
    except_op_queue_.dispatch_cancellations();
    for (std::size_t i = 0; i < timer_queues_.size(); ++i)
      timer_queues_[i]->dispatch_cancellations();

    // Check if the thread is supposed to stop.
    if (stop_thread_)
    {
      cleanup_operations_and_timers(lock);
      return;
    }

    // We can return immediately if there's no work to do and the reactor is
    // not supposed to block.
    if (!block && read_op_queue_.empty() && write_op_queue_.empty()
        && except_op_queue_.empty() && all_timer_queues_are_empty())
    {
      cleanup_operations_and_timers(lock);
      return;
    }

    // Determine how long to block while waiting for events.
    timespec timeout_buf = { 0, 0 };
    timespec* timeout = block ? get_timeout(timeout_buf) : &timeout_buf;

    wait_in_progress_ = true;
    lock.unlock();

    // Block on the kqueue descriptor.
    struct kevent events[128];
    int num_events = kevent(kqueue_fd_, 0, 0, events, 128, timeout);

    lock.lock();
    wait_in_progress_ = false;

    // Block signals while dispatching operations.
    asio::detail::signal_blocker sb;

    // Dispatch the waiting events.
    for (int i = 0; i < num_events; ++i)
    {
      int descriptor = events[i].ident;
      if (descriptor == interrupter_.read_descriptor())
      {
        interrupter_.reset();
      }
      else if (events[i].filter == EVFILT_READ)
      {
        // Dispatch operations associated with the descriptor.
        bool more_reads = false;
        bool more_except = false;
        if (events[i].flags & EV_ERROR)
        {
          asio::error_code error(
              events[i].data, asio::error::get_system_category());
          except_op_queue_.dispatch_all_operations(descriptor, error);
          read_op_queue_.dispatch_all_operations(descriptor, error);
        }
        else if (events[i].flags & EV_OOBAND)
        {
          asio::error_code error;
          more_except = except_op_queue_.dispatch_operation(descriptor, error);
          if (events[i].data > 0)
            more_reads = read_op_queue_.dispatch_operation(descriptor, error);
          else
            more_reads = read_op_queue_.has_operation(descriptor);
        }
        else
        {
          asio::error_code error;
          more_reads = read_op_queue_.dispatch_operation(descriptor, error);
          more_except = except_op_queue_.has_operation(descriptor);
        }

        // Update the descriptor in the kqueue.
        struct kevent event;
        if (more_reads)
          EV_SET(&event, descriptor, EVFILT_READ, EV_ADD, 0, 0, 0);
        else if (more_except)
          EV_SET(&event, descriptor, EVFILT_READ, EV_ADD, EV_OOBAND, 0, 0);
        else
          EV_SET(&event, descriptor, EVFILT_READ, EV_DELETE, 0, 0, 0);
        if (::kevent(kqueue_fd_, &event, 1, 0, 0, 0) == -1)
        {
          asio::error_code error(errno,
              asio::error::get_system_category());
          except_op_queue_.dispatch_all_operations(descriptor, error);
          read_op_queue_.dispatch_all_operations(descriptor, error);
        }
      }
      else if (events[i].filter == EVFILT_WRITE)
      {
        // Dispatch operations associated with the descriptor.
        bool more_writes = false;
        if (events[i].flags & EV_ERROR)
        {
          asio::error_code error(
              events[i].data, asio::error::get_system_category());
          write_op_queue_.dispatch_all_operations(descriptor, error);
        }
        else
        {
          asio::error_code error;
          more_writes = write_op_queue_.dispatch_operation(descriptor, error);
        }

        // Update the descriptor in the kqueue.
        struct kevent event;
        if (more_writes)
          EV_SET(&event, descriptor, EVFILT_WRITE, EV_ADD, 0, 0, 0);
        else
          EV_SET(&event, descriptor, EVFILT_WRITE, EV_DELETE, 0, 0, 0);
        if (::kevent(kqueue_fd_, &event, 1, 0, 0, 0) == -1)
        {
          asio::error_code error(errno,
              asio::error::get_system_category());
          write_op_queue_.dispatch_all_operations(descriptor, error);
        }
      }
    }

    read_op_queue_.dispatch_cancellations();
    write_op_queue_.dispatch_cancellations();
    except_op_queue_.dispatch_cancellations();
    for (std::size_t i = 0; i < timer_queues_.size(); ++i)
    {
      timer_queues_[i]->dispatch_timers();
      timer_queues_[i]->dispatch_cancellations();
    }

    // Issue any pending cancellations.
    for (std::size_t i = 0; i < pending_cancellations_.size(); ++i)
      cancel_ops_unlocked(pending_cancellations_[i]);
    pending_cancellations_.clear();

    cleanup_operations_and_timers(lock);
  }

  // Run the select loop in the thread.
  void run_thread()
  {
    asio::detail::mutex::scoped_lock lock(mutex_);
    while (!stop_thread_)
    {
      lock.unlock();
      run(true);
      lock.lock();
    }
  }

  // Entry point for the select loop thread.
  static void call_run_thread(kqueue_reactor* reactor)
  {
    reactor->run_thread();
  }

  // Interrupt the select loop.
  void interrupt()
  {
    interrupter_.interrupt();
  }

  // Create the kqueue file descriptor. Throws an exception if the descriptor
  // cannot be created.
  static int do_kqueue_create()
  {
    int fd = kqueue();
    if (fd == -1)
    {
      boost::throw_exception(
          asio::system_error(
            asio::error_code(errno,
              asio::error::get_system_category()),
            "kqueue"));
    }
    return fd;
  }

  // Check if all timer queues are empty.
  bool all_timer_queues_are_empty() const
  {
    for (std::size_t i = 0; i < timer_queues_.size(); ++i)
      if (!timer_queues_[i]->empty())
        return false;
    return true;
  }

  // Get the timeout value for the kevent call.
  timespec* get_timeout(timespec& ts)
  {
    if (all_timer_queues_are_empty())
      return 0;

    // By default we will wait no longer than 5 minutes. This will ensure that
    // any changes to the system clock are detected after no longer than this.
    boost::posix_time::time_duration minimum_wait_duration
      = boost::posix_time::minutes(5);

    for (std::size_t i = 0; i < timer_queues_.size(); ++i)
    {
      boost::posix_time::time_duration wait_duration
        = timer_queues_[i]->wait_duration();
      if (wait_duration < minimum_wait_duration)
        minimum_wait_duration = wait_duration;
    }

    if (minimum_wait_duration > boost::posix_time::time_duration())
    {
      ts.tv_sec = minimum_wait_duration.total_seconds();
      ts.tv_nsec = minimum_wait_duration.total_nanoseconds() % 1000000000;
    }
    else
    {
      ts.tv_sec = 0;
      ts.tv_nsec = 0;
    }

    return &ts;
  }

  // Cancel all operations associated with the given descriptor. The do_cancel
  // function of the handler objects will be invoked. This function does not
  // acquire the kqueue_reactor's mutex.
  void cancel_ops_unlocked(socket_type descriptor)
  {
    bool interrupt = read_op_queue_.cancel_operations(descriptor);
    interrupt = write_op_queue_.cancel_operations(descriptor) || interrupt;
    interrupt = except_op_queue_.cancel_operations(descriptor) || interrupt;
    if (interrupt)
      interrupter_.interrupt();
  }

  // Clean up operations and timers. We must not hold the lock since the
  // destructors may make calls back into this reactor. We make a copy of the
  // vector of timer queues since the original may be modified while the lock
  // is not held.
  void cleanup_operations_and_timers(
      asio::detail::mutex::scoped_lock& lock)
  {
    timer_queues_for_cleanup_ = timer_queues_;
    lock.unlock();
    read_op_queue_.cleanup_operations();
    write_op_queue_.cleanup_operations();
    except_op_queue_.cleanup_operations();
    for (std::size_t i = 0; i < timer_queues_for_cleanup_.size(); ++i)
      timer_queues_for_cleanup_[i]->cleanup_timers();
  }

  // Mutex to protect access to internal data.
  asio::detail::mutex mutex_;

  // The kqueue file descriptor.
  int kqueue_fd_;

  // Whether the kqueue wait call is currently in progress
  bool wait_in_progress_;

  // The interrupter is used to break a blocking kevent call.
  select_interrupter interrupter_;

  // The queue of read operations.
  reactor_op_queue<socket_type> read_op_queue_;

  // The queue of write operations.
  reactor_op_queue<socket_type> write_op_queue_;

  // The queue of except operations.
  reactor_op_queue<socket_type> except_op_queue_;

  // The timer queues.
  std::vector<timer_queue_base*> timer_queues_;

  // A copy of the timer queues, used when cleaning up timers. The copy is
  // stored as a class data member to avoid unnecessary memory allocation.
  std::vector<timer_queue_base*> timer_queues_for_cleanup_;

  // The descriptors that are pending cancellation.
  std::vector<socket_type> pending_cancellations_;

  // Does the reactor loop thread need to stop.
  bool stop_thread_;

  // The thread that is running the reactor loop.
  asio::detail::thread* thread_;

  // Whether the service has been shut down.
  bool shutdown_;
};

} // namespace detail
} // namespace asio

#endif // defined(ASIO_HAS_KQUEUE)

#include "asio/detail/pop_options.hpp"

#endif // ASIO_DETAIL_KQUEUE_REACTOR_HPP