//

// kqueue_reactor.hpp

// ~~~~~~~~~~~~~~~~~~

//

// Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)

// Copyright (c) 2005 Stefan Arentz (stefan at soze 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_KQUEUE_REACTOR_HPP

#define BOOST_ASIO_DETAIL_KQUEUE_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/kqueue_reactor_fwd.hpp>



#if defined(BOOST_ASIO_HAS_KQUEUE)



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

#include <cstddef>

#include <vector>

#include <sys/types.h>

#include <sys/event.h>

#include <sys/time.h>

#include <boost/config.hpp>

#include <boost/date_time/posix_time/posix_time_types.hpp>

#include <boost/throw_exception.hpp>

#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/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>



// Older versions of Mac OS X may not define EV_OOBAND.

#if !defined(EV_OOBAND)

# define EV_OOBAND EV_FLAG1

#endif // !defined(EV_OOBAND)



namespace boost {

namespace asio {

namespace detail {



template <bool Own_Thread>

class kqueue_reactor

  : public boost::asio::detail::service_base<kqueue_reactor<Own_Thread> >

{

public:

  // Constructor.

  kqueue_reactor(boost::asio::io_service& io_service)

    : boost::asio::detail::service_base<

        kqueue_reactor<Own_Thread> >(io_service),

      mutex_(),

      kqueue_fd_(do_kqueue_create()),

      wait_in_progress_(false),

      interrupter_(),

      read_op_queue_(),

      write_op_queue_(),

      except_op_queue_(),

      pending_cancellations_(),

      stop_thread_(false),

      thread_(0),

      shutdown_(false),

      need_kqueue_wait_(true)

  {

    // 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(&kqueue_reactor::call_run_thread, this));

    }



    // Add the interrupter's descriptor to the kqueue.

    struct kevent event;

    EV_SET(&event, interrupter_.read_descriptor(),

        EVFILT_READ, EV_ADD, 0, 0, 0);

    ::kevent(kqueue_fd_, &event, 1, 0, 0, 0);

  }



  // Destructor.

  ~kqueue_reactor()

  {

    shutdown_service();

    close(kqueue_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();

  }



  // Register a socket with the reactor. Returns 0 on success, system error

  // code on failure.

  int register_descriptor(socket_type)

  {

    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, Handler handler)

  {

    boost::asio::detail::mutex::scoped_lock lock(mutex_);



    if (shutdown_)

      return;



    if (!read_op_queue_.has_operation(descriptor))

      if (handler(boost::system::error_code()))

        return;



    if (read_op_queue_.enqueue_operation(descriptor, handler))

    {

      struct kevent event;

      EV_SET(&event, descriptor, EVFILT_READ, EV_ADD, 0, 0, 0);

      if (::kevent(kqueue_fd_, &event, 1, 0, 0, 0) == -1)

      {

        boost::system::error_code ec(errno,

            boost::asio::error::get_system_category());

        read_op_queue_.dispatch_all_operations(descriptor, ec);

      }

    }

  }



  // 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, Handler handler)

  {

    boost::asio::detail::mutex::scoped_lock lock(mutex_);



    if (shutdown_)

      return;



    if (!write_op_queue_.has_operation(descriptor))

      if (handler(boost::system::error_code()))

        return;



    if (write_op_queue_.enqueue_operation(descriptor, handler))

    {

      struct kevent event;

      EV_SET(&event, descriptor, EVFILT_WRITE, EV_ADD, 0, 0, 0);

      if (::kevent(kqueue_fd_, &event, 1, 0, 0, 0) == -1)

      {

        boost::system::error_code ec(errno,

            boost::asio::error::get_system_category());

        write_op_queue_.dispatch_all_operations(descriptor, ec);

      }

    }

  }



  // 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, Handler handler)

  {

    boost::asio::detail::mutex::scoped_lock lock(mutex_);



    if (shutdown_)

      return;



    if (except_op_queue_.enqueue_operation(descriptor, handler))

    {

      struct kevent event;

      if (read_op_queue_.has_operation(descriptor))

        EV_SET(&event, descriptor, EVFILT_READ, EV_ADD, 0, 0, 0);

      else

        EV_SET(&event, descriptor, EVFILT_READ, EV_ADD, EV_OOBAND, 0, 0);

      if (::kevent(kqueue_fd_, &event, 1, 0, 0, 0) == -1)

      {

        boost::system::error_code ec(errno,

            boost::asio::error::get_system_category());

        except_op_queue_.dispatch_all_operations(descriptor, ec);

      }

    }

  }



  // 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.

  template <typename Handler>

  void start_write_and_except_ops(socket_type descriptor, Handler handler)

  {

    boost::asio::detail::mutex::scoped_lock lock(mutex_);



    if (shutdown_)

      return;



    if (write_op_queue_.enqueue_operation(descriptor, handler))

    {

      struct kevent event;

      EV_SET(&event, descriptor, EVFILT_WRITE, EV_ADD, 0, 0, 0);

      if (::kevent(kqueue_fd_, &event, 1, 0, 0, 0) == -1)

      {

        boost::system::error_code ec(errno,

            boost::asio::error::get_system_category());

        write_op_queue_.dispatch_all_operations(descriptor, ec);

      }

    }



    if (except_op_queue_.enqueue_operation(descriptor, handler))

    {

      struct kevent event;

      if (read_op_queue_.has_operation(descriptor))

        EV_SET(&event, descriptor, EVFILT_READ, EV_ADD, 0, 0, 0);

      else

        EV_SET(&event, descriptor, EVFILT_READ, EV_ADD, EV_OOBAND, 0, 0);

      if (::kevent(kqueue_fd_, &event, 1, 0, 0, 0) == -1)

      {

        boost::system::error_code ec(errno,

            boost::asio::error::get_system_category());

        except_op_queue_.dispatch_all_operations(descriptor, ec);

        write_op_queue_.dispatch_all_operations(descriptor, ec);

      }

    }

  }



  // 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)

  {

    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

  // kqueue_reactor's mutex, and so should only be used from within a reactor

  // handler.

  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)

  {

    boost::asio::detail::mutex::scoped_lock lock(mutex_);



    // Remove the descriptor from kqueue.

    struct kevent event[2];

    EV_SET(&event[0], descriptor, EVFILT_READ, EV_DELETE, 0, 0, 0);

    EV_SET(&event[1], descriptor, EVFILT_WRITE, EV_DELETE, 0, 0, 0);

    ::kevent(kqueue_fd_, event, 2, 0, 0, 0);

    

    // 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<kqueue_reactor<Own_Thread> >;



  // Run the kqueue loop.

  void run(bool block)

  {

    boost::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 = (block || need_kqueue_wait_)

      ? kevent(kqueue_fd_, 0, 0, events, 128, timeout)

      : 0;



    lock.lock();

    wait_in_progress_ = false;



    // Block signals while dispatching operations.

    boost::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)

        {

          boost::system::error_code error(

              events[i].data, boost::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)

        {

          boost::system::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

        {

          boost::system::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)

        {

          boost::system::error_code error(errno,

              boost::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)

        {

          boost::system::error_code error(

              events[i].data, boost::asio::error::get_system_category());

          write_op_queue_.dispatch_all_operations(descriptor, error);

        }

        else

        {

          boost::system::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)

        {

          boost::system::error_code error(errno,

              boost::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();



    // Determine whether kqueue needs to be called next time the reactor is run.

    need_kqueue_wait_ = !read_op_queue_.empty()

      || !write_op_queue_.empty() || !except_op_queue_.empty();



    cleanup_operations_and_timers(lock);

  }



  // Run the select loop in the thread.

  void run_thread()

  {

    boost::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(

          boost::system::system_error(

            boost::system::error_code(errno,

              boost::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(

      boost::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.

  boost::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.

  boost::asio::detail::thread* thread_;



  // Whether the service has been shut down.

  bool shutdown_;



  // Whether we need to call kqueue the next time the reactor is run.

  bool need_kqueue_wait_;

};



} // namespace detail

} // namespace asio

} // namespace boost



#endif // defined(BOOST_ASIO_HAS_KQUEUE)



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



#endif // BOOST_ASIO_DETAIL_KQUEUE_REACTOR_HPP

