boost/asio/detail/dev_poll_reactor.hpp
// // dev_poll_reactor.hpp // ~~~~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2010 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) { 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_.perform_cancellations(); write_op_queue_.perform_cancellations(); except_op_queue_.perform_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_) { complete_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()) { complete_operations_and_timers(lock); return; } // Write the pending event registration changes to the /dev/poll descriptor. std::size_t events_size = sizeof(::pollfd) * pending_event_changes_.size(); if (events_size > 0) { errno = 0; int result = ::write(dev_poll_fd_, &pending_event_changes_[0], events_size); if (result != static_cast<int>(events_size)) { for (std::size_t i = 0; i < pending_event_changes_.size(); ++i) { int descriptor = pending_event_changes_[i].fd; boost::system::error_code ec = boost::system::error_code( errno, boost::asio::error::get_system_category()); read_op_queue_.perform_all_operations(descriptor, ec); write_op_queue_.perform_all_operations(descriptor, ec); except_op_queue_.perform_all_operations(descriptor, ec); } } pending_event_changes_.clear(); pending_event_change_index_.clear(); } int timeout = block ? get_timeout() : 0; wait_in_progress_ = true; lock.unlock(); // Block on the /dev/poll descriptor. ::pollfd events[128] = { { 0 } }; ::dvpoll dp = { 0 }; dp.dp_fds = events; dp.dp_nfds = 128; dp.dp_timeout = timeout; int num_events = ::ioctl(dev_poll_fd_, DP_POLL, &dp); lock.lock(); wait_in_progress_ = false; // Dispatch the waiting events. for (int i = 0; i < num_events; ++i) { int descriptor = events[i].fd; if (descriptor == interrupter_.read_descriptor()) { interrupter_.reset(); } else { bool more_reads = false; bool more_writes = false; bool more_except = false; boost::system::error_code ec; // Exception operations must be processed first to ensure that any // out-of-band data is read before normal data. if (events[i].events & (POLLPRI | POLLERR | POLLHUP)) more_except = except_op_queue_.perform_operation(descriptor, ec); else more_except = except_op_queue_.has_operation(descriptor); if (events[i].events & (POLLIN | POLLERR | POLLHUP)) more_reads = read_op_queue_.perform_operation(descriptor, ec); else more_reads = read_op_queue_.has_operation(descriptor); if (events[i].events & (POLLOUT | POLLERR | POLLHUP)) more_writes = write_op_queue_.perform_operation(descriptor, ec); else more_writes = write_op_queue_.has_operation(descriptor); if ((events[i].events & (POLLERR | POLLHUP)) != 0 && !more_except && !more_reads && !more_writes) { // If we have an event and no operations associated with the // descriptor then we need to delete the descriptor from /dev/poll. // The poll operation can produce POLLHUP or POLLERR events when there // is no operation pending, so if we do not remove the descriptor we // can end up in a tight polling loop. ::pollfd ev = { 0 }; ev.fd = descriptor; ev.events = POLLREMOVE; ev.revents = 0; ::write(dev_poll_fd_, &ev, sizeof(ev)); } else { ::pollfd ev = { 0 }; ev.fd = descriptor; ev.events = POLLERR | POLLHUP; if (more_reads) ev.events |= POLLIN; if (more_writes) ev.events |= POLLOUT; if (more_except) ev.events |= POLLPRI; ev.revents = 0; int result = ::write(dev_poll_fd_, &ev, sizeof(ev)); if (result != sizeof(ev)) { ec = boost::system::error_code(errno, boost::asio::error::get_system_category()); read_op_queue_.perform_all_operations(descriptor, ec); write_op_queue_.perform_all_operations(descriptor, ec); except_op_queue_.perform_all_operations(descriptor, ec); } } } } read_op_queue_.perform_cancellations(); write_op_queue_.perform_cancellations(); except_op_queue_.perform_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 (size_t i = 0; i < pending_cancellations_.size(); ++i) cancel_ops_unlocked(pending_cancellations_[i]); pending_cancellations_.clear(); complete_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(dev_poll_reactor* reactor) { reactor->run_thread(); } // Interrupt the select loop. void interrupt() { interrupter_.interrupt(); } // Create the /dev/poll file descriptor. Throws an exception if the descriptor // cannot be created. static int do_dev_poll_create() { int fd = ::open("/dev/poll", O_RDWR); if (fd == -1) { boost::throw_exception( boost::system::system_error( boost::system::error_code(errno, boost::asio::error::get_system_category()), "/dev/poll")); } 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 /dev/poll DP_POLL operation. The timeout // value is returned as a number of milliseconds. A return value of -1 // indicates that the poll should block indefinitely. int get_timeout() { if (all_timer_queues_are_empty()) return -1; // 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()) { int milliseconds = minimum_wait_duration.total_milliseconds(); return milliseconds > 0 ? milliseconds : 1; } else { return 0; } } // 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 dev_poll_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 complete_operations_and_timers( boost::asio::detail::mutex::scoped_lock& lock) { timer_queues_for_cleanup_ = timer_queues_; lock.unlock(); read_op_queue_.complete_operations(); write_op_queue_.complete_operations(); except_op_queue_.complete_operations(); for (std::size_t i = 0; i < timer_queues_for_cleanup_.size(); ++i) timer_queues_for_cleanup_[i]->complete_timers(); } // Add a pending event entry for the given descriptor. ::pollfd& add_pending_event_change(int descriptor) { hash_map<int, std::size_t>::iterator iter = pending_event_change_index_.find(descriptor); if (iter == pending_event_change_index_.end()) { std::size_t index = pending_event_changes_.size(); pending_event_changes_.reserve(pending_event_changes_.size() + 1); pending_event_change_index_.insert(std::make_pair(descriptor, index)); pending_event_changes_.push_back(::pollfd()); pending_event_changes_[index].fd = descriptor; pending_event_changes_[index].revents = 0; return pending_event_changes_[index]; } else { return pending_event_changes_[iter->second]; } } // Mutex to protect access to internal data. boost::asio::detail::mutex mutex_; // The /dev/poll file descriptor. int dev_poll_fd_; // Vector of /dev/poll events waiting to be written to the descriptor. std::vector< ::pollfd> pending_event_changes_; // Hash map to associate a descriptor with a pending event change index. hash_map<int, std::size_t> pending_event_change_index_; // Whether the DP_POLL operation is currently in progress bool wait_in_progress_; // The interrupter is used to break a blocking DP_POLL operation. 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_; }; } // namespace detail } // namespace asio } // namespace boost #endif // defined(BOOST_ASIO_HAS_DEV_POLL) #include <boost/asio/detail/pop_options.hpp> #endif // BOOST_ASIO_DETAIL_DEV_POLL_REACTOR_HPP