// // detail/impl/epoll_reactor.ipp // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2018 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 ASIO_DETAIL_IMPL_EPOLL_REACTOR_IPP #define ASIO_DETAIL_IMPL_EPOLL_REACTOR_IPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include "asio/detail/config.hpp" #if defined(ASIO_HAS_EPOLL) #include #include #include "asio/detail/epoll_reactor.hpp" #include "asio/detail/throw_error.hpp" #include "asio/error.hpp" #if defined(ASIO_HAS_TIMERFD) # include #endif // defined(ASIO_HAS_TIMERFD) #include "asio/detail/push_options.hpp" namespace asio { namespace detail { epoll_reactor::epoll_reactor(asio::execution_context& ctx) : execution_context_service_base(ctx), scheduler_(use_service(ctx)), mutex_(ASIO_CONCURRENCY_HINT_IS_LOCKING( REACTOR_REGISTRATION, scheduler_.concurrency_hint())), interrupter_(), epoll_fd_(do_epoll_create()), timer_fd_(do_timerfd_create()), shutdown_(false), registered_descriptors_mutex_(mutex_.enabled()) { // Add the interrupter's descriptor to epoll. epoll_event ev = { 0, { 0 } }; ev.events = EPOLLIN | EPOLLERR | EPOLLET; ev.data.ptr = &interrupter_; epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, interrupter_.read_descriptor(), &ev); interrupter_.interrupt(); // Add the timer descriptor to epoll. if (timer_fd_ != -1) { ev.events = EPOLLIN | EPOLLERR; ev.data.ptr = &timer_fd_; epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &ev); } } epoll_reactor::~epoll_reactor() { if (epoll_fd_ != -1) close(epoll_fd_); if (timer_fd_ != -1) close(timer_fd_); } void epoll_reactor::shutdown() { mutex::scoped_lock lock(mutex_); shutdown_ = true; lock.unlock(); op_queue ops; while (descriptor_state* state = registered_descriptors_.first()) { for (int i = 0; i < max_ops; ++i) ops.push(state->op_queue_[i]); state->shutdown_ = true; registered_descriptors_.free(state); } timer_queues_.get_all_timers(ops); scheduler_.abandon_operations(ops); } void epoll_reactor::notify_fork( asio::execution_context::fork_event fork_ev) { if (fork_ev == asio::execution_context::fork_child) { if (epoll_fd_ != -1) ::close(epoll_fd_); epoll_fd_ = -1; epoll_fd_ = do_epoll_create(); if (timer_fd_ != -1) ::close(timer_fd_); timer_fd_ = -1; timer_fd_ = do_timerfd_create(); interrupter_.recreate(); // Add the interrupter's descriptor to epoll. epoll_event ev = { 0, { 0 } }; ev.events = EPOLLIN | EPOLLERR | EPOLLET; ev.data.ptr = &interrupter_; epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, interrupter_.read_descriptor(), &ev); interrupter_.interrupt(); // Add the timer descriptor to epoll. if (timer_fd_ != -1) { ev.events = EPOLLIN | EPOLLERR; ev.data.ptr = &timer_fd_; epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &ev); } update_timeout(); // Re-register all descriptors with epoll. mutex::scoped_lock descriptors_lock(registered_descriptors_mutex_); for (descriptor_state* state = registered_descriptors_.first(); state != 0; state = state->next_) { ev.events = state->registered_events_; ev.data.ptr = state; int result = epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, state->descriptor_, &ev); if (result != 0) { asio::error_code ec(errno, asio::error::get_system_category()); asio::detail::throw_error(ec, "epoll re-registration"); } } } } void epoll_reactor::init_task() { scheduler_.init_task(); } int epoll_reactor::register_descriptor(socket_type descriptor, epoll_reactor::per_descriptor_data& descriptor_data) { descriptor_data = allocate_descriptor_state(); ASIO_HANDLER_REACTOR_REGISTRATION(( context(), static_cast(descriptor), reinterpret_cast(descriptor_data))); { mutex::scoped_lock descriptor_lock(descriptor_data->mutex_); descriptor_data->reactor_ = this; descriptor_data->descriptor_ = descriptor; descriptor_data->shutdown_ = false; for (int i = 0; i < max_ops; ++i) descriptor_data->try_speculative_[i] = true; } epoll_event ev = { 0, { 0 } }; ev.events = EPOLLIN | EPOLLERR | EPOLLHUP | EPOLLPRI | EPOLLET; descriptor_data->registered_events_ = ev.events; ev.data.ptr = descriptor_data; int result = epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, descriptor, &ev); if (result != 0) { if (errno == EPERM) { // This file descriptor type is not supported by epoll. However, if it is // a regular file then operations on it will not block. We will allow // this descriptor to be used and fail later if an operation on it would // otherwise require a trip through the reactor. descriptor_data->registered_events_ = 0; return 0; } return errno; } return 0; } int epoll_reactor::register_internal_descriptor( int op_type, socket_type descriptor, epoll_reactor::per_descriptor_data& descriptor_data, reactor_op* op) { descriptor_data = allocate_descriptor_state(); ASIO_HANDLER_REACTOR_REGISTRATION(( context(), static_cast(descriptor), reinterpret_cast(descriptor_data))); { mutex::scoped_lock descriptor_lock(descriptor_data->mutex_); descriptor_data->reactor_ = this; descriptor_data->descriptor_ = descriptor; descriptor_data->shutdown_ = false; descriptor_data->op_queue_[op_type].push(op); for (int i = 0; i < max_ops; ++i) descriptor_data->try_speculative_[i] = true; } epoll_event ev = { 0, { 0 } }; ev.events = EPOLLIN | EPOLLERR | EPOLLHUP | EPOLLPRI | EPOLLET; descriptor_data->registered_events_ = ev.events; ev.data.ptr = descriptor_data; int result = epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, descriptor, &ev); if (result != 0) return errno; return 0; } void epoll_reactor::move_descriptor(socket_type, epoll_reactor::per_descriptor_data& target_descriptor_data, epoll_reactor::per_descriptor_data& source_descriptor_data) { target_descriptor_data = source_descriptor_data; source_descriptor_data = 0; } void epoll_reactor::start_op(int op_type, socket_type descriptor, epoll_reactor::per_descriptor_data& descriptor_data, reactor_op* op, bool is_continuation, bool allow_speculative) { if (!descriptor_data) { op->ec_ = asio::error::bad_descriptor; post_immediate_completion(op, is_continuation); return; } mutex::scoped_lock descriptor_lock(descriptor_data->mutex_); if (descriptor_data->shutdown_) { post_immediate_completion(op, is_continuation); return; } if (descriptor_data->op_queue_[op_type].empty()) { if (allow_speculative && (op_type != read_op || descriptor_data->op_queue_[except_op].empty())) { if (descriptor_data->try_speculative_[op_type]) { if (reactor_op::status status = op->perform()) { if (status == reactor_op::done_and_exhausted) if (descriptor_data->registered_events_ != 0) descriptor_data->try_speculative_[op_type] = false; descriptor_lock.unlock(); scheduler_.post_immediate_completion(op, is_continuation); return; } } if (descriptor_data->registered_events_ == 0) { op->ec_ = asio::error::operation_not_supported; scheduler_.post_immediate_completion(op, is_continuation); return; } if (op_type == write_op) { if ((descriptor_data->registered_events_ & EPOLLOUT) == 0) { epoll_event ev = { 0, { 0 } }; ev.events = descriptor_data->registered_events_ | EPOLLOUT; ev.data.ptr = descriptor_data; if (epoll_ctl(epoll_fd_, EPOLL_CTL_MOD, descriptor, &ev) == 0) { descriptor_data->registered_events_ |= ev.events; } else { op->ec_ = asio::error_code(errno, asio::error::get_system_category()); scheduler_.post_immediate_completion(op, is_continuation); return; } } } } else if (descriptor_data->registered_events_ == 0) { op->ec_ = asio::error::operation_not_supported; scheduler_.post_immediate_completion(op, is_continuation); return; } else { if (op_type == write_op) { descriptor_data->registered_events_ |= EPOLLOUT; } epoll_event ev = { 0, { 0 } }; ev.events = descriptor_data->registered_events_; ev.data.ptr = descriptor_data; epoll_ctl(epoll_fd_, EPOLL_CTL_MOD, descriptor, &ev); } } descriptor_data->op_queue_[op_type].push(op); scheduler_.work_started(); } void epoll_reactor::cancel_ops(socket_type, epoll_reactor::per_descriptor_data& descriptor_data) { if (!descriptor_data) return; mutex::scoped_lock descriptor_lock(descriptor_data->mutex_); op_queue ops; for (int i = 0; i < max_ops; ++i) { while (reactor_op* op = descriptor_data->op_queue_[i].front()) { op->ec_ = asio::error::operation_aborted; descriptor_data->op_queue_[i].pop(); ops.push(op); } } descriptor_lock.unlock(); scheduler_.post_deferred_completions(ops); } void epoll_reactor::deregister_descriptor(socket_type descriptor, epoll_reactor::per_descriptor_data& descriptor_data, bool closing) { if (!descriptor_data) return; mutex::scoped_lock descriptor_lock(descriptor_data->mutex_); if (!descriptor_data->shutdown_) { if (closing) { // The descriptor will be automatically removed from the epoll set when // it is closed. } else if (descriptor_data->registered_events_ != 0) { epoll_event ev = { 0, { 0 } }; epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, descriptor, &ev); } op_queue ops; for (int i = 0; i < max_ops; ++i) { while (reactor_op* op = descriptor_data->op_queue_[i].front()) { op->ec_ = asio::error::operation_aborted; descriptor_data->op_queue_[i].pop(); ops.push(op); } } descriptor_data->descriptor_ = -1; descriptor_data->shutdown_ = true; descriptor_lock.unlock(); ASIO_HANDLER_REACTOR_DEREGISTRATION(( context(), static_cast(descriptor), reinterpret_cast(descriptor_data))); scheduler_.post_deferred_completions(ops); // Leave descriptor_data set so that it will be freed by the subsequent // call to cleanup_descriptor_data. } else { // We are shutting down, so prevent cleanup_descriptor_data from freeing // the descriptor_data object and let the destructor free it instead. descriptor_data = 0; } } void epoll_reactor::deregister_internal_descriptor(socket_type descriptor, epoll_reactor::per_descriptor_data& descriptor_data) { if (!descriptor_data) return; mutex::scoped_lock descriptor_lock(descriptor_data->mutex_); if (!descriptor_data->shutdown_) { epoll_event ev = { 0, { 0 } }; epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, descriptor, &ev); op_queue ops; for (int i = 0; i < max_ops; ++i) ops.push(descriptor_data->op_queue_[i]); descriptor_data->descriptor_ = -1; descriptor_data->shutdown_ = true; descriptor_lock.unlock(); ASIO_HANDLER_REACTOR_DEREGISTRATION(( context(), static_cast(descriptor), reinterpret_cast(descriptor_data))); // Leave descriptor_data set so that it will be freed by the subsequent // call to cleanup_descriptor_data. } else { // We are shutting down, so prevent cleanup_descriptor_data from freeing // the descriptor_data object and let the destructor free it instead. descriptor_data = 0; } } void epoll_reactor::cleanup_descriptor_data( per_descriptor_data& descriptor_data) { if (descriptor_data) { free_descriptor_state(descriptor_data); descriptor_data = 0; } } void epoll_reactor::run(long usec, op_queue& ops) { // This code relies on the fact that the scheduler queues the reactor task // behind all descriptor operations generated by this function. This means, // that by the time we reach this point, any previously returned descriptor // operations have already been dequeued. Therefore it is now safe for us to // reuse and return them for the scheduler to queue again. // Calculate timeout. Check the timer queues only if timerfd is not in use. int timeout; if (usec == 0) timeout = 0; else { timeout = (usec < 0) ? -1 : ((usec - 1) / 1000 + 1); if (timer_fd_ == -1) { mutex::scoped_lock lock(mutex_); timeout = get_timeout(timeout); } } // Block on the epoll descriptor. epoll_event events[128]; int num_events = epoll_wait(epoll_fd_, events, 128, timeout); #if defined(ASIO_ENABLE_HANDLER_TRACKING) // Trace the waiting events. for (int i = 0; i < num_events; ++i) { void* ptr = events[i].data.ptr; if (ptr == &interrupter_) { // Ignore. } # if defined(ASIO_HAS_TIMERFD) else if (ptr == &timer_fd_) { // Ignore. } # endif // defined(ASIO_HAS_TIMERFD) else { unsigned event_mask = 0; if ((events[i].events & EPOLLIN) != 0) event_mask |= ASIO_HANDLER_REACTOR_READ_EVENT; if ((events[i].events & EPOLLOUT)) event_mask |= ASIO_HANDLER_REACTOR_WRITE_EVENT; if ((events[i].events & (EPOLLERR | EPOLLHUP)) != 0) event_mask |= ASIO_HANDLER_REACTOR_ERROR_EVENT; ASIO_HANDLER_REACTOR_EVENTS((context(), reinterpret_cast(ptr), event_mask)); } } #endif // defined(ASIO_ENABLE_HANDLER_TRACKING) #if defined(ASIO_HAS_TIMERFD) bool check_timers = (timer_fd_ == -1); #else // defined(ASIO_HAS_TIMERFD) bool check_timers = true; #endif // defined(ASIO_HAS_TIMERFD) // Dispatch the waiting events. for (int i = 0; i < num_events; ++i) { void* ptr = events[i].data.ptr; if (ptr == &interrupter_) { // No need to reset the interrupter since we're leaving the descriptor // in a ready-to-read state and relying on edge-triggered notifications // to make it so that we only get woken up when the descriptor's epoll // registration is updated. #if defined(ASIO_HAS_TIMERFD) if (timer_fd_ == -1) check_timers = true; #else // defined(ASIO_HAS_TIMERFD) check_timers = true; #endif // defined(ASIO_HAS_TIMERFD) } #if defined(ASIO_HAS_TIMERFD) else if (ptr == &timer_fd_) { check_timers = true; } #endif // defined(ASIO_HAS_TIMERFD) else { // The descriptor operation doesn't count as work in and of itself, so we // don't call work_started() here. This still allows the scheduler to // stop if the only remaining operations are descriptor operations. descriptor_state* descriptor_data = static_cast(ptr); if (!ops.is_enqueued(descriptor_data)) { descriptor_data->set_ready_events(events[i].events); ops.push(descriptor_data); } else { descriptor_data->add_ready_events(events[i].events); } } } if (check_timers) { mutex::scoped_lock common_lock(mutex_); timer_queues_.get_ready_timers(ops); #if defined(ASIO_HAS_TIMERFD) if (timer_fd_ != -1) { itimerspec new_timeout; itimerspec old_timeout; int flags = get_timeout(new_timeout); timerfd_settime(timer_fd_, flags, &new_timeout, &old_timeout); } #endif // defined(ASIO_HAS_TIMERFD) } } void epoll_reactor::interrupt() { epoll_event ev = { 0, { 0 } }; ev.events = EPOLLIN | EPOLLERR | EPOLLET; ev.data.ptr = &interrupter_; epoll_ctl(epoll_fd_, EPOLL_CTL_MOD, interrupter_.read_descriptor(), &ev); } int epoll_reactor::do_epoll_create() { #if defined(EPOLL_CLOEXEC) int fd = epoll_create1(EPOLL_CLOEXEC); #else // defined(EPOLL_CLOEXEC) int fd = -1; errno = EINVAL; #endif // defined(EPOLL_CLOEXEC) if (fd == -1 && (errno == EINVAL || errno == ENOSYS)) { fd = epoll_create(epoll_size); if (fd != -1) ::fcntl(fd, F_SETFD, FD_CLOEXEC); } if (fd == -1) { asio::error_code ec(errno, asio::error::get_system_category()); asio::detail::throw_error(ec, "epoll"); } return fd; } int epoll_reactor::do_timerfd_create() { #if defined(ASIO_HAS_TIMERFD) # if defined(TFD_CLOEXEC) int fd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC); # else // defined(TFD_CLOEXEC) int fd = -1; errno = EINVAL; # endif // defined(TFD_CLOEXEC) if (fd == -1 && errno == EINVAL) { fd = timerfd_create(CLOCK_MONOTONIC, 0); if (fd != -1) ::fcntl(fd, F_SETFD, FD_CLOEXEC); } return fd; #else // defined(ASIO_HAS_TIMERFD) return -1; #endif // defined(ASIO_HAS_TIMERFD) } epoll_reactor::descriptor_state* epoll_reactor::allocate_descriptor_state() { mutex::scoped_lock descriptors_lock(registered_descriptors_mutex_); return registered_descriptors_.alloc(ASIO_CONCURRENCY_HINT_IS_LOCKING( REACTOR_IO, scheduler_.concurrency_hint())); } void epoll_reactor::free_descriptor_state(epoll_reactor::descriptor_state* s) { mutex::scoped_lock descriptors_lock(registered_descriptors_mutex_); registered_descriptors_.free(s); } void epoll_reactor::do_add_timer_queue(timer_queue_base& queue) { mutex::scoped_lock lock(mutex_); timer_queues_.insert(&queue); } void epoll_reactor::do_remove_timer_queue(timer_queue_base& queue) { mutex::scoped_lock lock(mutex_); timer_queues_.erase(&queue); } void epoll_reactor::update_timeout() { #if defined(ASIO_HAS_TIMERFD) if (timer_fd_ != -1) { itimerspec new_timeout; itimerspec old_timeout; int flags = get_timeout(new_timeout); timerfd_settime(timer_fd_, flags, &new_timeout, &old_timeout); return; } #endif // defined(ASIO_HAS_TIMERFD) interrupt(); } int epoll_reactor::get_timeout(int msec) { // 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. const int max_msec = 5 * 60 * 1000; return timer_queues_.wait_duration_msec( (msec < 0 || max_msec < msec) ? max_msec : msec); } #if defined(ASIO_HAS_TIMERFD) int epoll_reactor::get_timeout(itimerspec& ts) { ts.it_interval.tv_sec = 0; ts.it_interval.tv_nsec = 0; long usec = timer_queues_.wait_duration_usec(5 * 60 * 1000 * 1000); ts.it_value.tv_sec = usec / 1000000; ts.it_value.tv_nsec = usec ? (usec % 1000000) * 1000 : 1; return usec ? 0 : TFD_TIMER_ABSTIME; } #endif // defined(ASIO_HAS_TIMERFD) struct epoll_reactor::perform_io_cleanup_on_block_exit { explicit perform_io_cleanup_on_block_exit(epoll_reactor* r) : reactor_(r), first_op_(0) { } ~perform_io_cleanup_on_block_exit() { if (first_op_) { // Post the remaining completed operations for invocation. if (!ops_.empty()) reactor_->scheduler_.post_deferred_completions(ops_); // A user-initiated operation has completed, but there's no need to // explicitly call work_finished() here. Instead, we'll take advantage of // the fact that the scheduler will call work_finished() once we return. } else { // No user-initiated operations have completed, so we need to compensate // for the work_finished() call that the scheduler will make once this // operation returns. reactor_->scheduler_.compensating_work_started(); } } epoll_reactor* reactor_; op_queue ops_; operation* first_op_; }; epoll_reactor::descriptor_state::descriptor_state(bool locking) : operation(&epoll_reactor::descriptor_state::do_complete), mutex_(locking) { } operation* epoll_reactor::descriptor_state::perform_io(uint32_t events) { mutex_.lock(); perform_io_cleanup_on_block_exit io_cleanup(reactor_); mutex::scoped_lock descriptor_lock(mutex_, mutex::scoped_lock::adopt_lock); // Exception operations must be processed first to ensure that any // out-of-band data is read before normal data. static const int flag[max_ops] = { EPOLLIN, EPOLLOUT, EPOLLPRI }; for (int j = max_ops - 1; j >= 0; --j) { if (events & (flag[j] | EPOLLERR | EPOLLHUP)) { try_speculative_[j] = true; while (reactor_op* op = op_queue_[j].front()) { if (reactor_op::status status = op->perform()) { op_queue_[j].pop(); io_cleanup.ops_.push(op); if (status == reactor_op::done_and_exhausted) { try_speculative_[j] = false; break; } } else break; } } } // The first operation will be returned for completion now. The others will // be posted for later by the io_cleanup object's destructor. io_cleanup.first_op_ = io_cleanup.ops_.front(); io_cleanup.ops_.pop(); return io_cleanup.first_op_; } void epoll_reactor::descriptor_state::do_complete( void* owner, operation* base, const asio::error_code& ec, std::size_t bytes_transferred) { if (owner) { descriptor_state* descriptor_data = static_cast(base); uint32_t events = static_cast(bytes_transferred); if (operation* op = descriptor_data->perform_io(events)) { op->complete(owner, ec, 0); } } } } // namespace detail } // namespace asio #include "asio/detail/pop_options.hpp" #endif // defined(ASIO_HAS_EPOLL) #endif // ASIO_DETAIL_IMPL_EPOLL_REACTOR_IPP