boost/asio/detail/timer_queue.hpp
// // detail/timer_queue.hpp // ~~~~~~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2017 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_TIMER_QUEUE_HPP #define BOOST_ASIO_DETAIL_TIMER_QUEUE_HPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include <boost/asio/detail/config.hpp> #include <cstddef> #include <vector> #include <boost/asio/detail/cstdint.hpp> #include <boost/asio/detail/date_time_fwd.hpp> #include <boost/asio/detail/limits.hpp> #include <boost/asio/detail/op_queue.hpp> #include <boost/asio/detail/timer_queue_base.hpp> #include <boost/asio/detail/wait_op.hpp> #include <boost/asio/error.hpp> #include <boost/asio/detail/push_options.hpp> namespace boost { namespace asio { namespace detail { template <typename Time_Traits> class timer_queue : public timer_queue_base { public: // The time type. typedef typename Time_Traits::time_type time_type; // The duration type. typedef typename Time_Traits::duration_type duration_type; // Per-timer data. class per_timer_data { public: per_timer_data() : next_(0), prev_(0) {} private: friend class timer_queue; // The operations waiting on the timer. op_queue<wait_op> op_queue_; // The index of the timer in the heap. std::size_t heap_index_; // Pointers to adjacent timers in a linked list. per_timer_data* next_; per_timer_data* prev_; }; // Constructor. timer_queue() : timers_(), heap_() { } // Add a new timer to the queue. Returns true if this is the timer that is // earliest in the queue, in which case the reactor's event demultiplexing // function call may need to be interrupted and restarted. bool enqueue_timer(const time_type& time, per_timer_data& timer, wait_op* op) { // Enqueue the timer object. if (timer.prev_ == 0 && &timer != timers_) { if (this->is_positive_infinity(time)) { // No heap entry is required for timers that never expire. timer.heap_index_ = (std::numeric_limits<std::size_t>::max)(); } else { // Put the new timer at the correct position in the heap. This is done // first since push_back() can throw due to allocation failure. timer.heap_index_ = heap_.size(); heap_entry entry = { time, &timer }; heap_.push_back(entry); up_heap(heap_.size() - 1); } // Insert the new timer into the linked list of active timers. timer.next_ = timers_; timer.prev_ = 0; if (timers_) timers_->prev_ = &timer; timers_ = &timer; } // Enqueue the individual timer operation. timer.op_queue_.push(op); // Interrupt reactor only if newly added timer is first to expire. return timer.heap_index_ == 0 && timer.op_queue_.front() == op; } // Whether there are no timers in the queue. virtual bool empty() const { return timers_ == 0; } // Get the time for the timer that is earliest in the queue. virtual long wait_duration_msec(long max_duration) const { if (heap_.empty()) return max_duration; return this->to_msec( Time_Traits::to_posix_duration( Time_Traits::subtract(heap_[0].time_, Time_Traits::now())), max_duration); } // Get the time for the timer that is earliest in the queue. virtual long wait_duration_usec(long max_duration) const { if (heap_.empty()) return max_duration; return this->to_usec( Time_Traits::to_posix_duration( Time_Traits::subtract(heap_[0].time_, Time_Traits::now())), max_duration); } // Dequeue all timers not later than the current time. virtual void get_ready_timers(op_queue<operation>& ops) { if (!heap_.empty()) { const time_type now = Time_Traits::now(); while (!heap_.empty() && !Time_Traits::less_than(now, heap_[0].time_)) { per_timer_data* timer = heap_[0].timer_; ops.push(timer->op_queue_); remove_timer(*timer); } } } // Dequeue all timers. virtual void get_all_timers(op_queue<operation>& ops) { while (timers_) { per_timer_data* timer = timers_; timers_ = timers_->next_; ops.push(timer->op_queue_); timer->next_ = 0; timer->prev_ = 0; } heap_.clear(); } // Cancel and dequeue operations for the given timer. std::size_t cancel_timer(per_timer_data& timer, op_queue<operation>& ops, std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)()) { std::size_t num_cancelled = 0; if (timer.prev_ != 0 || &timer == timers_) { while (wait_op* op = (num_cancelled != max_cancelled) ? timer.op_queue_.front() : 0) { op->ec_ = boost::asio::error::operation_aborted; timer.op_queue_.pop(); ops.push(op); ++num_cancelled; } if (timer.op_queue_.empty()) remove_timer(timer); } return num_cancelled; } private: // Move the item at the given index up the heap to its correct position. void up_heap(std::size_t index) { while (index > 0) { std::size_t parent = (index - 1) / 2; if (!Time_Traits::less_than(heap_[index].time_, heap_[parent].time_)) break; swap_heap(index, parent); index = parent; } } // Move the item at the given index down the heap to its correct position. void down_heap(std::size_t index) { std::size_t child = index * 2 + 1; while (child < heap_.size()) { std::size_t min_child = (child + 1 == heap_.size() || Time_Traits::less_than( heap_[child].time_, heap_[child + 1].time_)) ? child : child + 1; if (Time_Traits::less_than(heap_[index].time_, heap_[min_child].time_)) break; swap_heap(index, min_child); index = min_child; child = index * 2 + 1; } } // Swap two entries in the heap. void swap_heap(std::size_t index1, std::size_t index2) { heap_entry tmp = heap_[index1]; heap_[index1] = heap_[index2]; heap_[index2] = tmp; heap_[index1].timer_->heap_index_ = index1; heap_[index2].timer_->heap_index_ = index2; } // Remove a timer from the heap and list of timers. void remove_timer(per_timer_data& timer) { // Remove the timer from the heap. std::size_t index = timer.heap_index_; if (!heap_.empty() && index < heap_.size()) { if (index == heap_.size() - 1) { heap_.pop_back(); } else { swap_heap(index, heap_.size() - 1); heap_.pop_back(); if (index > 0 && Time_Traits::less_than( heap_[index].time_, heap_[(index - 1) / 2].time_)) up_heap(index); else down_heap(index); } } // Remove the timer from the linked list of active timers. if (timers_ == &timer) timers_ = timer.next_; if (timer.prev_) timer.prev_->next_ = timer.next_; if (timer.next_) timer.next_->prev_= timer.prev_; timer.next_ = 0; timer.prev_ = 0; } // Determine if the specified absolute time is positive infinity. template <typename Time_Type> static bool is_positive_infinity(const Time_Type&) { return false; } // Determine if the specified absolute time is positive infinity. template <typename T, typename TimeSystem> static bool is_positive_infinity( const boost::date_time::base_time<T, TimeSystem>& time) { return time.is_pos_infinity(); } // Helper function to convert a duration into milliseconds. template <typename Duration> long to_msec(const Duration& d, long max_duration) const { if (d.ticks() <= 0) return 0; int64_t msec = d.total_milliseconds(); if (msec == 0) return 1; if (msec > max_duration) return max_duration; return static_cast<long>(msec); } // Helper function to convert a duration into microseconds. template <typename Duration> long to_usec(const Duration& d, long max_duration) const { if (d.ticks() <= 0) return 0; int64_t usec = d.total_microseconds(); if (usec == 0) return 1; if (usec > max_duration) return max_duration; return static_cast<long>(usec); } // The head of a linked list of all active timers. per_timer_data* timers_; struct heap_entry { // The time when the timer should fire. time_type time_; // The associated timer with enqueued operations. per_timer_data* timer_; }; // The heap of timers, with the earliest timer at the front. std::vector<heap_entry> heap_; }; } // namespace detail } // namespace asio } // namespace boost #include <boost/asio/detail/pop_options.hpp> #endif // BOOST_ASIO_DETAIL_TIMER_QUEUE_HPP