231 lines
7.4 KiB
C++
231 lines
7.4 KiB
C++
#ifndef OSMIUM_THREAD_QUEUE_HPP
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#define OSMIUM_THREAD_QUEUE_HPP
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/*
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This file is part of Osmium (http://osmcode.org/libosmium).
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Copyright 2013-2017 Jochen Topf <jochen@topf.org> and others (see README).
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Boost Software License - Version 1.0 - August 17th, 2003
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Permission is hereby granted, free of charge, to any person or organization
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obtaining a copy of the software and accompanying documentation covered by
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this license (the "Software") to use, reproduce, display, distribute,
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execute, and transmit the Software, and to prepare derivative works of the
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Software, and to permit third-parties to whom the Software is furnished to
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do so, all subject to the following:
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The copyright notices in the Software and this entire statement, including
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the above license grant, this restriction and the following disclaimer,
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must be included in all copies of the Software, in whole or in part, and
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all derivative works of the Software, unless such copies or derivative
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works are solely in the form of machine-executable object code generated by
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a source language processor.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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DEALINGS IN THE SOFTWARE.
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*/
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#include <chrono>
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#include <condition_variable>
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#include <cstddef>
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#include <mutex>
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#include <queue>
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#include <string>
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#include <thread>
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#include <utility> // IWYU pragma: keep
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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# include <atomic>
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# include <iostream>
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#endif
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namespace osmium {
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namespace thread {
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static const std::chrono::milliseconds max_wait{10};
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/**
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* A thread-safe queue.
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*/
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template <typename T>
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class Queue {
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/// Maximum size of this queue. If the queue is full pushing to
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/// the queue will block.
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const size_t m_max_size;
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/// Name of this queue (for debugging only).
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const std::string m_name;
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mutable std::mutex m_mutex;
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std::queue<T> m_queue;
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/// Used to signal consumers when data is available in the queue.
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std::condition_variable m_data_available;
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/// Used to signal producers when queue is not full.
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std::condition_variable m_space_available;
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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/// The largest size the queue has been so far.
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size_t m_largest_size;
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/// The number of times push() was called on the queue.
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std::atomic<int> m_push_counter;
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/// The number of times the queue was full and a thread pushing
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/// to the queue was blocked.
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std::atomic<int> m_full_counter;
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/**
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* The number of times wait_and_pop(with_timeout)() was called
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* on the queue.
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*/
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std::atomic<int> m_pop_counter;
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/// The number of times the queue was full and a thread pushing
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/// to the queue was blocked.
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std::atomic<int> m_empty_counter;
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#endif
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public:
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/**
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* Construct a multithreaded queue.
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*
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* @param max_size Maximum number of elements in the queue. Set to
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* 0 for an unlimited size.
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* @param name Optional name for this queue. (Used for debugging.)
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*/
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explicit Queue(size_t max_size = 0, const std::string& name = "") :
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m_max_size(max_size),
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m_name(name),
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m_mutex(),
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m_queue(),
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m_data_available(),
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m_space_available()
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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,
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m_largest_size(0),
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m_push_counter(0),
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m_full_counter(0),
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m_pop_counter(0),
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m_empty_counter(0)
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#endif
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{
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}
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~Queue() {
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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std::cerr << "queue '" << m_name
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<< "' with max_size=" << m_max_size
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<< " had largest size " << m_largest_size
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<< " and was full " << m_full_counter
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<< " times in " << m_push_counter
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<< " push() calls and was empty " << m_empty_counter
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<< " times in " << m_pop_counter
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<< " pop() calls\n";
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#endif
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}
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/**
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* Push an element onto the queue. If the queue has a max size,
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* this call will block if the queue is full.
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*/
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void push(T value) {
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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++m_push_counter;
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#endif
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if (m_max_size) {
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while (size() >= m_max_size) {
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std::unique_lock<std::mutex> lock{m_mutex};
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m_space_available.wait_for(lock, max_wait, [this] {
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return m_queue.size() < m_max_size;
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});
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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++m_full_counter;
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#endif
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}
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}
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std::lock_guard<std::mutex> lock{m_mutex};
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m_queue.push(std::move(value));
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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if (m_largest_size < m_queue.size()) {
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m_largest_size = m_queue.size();
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}
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#endif
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m_data_available.notify_one();
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}
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void wait_and_pop(T& value) {
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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++m_pop_counter;
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#endif
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std::unique_lock<std::mutex> lock{m_mutex};
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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if (m_queue.empty()) {
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++m_empty_counter;
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}
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#endif
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m_data_available.wait(lock, [this] {
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return !m_queue.empty();
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});
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if (!m_queue.empty()) {
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value = std::move(m_queue.front());
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m_queue.pop();
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lock.unlock();
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if (m_max_size) {
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m_space_available.notify_one();
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}
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}
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}
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bool try_pop(T& value) {
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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++m_pop_counter;
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#endif
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{
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std::lock_guard<std::mutex> lock{m_mutex};
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if (m_queue.empty()) {
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#ifdef OSMIUM_DEBUG_QUEUE_SIZE
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++m_empty_counter;
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#endif
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return false;
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}
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value = std::move(m_queue.front());
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m_queue.pop();
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}
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if (m_max_size) {
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m_space_available.notify_one();
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}
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return true;
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}
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bool empty() const {
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std::lock_guard<std::mutex> lock{m_mutex};
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return m_queue.empty();
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}
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size_t size() const {
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std::lock_guard<std::mutex> lock{m_mutex};
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return m_queue.size();
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}
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}; // class Queue
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} // namespace thread
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} // namespace osmium
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#endif // OSMIUM_THREAD_QUEUE_HPP
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