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/*
* This file is part of the AzerothCore Project. See AUTHORS file for Copyright information
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Affero General Public License as published by the
* Free Software Foundation; either version 3 of the License, or (at your
* option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _PCQ_H
#define _PCQ_H
#include <condition_variable>
#include <queue>
#include <atomic>
#include <mutex>
template <typename T>
class ProducerConsumerQueue
{
private:
mutable std::mutex _queueLock;
std::queue<T> _queue;
std::condition_variable _condition;
std::atomic<bool> _cancel{};
std::atomic<bool> _shutdown{};
public:
ProducerConsumerQueue() = default;
void Push(const T& value)
{
{
std::lock_guard<std::mutex> lock(_queueLock);
_queue.push(std::move(value));
}
_condition.notify_one();
}
bool Empty() const
{
std::lock_guard<std::mutex> lock(_queueLock);
return _queue.empty();
}
[[nodiscard]] std::size_t Size() const
{
std::lock_guard<std::mutex> lock(_queueLock);
return _queue.size();
}
bool Pop(T& value)
{
std::lock_guard<std::mutex> lock(_queueLock);
if (_queue.empty() || _cancel)
return false;
value = std::move(_queue.front());
_queue.pop();
return true;
}
void WaitAndPop(T& value)
{
std::unique_lock<std::mutex> lock(_queueLock);
// Wait for the queue to have an element or the cancel/shutdown flag
_condition.wait(lock, [this] { return !_queue.empty() || _cancel || _shutdown; });
if (_queue.empty() || _cancel)
return;
value = std::move(_queue.front());
_queue.pop();
}
// Clears the queue and immediately stops any consumers.
void Cancel()
{
std::lock_guard<std::mutex> lock(_queueLock);
while (!_queue.empty()) {
T& value = _queue.front();
DeleteQueuedObject(value);
_queue.pop();
}
_cancel = true;
_condition.notify_all();
}
// Graceful stop: waits for the queue to become empty before stopping consumers.
void Shutdown()
{
_shutdown = true;
_condition.notify_all();
}
private:
template<typename E = T>
typename std::enable_if<std::is_pointer<E>::value>::type DeleteQueuedObject(E& obj)
{
delete obj;
}
template<typename E = T>
typename std::enable_if<!std::is_pointer<E>::value>::type DeleteQueuedObject(E const& /*obj*/) { }
};
#endif
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