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/********************************************************************
* libavio/include/Queue.h
*
* Copyright (c) 2022 Stephen Rhodes
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*********************************************************************/
#ifndef QUEUE_H
#define QUEUE_H
#include <iostream>
#include <vector>
#include <mutex>
#include <thread>
#include <condition_variable>
#include <exception>
#include <functional>
namespace avio
{
class QueueClosedException : public std::exception {
public:
const char* what() const throw() {
return "attempt to access closed queue";
}
};
template <typename T>
class Queue
{
public:
Queue(size_t max_size = 1);
void push(T const&);
T pop();
void pop(T&);
T peek();
int size();
void close();
bool full() { return m_size == m_max_size; }
bool empty() { return m_front == -1; }
bool closed() { return m_closed; }
void clear() { m_front = m_rear = -1; }
void set_max_size(int arg);
private:
std::vector<T> m_data;
int m_max_size;
int m_front = -1;
int m_rear = -1;
std::mutex n_mutex;
std::condition_variable m_cond_push, m_cond_pop;
bool m_closed = false;
int m_size = 0;
};
template <typename T>
Queue<T>::Queue(size_t max_size) : m_max_size(max_size)
{
m_data.reserve(max_size);
}
template <typename T>
void Queue<T>::set_max_size(int arg)
{
m_max_size = arg;
m_data.reserve(m_max_size);
}
template <typename T>
void Queue<T>::push(T const& element)
{
std::unique_lock<std::mutex> lock(n_mutex);
while (full()) {
if (m_closed) break;
m_cond_push.wait(lock);
}
if (m_closed) throw QueueClosedException();
if (m_front == -1) m_front = m_rear = 0;
else if (m_rear == m_max_size - 1 && m_front != 0) m_rear = 0;
else m_rear++;
if (m_data.size() < m_rear + 1) m_data.push_back(element);
else m_data[m_rear] = element;
m_size++;
m_cond_pop.notify_one();
}
template <typename T>
T Queue<T>::pop()
{
std::unique_lock<std::mutex> lock(n_mutex);
while (empty()) {
if (m_closed) break;
m_cond_pop.wait(lock);
}
if (m_closed) throw QueueClosedException();
T& result = m_data[m_front];
if (m_front == m_rear) m_front = m_rear = -1;
else if (m_front == m_max_size - 1) m_front = 0;
else m_front++;
m_size--;
m_cond_push.notify_one();
return result;
}
template <typename T>
void Queue<T>::pop(T& arg)
{
std::unique_lock<std::mutex> lock(n_mutex);
while (empty()) {
if (m_closed) break;
m_cond_pop.wait(lock);
}
if (m_closed) throw QueueClosedException();
arg = m_data[m_front];
if (m_front == m_rear) m_front = m_rear = -1;
else if (m_front == m_max_size - 1) m_front = 0;
else m_front++;
m_size--;
m_cond_push.notify_one();
}
template <typename T>
T Queue<T>::peek()
{
std::unique_lock<std::mutex> lock(n_mutex);
while (empty()) {
if (m_closed) break;
m_cond_pop.wait(lock);
}
if (m_closed) throw QueueClosedException();
T result = T(m_data[m_front]);
return result;
}
template <typename T>
int Queue<T>::size()
{
std::lock_guard<std::mutex> lock(n_mutex);
return m_size;
}
template <typename T>
void Queue<T>::close()
{
std::unique_lock<std::mutex> lock(n_mutex);
m_closed = true;
m_cond_push.notify_all();
m_cond_pop.notify_all();
}
}
#endif // QUEUE_H
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