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safe_queue.h
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safe_queue.h
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//
// Created by tangwei12 on 2018/7/3.
//
#pragma once
#include <queue>
#include <mutex>
#include <condition_variable>
// see: https://stackoverflow.com/questions/36762248/why-is-stdqueue-not-thread-safe
template <typename T>
class SharedQueue
{
public:
SharedQueue();
~SharedQueue();
T& front();
void pop_front();
void push_back(const T& item);
void push_back(T&& item);
int size();
bool empty();
private:
std::deque<T> queue_;
std::mutex mutex_;
std::condition_variable cond_;
};
template <typename T>
SharedQueue<T>::SharedQueue(){}
template <typename T>
SharedQueue<T>::~SharedQueue(){}
template <typename T>
T& SharedQueue<T>::front()
{
std::unique_lock<std::mutex> mlock(mutex_);
while (queue_.empty())
{
cond_.wait(mlock);
}
return queue_.front();
}
template <typename T>
void SharedQueue<T>::pop_front()
{
std::unique_lock<std::mutex> mlock(mutex_);
while (queue_.empty())
{
cond_.wait(mlock);
}
queue_.pop_front();
}
template <typename T>
void SharedQueue<T>::push_back(const T& item)
{
std::unique_lock<std::mutex> mlock(mutex_);
queue_.push_back(item);
mlock.unlock(); // unlock before notificiation to minimize mutex con
cond_.notify_one(); // notify one waiting thread
}
template <typename T>
void SharedQueue<T>::push_back(T&& item)
{
std::unique_lock<std::mutex> mlock(mutex_);
queue_.push_back(std::move(item));
mlock.unlock(); // unlock before notificiation to minimize mutex con
cond_.notify_one(); // notify one waiting thread
}
template <typename T>
int SharedQueue<T>::size()
{
std::unique_lock<std::mutex> mlock(mutex_);
int size = queue_.size();
mlock.unlock();
return size;
}
template <typename T>
bool SharedQueue<T>::empty()
{
std::unique_lock<std::mutex> mlock(mutex_);
bool is_empty = queue_.empty();
mlock.unlock();
return is_empty;
}