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/*
Copyright (C) 2007, 2008, 2009, 2010, 2011 Her Majesty the Queen in
Right of Canada (Communications Research Center Canada)
Copyright (C) 2013, 2014
Matthias P. Braendli, matthias.braendli@mpb.li
An implementation for a threadsafe queue using boost thread library
When creating a ThreadsafeQueue, one can specify the minimal number
of elements it must contain before it is possible to take one
element out.
*/
/*
This file is part of ODR-DabMod.
ODR-DabMod is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
ODR-DabMod 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with ODR-DabMod. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef THREADSAFE_QUEUE_H
#define THREADSAFE_QUEUE_H
#include <boost/thread.hpp>
#include <queue>
/* This queue is meant to be used by two threads. One producer
* that pushes elements into the queue, and one consumer that
* retrieves the elements.
*
* The queue can make the consumer block until enough elements
* are available.
*/
template<typename T>
class ThreadsafeQueue
{
public:
/* Create a new queue without any minimum required
* fill before it is possible to pop an element
*/
ThreadsafeQueue() : the_required_size(1) {}
/* Create a queue where it has to contain at least
* required_size elements before pop is possible
*/
ThreadsafeQueue(size_t required_size) : the_required_size(required_size) {
}
/* Push one element into the queue, and notify another thread that
* might be waiting.
*
* returns the new queue size.
*/
size_t push(T const& val)
{
boost::mutex::scoped_lock lock(the_mutex);
the_queue.push(val);
size_t queue_size = the_queue.size();
lock.unlock();
notify();
return queue_size;
}
void notify()
{
the_condition_variable.notify_one();
}
bool empty() const
{
boost::mutex::scoped_lock lock(the_mutex);
return the_queue.empty();
}
size_t size() const
{
return the_queue.size();
}
bool try_pop(T& popped_value)
{
boost::mutex::scoped_lock lock(the_mutex);
if(the_queue.size() < the_required_size)
{
return false;
}
popped_value = the_queue.front();
the_queue.pop();
return true;
}
void wait_and_pop(T& popped_value)
{
boost::mutex::scoped_lock lock(the_mutex);
while(the_queue.size() < the_required_size) {
the_condition_variable.wait(lock);
}
popped_value = the_queue.front();
the_queue.pop();
}
private:
std::queue<T> the_queue;
mutable boost::mutex the_mutex;
boost::condition_variable the_condition_variable;
size_t the_required_size;
};
#endif
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