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// @file queue.h
/* Copyright 2009 10gen Inc.
*
* 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.
*/
#pragma once
#include "../pch.h"
#include <queue>
#include "../util/timer.h"
namespace mongo {
/**
* simple blocking queue
*/
template<typename T> class BlockingQueue : boost::noncopyable {
public:
BlockingQueue() : _lock("BlockingQueue") { }
void push(T const& t) {
scoped_lock l( _lock );
_queue.push( t );
_condition.notify_one();
}
bool empty() const {
scoped_lock l( _lock );
return _queue.empty();
}
size_t size() const {
scoped_lock l( _lock );
return _queue.size();
}
bool tryPop( T & t ) {
scoped_lock l( _lock );
if ( _queue.empty() )
return false;
t = _queue.front();
_queue.pop();
return true;
}
T blockingPop() {
scoped_lock l( _lock );
while( _queue.empty() )
_condition.wait( l.boost() );
T t = _queue.front();
_queue.pop();
return t;
}
/**
* blocks waiting for an object until maxSecondsToWait passes
* if got one, return true and set in t
* otherwise return false and t won't be changed
*/
bool blockingPop( T& t , int maxSecondsToWait ) {
Timer timer;
boost::xtime xt;
boost::xtime_get(&xt, boost::TIME_UTC);
xt.sec += maxSecondsToWait;
scoped_lock l( _lock );
while( _queue.empty() ) {
if ( ! _condition.timed_wait( l.boost() , xt ) )
return false;
}
t = _queue.front();
_queue.pop();
return true;
}
private:
std::queue<T> _queue;
mutable mongo::mutex _lock;
boost::condition _condition;
};
}
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