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/*
* Copyright (c) 2013 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Ali Saidi
*/
#ifndef __BASE_BARRIER_HH__
#define __BASE_BARRIER_HH__
#include <condition_variable>
class Barrier
{
private:
/// Mutex to protect access to numLeft and generation
std::mutex bMutex;
/// Condition variable for waiting on barrier
std::condition_variable bCond;
/// Number of threads we should be waiting for before completing the barrier
unsigned numWaiting;
/// Generation of this barrier
unsigned generation;
/// Number of threads remaining for the current generation
unsigned numLeft;
public:
Barrier(unsigned _numWaiting)
: numWaiting(_numWaiting), generation(0), numLeft(_numWaiting)
{}
bool
wait()
{
std::unique_lock<std::mutex> lock(bMutex);
unsigned int gen = generation;
if (--numLeft == 0) {
generation++;
numLeft = numWaiting;
bCond.notify_all();
return true;
}
while (gen == generation)
bCond.wait(lock);
return false;
}
};
#endif // __BASE_BARRIER_HH__
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