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ThreadCounter.h
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ThreadCounter.h
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/*
Pharmer: Efficient and Exact 3D Pharmacophore Search
Copyright (C) 2011 David Ryan Koes and the University of Pittsburgh
This program 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 2
of the License, or (at your option) any later version.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/*
* ThreadCounter.h
*
* Created on: Aug 2, 2010
* Author: dkoes
*/
#ifndef THREADCOUNTER_H_
#define THREADCOUNTER_H_
//thread safe counter for running threads (upto hardware supported)
class ThreadCounter
{
unsigned maxThreads;
unsigned count;
public:
//override hardware
ThreadCounter(unsigned n): maxThreads(n), count(0) {}
//return true if there's an available thread
//it is assumed the caller will then spawn a thread and call reduceThreadCount
bool threadAvailable()
{
if(count < maxThreads)
{
unsigned cur = __sync_fetch_and_add(&count, 1);
if(cur < maxThreads)
return true;
//someone else beat us to it
__sync_fetch_and_sub(&count, 1);
return false;
}
else
return false;
}
void reduceThreadCount()
{
__sync_fetch_and_sub(&count, 1);
}
};
#endif /* THREADCOUNTER_H_ */