http://stxxl.sourceforge.net
<dementiev@mpi-sb.mpg.de>
http://www.boost.org/LICENSE_1_0.txt
#ifndef STXXL_SEMAPHORE_HEADER
#define STXXL_SEMAPHORE_HEADER
#ifdef STXXL_BOOST_THREADS
#include <boost/thread/mutex.hpp>
#include <boost/thread/condition.hpp>
#else
#include <pthread.h>
#endif
#include <stxxl/bits/noncopyable.h>
#include <stxxl/bits/common/error_handling.h>
__STXXL_BEGIN_NAMESPACE
class semaphore : private noncopyable
{
int v;
#ifdef STXXL_BOOST_THREADS
boost::mutex mutex;
boost::condition cond;
#else
pthread_mutex_t mutex;
pthread_cond_t cond;
#endif
public:
semaphore(int init_value = 1) : v(init_value)
{
#ifndef STXXL_BOOST_THREADS
check_pthread_call(pthread_mutex_init(&mutex, NULL));
check_pthread_call(pthread_cond_init(&cond, NULL));
#endif
}
~semaphore()
{
#ifndef STXXL_BOOST_THREADS
int res = pthread_mutex_trylock(&mutex);
if (res == 0 || res == EBUSY) {
check_pthread_call(pthread_mutex_unlock(&mutex));
} else
stxxl_function_error(resource_error);
check_pthread_call(pthread_mutex_destroy(&mutex));
check_pthread_call(pthread_cond_destroy(&cond));
#endif
}
int operator ++ (int)
{
#ifdef STXXL_BOOST_THREADS
boost::mutex::scoped_lock Lock(mutex);
int res = ++v;
Lock.unlock();
cond.notify_one();
#else
check_pthread_call(pthread_mutex_lock(&mutex));
int res = ++v;
check_pthread_call(pthread_mutex_unlock(&mutex));
check_pthread_call(pthread_cond_signal(&cond));
#endif
return res;
}
int operator -- (int)
{
#ifdef STXXL_BOOST_THREADS
boost::mutex::scoped_lock Lock(mutex);
while (v <= 0)
cond.wait(Lock);
int res = --v;
#else
check_pthread_call(pthread_mutex_lock(&mutex));
while (v <= 0)
check_pthread_call(pthread_cond_wait(&cond, &mutex));
int res = --v;
check_pthread_call(pthread_mutex_unlock(&mutex));
#endif
return res;
}
int decrement()
{
#ifdef STXXL_BOOST_THREADS
boost::mutex::scoped_lock Lock(mutex);
return (--v);
#else
check_pthread_call(pthread_mutex_lock(&mutex));
int res = --v;
check_pthread_call(pthread_mutex_unlock(&mutex));
return res;
#endif
}
};
__STXXL_END_NAMESPACE
#endif