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/*
Copyright (C) 2010 Paul Davis
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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "pbd/semutils.h"
#include "pbd/failed_constructor.h"
using namespace PBD;
Semaphore::Semaphore (const char* name, int val)
{
#ifdef WINDOWS_SEMAPHORE
if ((_sem = CreateSemaphore(NULL, val, 32767, name)) == NULL) {
throw failed_constructor ();
}
#elif __APPLE__
if ((_sem = sem_open (name, O_CREAT, 0600, val)) == (sem_t*) SEM_FAILED) {
throw failed_constructor ();
}
/* this semaphore does not exist for IPC */
if (sem_unlink (name)) {
throw failed_constructor ();
}
#else
(void) name; /* stop gcc warning on !Apple systems */
if (sem_init (&_sem, 0, val)) {
throw failed_constructor ();
}
#endif
}
Semaphore::~Semaphore ()
{
#ifdef WINDOWS_SEMAPHORE
CloseHandle(_sem);
#elif __APPLE__
sem_close (ptr_to_sem());
#endif
}
#ifdef WINDOWS_SEMAPHORE
int
Semaphore::signal ()
{
// non-zero on success, opposite to posix
return !ReleaseSemaphore(_sem, 1, NULL);
}
int
Semaphore::wait ()
{
DWORD result = 0;
result = WaitForSingleObject(_sem, INFINITE);
return (result == WAIT_OBJECT_0);
}
int
Semaphore::reset ()
{
int rv = -1;
DWORD result;
do {
++rv;
result = WaitForSingleObject(_sem, 0);
} while (result == WAIT_OBJECT_0);
return rv;
}
#endif
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