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/*
Copyright (C) 2005-2009 Michel de Boer <michel@twinklephone.com>
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, see <https://www.gnu.org/licenses/>.
*/
#include <cerrno>
#include <cstring>
#include <string>
#include "sema.h"
#include "util.h"
using namespace std;
t_semaphore::t_semaphore(unsigned int value) {
int ret;
ret = sem_init(&sem, 0, value);
if (ret != 0) {
string err = get_error_str(errno);
string exception =
"t_semaphore::t_semaphore failed to create a semaphore.\n";
exception += err;
throw exception;
}
}
t_semaphore::~t_semaphore() {
sem_destroy(&sem);
}
void t_semaphore::up(void) {
int ret;
ret = sem_post(&sem);
if (ret != 0) {
string err = get_error_str(errno);
string exception = "t_semaphore::up failed.\n";
exception += err;
throw exception;
}
}
void t_semaphore::down(void) {
while (true) {
int ret = sem_wait(&sem);
if (ret != 0 && errno == EINTR) {
// In NPTL threading sem_wait can be interrupted.
// In LinuxThreads threading sem_wait is non-interruptable.
// Continue with sem_wait if an interrupt is caught.
continue;
}
break;
}
}
bool t_semaphore::try_down(void) {
int ret;
ret = sem_trywait(&sem);
return (ret == 0);
}
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