Semaphore.cc

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/*
 * Semaphore.cc
 *
 * Smalltalk like class library for C++
 * Semaphore.
 *
 * Copyright (c) 2003 Milan Cermak
 */
/*
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <stdio.h>
#include <semaphore.h>
#include <errno.h>

#include <stlib/os/Semaphore.h>
#include <stlib/OSError.h>

using namespace OS;

Semaphore::Semaphore(void)
{
    sem_init(&handle, 0, 0);
}

Semaphore::~Semaphore(void)
{
    sem_destroy(&handle);
}

/* Instance creation protocol */
Semaphore *Semaphore::forMutualExclusion(void)
{
    Semaphore *mutex = new Semaphore;
    mutex->signal();
    return mutex;
}

/* Communication protocol */
void Semaphore::signal(void)
{
    sem_post(&handle);
}

void Semaphore::wait(void)
{
    int retCode;

    do {
        retCode = sem_wait(&handle);
    } while (retCode == -1 && errno == EINTR);
    if (retCode == -1) {
        (new OSError(new String(sys_errlist[errno]), __PRETTY_FUNCTION__))
            ->raiseFrom(this);
    }
}

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