src/thread/pthread/SDL_syssem.c
author Sam Lantinga <slouken@libsdl.org>
Mon, 20 Feb 2012 23:51:53 -0500
changeset 6298 9110462bfc57
parent 6219 8e94af244f2c
child 6885 700f1b25f77f
permissions -rwxr-xr-x
Fixed bug 1426 - SDL_SemWaitTimeout returns -1 and sets error instead of SDL_MUTEX_TIMEDOUT on time out deraj 2012-02-19 19:01:08 PST Fix to treat ETIMEDOUT as a time out instead of an error (and update the test)

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_config.h"

#include <errno.h>
#include <pthread.h>
#include <semaphore.h>
#include <sys/time.h>

#include "SDL_thread.h"
#include "SDL_timer.h"

/* Wrapper around POSIX 1003.1b semaphores */

#if defined(__MACOSX__) || defined(__IPHONEOS__)
/* Mac OS X doesn't support sem_getvalue() as of version 10.4 */
#include "../generic/SDL_syssem.c"
#else

struct SDL_semaphore
{
    sem_t sem;
};

/* Create a semaphore, initialized with value */
SDL_sem *
SDL_CreateSemaphore(Uint32 initial_value)
{
    SDL_sem *sem = (SDL_sem *) SDL_malloc(sizeof(SDL_sem));
    if (sem) {
        if (sem_init(&sem->sem, 0, initial_value) < 0) {
            SDL_SetError("sem_init() failed");
            SDL_free(sem);
            sem = NULL;
        }
    } else {
        SDL_OutOfMemory();
    }
    return sem;
}

void
SDL_DestroySemaphore(SDL_sem * sem)
{
    if (sem) {
        sem_destroy(&sem->sem);
        SDL_free(sem);
    }
}

int
SDL_SemTryWait(SDL_sem * sem)
{
    int retval;

    if (!sem) {
        SDL_SetError("Passed a NULL semaphore");
        return -1;
    }
    retval = SDL_MUTEX_TIMEDOUT;
    if (sem_trywait(&sem->sem) == 0) {
        retval = 0;
    }
    return retval;
}

int
SDL_SemWait(SDL_sem * sem)
{
    int retval;

    if (!sem) {
        SDL_SetError("Passed a NULL semaphore");
        return -1;
    }

    retval = sem_wait(&sem->sem);
    if (retval < 0) {
        SDL_SetError("sem_wait() failed");
    }
    return retval;
}

int
SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
{
    int retval;
#ifdef HAVE_SEM_TIMEDWAIT
    struct timeval now;
    struct timespec ts_timeout;
#else
    Uint32 end;
#endif

    if (!sem) {
        SDL_SetError("Passed a NULL semaphore");
        return -1;
    }

    /* Try the easy cases first */
    if (timeout == 0) {
        return SDL_SemTryWait(sem);
    }
    if (timeout == SDL_MUTEX_MAXWAIT) {
        return SDL_SemWait(sem);
    }

#ifdef HAVE_SEM_TIMEDWAIT
    /* Setup the timeout. sem_timedwait doesn't wait for
    * a lapse of time, but until we reach a certain time.
    * This time is now plus the timeout.
    */
    gettimeofday(&now, NULL);

    /* Add our timeout to current time */
    now.tv_usec += (timeout % 1000) * 1000;
    now.tv_sec += timeout / 1000;

    /* Wrap the second if needed */
    if ( now.tv_usec >= 1000000 ) {
        now.tv_usec -= 1000000;
        now.tv_sec ++;
    }

    /* Convert to timespec */
    ts_timeout.tv_sec = now.tv_sec;
    ts_timeout.tv_nsec = now.tv_usec * 1000;

    /* Wait. */
    do {
        retval = sem_timedwait(&sem->sem, &ts_timeout);
    } while (retval < 0 && errno == EINTR);

    if (retval < 0) {
        if (errno == ETIMEDOUT) {
            retval = SDL_MUTEX_TIMEDOUT;
        } else {
            SDL_SetError(strerror(errno));
        }
    }
#else
    end = SDL_GetTicks() + timeout;
    while ((retval = SDL_SemTryWait(sem)) == SDL_MUTEX_TIMEDOUT) {
        if ((SDL_GetTicks() - end) >= 0) {
            break;
        }
        SDL_Delay(0);
    }
#endif /* HAVE_SEM_TIMEDWAIT */

    return retval;
}

Uint32
SDL_SemValue(SDL_sem * sem)
{
    int ret = 0;
    if (sem) {
        sem_getvalue(&sem->sem, &ret);
        if (ret < 0) {
            ret = 0;
        }
    }
    return (Uint32) ret;
}

int
SDL_SemPost(SDL_sem * sem)
{
    int retval;

    if (!sem) {
        SDL_SetError("Passed a NULL semaphore");
        return -1;
    }

    retval = sem_post(&sem->sem);
    if (retval < 0) {
        SDL_SetError("sem_post() failed");
    }
    return retval;
}

#endif /* __MACOSX__ */
/* vi: set ts=4 sw=4 expandtab: */