view src/thread/pthread/SDL_sysmutex.c @ 2349:0381047f2210 gsoc2008_iphone

The class SDL_uikitappdelegate acts as the UIApplicationDelegate for an iPhone SDL project. This class is reponsible for application control flow, including initial setup of working directory, forwarding command line arguments to the user's main function, and handling application termination.
author Holmes Futrell <hfutrell@umail.ucsb.edu>
date Thu, 17 Jul 2008 22:29:37 +0000
parents c121d94672cb
children 99210400e8b9
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 Sam Lantinga

    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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

#include <pthread.h>

#include "SDL_thread.h"

#if !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX && \
    !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP
#define FAKE_RECURSIVE_MUTEX
#endif

struct SDL_mutex
{
    pthread_mutex_t id;
#if FAKE_RECURSIVE_MUTEX
    int recursive;
    pthread_t owner;
#endif
};

SDL_mutex *
SDL_CreateMutex(void)
{
    SDL_mutex *mutex;
    pthread_mutexattr_t attr;

    /* Allocate the structure */
    mutex = (SDL_mutex *) SDL_calloc(1, sizeof(*mutex));
    if (mutex) {
        pthread_mutexattr_init(&attr);
#if SDL_THREAD_PTHREAD_RECURSIVE_MUTEX
        pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
#elif SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP
        pthread_mutexattr_setkind_np(&attr, PTHREAD_MUTEX_RECURSIVE_NP);
#else
        /* No extra attributes necessary */
#endif
        if (pthread_mutex_init(&mutex->id, &attr) != 0) {
            SDL_SetError("pthread_mutex_init() failed");
            SDL_free(mutex);
            mutex = NULL;
        }
    } else {
        SDL_OutOfMemory();
    }
    return (mutex);
}

void
SDL_DestroyMutex(SDL_mutex * mutex)
{
    if (mutex) {
        pthread_mutex_destroy(&mutex->id);
        SDL_free(mutex);
    }
}

/* Lock the mutex */
int
SDL_mutexP(SDL_mutex * mutex)
{
    int retval;
#if FAKE_RECURSIVE_MUTEX
    pthread_t this_thread;
#endif

    if (mutex == NULL) {
        SDL_SetError("Passed a NULL mutex");
        return -1;
    }

    retval = 0;
#if FAKE_RECURSIVE_MUTEX
    this_thread = pthread_self();
    if (mutex->owner == this_thread) {
        ++mutex->recursive;
    } else {
        /* The order of operations is important.
           We set the locking thread id after we obtain the lock
           so unlocks from other threads will fail.
         */
        if (pthread_mutex_lock(&mutex->id) == 0) {
            mutex->owner = this_thread;
            mutex->recursive = 0;
        } else {
            SDL_SetError("pthread_mutex_lock() failed");
            retval = -1;
        }
    }
#else
    if (pthread_mutex_lock(&mutex->id) < 0) {
        SDL_SetError("pthread_mutex_lock() failed");
        retval = -1;
    }
#endif
    return retval;
}

int
SDL_mutexV(SDL_mutex * mutex)
{
    int retval;

    if (mutex == NULL) {
        SDL_SetError("Passed a NULL mutex");
        return -1;
    }

    retval = 0;
#if FAKE_RECURSIVE_MUTEX
    /* We can only unlock the mutex if we own it */
    if (pthread_self() == mutex->owner) {
        if (mutex->recursive) {
            --mutex->recursive;
        } else {
            /* The order of operations is important.
               First reset the owner so another thread doesn't lock
               the mutex and set the ownership before we reset it,
               then release the lock semaphore.
             */
            mutex->owner = 0;
            pthread_mutex_unlock(&mutex->id);
        }
    } else {
        SDL_SetError("mutex not owned by this thread");
        retval = -1;
    }

#else
    if (pthread_mutex_unlock(&mutex->id) < 0) {
        SDL_SetError("pthread_mutex_unlock() failed");
        retval = -1;
    }
#endif /* FAKE_RECURSIVE_MUTEX */

    return retval;
}

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