/*

  Simple DirectMedia Layer

  Copyright (C) 1997-2013 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"

#define _GNU_SOURCE

#include <pthread.h>

#include <errno.h>

#include "SDL_thread.h"

#if !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX && \

    !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP

#define FAKE_RECURSIVE_MUTEX 1

#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_LockMutex(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_TryLockMutex(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 if (errno == EBUSY) {

            retval = SDL_MUTEX_TIMEDOUT;

        } else {

            SDL_SetError("pthread_mutex_trylock() failed");

            retval = -1;

        }

    }

#else

    if (pthread_mutex_trylock(&mutex->id) != 0) {

        if (errno == EBUSY) {

            retval = SDL_MUTEX_TIMEDOUT;

        } else {

            SDL_SetError("pthread_mutex_trylock() failed");

            retval = -1;

        }

    }

#endif

    return retval;

}

int

SDL_UnlockMutex(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;

}

/* vi: set ts=4 sw=4 expandtab: */