threads.c

video linux conference

/*****************************************************************************
 * threads.c : threads implementation for the VideoLAN client
 *****************************************************************************
 * Copyright (C) 1999-2004 VideoLAN
 * $Id: threads.c 10706 2005-04-16 12:30:45Z courmisch $
 *
 * Authors: Jean-Marc Dressler <[e-mail]>
 *          Samuel Hocevar <[e-mail]>
 *          Gildas Bazin <[e-mail]>
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 *****************************************************************************/

#include <vlc/vlc.h>

#include <stdlib.h>

#define VLC_THREADS_UNINITIALIZED  0
#define VLC_THREADS_PENDING        1
#define VLC_THREADS_ERROR          2
#define VLC_THREADS_READY          3

/*****************************************************************************
 * Global mutex for lazy initialization of the threads system
 *****************************************************************************/
static volatile unsigned i_initializations = 0;
static volatile int i_status = VLC_THREADS_UNINITIALIZED;
static vlc_object_t *p_root;

#if defined( PTH_INIT_IN_PTH_H )
#elif defined( ST_INIT_IN_ST_H )
#elif defined( UNDER_CE )
#elif defined( WIN32 )
#elif defined( HAVE_KERNEL_SCHEDULER_H )
#elif defined( PTHREAD_COND_T_IN_PTHREAD_H )
    static pthread_mutex_t once_mutex = PTHREAD_MUTEX_INITIALIZER;
#elif defined( HAVE_CTHREADS_H )
#endif

/*****************************************************************************
 * Global variable for named mutexes
 *****************************************************************************/
typedef struct vlc_namedmutex_t vlc_namedmutex_t;
struct vlc_namedmutex_t
{
    vlc_mutex_t lock;

    char *psz_name;
    int i_usage;
    vlc_namedmutex_t *p_next;
};

/*****************************************************************************
 * vlc_threads_init: initialize threads system
 *****************************************************************************
 * This function requires lazy initialization of a global lock in order to
 * keep the library really thread-safe. Some architectures don't support this
 * and thus do not guarantee the complete reentrancy.
 *****************************************************************************/
int __vlc_threads_init( vlc_object_t *p_this )
{
    libvlc_t *p_libvlc = (libvlc_t *)p_this;
    int i_ret = VLC_SUCCESS;

    /* If we have lazy mutex initialization, use it. Otherwise, we just
     * hope nothing wrong happens. */
#if defined( PTH_INIT_IN_PTH_H )
#elif defined( ST_INIT_IN_ST_H )
#elif defined( UNDER_CE )
#elif defined( WIN32 )
#elif defined( HAVE_KERNEL_SCHEDULER_H )
#elif defined( PTHREAD_COND_T_IN_PTHREAD_H )
    pthread_mutex_lock( &once_mutex );
#elif defined( HAVE_CTHREADS_H )
#endif

    if( i_status == VLC_THREADS_UNINITIALIZED )
    {
        i_status = VLC_THREADS_PENDING;

        /* We should be safe now. Do all the initialization stuff we want. */
        p_libvlc->b_ready = VLC_FALSE;

#if defined( PTH_INIT_IN_PTH_H )
        i_ret = ( pth_init() == FALSE );

#elif defined( ST_INIT_IN_ST_H )
        i_ret = st_init();

#elif defined( UNDER_CE )
        /* Nothing to initialize */

#elif defined( WIN32 )
        /* Dynamically get the address of SignalObjectAndWait */
        if( GetVersion() < 0x80000000 )
        {
            HINSTANCE hInstLib;

            /* We are running on NT/2K/XP, we can use SignalObjectAndWait */
            hInstLib = LoadLibrary( "kernel32" );
            if( hInstLib )
            {
                p_libvlc->SignalObjectAndWait =
                    (SIGNALOBJECTANDWAIT)GetProcAddress( hInstLib,
                                                     "SignalObjectAndWait" );
            }
        }
        else
        {
            p_libvlc->SignalObjectAndWait = NULL;
        }

        p_libvlc->b_fast_mutex = 0;
        p_libvlc->i_win9x_cv = 0;

#elif defined( HAVE_KERNEL_SCHEDULER_H )
#elif defined( PTHREAD_COND_T_IN_PTHREAD_H )
#elif defined( HAVE_CTHREADS_H )
#endif

        p_root = vlc_object_create( p_libvlc, VLC_OBJECT_ROOT );
        if( p_root == NULL )
            i_ret = VLC_ENOMEM;

        if( i_ret )
        {
            i_status = VLC_THREADS_ERROR;
        }
        else
        {
            i_initializations++;
            i_status = VLC_THREADS_READY;
        }
    }
    else
    {
        /* Just increment the initialization count */
        i_initializations++;
    }

    /* If we have lazy mutex initialization support, unlock the mutex;
     * otherwize, do a naive wait loop. */
#if defined( PTH_INIT_IN_PTH_H )
    while( i_status == VLC_THREADS_PENDING ) msleep( THREAD_SLEEP );
#elif defined( ST_INIT_IN_ST_H )
    while( i_status == VLC_THREADS_PENDING ) msleep( THREAD_SLEEP );
#elif defined( UNDER_CE )
    while( i_status == VLC_THREADS_PENDING ) msleep( THREAD_SLEEP );
#elif defined( WIN32 )
    while( i_status == VLC_THREADS_PENDING ) msleep( THREAD_SLEEP );
#elif defined( HAVE_KERNEL_SCHEDULER_H )
    while( i_status == VLC_THREADS_PENDING ) msleep( THREAD_SLEEP );
#elif defined( PTHREAD_COND_T_IN_PTHREAD_H )
    pthread_mutex_unlock( &once_mutex );
#elif defined( HAVE_CTHREADS_H )
    while( i_status == VLC_THREADS_PENDING ) msleep( THREAD_SLEEP );
#endif

    if( i_status != VLC_THREADS_READY )
    {
        return VLC_ETHREAD;
    }

    return i_ret;
}

/*****************************************************************************
 * vlc_threads_end: stop threads system
 *****************************************************************************
 * FIXME: This function is far from being threadsafe.
 *****************************************************************************/
int __vlc_threads_end( vlc_object_t *p_this )
{
#if defined( PTH_INIT_IN_PTH_H )
#elif defined( ST_INIT_IN_ST_H )
#elif defined( UNDER_CE )
#elif defined( WIN32 )
#elif defined( HAVE_KERNEL_SCHEDULER_H )
#elif defined( PTHREAD_COND_T_IN_PTHREAD_H )
    pthread_mutex_lock( &once_mutex );
#elif defined( HAVE_CTHREADS_H )
#endif

    if( i_initializations == 0 )
        return VLC_EGENERIC;

    i_initializations--;
    if( i_initializations == 0 )
    {
        i_status = VLC_THREADS_UNINITIALIZED;
        vlc_object_destroy( p_root );
    }

#if defined( PTH_INIT_IN_PTH_H )
    if( i_initializations == 0 )
    {
        return ( pth_kill() == FALSE );
    }

#elif defined( ST_INIT_IN_ST_H )
#elif defined( UNDER_CE )
#elif defined( WIN32 )
#elif defined( HAVE_KERNEL_SCHEDULER_H )
#elif defined( PTHREAD_COND_T_IN_PTHREAD_H )
    pthread_mutex_unlock( &once_mutex );
#elif defined( HAVE_CTHREADS_H )
#endif
    return VLC_SUCCESS;
}

/*****************************************************************************
 * vlc_mutex_init: initialize a mutex
 *****************************************************************************/
int __vlc_mutex_init( vlc_object_t *p_this, vlc_mutex_t *p_mutex )
{
    p_mutex->p_this = p_this;

#if defined( PTH_INIT_IN_PTH_H )
    return ( pth_mutex_init( &p_mutex->mutex ) == FALSE );

#elif defined( ST_INIT_IN_ST_H )
    p_mutex->mutex = st_mutex_new();
    return ( p_mutex->mutex == NULL ) ? errno : 0;

#elif defined( UNDER_CE )
    InitializeCriticalSection( &p_mutex->csection );
    return 0;

#elif defined( WIN32 )
    /* We use mutexes on WinNT/2K/XP because we can use the SignalObjectAndWait
     * function and have a 100% correct vlc_cond_wait() implementation.
     * As this function is not available on Win9x, we can use the faster
     * CriticalSections */
    if( p_this->p_libvlc->SignalObjectAndWait &&
        !p_this->p_libvlc->b_fast_mutex )
    {
        /* We are running on NT/2K/XP, we can use SignalObjectAndWait */
        p_mutex->mutex = CreateMutex( 0, FALSE, 0 );
        return ( p_mutex->mutex != NULL ? 0 : 1 );
    }
    else
    {
        p_mutex->mutex = NULL;
        InitializeCriticalSection( &p_mutex->csection );
        return 0;
    }

#elif defined( HAVE_KERNEL_SCHEDULER_H )
    /* check the arguments and whether it's already been initialized */
    if( p_mutex == NULL )
    {
        return B_BAD_VALUE;
    }

    if( p_mutex->init == 9999 )
    {
        return EALREADY;
    }

    p_mutex->lock = create_sem( 1, "BeMutex" );
    if( p_mutex->lock < B_NO_ERROR )
    {
        return( -1 );
    }

    p_mutex->init = 9999;
    return B_OK;

#elif defined( PTHREAD_COND_T_IN_PTHREAD_H )
#   if defined(DEBUG) && defined(SYS_LINUX)
    {
        /* Create error-checking mutex to detect problems more easily. */
        pthread_mutexattr_t attr;
        int                 i_result;

        pthread_mutexattr_init( &attr );
        pthread_mutexattr_setkind_np( &attr, PTHREAD_MUTEX_ERRORCHECK_NP );
        i_result = pthread_mutex_init( &p_mutex->mutex, &attr );
        pthread_mutexattr_destroy( &attr );
        return( i_result );
    }
#   endif
    return pthread_mutex_init( &p_mutex->mutex, NULL );

#elif defined( HAVE_CTHREADS_H )
    mutex_init( p_mutex );
    return 0;

#endif
}

/*****************************************************************************
 * vlc_mutex_destroy: destroy a mutex, inner version
 *****************************************************************************/
int __vlc_mutex_destroy( char * psz_file, int i_line, vlc_mutex_t *p_mutex )
{
    int i_result;
    /* In case of error : */
    int i_thread = -1;
    const char * psz_error = "";

#if defined( PTH_INIT_IN_PTH_H )
    return 0;

#elif defined( ST_INIT_IN_ST_H )
    i_result = st_mutex_destroy( p_mutex->mutex );

#elif defined( UNDER_CE )
    DeleteCriticalSection( &p_mutex->csection );
    return 0;

#elif defined( WIN32 )
    if( p_mutex->mutex )
    {
        CloseHandle( p_mutex->mutex );
    }
    else
    {
        DeleteCriticalSection( &p_mutex->csection );
    }
    return 0;

#elif defined( HAVE_KERNEL_SCHEDULER_H )
    if( p_mutex->init == 9999 )
    {
        delete_sem( p_mutex->lock );
    }

    p_mutex->init = 0;
    return B_OK;

#elif defined( PTHREAD_COND_T_IN_PTHREAD_H )
    i_result = pthread_mutex_destroy( &p_mutex->mutex );
    if ( i_result )
    {
        i_thread = (int)pthread_self();
        psz_error = strerror(i_result);
    }

#elif defined( HAVE_CTHREADS_H )
    return 0;

#endif

    if( i_result )
    {
        msg_Err( p_mutex->p_this,
                 "thread %d: mutex_destroy failed at %s:%d (%d:%s)",
                 i_thread, psz_file, i_line, i_result, psz_error );
    }
    return i_result;
}

/*****************************************************************************
 * vlc_cond_init: initialize a condition
 *****************************************************************************/
int __vlc_cond_init( vlc_object_t *p_this, vlc_cond_t *p_condvar )
{
    p_condvar->p_this = p_this;

#if defined( PTH_INIT_IN_PTH_H )
    return ( pth_cond_init( &p_condvar->cond ) == FALSE );

#elif defined( ST_INIT_IN_ST_H )
    p_condvar->cond = st_cond_new();
    return ( p_condvar->cond == NULL ) ? errno : 0;

#elif defined( UNDER_CE )
    /* Initialize counter */
    p_condvar->i_waiting_threads = 0;

    /* Create an auto-reset event. */
    p_condvar->event = CreateEvent( NULL,   /* no security */
                                    FALSE,  /* auto-reset event */
                                    FALSE,  /* start non-signaled */
                                    NULL ); /* unnamed */
    return !p_condvar->event;

#elif defined( WIN32 )
    /* Initialize counter */
    p_condvar->i_waiting_threads = 0;

    /* Misc init */
    p_condvar->i_win9x_cv = p_this->p_libvlc->i_win9x_cv;
    p_condvar->SignalObjectAndWait = p_this->p_libvlc->SignalObjectAndWait;