src/misc/threads.c

   1 /*****************************************************************************
   2  * threads.c : threads implementation for the VideoLAN client
   3  *****************************************************************************
   4  * Copyright (C) 1999-2008 the VideoLAN team
   5  * $Id$
   6  *
   7  * Authors: Jean-Marc Dressler <polux@via.ecp.fr>
   8  *          Samuel Hocevar <sam@zoy.org>
   9  *          Gildas Bazin <gbazin@netcourrier.com>
  10  *          Clément Sténac
  11  *          Rémi Denis-Courmont
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 of the License, or
  16  * (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program; if not, write to the Free Software
  25  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  26  *****************************************************************************/
  27
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #include <vlc_common.h>
  33
  34 #include "libvlc.h"
  35 #include <assert.h>
  36 #include <errno.h>
  37 #ifdef HAVE_UNISTD_H
  38 # include <unistd.h>
  39 #endif
  40
  41 #if defined( LIBVLC_USE_PTHREAD )
  42 # include <sched.h>
  43 #endif
  44
  45 struct vlc_thread_boot
  46 {
  47     void * (*entry) (vlc_object_t *);
  48     vlc_object_t *object;
  49 };
  50
  51 static void *thread_entry (void *data)
  52 {
  53     vlc_object_t *obj = ((struct vlc_thread_boot *)data)->object;
  54     void *(*func) (vlc_object_t *) = ((struct vlc_thread_boot *)data)->entry;
  55
  56     free (data);
  57     msg_Dbg (obj, "thread started");
  58     func (obj);
  59     msg_Dbg (obj, "thread ended");
  60
  61     return NULL;
  62 }
  63
  64 #undef vlc_thread_create
  65 /*****************************************************************************
  66  * vlc_thread_create: create a thread
  67  *****************************************************************************
  68  * Note that i_priority is only taken into account on platforms supporting
  69  * userland real-time priority threads.
  70  *****************************************************************************/
  71 int vlc_thread_create( vlc_object_t *p_this, void *(*func) ( vlc_object_t * ),
  72                        int i_priority )
  73 {
  74     int i_ret;
  75     vlc_object_internals_t *p_priv = vlc_internals( p_this );
  76
  77     struct vlc_thread_boot *boot = malloc (sizeof (*boot));
  78     if (boot == NULL)
  79         return errno;
  80     boot->entry = func;
  81     boot->object = p_this;
  82
  83     /* Make sure we don't re-create a thread if the object has already one */
  84     assert( !p_priv->b_thread );
  85
  86     i_ret = vlc_clone( &p_priv->thread_id, thread_entry, boot, i_priority );
  87     if( i_ret == 0 )
  88         p_priv->b_thread = true;
  89     else
  90     {
  91         errno = i_ret;
  92         msg_Err( p_this, "cannot create thread (%m)" );
  93         free (boot);
  94     }
  95
  96     return i_ret;
  97 }
  98
  99 #undef vlc_thread_set_priority
 100 /*****************************************************************************
 101  * vlc_thread_set_priority: set the priority of the current thread when we
 102  * couldn't set it in vlc_thread_create (for instance for the main thread)
 103  *****************************************************************************/
 104 int vlc_thread_set_priority( vlc_object_t *p_this, int i_priority )
 105 {
 106     vlc_object_internals_t *p_priv = vlc_internals( p_this );
 107
 108     if( !p_priv->b_thread )
 109     {
 110         msg_Err( p_this, "couldn't set priority of non-existent thread" );
 111         return ESRCH;
 112     }
 113
 114 #if defined( LIBVLC_USE_PTHREAD )
 115 # ifndef __APPLE__
 116     if( var_InheritBool( p_this, "rt-priority" ) )
 117 # endif
 118     {
 119         int i_error, i_policy;
 120         struct sched_param param;
 121
 122         memset( &param, 0, sizeof(struct sched_param) );
 123         if( config_GetType( p_this, "rt-offset" ) )
 124             i_priority += var_InheritInteger( p_this, "rt-offset" );
 125         if( i_priority <= 0 )
 126         {
 127             param.sched_priority = (-1) * i_priority;
 128             i_policy = SCHED_OTHER;
 129         }
 130         else
 131         {
 132             param.sched_priority = i_priority;
 133             i_policy = SCHED_RR;
 134         }
 135         if( (i_error = pthread_setschedparam( p_priv->thread_id,
 136                                               i_policy, &param )) )
 137         {
 138             errno = i_error;
 139             msg_Warn( p_this, "cannot set thread priority (%m)" );
 140             i_priority = 0;
 141         }
 142     }
 143
 144 #elif defined( WIN32 ) || defined( UNDER_CE )
 145
 146 #warning vlc_thread_set_priority() is BROKEN
 147     if( true /*!SetThreadPriority(p_priv->thread_id->id, i_priority)*/ )
 148     {
 149         msg_Warn( p_this, "couldn't set a faster priority" );
 150         return 1;
 151     }
 152
 153 #endif
 154
 155     return 0;
 156 }
 157
 158 #undef vlc_thread_join
 159 /*****************************************************************************
 160  * vlc_thread_join: wait until a thread exits, inner version
 161  *****************************************************************************/
 162 void vlc_thread_join( vlc_object_t *p_this )
 163 {
 164     vlc_object_internals_t *p_priv = vlc_internals( p_this );
 165
 166     vlc_join( p_priv->thread_id, NULL );
 167     p_priv->b_thread = false;
 168 }
 169
 170 void vlc_thread_cancel (vlc_object_t *obj)
 171 {
 172     vlc_object_internals_t *priv = vlc_internals (obj);
 173
 174     if (priv->b_thread)
 175         vlc_cancel (priv->thread_id);
 176 }
 177
 178 /*** Global locks ***/
 179
 180 void vlc_global_mutex (unsigned n, bool acquire)
 181 {
 182     static vlc_mutex_t locks[] = {
 183         VLC_STATIC_MUTEX,
 184         VLC_STATIC_MUTEX,
 185         VLC_STATIC_MUTEX,
 186     };
 187     assert (n < (sizeof (locks) / sizeof (locks[0])));
 188     vlc_mutex_t *lock = locks + n;
 189
 190     if (acquire)
 191         vlc_mutex_lock (lock);
 192     else
 193         vlc_mutex_unlock (lock);
 194
 195     /* Compile-time assertion ;-) */
 196     char enough_locks[(sizeof (locks) / sizeof (locks[0])) - VLC_MAX_MUTEX];
 197     (void) enough_locks;
 198 }