src/misc/events.c

   1 /*****************************************************************************
   2  * events.c: events interface
   3  * This library provides an interface to the send and receive events.
   4  * It is more lightweight than variable based callback.
   5  *****************************************************************************
   6  * Copyright (C) 1998-2005 the VideoLAN team
   7  * $Id$
   8  *
   9  * Authors: Pierre d'Herbemont <pdherbemont # videolan.org >
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  24  *****************************************************************************/
  25
  26 /*****************************************************************************
  27  * Preamble
  28  *****************************************************************************/
  29
  30 #ifdef HAVE_CONFIG_H
  31 # include "config.h"
  32 #endif
  33
  34 #include <vlc_common.h>
  35
  36 #include <assert.h>
  37
  38 #include <vlc_events.h>
  39 #include <vlc_arrays.h>
  40
  41 /*****************************************************************************
  42  * Documentation : Read vlc_events.h
  43  *****************************************************************************/
  44
  45 //#define DEBUG_EVENT
  46
  47 /*****************************************************************************
  48  *  Private types.
  49  *****************************************************************************/
  50
  51 typedef struct vlc_event_listener_t
  52 {
  53     void *               p_user_data;
  54     vlc_event_callback_t pf_callback;
  55 #ifdef DEBUG_EVENT
  56     char *               psz_debug_name;
  57 #endif
  58 } vlc_event_listener_t;
  59
  60 typedef struct vlc_event_listeners_group_t
  61 {
  62     vlc_event_type_t    event_type;
  63     DECL_ARRAY(struct vlc_event_listener_t *) listeners;
  64
  65    /* Used in vlc_event_send() to make sure to behave
  66       Correctly when vlc_event_detach was called during
  67       a callback */
  68     bool          b_sublistener_removed;
  69
  70 } vlc_event_listeners_group_t;
  71
  72 #ifdef DEBUG_EVENT
  73 static const char ppsz_event_type_to_name[][40] =
  74 {
  75     [vlc_InputStateChanged]             = "vlc_InputStateChanged",
  76     [vlc_InputSelectedStreamChanged]    = "vlc_InputSelectedStreamChanged",
  77
  78     [vlc_InputItemMetaChanged]          = "vlc_InputItemMetaChanged",
  79     [vlc_InputItemSubItemAdded]         = "vlc_InputItemSubItemAdded",
  80     [vlc_InputItemDurationChanged]      = "vlc_InputItemDurationChanged",
  81     [vlc_InputItemPreparsedChanged]     = "vlc_InputItemPreparsedChanged",
  82     [vlc_InputItemNameChanged]          = "vlc_InputItemNameChanged",
  83     [vlc_InputItemInfoChanged]          = "vlc_InputItemInfoChanged",
  84     [vlc_InputItemErrorWhenReadingChanged] = "vlc_InputItemErrorWhenReadingChanged",
  85
  86     [vlc_ServicesDiscoveryItemAdded]    = "vlc_ServicesDiscoveryItemAdded",
  87     [vlc_ServicesDiscoveryItemRemoved]  = "vlc_ServicesDiscoveryItemRemoved",
  88     [vlc_ServicesDiscoveryStarted]      = "vlc_ServicesDiscoveryStarted",
  89     [vlc_ServicesDiscoveryEnded]        = "vlc_ServicesDiscoveryEnded"
  90 };
  91 #endif
  92
  93 static bool
  94 listeners_are_equal( vlc_event_listener_t * listener1,
  95                      vlc_event_listener_t * listener2 )
  96 {
  97     return listener1->pf_callback == listener2->pf_callback &&
  98            listener1->p_user_data == listener2->p_user_data;
  99 }
 100
 101 static bool
 102 group_contains_listener( vlc_event_listeners_group_t * group,
 103                          vlc_event_listener_t * searched_listener )
 104 {
 105     vlc_event_listener_t * listener;
 106     FOREACH_ARRAY( listener, group->listeners )
 107         if( listeners_are_equal(searched_listener, listener) )
 108             return true;
 109     FOREACH_END()
 110     return false;
 111 }
 112
 113 /*****************************************************************************
 114  *
 115  *****************************************************************************/
 116
 117 #undef vlc_event_manager_init
 118 /**
 119  * Initialize event manager object
 120  * p_obj is the object that contains the event manager. But not
 121  * necessarily a vlc_object_t (an input_item_t is not a vlc_object_t
 122  * for instance).
 123  * p_parent_obj gives a libvlc instance
 124  */
 125 int vlc_event_manager_init( vlc_event_manager_t * p_em, void * p_obj,
 126                             vlc_object_t * p_parent_obj )
 127 {
 128     p_em->p_obj = p_obj;
 129     p_em->p_parent_object = p_parent_obj;
 130     vlc_mutex_init( &p_em->object_lock );
 131
 132     /* We need a recursive lock here, because we need to be able
 133      * to call libvlc_event_detach even if vlc_event_send is in
 134      * the call frame.
 135      * This ensures that after libvlc_event_detach, the callback
 136      * will never gets triggered.
 137      * */
 138     vlc_mutex_init_recursive( &p_em->event_sending_lock );
 139     ARRAY_INIT( p_em->listeners_groups );
 140     return VLC_SUCCESS;
 141 }
 142
 143 /**
 144  * Destroy the event manager
 145  */
 146 void vlc_event_manager_fini( vlc_event_manager_t * p_em )
 147 {
 148     struct vlc_event_listeners_group_t * listeners_group;
 149     struct vlc_event_listener_t * listener;
 150
 151     vlc_mutex_destroy( &p_em->object_lock );
 152     vlc_mutex_destroy( &p_em->event_sending_lock );
 153
 154     FOREACH_ARRAY( listeners_group, p_em->listeners_groups )
 155         FOREACH_ARRAY( listener, listeners_group->listeners )
 156             free( listener );
 157         FOREACH_END()
 158         ARRAY_RESET( listeners_group->listeners );
 159         free( listeners_group );
 160     FOREACH_END()
 161     ARRAY_RESET( p_em->listeners_groups );
 162 }
 163
 164 /**
 165  * Register the event manager
 166  */
 167 int vlc_event_manager_register_event_type(
 168         vlc_event_manager_t * p_em,
 169         vlc_event_type_t event_type )
 170 {
 171     vlc_event_listeners_group_t * listeners_group;
 172     listeners_group = malloc(sizeof(vlc_event_listeners_group_t));
 173
 174     if( !listeners_group )
 175         return VLC_ENOMEM;
 176
 177     listeners_group->event_type = event_type;
 178     ARRAY_INIT( listeners_group->listeners );
 179
 180     vlc_mutex_lock( &p_em->object_lock );
 181     ARRAY_APPEND( p_em->listeners_groups, listeners_group );
 182     vlc_mutex_unlock( &p_em->object_lock );
 183
 184     return VLC_SUCCESS;
 185 }
 186
 187 /**
 188  * Send an event to the listener attached to this p_em.
 189  */
 190 void vlc_event_send( vlc_event_manager_t * p_em,
 191                      vlc_event_t * p_event )
 192 {
 193     vlc_event_listeners_group_t * listeners_group = NULL;
 194     vlc_event_listener_t * listener;
 195     vlc_event_listener_t * array_of_cached_listeners = NULL;
 196     vlc_event_listener_t * cached_listener;
 197     int i, i_cached_listeners = 0;
 198
 199     /* Fill event with the sending object now */
 200     p_event->p_obj = p_em->p_obj;
 201
 202     vlc_mutex_lock( &p_em->object_lock );
 203     FOREACH_ARRAY( listeners_group, p_em->listeners_groups )
 204         if( listeners_group->event_type == p_event->type )
 205         {
 206             if( listeners_group->listeners.i_size <= 0 )
 207                 break;
 208
 209             /* Save the function to call */
 210             i_cached_listeners = listeners_group->listeners.i_size;
 211             array_of_cached_listeners = malloc(
 212                     sizeof(vlc_event_listener_t)*i_cached_listeners );
 213             if( !array_of_cached_listeners )
 214             {
 215                 vlc_mutex_unlock( &p_em->object_lock );
 216                 return;
 217             }
 218
 219             cached_listener = array_of_cached_listeners;
 220             FOREACH_ARRAY( listener, listeners_group->listeners )
 221                 memcpy( cached_listener, listener, sizeof(vlc_event_listener_t));
 222 #ifdef DEBUG_EVENT
 223                 cached_listener->psz_debug_name = strdup(cached_listener->psz_debug_name);
 224 #endif
 225                 cached_listener++;
 226             FOREACH_END()
 227
 228             break;
 229         }
 230     FOREACH_END()
 231     vlc_mutex_unlock( &p_em->object_lock );
 232
 233     /* Call the function attached */
 234     cached_listener = array_of_cached_listeners;
 235
 236     if( !listeners_group || !array_of_cached_listeners )
 237     {
 238         free( array_of_cached_listeners );
 239         return;
 240     }
 241
 242     vlc_mutex_lock( &p_em->event_sending_lock ) ;
 243
 244     /* Track item removed from *this* thread, with a simple flag */
 245     listeners_group->b_sublistener_removed = false;
 246
 247     for( i = 0; i < i_cached_listeners; i++ )
 248     {
 249 #ifdef DEBUG_EVENT
 250         msg_Dbg( p_em->p_parent_object,
 251                     "Calling '%s' with a '%s' event (data %p)",
 252                     cached_listener->psz_debug_name,
 253                     ppsz_event_type_to_name[p_event->type],
 254                     cached_listener->p_user_data );
 255         free(cached_listener->psz_debug_name);
 256 #endif
 257         /* No need to lock on listeners_group, a listener group can't be removed */
 258         if( listeners_group->b_sublistener_removed )
 259         {
 260             /* If a callback was removed, this gets called */
 261             bool valid_listener;
 262             vlc_mutex_lock( &p_em->object_lock );
 263             valid_listener = group_contains_listener( listeners_group, cached_listener );
 264             vlc_mutex_unlock( &p_em->object_lock );
 265             if( !valid_listener )
 266             {
 267 #ifdef DEBUG_EVENT
 268                 msg_Dbg( p_em->p_parent_object, "Callback was removed during execution" );
 269 #endif
 270                 cached_listener++;
 271                 continue;
 272             }
 273         }
 274         cached_listener->pf_callback( p_event, cached_listener->p_user_data );
 275         cached_listener++;
 276     }
 277     vlc_mutex_unlock( &p_em->event_sending_lock );
 278
 279     free( array_of_cached_listeners );
 280 }
 281
 282 #undef vlc_event_attach
 283 /**
 284  * Add a callback for an event.
 285  */
 286 int vlc_event_attach( vlc_event_manager_t * p_em,
 287                       vlc_event_type_t event_type,
 288                       vlc_event_callback_t pf_callback,
 289                       void *p_user_data,
 290                       const char * psz_debug_name )
 291 {
 292     vlc_event_listeners_group_t * listeners_group;
 293     vlc_event_listener_t * listener;
 294     listener = malloc(sizeof(vlc_event_listener_t));
 295     if( !listener )
 296         return VLC_ENOMEM;
 297
 298     listener->p_user_data = p_user_data;
 299     listener->pf_callback = pf_callback;
 300 #ifdef DEBUG_EVENT
 301     listener->psz_debug_name = strdup( psz_debug_name );
 302 #else
 303     (void)psz_debug_name;
 304 #endif
 305
 306     vlc_mutex_lock( &p_em->object_lock );
 307     FOREACH_ARRAY( listeners_group, p_em->listeners_groups )
 308         if( listeners_group->event_type == event_type )
 309         {
 310             ARRAY_APPEND( listeners_group->listeners, listener );
 311 #ifdef DEBUG_EVENT
 312                 msg_Dbg( p_em->p_parent_object,
 313                     "Listening to '%s' event with '%s' (data %p)",
 314                     ppsz_event_type_to_name[event_type],
 315                     listener->psz_debug_name,
 316                     listener->p_user_data );
 317 #endif
 318             vlc_mutex_unlock( &p_em->object_lock );
 319             return VLC_SUCCESS;
 320         }
 321     FOREACH_END()
 322     vlc_mutex_unlock( &p_em->object_lock );
 323
 324     msg_Err( p_em->p_parent_object, "cannot attach to an object event" );
 325     free(listener);
 326     return VLC_EGENERIC;
 327 }
 328
 329 /**
 330  * Remove a callback for an event.
 331  */
 332
 333 int vlc_event_detach( vlc_event_manager_t *p_em,
 334                       vlc_event_type_t event_type,
 335                       vlc_event_callback_t pf_callback,
 336                       void *p_user_data )
 337 {
 338     vlc_event_listeners_group_t * listeners_group;
 339     struct vlc_event_listener_t * listener;
 340
 341     vlc_mutex_lock( &p_em->object_lock );
 342     vlc_mutex_lock( &p_em->event_sending_lock );
 343     FOREACH_ARRAY( listeners_group, p_em->listeners_groups )
 344         if( listeners_group->event_type == event_type )
 345         {
 346             FOREACH_ARRAY( listener, listeners_group->listeners )
 347                 if( listener->pf_callback == pf_callback &&
 348                     listener->p_user_data == p_user_data )
 349                 {
 350                     /* Tell vlc_event_send, we did remove an item from that group,
 351                        in case vlc_event_send is in our caller stack  */
 352                     listeners_group->b_sublistener_removed = true;
 353
 354                     /* that's our listener */
 355                     ARRAY_REMOVE( listeners_group->listeners,
 356                         fe_idx /* This comes from the macro (and that's why
 357                                   I hate macro) */ );
 358 #ifdef DEBUG_EVENT
 359                     msg_Dbg( p_em->p_parent_object,
 360                         "Detaching '%s' from '%s' event (data %p)",
 361                         listener->psz_debug_name,
 362                         ppsz_event_type_to_name[event_type],
 363                         listener->p_user_data );
 364
 365                     free( listener->psz_debug_name );
 366 #endif
 367                     free( listener );
 368                     vlc_mutex_unlock( &p_em->event_sending_lock );
 369                     vlc_mutex_unlock( &p_em->object_lock );
 370                     return VLC_SUCCESS;
 371                 }
 372             FOREACH_END()
 373         }
 374     FOREACH_END()
 375     vlc_mutex_unlock( &p_em->event_sending_lock );
 376     vlc_mutex_unlock( &p_em->object_lock );
 377
 378     msg_Warn( p_em->p_parent_object, "cannot detach from an object event" );
 379
 380     return VLC_EGENERIC;
 381 }
 382