libvlc: Allow event to be dispatched asynchronously.

src/Makefile.am

@@ -427,6 +427,7 @@ SOURCES_libvlc = \
 
 SOURCES_libvlc_control = \
 	control/libvlc_internal.h \
+	control/event_internal.h \
 	control/media_internal.h \
 	control/media_list_internal.h \
 	control/media_list_view_internal.h \
@@ -438,6 +439,7 @@ SOURCES_libvlc_control = \
 	control/video.c \
 	control/audio.c \
 	control/event.c \
+	control/event_async.c \
 	control/flat_media_list_view.c \
 	control/hierarchical_media_list_view.c \
 	control/hierarchical_node_media_list_view.c \

src/control/event.c

@@ -22,23 +22,22 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  *****************************************************************************/
 
-#include "libvlc_internal.h"
 #include <vlc/libvlc.h>
-#include <vlc_playlist.h>
+
+#include "libvlc_internal.h"
+#include "event_internal.h"
+
+typedef struct libvlc_event_listeners_group_t
+{
+    libvlc_event_type_t event_type;
+    vlc_array_t listeners;
+    bool b_sublistener_removed;
+} libvlc_event_listeners_group_t;
 
 /*
  * Private functions
  */
 
-static bool
-listeners_are_equal( libvlc_event_listener_t * listener1,
-                     libvlc_event_listener_t * listener2 )
-{
-    return listener1->event_type  == listener2->event_type &&
-           listener1->pf_callback == listener2->pf_callback &&
-           listener1->p_user_data == listener2->p_user_data;
-}
-
 static bool
 group_contains_listener( libvlc_event_listeners_group_t * group,
                          libvlc_event_listener_t * searched_listener )
@@ -75,7 +74,10 @@ libvlc_event_manager_new( void * p_obj, libvlc_instance_t * p_libvlc_inst,
     }
 
     p_em->p_obj = p_obj;
+    p_em->p_obj = p_obj;
+    p_em->async_event_queue = NULL;
     p_em->p_libvlc_instance = p_libvlc_inst;
+
     libvlc_retain( p_libvlc_inst );
     vlc_array_init( &p_em->listeners_groups );
     vlc_mutex_init( &p_em->object_lock );
@@ -93,6 +95,8 @@ void libvlc_event_manager_release( libvlc_event_manager_t * p_em )
     libvlc_event_listeners_group_t * p_lg;
     int i,j ;
 
+    libvlc_event_async_fini(p_em);
+
     vlc_mutex_destroy( &p_em->event_sending_lock );
     vlc_mutex_destroy( &p_em->object_lock );
 
@@ -165,7 +169,8 @@ void libvlc_event_send( libvlc_event_manager_t * p_em,
             if( vlc_array_count( &listeners_group->listeners ) <= 0 )
                 break;
 
-            /* Cache a copy of the listener to avoid locking issues */
+            /* Cache a copy of the listener to avoid locking issues,
+             * and allow that edition of listeners during callbacks will garantee immediate effect. */
             i_cached_listeners = vlc_array_count(&listeners_group->listeners);
             array_listeners_cached = malloc(sizeof(libvlc_event_listener_t)*(i_cached_listeners));
             if( !array_listeners_cached )
@@ -200,22 +205,32 @@ void libvlc_event_send( libvlc_event_manager_t * p_em,
     listeners_group->b_sublistener_removed = false;
     for( i = 0; i < i_cached_listeners; i++ )
     {
-        if( listeners_group->b_sublistener_removed )
+        if(listener_cached->is_asynchronous)
         {
-            /* If a callback was removed, this gets called */
-            bool valid_listener;
-            vlc_mutex_lock( &p_em->object_lock );
-            valid_listener = group_contains_listener( listeners_group, listener_cached );
-            vlc_mutex_unlock( &p_em->object_lock );
-            if( !valid_listener )
+            /* The listener wants not to block the emitter during event callback */
+            libvlc_event_async_dispatch(p_em, listener_cached, p_event);
+        }
+        else
+        {
+            /* The listener wants to block the emitter during event callback */
+            
+            listener_cached->pf_callback( p_event, listener_cached->p_user_data );
+            listener_cached++;
+            
+            if( listeners_group->b_sublistener_removed )
             {
-                listener_cached++;
-                continue;
-            }
+                /* If a callback was removed, this gets called */
+                bool valid_listener;
+                vlc_mutex_lock( &p_em->object_lock );
+                valid_listener = group_contains_listener( listeners_group, listener_cached );
+                vlc_mutex_unlock( &p_em->object_lock );
+                if( !valid_listener )
+                {
+                    listener_cached++;
+                    continue;
+                }
+            }            
         }
-
-        listener_cached->pf_callback( p_event, listener_cached->p_user_data );
-        listener_cached++;
     }
     vlc_mutex_unlock( &p_em->event_sending_lock );
 
@@ -287,31 +302,34 @@ const char * libvlc_event_type_name( libvlc_event_type_t event_type )
 }
 
 /**************************************************************************
- *       libvlc_event_attach (public) :
+ *       event_attach (internal) :
  *
  * Add a callback for an event.
  **************************************************************************/
-void libvlc_event_attach( libvlc_event_manager_t * p_event_manager,
-                          libvlc_event_type_t event_type,
-                          libvlc_callback_t pf_callback,
-                          void *p_user_data,
-                          libvlc_exception_t *p_e )
+static
+void event_attach( libvlc_event_manager_t * p_event_manager,
+                         libvlc_event_type_t event_type,
+                         libvlc_callback_t pf_callback,
+                         void *p_user_data,
+                         bool is_asynchronous,
+                         libvlc_exception_t *p_e )
 {
     libvlc_event_listeners_group_t * listeners_group;
     libvlc_event_listener_t * listener;
     int i;
-
+    
     listener = malloc(sizeof(libvlc_event_listener_t));
     if( !listener )
     {
         libvlc_exception_raise( p_e, "No Memory left" );
         return;
     }
-
+    
     listener->event_type = event_type;
     listener->p_user_data = p_user_data;
     listener->pf_callback = pf_callback;
-
+    listener->is_asynchronous = is_asynchronous;
+    
     vlc_mutex_lock( &p_event_manager->object_lock );
     for( i = 0; i < vlc_array_count(&p_event_manager->listeners_groups); i++ )
     {
@@ -324,11 +342,39 @@ void libvlc_event_attach( libvlc_event_manager_t * p_event_manager,
         }
     }
     vlc_mutex_unlock( &p_event_manager->object_lock );
-
+    
     free(listener);
     libvlc_exception_raise( p_e,
-            "This object event manager doesn't know about '%s' events",
-            libvlc_event_type_name(event_type));
+                           "This object event manager doesn't know about '%s' events",
+                           libvlc_event_type_name(event_type));
+}
+
+/**************************************************************************
+ *       libvlc_event_attach (public) :
+ *
+ * Add a callback for an event.
+ **************************************************************************/
+void libvlc_event_attach( libvlc_event_manager_t * p_event_manager,
+                         libvlc_event_type_t event_type,
+                         libvlc_callback_t pf_callback,
+                         void *p_user_data,
+                         libvlc_exception_t *p_e )
+{
+    event_attach(p_event_manager, event_type, pf_callback, p_user_data, false /* synchronous */, p_e);
+}
+
+/**************************************************************************
+ *       libvlc_event_attach (public) :
+ *
+ * Add a callback for an event.
+ **************************************************************************/
+void libvlc_event_attach_async( libvlc_event_manager_t * p_event_manager,
+                         libvlc_event_type_t event_type,
+                         libvlc_callback_t pf_callback,
+                         void *p_user_data,
+                         libvlc_exception_t *p_e )
+{
+    event_attach(p_event_manager, event_type, pf_callback, p_user_data, true /* asynchronous */, p_e);
 }
 
 /**************************************************************************
@@ -345,7 +391,8 @@ void libvlc_event_detach( libvlc_event_manager_t *p_event_manager,
     libvlc_event_listeners_group_t * listeners_group;
     libvlc_event_listener_t * listener;
     int i, j;
-
+    bool found = false;
+    
     vlc_mutex_lock( &p_event_manager->event_sending_lock );
     vlc_mutex_lock( &p_event_manager->object_lock );
     for( i = 0; i < vlc_array_count(&p_event_manager->listeners_groups); i++)
@@ -368,9 +415,8 @@ void libvlc_event_detach( libvlc_event_manager_t *p_event_manager,
 
                     free( listener );
                     vlc_array_remove( &listeners_group->listeners, j );
-                    vlc_mutex_unlock( &p_event_manager->object_lock );
-                    vlc_mutex_unlock( &p_event_manager->event_sending_lock );
-                    return;
+                    found = true;
+                    break;
                 }
             }
         }
@@ -378,7 +424,19 @@ void libvlc_event_detach( libvlc_event_manager_t *p_event_manager,
     vlc_mutex_unlock( &p_event_manager->object_lock );
     vlc_mutex_unlock( &p_event_manager->event_sending_lock );
 
-    libvlc_exception_raise( p_e,
-            "This object event manager doesn't know about '%s,%p,%p' event observer",
-            libvlc_event_type_name(event_type), pf_callback, p_user_data );
+    /* Now make sure any pending async event won't get fired after that point */
+    libvlc_event_listener_t listener_to_remove;
+    listener_to_remove.event_type  = event_type;
+    listener_to_remove.pf_callback = pf_callback;
+    listener_to_remove.p_user_data = p_user_data;
+    listener_to_remove.is_asynchronous = true;
+
+    libvlc_event_async_ensure_listener_removal(p_event_manager, &listener_to_remove);
+
+    if(!found)
+    {
+        libvlc_exception_raise( p_e,
+                               "This object event manager doesn't know about '%s,%p,%p' event observer",
+                               libvlc_event_type_name(event_type), pf_callback, p_user_data );        
+    }
 }

src/control/event_async.c

+/*****************************************************************************
+ * event.c: New libvlc event control API
+ *****************************************************************************
+ * Copyright (C) 2007 the VideoLAN team
+ * $Id $
+ *
+ * Authors: Filippo Carone <filippo@carone.org>
+ *          Pierre d'Herbemont <pdherbemont # videolan.org>
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#include <vlc/libvlc.h>
+
+#include "libvlc_internal.h"
+#include "event_internal.h"
+
+struct queue_elmt {
+    libvlc_event_listener_t listener;
+    libvlc_event_t event;
+    struct queue_elmt * next;
+};
+
+struct libvlc_event_async_queue {
+    struct queue_elmt * elements;
+    vlc_mutex_t lock;
+    vlc_cond_t signal;
+    vlc_thread_t thread;
+};
+
+/*
+ * Utilities
+ */
+
+static void*  event_async_loop(void * arg);
+
+static inline struct libvlc_event_async_queue * queue(libvlc_event_manager_t * p_em)
+{
+    return p_em->async_event_queue;
+}
+
+static inline bool is_queue_initialized(libvlc_event_manager_t * p_em)
+{
+    return queue(p_em) != NULL;
+}
+
+/* Lock must be held */
+static void push(libvlc_event_manager_t * p_em, libvlc_event_listener_t * listener, libvlc_event_t * event)
+{
+#ifndef NDEBUG
+    static const long MaxQueuedItem = 300000;
+    long count = 0;
+#endif
+    
+    struct queue_elmt * elmt = malloc(sizeof(struct queue_elmt));
+    elmt->listener = *listener;
+    elmt->event = *event;
+    elmt->next = NULL;
+    
+    /* Append to the end of the queue */
+    struct queue_elmt * iter = queue(p_em)->elements;
+    if(!iter)
+    {
+        queue(p_em)->elements = elmt;
+        return;
+    }
+
+    while (iter->next) {
+        iter = iter->next;
+#ifndef NDEBUG
+        if(count++ > MaxQueuedItem)
+        {
+            fprintf(stderr, "Warning: libvlc event overflow.\n");
+            abort();
+        }
+#endif
+    }
+    iter->next = elmt;
+}
+
+/* Lock must be held */
+static bool pop(libvlc_event_manager_t * p_em, libvlc_event_listener_t * listener, libvlc_event_t * event)
+{
+    if(!queue(p_em)->elements)
+        return false; /* No elements */
+
+    *listener = queue(p_em)->elements->listener;
+    *event = queue(p_em)->elements->event;
+    
+    struct queue_elmt * elmt = queue(p_em)->elements;
+    queue(p_em)->elements = elmt->next;
+    free(elmt);
+    return true;
+}
+
+/* Lock must be held */
+static void pop_listener(libvlc_event_manager_t * p_em, libvlc_event_listener_t * listener)
+{
+    struct queue_elmt * iter = queue(p_em)->elements;
+    struct queue_elmt * prev = NULL;
+    while (iter) {
+        if(listeners_are_equal(&iter->listener, listener))
+        {
+            if(!prev)
+                queue(p_em)->elements = iter->next;
+            else
+                prev->next = iter->next;
+            free(iter);
+        }
+        prev = iter;
+        iter = iter->next;
+    }
+}
+
+/**************************************************************************
+ *       libvlc_event_async_fini (internal) :
+ *
+ * Destroy what might have been created by.
+ **************************************************************************/
+void
+libvlc_event_async_fini(libvlc_event_manager_t * p_em)
+{    
+    if(!is_queue_initialized(p_em)) return;
+    
+    vlc_thread_t thread = queue(p_em)->thread;
+    if(thread)
+    {
+        vlc_cancel(thread);
+        vlc_join(thread, NULL);
+    }
+
+    vlc_mutex_destroy(&queue(p_em)->lock);
+    vlc_cond_destroy(&queue(p_em)->signal);
+
+    struct queue_elmt * iter = queue(p_em)->elements;
+    while (iter) {
+        struct queue_elmt * elemt_to_delete = iter;
+        iter = iter->next;
+        free(elemt_to_delete);
+    }
+    
+    free(queue(p_em));
+}
+
+/**************************************************************************
+ *       libvlc_event_async_init (private) :
+ *
+ * Destroy what might have been created by.
+ **************************************************************************/
+static void
+libvlc_event_async_init(libvlc_event_manager_t * p_em)
+{
+    p_em->async_event_queue = calloc(1, sizeof(struct libvlc_event_async_queue));
+
+    int error = vlc_clone (&queue(p_em)->thread, event_async_loop, p_em, VLC_THREAD_PRIORITY_LOW);
+    if(error)
+    {
+        free(p_em->async_event_queue);
+        p_em->async_event_queue = NULL;
+        return;
+    }
+
+    vlc_mutex_init_recursive(&queue(p_em)->lock); // Beware, this is re-entrant
+    vlc_cond_init(&queue(p_em)->signal);
+}
+
+/**************************************************************************
+ *       libvlc_event_async_ensure_listener_removal (internal) :
+ *
+ * Make sure no more message will be issued to the listener.
+ **************************************************************************/
+void
+libvlc_event_async_ensure_listener_removal(libvlc_event_manager_t * p_em, libvlc_event_listener_t * listener)
+{
+    if(!is_queue_initialized(p_em)) return;
+
+    vlc_mutex_lock(&queue(p_em)->lock);
+    pop_listener(p_em, listener);
+    vlc_mutex_unlock(&queue(p_em)->lock);
+}
+
+/**************************************************************************
+ *       libvlc_event_async_dispatch (internal) :
+ *
+ * Send an event in an asynchronous way.
+ **************************************************************************/
+void
+libvlc_event_async_dispatch(libvlc_event_manager_t * p_em, libvlc_event_listener_t * listener, libvlc_event_t * event)
+{
+    // We do a lazy init here, to prevent constructing the thread when not needed.
+    vlc_mutex_lock(&p_em->object_lock);
+    if(!queue(p_em))
+        libvlc_event_async_init(p_em);
+    vlc_mutex_unlock(&p_em->object_lock);
+
+    vlc_mutex_lock(&queue(p_em)->lock);
+    push(p_em, listener, event);
+    vlc_cond_signal(&queue(p_em)->signal);
+    vlc_mutex_unlock(&queue(p_em)->lock);
+}
+
+/**************************************************************************
+ *       event_async_loop (private) :
+ *
+ * Send queued events.
+ **************************************************************************/
+static void * event_async_loop(void * arg)
+{
+    libvlc_event_manager_t * p_em = arg;
+    libvlc_event_listener_t listener;
+    libvlc_event_t event;
+
+    vlc_mutex_lock(&queue(p_em)->lock);
+    vlc_cleanup_push(vlc_cleanup_lock, &queue(p_em)->lock);
+    while (true) {
+        int has_listener = pop(p_em, &listener, &event);
+        if (has_listener)
+            listener.pf_callback( &event, listener.p_user_data ); // This might edit the queue, ->lock is recursive
+        else
+            vlc_cond_wait(&queue(p_em)->signal, &queue(p_em)->lock);
+    }
+    vlc_cleanup_pop();
+    vlc_mutex_unlock(&queue(p_em)->lock);
+    return NULL;
+}

src/control/event_internal.h

+/*****************************************************************************
+ * libvlc_internal.h : Definition of opaque structures for libvlc exported API
+ * Also contains some internal utility functions
+ *****************************************************************************
+ * Copyright (C) 2005-2009 the VideoLAN team
+ * $Id$
+ *
+ * Authors: Clément Stenac <zorglub@videolan.org>
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifndef _LIBVLC_EVENT_H
+#define _LIBVLC_EVENT_H 1
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <vlc/libvlc_structures.h>
+#include <vlc/libvlc.h>
+#include <vlc/libvlc_events.h>
+
+#include <vlc_common.h>
+
+
+/*
+ * Event Handling
+ */
+
+/* Example usage
+ *
+ * struct libvlc_cool_object_t
+ * {
+ *        ...
+ *        libvlc_event_manager_t * p_event_manager;
+ *        ...
+ * }
+ *
+ * libvlc_my_cool_object_new()
+ * {
+ *        ...
+ *        p_self->p_event_manager = libvlc_event_manager_new( p_self,
+ *                                                   p_self->p_libvlc_instance, p_e);
+ *        libvlc_event_manager_register_event_type(p_self->p_event_manager,
+ *                libvlc_MyCoolObjectDidSomething, p_e)
+ *        ...
+ * }
+ *
+ * libvlc_my_cool_object_release()
+ * {
+ *         ...
+ *         libvlc_event_manager_release( p_self->p_event_manager );
+ *         ...
+ * }
+ *
+ * libvlc_my_cool_object_do_something()
+ * {
+ *        ...
+ *        libvlc_event_t event;
+ *        event.type = libvlc_MyCoolObjectDidSomething;
+ *        event.u.my_cool_object_did_something.what_it_did = kSomething;
+ *        libvlc_event_send( p_self->p_event_manager, &event );
+ * }
+ * */
+
+typedef struct libvlc_event_listener_t
+{
+    libvlc_event_type_t event_type;
+    void *              p_user_data;
+    libvlc_callback_t   pf_callback;
+    bool                is_asynchronous;
+} libvlc_event_listener_t;
+
+typedef struct libvlc_event_manager_t
+{
+    void * p_obj;
+    struct libvlc_instance_t * p_libvlc_instance;
+    vlc_array_t listeners_groups;
+    vlc_mutex_t object_lock;
+    vlc_mutex_t event_sending_lock;
+    struct libvlc_event_async_queue * async_event_queue;
+} libvlc_event_sender_t;
+
+
+static inline bool
+listeners_are_equal( libvlc_event_listener_t * listener1,
+                    libvlc_event_listener_t * listener2 )
+{
+    return listener1->event_type  == listener2->event_type &&
+    listener1->pf_callback == listener2->pf_callback &&
+    listener1->p_user_data == listener2->p_user_data &&
+    listener1->is_asynchronous == listener2->is_asynchronous;
+}
+
+/* event_async.c */
+void libvlc_event_async_fini(libvlc_event_manager_t * p_em);
+void libvlc_event_async_dispatch(libvlc_event_manager_t * p_em, libvlc_event_listener_t * listener, libvlc_event_t * event);
+void libvlc_event_async_ensure_listener_removal(libvlc_event_manager_t * p_em, libvlc_event_listener_t * listener);
+
+#endif

src/control/libvlc_internal.h

@@ -69,68 +69,6 @@ struct libvlc_instance_t
     struct libvlc_callback_entry_list_t *p_callback_list;
 };
 
-/*
- * Event Handling
- */
-/* Example usage
- *
- * struct libvlc_cool_object_t
- * {
- *        ...
- *        libvlc_event_manager_t * p_event_manager;
- *        ...
- * }
- *
- * libvlc_my_cool_object_new()
- * {
- *        ...
- *        p_self->p_event_manager = libvlc_event_manager_new( p_self,
- *                                                   p_self->p_libvlc_instance, p_e);
- *        libvlc_event_manager_register_event_type(p_self->p_event_manager,
- *                libvlc_MyCoolObjectDidSomething, p_e)
- *        ...
- * }
- *
- * libvlc_my_cool_object_release()
- * {
- *         ...
- *         libvlc_event_manager_release( p_self->p_event_manager );
- *         ...
- * }
- *
- * libvlc_my_cool_object_do_something()
- * {
- *        ...
- *        libvlc_event_t event;
- *        event.type = libvlc_MyCoolObjectDidSomething;
- *        event.u.my_cool_object_did_something.what_it_did = kSomething;
- *        libvlc_event_send( p_self->p_event_manager, &event );
- * }
- * */
-
-typedef struct libvlc_event_listener_t
-{
-    libvlc_event_type_t event_type;
-    void *              p_user_data;
-    libvlc_callback_t   pf_callback;
-} libvlc_event_listener_t;
-
-typedef struct libvlc_event_listeners_group_t
-{
-    libvlc_event_type_t event_type;
-    vlc_array_t listeners;
-    bool b_sublistener_removed;
-} libvlc_event_listeners_group_t;
-
-typedef struct libvlc_event_manager_t
-{
-    void * p_obj;
-    struct libvlc_instance_t * p_libvlc_instance;
-    vlc_array_t listeners_groups;
-    vlc_mutex_t object_lock;
-    vlc_mutex_t event_sending_lock;
-} libvlc_event_sender_t;
-
 
 /***************************************************************************
  * Other internal functions
@@ -153,6 +91,11 @@ void libvlc_event_send(
         libvlc_event_manager_t * p_em,
         libvlc_event_t * p_event );
 
+void libvlc_event_attach_async( libvlc_event_manager_t * p_event_manager,
+                               libvlc_event_type_t event_type,
+                               libvlc_callback_t pf_callback,
+                               void *p_user_data,
+                               libvlc_exception_t *p_e );
 
 /* Exception shorcuts */