preparser: add vlc_preparser_req_Release API

Explicit API to release vlc_preparser_req* from user side.
Safe to call this from within the on_ended callback.

include/vlc_preparser.h

@@ -49,6 +49,13 @@ typedef struct vlc_preparser_t vlc_preparser_t;
  * Identifies a request submitted via vlc_preparser_Push(),
  * vlc_preparser_GenerateThumbnail(), or vlc_preparser_GenerateThumbnailToFiles().
  * It can be passed to vlc_preparser_Cancel() to cancel that request.
+ *
+ * @note
+ * - Validity starts when a submit function returns a non-NULL handle and ends
+ *   with vlc_preparser_req_Release().
+ *
+ * - The user must ensure that callbacks and their context remain valid
+ *   until request termination.
  */
 typedef struct vlc_preparser_req vlc_preparser_req;
 
@@ -426,6 +433,25 @@ VLC_API size_t vlc_preparser_Cancel( vlc_preparser_t *preparser,
  */
 VLC_API input_item_t *vlc_preparser_req_GetItem(vlc_preparser_req *req);
 
+/**
+ * Release a preparser request handle.
+ *
+ * @param req the preparser request handle
+ *
+ * @note
+ * - The request handle is retained when returned by a submit function.
+ *
+ * - Mandatory to call to avoid memory leaks.
+ *
+ * - It is safe to call this API from within the on_ended callback.
+ *
+ * - The request handle should not be used after calling this function.
+ *
+ * - If called on an active request, it doesn't cancel the preparsing request,
+ *   use vlc_preparser_Cancel() for that.
+ */
+VLC_API void vlc_preparser_req_Release( vlc_preparser_req *req );
+
 /**
  * This function destroys the preparser object and thread.
  *

lib/media.c

@@ -307,7 +307,6 @@ static void send_parsed_changed( libvlc_media_t *p_md,
 static void input_item_preparse_ended(vlc_preparser_req *req,
                                       int status, void *user_data)
 {
-    VLC_UNUSED(req);
     libvlc_media_t * p_md = user_data;
     libvlc_media_parsed_status_t new_status;
 
@@ -329,6 +328,7 @@ static void input_item_preparse_ended(vlc_preparser_req *req,
             vlc_assert_unreachable();
     }
     send_parsed_changed( p_md, new_status );
+    vlc_preparser_req_Release( req );
     p_md->req = NULL;
 
     if (atomic_fetch_sub_explicit(&p_md->worker_count, 1,
@@ -934,7 +934,6 @@ struct libvlc_media_thumbnail_request_t
 static void media_on_thumbnail_ready( vlc_preparser_req *request, int status,
                                       picture_t* thumbnail, void* data )
 {
-    (void) request;
     (void) status;
 
     libvlc_media_thumbnail_request_t *req = data;
@@ -950,6 +949,8 @@ static void media_on_thumbnail_ready( vlc_preparser_req *request, int status,
     libvlc_event_send( &p_media->event_manager, &event );
     if ( pic != NULL )
         libvlc_picture_release( pic );
+
+    vlc_preparser_req_Release( request );
 }
 
 // Start an asynchronous thumbnail generation

modules/gui/qt/player/player_controller.cpp

@@ -1026,6 +1026,7 @@ static void on_preparse_ended_callback(vlc_preparser_req *req,
     input_item_t *p_item = vlc_preparser_req_GetItem(req);
     PlayerControllerPrivate *me = reinterpret_cast<PlayerControllerPrivate *>(userdata);
     me->onArtFetchEnded(p_item, input_item_IsArtFetched(p_item));
+    vlc_preparser_req_Release(req);
 }
 
 

modules/misc/medialibrary/Thumbnailer.cpp

@@ -49,7 +49,7 @@ Thumbnailer::Thumbnailer( vlc_medialibrary_module_t* ml )
         throw std::runtime_error( "Failed to instantiate a vlc_preparser_t" );
 }
 
-void Thumbnailer::onThumbnailToFilesComplete(vlc_preparser_req *, int ,
+void Thumbnailer::onThumbnailToFilesComplete(vlc_preparser_req *req, int ,
                                              const bool *result_array,
                                              size_t result_count, void *data)
 {
@@ -64,6 +64,7 @@ void Thumbnailer::onThumbnailToFilesComplete(vlc_preparser_req *, int ,
     }
     ctx->thumbnailer->m_currentContext = nullptr;
     ctx->thumbnailer->m_cond.broadcast();
+    vlc_preparser_req_Release( req );
 }
 
 bool Thumbnailer::generate( const medialibrary::IMedia&, const std::string& mrl,

src/libvlccore.sym

@@ -1055,5 +1055,6 @@ vlc_preparser_GenerateThumbnail
 vlc_preparser_GenerateThumbnailToFiles
 vlc_preparser_Cancel
 vlc_preparser_req_GetItem
+vlc_preparser_req_Release
 vlc_preparser_Delete
 vlc_preparser_SetTimeout

src/media_source/media_tree.c

@@ -177,6 +177,7 @@ media_subtree_preparse_ended(vlc_preparser_req *req, int status, void *user_data
     }
     vlc_media_tree_Notify(tree, on_preparse_end, subtree_root, status);
     vlc_media_tree_Unlock(tree);
+    vlc_preparser_req_Release(req);
 }
 
 static inline void

src/playlist/preparse.c

@@ -103,6 +103,7 @@ on_preparse_ended(vlc_preparser_req *req, int status, void *userdata)
         vlc_playlist_Notify(playlist, on_items_updated, index,
                             &playlist->items.data[index], 1);
     vlc_playlist_Unlock(playlist);
+    vlc_preparser_req_Release(req);
 }
 
 static const struct vlc_preparser_cbs preparser_callbacks = {

src/preparser/preparser.c

@@ -87,6 +87,8 @@ struct vlc_preparser_req
     struct vlc_runnable runnable; /**< to be passed to the executor */
 
     struct vlc_list node; /**< node of vlc_preparser_t.submitted_tasks */
+
+    vlc_atomic_rc_t rc;
 };
 
 static struct vlc_preparser_req *
@@ -106,6 +108,7 @@ PreparserRequestNew(vlc_preparser_t *preparser, void (*run)(void *), input_item_
     req->pic = NULL;
     req->outputs = NULL;
     req->output_count = 0;
+    vlc_atomic_rc_init(&req->rc);
 
     if (thumb_arg == NULL)
         req->thumb_arg = (struct vlc_thumbnailer_arg) {
@@ -220,7 +223,7 @@ OnArtFetchEnded(input_item_t *item, bool fetched, void *userdata)
     struct vlc_preparser_req *req = userdata;
 
     NotifyPreparseEnded(req);
-    PreparserRequestDelete(req);
+    vlc_preparser_req_Release(req);
 }
 
 static const input_fetcher_callbacks_t input_fetcher_callbacks = {
@@ -312,7 +315,7 @@ ParserRun(void *userdata)
 
 end:
     NotifyPreparseEnded(req);
-    PreparserRequestDelete(req);
+    vlc_preparser_req_Release(req);
 }
 
 static bool
@@ -429,7 +432,7 @@ error:
         req->cbs.thumbnailer_to_files->on_ended(req, req->preparse_status,
                                                 NULL, 0, req->userdata);
     picture_Release(pic);
-    PreparserRequestDelete(req);
+    vlc_preparser_req_Release(req);
     free(result_array);
 }
 
@@ -542,7 +545,7 @@ ThumbnailerRun(void *userdata)
 
 error:
     if (req != NULL)
-        PreparserRequestDelete(req);
+        vlc_preparser_req_Release(req);
 }
 
 static void
@@ -555,6 +558,13 @@ Interrupt(struct vlc_preparser_req *req)
     vlc_sem_post(&req->preparse_ended);
 }
 
+static struct vlc_preparser_req *
+PreparserRequestRetain(struct vlc_preparser_req *req)
+{
+    vlc_atomic_rc_inc(&req->rc);
+    return req;
+}
+
 vlc_preparser_t* vlc_preparser_New( vlc_object_t *parent,
                                     const struct vlc_preparser_cfg *cfg )
 {
@@ -670,11 +680,11 @@ vlc_preparser_Push( vlc_preparser_t *preparser, input_item_t *item,
 
         vlc_executor_Submit(preparser->parser, &req->runnable);
 
-        return req;
+        return PreparserRequestRetain(req);
     }
 
     int ret = Fetch(req);
-    return ret == VLC_SUCCESS ? req : NULL;
+    return ret == VLC_SUCCESS ? PreparserRequestRetain(req) : NULL;
 }
 
 vlc_preparser_req *
@@ -700,7 +710,7 @@ vlc_preparser_GenerateThumbnail( vlc_preparser_t *preparser, input_item_t *item,
 
     vlc_executor_Submit(preparser->thumbnailer, &req->runnable);
 
-    return req;
+    return PreparserRequestRetain(req);
 }
 
 static int
@@ -834,7 +844,7 @@ vlc_preparser_GenerateThumbnailToFiles( vlc_preparser_t *preparser, input_item_t
 
     vlc_executor_Submit(preparser->thumbnailer, &req->runnable);
 
-    return req;
+    return PreparserRequestRetain(req);
 }
 
 size_t vlc_preparser_Cancel( vlc_preparser_t *preparser, vlc_preparser_req *req )
@@ -900,7 +910,7 @@ size_t vlc_preparser_Cancel( vlc_preparser_t *preparser, vlc_preparser_req *req
                                                                 NULL, 0,
                                                                 req_itr->userdata);
                 }
-                PreparserRequestDelete(req_itr);
+                vlc_preparser_req_Release(req_itr);
 
                 /* Small optimisation in the likely case where the user cancel
                  * only one task */
@@ -931,6 +941,15 @@ void vlc_preparser_SetTimeout( vlc_preparser_t *preparser,
     preparser->timeout = timeout;
 }
 
+void vlc_preparser_req_Release( vlc_preparser_req *req )
+{
+    assert(req != NULL);
+    if (!vlc_atomic_rc_dec(&req->rc))
+        return;
+
+    PreparserRequestDelete(req);
+}
+
 void vlc_preparser_Delete( vlc_preparser_t *preparser )
 {
     /* In case vlc_preparser_Deactivate() has not been called */

test/libvlc/media.c

@@ -211,21 +211,21 @@ static void test_media_tracks(libvlc_instance_t *vlc)
 static void input_item_preparse_timeout( vlc_preparser_req *req,
                                          int status, void *user_data )
 {
-    VLC_UNUSED(req);
     vlc_sem_t *p_sem = user_data;
 
     assert( status == VLC_ETIMEOUT );
     vlc_sem_post(p_sem);
+    vlc_preparser_req_Release(req);
 }
 
 static void input_item_preparse_cancel( vlc_preparser_req *req,
                                         int status, void *user_data )
 {
-    VLC_UNUSED(req);
     vlc_sem_t *p_sem = user_data;
 
     assert( status == -EINTR );
     vlc_sem_post(p_sem);
+    vlc_preparser_req_Release(req);
 }
 
 static void test_input_metadata_timeout(libvlc_instance_t *vlc, int timeout,

test/src/preparser/thumbnail.c

@@ -71,7 +71,6 @@ struct test_ctx
 static void thumbnailer_callback( vlc_preparser_req *req, int status,
                                   picture_t* thumbnail, void *data )
 {
-    (void) req;
     struct test_ctx* p_ctx = data;
     vlc_mutex_lock( &p_ctx->lock );
 
@@ -113,6 +112,7 @@ static void thumbnailer_callback( vlc_preparser_req *req, int status,
     p_ctx->b_done = true;
     vlc_cond_signal( &p_ctx->cond );
     vlc_mutex_unlock( &p_ctx->lock );
+    vlc_preparser_req_Release( req );
 }
 
 static void test_thumbnails( libvlc_instance_t* p_vlc )
@@ -189,12 +189,12 @@ static void test_thumbnails( libvlc_instance_t* p_vlc )
 static void thumbnailer_callback_cancel( vlc_preparser_req *req, int status,
                                          picture_t* p_thumbnail, void *data )
 {
-    (void) req;
     assert( p_thumbnail == NULL );
     assert( status == -EINTR );
 
     vlc_sem_t *sem = data;
     vlc_sem_post(sem);
+    vlc_preparser_req_Release(req);
 }
 
 static void test_cancel_thumbnail( libvlc_instance_t* p_vlc )

test/src/preparser/thumbnail_to_files.c

@@ -112,13 +112,13 @@ static void parser_on_ended(vlc_preparser_req *req, int status, void *userdata)
     assert(es_fmt->video.i_height == test_entry->out_height);
 
     vlc_sem_post(&context->sem);
+    vlc_preparser_req_Release(req);
 }
 
 static void on_ended(vlc_preparser_req *req, int status,
                      const bool *result_array, size_t result_count, void *data)
 {
     struct context *context = data;
-    (void) req;
     assert(status == VLC_SUCCESS);
     assert(context->test_count == result_count);
 
@@ -163,6 +163,7 @@ static void on_ended(vlc_preparser_req *req, int status,
             input_item_Release(thumb);
         }
     }
+    vlc_preparser_req_Release(req);
 }
 
 static int get_formats(enum vlc_thumbnailer_format *out_format,