[grilo-plugins] local-metadata: Query for media art existence

[Philip Withnall <pwithnall src gnome org>]

commit 519d205fee5082ef909ebfa0777944f529421184
Author: Philip Withnall <philip withnall collabora co uk>
Date:   Tue Jul 7 08:55:19 2015 +0100

    local-metadata: Query for media art existence
    
    Don’t set the media art on a GrlMedia if it doesn’t exist — libmediaart
    unconditionally returns a path for where it would expect the media art
    for a file to be, without checking that some art actually exists at that
    path. That’s our job.
    
    Asynchronously query for the file info to check it exists. Ignore
    whether the media art is readable; that’s for the caller to handle when
    they try to read it (and is consistent with the other thumbnail URIs
    Grilo returns).
    
    https://bugzilla.gnome.org/show_bug.cgi?id=752057

 src/local-metadata/grl-local-metadata.c |   65 ++++++++++++++++++++++++++-----
 1 files changed, 55 insertions(+), 10 deletions(-)
---
diff --git a/src/local-metadata/grl-local-metadata.c b/src/local-metadata/grl-local-metadata.c
index e34c0b4..4d55976 100644
--- a/src/local-metadata/grl-local-metadata.c
+++ b/src/local-metadata/grl-local-metadata.c
@@ -837,32 +837,77 @@ resolve_image (ResolveData         *resolve_data,
 }
 
 static void
+resolve_album_art_cb (GObject       *source_object,
+                      GAsyncResult  *result,
+                      gpointer       user_data)
+{
+  GFile *cache_file;
+  ResolveData *resolve_data;
+  GCancellable *cancellable = NULL;
+  GFileInfo *info = NULL;
+  GError *error = NULL;
+
+  cache_file = G_FILE (source_object);
+  resolve_data = user_data;
+
+  cancellable = grl_operation_get_data (resolve_data->rs->operation_id);
+  info = g_file_query_info_finish (cache_file, result, &error);
+
+  if (info != NULL) {
+    /* Success, the album art exists. */
+    gchar *cache_uri = g_file_get_uri (cache_file);
+    grl_media_set_thumbnail (resolve_data->rs->media, cache_uri);
+    g_free (cache_uri);
+  } else if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND)) {
+    /* Ignore G_IO_ERROR_NOT_FOUND. */
+    g_clear_error (&error);
+  }
+
+  resolve_data_finish_operation (resolve_data, "album-art", error);
+
+  g_clear_object (&info);
+  g_clear_error (&error);
+  g_clear_object (&cancellable);
+}
+
+static void
 resolve_album_art (ResolveData         *resolve_data,
                    resolution_flags_t   flags)
 {
   const gchar *artist, *album;
-  char *cache_uri = NULL;
+  GCancellable *cancellable = NULL;
+  GFile *cache_file = NULL;
 
   resolve_data_start_operation (resolve_data, "album-art");
 
   artist = grl_media_audio_get_artist (GRL_MEDIA_AUDIO (resolve_data->rs->media));
   album = grl_media_audio_get_album (GRL_MEDIA_AUDIO (resolve_data->rs->media));
 
-  if (!artist || !album) {
-    resolve_data_finish_operation (resolve_data, "album-art", NULL);
-    return;
-  }
+  if (!artist || !album)
+    goto done;
 
-  media_art_get_path (artist, album, "album", &cache_uri);
+  cancellable = g_cancellable_new ();
+  grl_operation_set_data_full (resolve_data->rs->operation_id,
+                               g_object_ref (cancellable),
+                               (GDestroyNotify) g_object_unref);
 
-  if (cache_uri)
-    grl_media_set_thumbnail (resolve_data->rs->media, cache_uri);
-  else
+  media_art_get_file (artist, album, "album", &cache_file);
+
+  if (cache_file) {
+    /* Check whether the cache file exists. */
+    resolve_data_start_operation (resolve_data, "album-art");
+    g_file_query_info_async (cache_file, G_FILE_ATTRIBUTE_ACCESS_CAN_READ,
+                             G_FILE_QUERY_INFO_NONE, G_PRIORITY_DEFAULT,
+                             cancellable, resolve_album_art_cb, resolve_data);
+  } else {
     GRL_DEBUG ("Found no thumbnail for artist %s and album %s", artist, album);
+  }
 
+done:
   resolve_data_finish_operation (resolve_data, "album-art", NULL);
 
-  g_free (cache_uri);
+  g_clear_object (&cache_file);
+  g_clear_object (&cancellable);
 }
 
 static gboolean