[rygel] media-export: Make singleton getters non-throwing.

[Krzesimir Nowak <krnowak src gnome org>]

commit 77e85a0ca4253795a93f99d91d825aadc81a0a0f
Author: Krzesimir Nowak <krnowak openismus com>
Date:   Mon Feb 11 15:52:15 2013 +0100

    media-export: Make singleton getters non-throwing.
    
    When loading a plugin we are ensuring that media cache could be
    opened. If opening a database (or upgrading it) fail then plugin is
    not loaded.
    
    Fixes https://bugzilla.gnome.org/show_bug.cgi?id=692362

 .../rygel-media-export-db-container.vala           |    5 +--
 .../rygel-media-export-dummy-container.vala        |    7 +--
 .../media-export/rygel-media-export-harvester.vala |    6 ++-
 .../rygel-media-export-harvesting-task.vala        |   14 +-----
 .../rygel-media-export-media-cache.vala            |   10 +++--
 .../media-export/rygel-media-export-plugin.vala    |   40 ++++++++++++-------
 .../rygel-media-export-root-container.vala         |   11 +++--
 7 files changed, 48 insertions(+), 45 deletions(-)
---
diff --git a/src/plugins/media-export/rygel-media-export-db-container.vala b/src/plugins/media-export/rygel-media-export-db-container.vala
index 28aec72..58c00e8 100644
--- a/src/plugins/media-export/rygel-media-export-db-container.vala
+++ b/src/plugins/media-export/rygel-media-export-db-container.vala
@@ -37,10 +37,7 @@ public class Rygel.MediaExport.DBContainer : MediaContainer,
     public override void constructed () {
         base.constructed ();
 
-        try {
-            this.media_db = MediaCache.get_default ();
-        } catch (Error error) { }
-
+        this.media_db = MediaCache.get_default ();
         this.search_classes = new ArrayList<string> ();
         this.container_updated.connect ( () => {
                 this.child_count = this.count_children ();
diff --git a/src/plugins/media-export/rygel-media-export-dummy-container.vala b/src/plugins/media-export/rygel-media-export-dummy-container.vala
index 6329e44..ff8ca98 100644
--- a/src/plugins/media-export/rygel-media-export-dummy-container.vala
+++ b/src/plugins/media-export/rygel-media-export-dummy-container.vala
@@ -25,10 +25,7 @@ internal class Rygel.MediaExport.DummyContainer : TrackableDbContainer {
 
     public DummyContainer (File           file,
                            MediaContainer parent) {
-        MediaCache cache = null;
-        try {
-            cache = MediaCache.get_default ();
-        } catch (Error error) { }
+        var cache = MediaCache.get_default ();
 
         base (MediaCache.get_id (file), file.get_basename ());
 
@@ -45,7 +42,7 @@ internal class Rygel.MediaExport.DummyContainer : TrackableDbContainer {
         this.file = file;
         this.uris.add (file.get_uri ());
         try {
-            this.children = MediaCache.get_default ().get_child_ids (this.id);
+            this.children = cache.get_child_ids (this.id);
             this.child_count = this.children.size;
         } catch (Error error) {
             this.children = new ArrayList<string> ();
diff --git a/src/plugins/media-export/rygel-media-export-harvester.vala b/src/plugins/media-export/rygel-media-export-harvester.vala
index c882948..9fa5f0b 100644
--- a/src/plugins/media-export/rygel-media-export-harvester.vala
+++ b/src/plugins/media-export/rygel-media-export-harvester.vala
@@ -204,11 +204,13 @@ internal class Rygel.MediaExport.Harvester : GLib.Object {
                 debug ("%s is not eligible for extraction", file.get_uri ());
             }
         } catch (Error error) {
-            warning (_("Failed to access media cache: %s"), error.message);
+            warning (_("Failed to query info of a file %s: %s"),
+                     file.get_uri (),
+                     error.message);
         }
     }
 
-    private void on_file_removed (File file) throws Error {
+    private void on_file_removed (File file) {
         var cache = MediaCache.get_default ();
         if (this.extraction_grace_timers.has_key (file)) {
             Source.remove (this.extraction_grace_timers[file]);
diff --git a/src/plugins/media-export/rygel-media-export-harvesting-task.vala b/src/plugins/media-export/rygel-media-export-harvesting-task.vala
index 0044d05..a2e2e8f 100644
--- a/src/plugins/media-export/rygel-media-export-harvesting-task.vala
+++ b/src/plugins/media-export/rygel-media-export-harvesting-task.vala
@@ -64,15 +64,7 @@ public class Rygel.MediaExport.HarvestingTask : Rygel.StateMachine,
         this.extractor = extractor;
         this.origin = file;
         this.parent = parent;
-
-        try {
-            this.cache = MediaCache.get_default ();
-        } catch (Error error) {
-            // This should not happen. As the harvesting tasks are created
-            // long after the first call to get_default which - if fails -
-            // will make the whole root-container creation fail
-            assert_not_reached ();
-        }
+        this.cache = MediaCache.get_default ();
 
         this.extractor.extraction_done.connect (on_extracted_cb);
         this.extractor.error.connect (on_extractor_error_cb);
@@ -376,13 +368,13 @@ public class Rygel.MediaExport.HarvestingTask : Rygel.StateMachine,
         if (this.files.is_empty &&
             !this.containers.is_empty ()) {
             var container = this.containers.peek_head ();
+            var cache = MediaCache.get_default ();
             try {
-                var cache = MediaCache.get_default ();
                 if (cache.get_child_count (container.id) == 0) {
                     var parent = container.parent as TrackableContainer;
                     parent.remove_child_tracked.begin (container, () => {
                         try {
-                            MediaCache.get_default ().save_container (parent);
+                            cache.save_container (parent);
                         } catch (Error error) { }
                     });
                 }
diff --git a/src/plugins/media-export/rygel-media-export-media-cache.vala b/src/plugins/media-export/rygel-media-export-media-cache.vala
index 5b470eb..bfccc3d 100644
--- a/src/plugins/media-export/rygel-media-export-media-cache.vala
+++ b/src/plugins/media-export/rygel-media-export-media-cache.vala
@@ -71,12 +71,14 @@ public class Rygel.MediaExport.MediaCache : Object {
                                             file.get_uri ());
     }
 
-    public static MediaCache get_default () throws Error {
-        if (instance == null) {
-            instance = new MediaCache ();
+    public static void ensure_exists () throws Error {
+        if (MediaCache.instance == null) {
+            MediaCache.instance = new MediaCache ();
         }
+    }
 
-        return instance;
+    public static MediaCache get_default () {
+        return MediaCache.instance;
     }
 
     // Public functions
diff --git a/src/plugins/media-export/rygel-media-export-plugin.vala b/src/plugins/media-export/rygel-media-export-plugin.vala
index c0b6972..977bf50 100644
--- a/src/plugins/media-export/rygel-media-export-plugin.vala
+++ b/src/plugins/media-export/rygel-media-export-plugin.vala
@@ -35,24 +35,31 @@ public void module_init (PluginLoader loader) {
         return;
     }
 
-    // Instantiate the plugin object:
-    var plugin = new MediaExport.Plugin ();
+    try {
+        // Instantiate the plugin object (it may fail if loading
+        // database did not succeed):
+        var plugin = new MediaExport.Plugin ();
 
-    // Check what other plugins are loaded,
-    // and check when other plugins are loaded later:
-    Idle.add (() => {
-       foreach (var loaded_plugin in loader.list_plugins ()) {
-            on_plugin_available (loaded_plugin, plugin);
-       }
+        // Check what other plugins are loaded,
+        // and check when other plugins are loaded later:
+        Idle.add (() => {
+           foreach (var loaded_plugin in loader.list_plugins ()) {
+                on_plugin_available (loaded_plugin, plugin);
+           }
 
-       loader.plugin_available.connect ((new_plugin) => {
-           on_plugin_available (new_plugin, plugin);
-       });
+           loader.plugin_available.connect ((new_plugin) => {
+               on_plugin_available (new_plugin, plugin);
+           });
 
-       return false;
-    });
+           return false;
+        });
 
-    loader.add_plugin (plugin);
+        loader.add_plugin (plugin);
+    } catch (Error error) {
+        warning ("Failed to load %s: %s",
+                 MediaExport.Plugin.NAME,
+                 error.message);
+    }
 }
 
 public void on_plugin_available (Plugin plugin, Plugin our_plugin) {
@@ -108,7 +115,10 @@ public class Rygel.MediaExport.Plugin : Rygel.MediaServerPlugin {
     /**
      * Instantiate the plugin.
      */
-    public Plugin () {
+    public Plugin () throws Error {
+        // Ensure that root container could be created and thus
+        // database could be opened:
+        RootContainer.ensure_exists ();
         // Call the base constructor,
         // passing the instance of our root container.
         base (RootContainer.get_instance (),
diff --git a/src/plugins/media-export/rygel-media-export-root-container.vala b/src/plugins/media-export/rygel-media-export-root-container.vala
index f54a934..66925e7 100644
--- a/src/plugins/media-export/rygel-media-export-root-container.vala
+++ b/src/plugins/media-export/rygel-media-export-root-container.vala
@@ -60,14 +60,17 @@ public class Rygel.MediaExport.RootContainer : TrackableDbContainer {
                                                    Rygel.MusicItem.UPNP_CLASS +
                                                    ",";
 
+    public static void ensure_exists () throws Error {
+        if (RootContainer.instance == null) {
+            MediaCache.ensure_exists ();
+            RootContainer.instance = new RootContainer ();
+        }
+    }
+
     /**
      * Get the single instance of the root container.
      */
     public static MediaContainer get_instance () {
-        if (RootContainer.instance == null) {
-                RootContainer.instance = new RootContainer ();
-        }
-
         return RootContainer.instance;
     }