[grilo] core: Add synchronous version of grl_media_source_metadata() function

[Juan A. Suarez Romero <jasuarez src gnome org>]

commit c5ae7759b267081aca8865e5d1a4e70919e1eebe
Author: Juan A. Suarez Romero <jasuarez igalia com>
Date:   Mon Jul 12 14:03:10 2010 +0200

    core: Add synchronous version of grl_media_source_metadata() function
    
    Most of Grilo functions are asynchronous.
    
    But there are some cases, when user do not want to deal with asynchronous
    stuff, that having the appropriate synchronous verison would be useful.
    
    So this patch adds this sychronous version in grl_media_source_metadata() for
    free. This means that plugin author should not worry about dealing with
    synchronous versions of the calls; she just implemement the asynchronous one,
    as usual. Grilo will use this asynchronous version to implement a synchronous
    one over it.
    
    While running grl_media_source_metadata_sync() function, all remaining events
    and idle functions are still functions, so they will be received and executed
    even when waiting for the operation to be completed.

 src/grl-media-source.c |   88 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/grl-media-source.h |    7 ++++
 2 files changed, 95 insertions(+), 0 deletions(-)
---
diff --git a/src/grl-media-source.c b/src/grl-media-source.c
index 5aaa483..3ceb28a 100644
--- a/src/grl-media-source.c
+++ b/src/grl-media-source.c
@@ -139,6 +139,12 @@ struct MetadataRelayCb {
   GrlMediaSourceMetadataSpec *spec;
 };
 
+struct OperationAsyncCb {
+  gboolean complete;
+  gpointer data;
+  GError *error;
+};
+
 struct OperationState {
   gboolean cancelled;
   gboolean completed;
@@ -792,6 +798,24 @@ metadata_result_relay_cb (GrlMediaSource *source,
   g_free (mrc);
 }
 
+static void
+metadata_result_async_cb (GrlMediaSource *source,
+                          GrlMedia *media,
+                          gpointer user_data,
+                          const GError *error)
+{
+  struct OperationAsyncCb *oa = (struct OperationAsyncCb *) user_data;
+
+  g_debug ("metadata_result_async_cb");
+
+  if (error) {
+    oa->error = g_error_copy (error);
+  }
+
+  oa->data = media;
+  oa->complete = TRUE;
+}
+
 static gint
 compare_sorted_results (gconstpointer a, gconstpointer b)
 {
@@ -1091,6 +1115,22 @@ metadata_full_resolution_ctl_cb (GrlMediaSource *source,
   }
 }
 
+static void
+wait_for_async_operation_complete (struct OperationAsyncCb *oa)
+{
+  GMainLoop *ml;
+  GMainContext *mc;
+
+  ml = g_main_loop_new (NULL, TRUE);
+  mc = g_main_loop_get_context (ml);
+
+ while (!oa->complete) {
+    g_main_context_iteration (mc, TRUE);
+  }
+
+  g_main_loop_unref (ml);
+}
+
 /* ================ API ================ */
 
 /**
@@ -1596,6 +1636,54 @@ grl_media_source_metadata (GrlMediaSource *source,
   return metadata_id;
 }
 
+/**
+ * grl_media_source_metadata_sync:
+ * @source: a media source
+ * @media: a data transfer object
+ * @keys: the list of #GrlKeyID to request
+ * @flags: the resolution mode
+ * @error: a #GError, or @NULL
+ *
+ * This method is intended to fetch the requested keys of metadata of
+ * a given @media to the media source.
+ *
+ * This method is synchronous.
+ *
+ * Returns: the updated #GrlMedia
+ */
+GrlMedia *
+grl_media_source_metadata_sync (GrlMediaSource *source,
+                                GrlMedia *media,
+                                const GList *keys,
+                                GrlMetadataResolutionFlags flags,
+                                GError **error)
+{
+  struct OperationAsyncCb *oa;
+
+  oa = g_slice_new0 (struct OperationAsyncCb);
+
+  grl_media_source_metadata (source,
+                             media,
+                             keys,
+                             flags,
+                             metadata_result_async_cb,
+                             oa);
+
+  wait_for_async_operation_complete (oa);
+
+  if (oa->error) {
+    if (error) {
+      *error = oa->error;
+    } else {
+      g_error_free (oa->error);
+    }
+  }
+
+  g_slice_free (struct OperationAsyncCb, oa);
+
+  return media;
+}
+
 static GrlSupportedOps
 grl_media_source_supported_operations (GrlMetadataSource *metadata_source)
 {
diff --git a/src/grl-media-source.h b/src/grl-media-source.h
index cb8e886..6430351 100644
--- a/src/grl-media-source.h
+++ b/src/grl-media-source.h
@@ -362,6 +362,13 @@ guint grl_media_source_metadata (GrlMediaSource *source,
                                  GrlMediaSourceMetadataCb callback,
                                  gpointer user_data);
 
+GrlMedia *grl_media_source_metadata_sync (GrlMediaSource *source,
+                                          GrlMedia *media,
+                                          const GList *keys,
+                                          GrlMetadataResolutionFlags flags,
+                                          GError **error);
+
+
 void grl_media_source_store (GrlMediaSource *source,
                              GrlMediaBox *parent,
                              GrlMedia *media,