idle: added "update" event

Some clients have visual feedback for "database update is running".
Using the "database" idle event is unreliable, because it is only
emitted when the database was actually modified.  This patch adds the
"update" event, which is emitted when the update is started, and again
when the update is finished, disregarding whether it has been
modified.

5 files changed, 20 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index a8828d34..168c3dc4 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,7 @@
 ver 0.16 (20??/??/??)
 * protocol:
   - send song modification time to client
+  - added "update" idle event
 * decoders:
   - ffmpeg: support multiple tags
 * mixers:
diff --git a/doc/protocol.xml b/doc/protocol.xml
index 7ef1dc37..6b2ff587 100644
--- a/doc/protocol.xml
+++ b/doc/protocol.xml
@@ -134,7 +134,16 @@
               <listitem>
                 <para>
                   <returnvalue>database</returnvalue>: the song database
-                  has been updated
+                  has been modified
+                </para>
+              </listitem>
+              <listitem>
+                <para>
+                  <returnvalue>update</returnvalue>: a database update
+                  has started or finished.  If the database was
+                  modified during the update, the
+                  <returnvalue>database</returnvalue> event is also
+                  emitted.
                 </para>
               </listitem>
               <listitem>
diff --git a/src/idle.c b/src/idle.c
index 11b57376..c0bb7a90 100644
--- a/src/idle.c
+++ b/src/idle.c
@@ -40,6 +40,7 @@ static const char *const idle_names[] = {
 	"output",
 	"options",
 	"sticker",
+	"update",
         NULL
 };
 
diff --git a/src/idle.h b/src/idle.h
index a69acabb..c8ed57f7 100644
--- a/src/idle.h
+++ b/src/idle.h
@@ -50,6 +50,9 @@ enum {
 
 	/** a sticker has been modified. */
 	IDLE_STICKER = 0x80,
+
+	/** a database update has started or finished. */
+	IDLE_UPDATE = 0x100,
 };
 
 /**
diff --git a/src/update.c b/src/update.c
index 1088f533..d3e3b765 100644
--- a/src/update.c
+++ b/src/update.c
@@ -822,6 +822,9 @@ directory_update_init(char *path)
 		return next_task_id > update_task_id_max ?  1 : next_task_id;
 	}
 	spawn_update_task(path);
+
+	idle_add(IDLE_UPDATE);
+
 	return update_task_id;
 }
 
@@ -861,6 +864,8 @@ static void update_finished_event(void)
 
 	g_thread_join(update_thr);
 
+	idle_add(IDLE_UPDATE);
+
 	if (modified) {
 		/* send "idle" events */
 		playlistVersionChange(&g_playlist);