[cache/scan] Let notifications from db.c about library updates go through

filescanner/listener instead of directly to the cache

src/library/filescanner.c

@@ -61,6 +61,7 @@
 #include "player.h"
 #include "cache.h"
 #include "artwork.h"
+#include "listener.h"
 #include "commands.h"
 #include "library.h"
 
@@ -107,13 +108,19 @@ struct stacked_dir {
 
 static int inofd;
 static struct event *inoev;
+static struct event *updateev;
 static struct deferred_pl *playlists;
 static struct stacked_dir *dirstack;
 
+// After being told by db that the library was updated through update_trigger(),
+// wait 60 seconds before notifying listeners of LISTENER_DATABASE. This is to
+// avoid bombarding the listeners while there are many db updates, and to make
+// sure they only get a single update (useful for the cache).
+static struct timeval library_update_wait = { 60, 0 };
+
 /* From library.c */
 extern struct event_base *evbase_lib;
 
-
 #ifndef __linux__
 struct deferred_file
 {
@@ -841,6 +848,8 @@ bulk_scan(int flags)
     {
       DPRINTF(E_LOG, L_SCAN, "Bulk library scan completed in %.f sec\n", difftime(end, start));
     }
+
+  listener_notify(LISTENER_DATABASE); // TODO Move to library.c
 }
 
 static int
@@ -1469,6 +1478,21 @@ filescanner_initscan()
   return 0;
 }
 
+static void
+update_trigger_cb(int fd, short what, void *arg)
+{
+  listener_notify(LISTENER_DATABASE);
+}
+
+static enum command_state
+update_trigger(void *arg, int *retval)
+{
+  evtimer_add(updateev, &library_update_wait);
+
+  *retval = 0;
+  return COMMAND_END;
+}
+
 static int
 filescanner_rescan()
 {
@@ -1494,6 +1518,16 @@ filescanner_fullrescan()
   return 0;
 }
 
+// TODO Move to abstraction
+void
+library_update_trigger(void)
+{
+  if (scanning)
+    return;
+
+  commands_exec_async(cmdbase, update_trigger, NULL);
+}
+
 /* Thread: main */
 static int
 filescanner_init(void)
@@ -1501,8 +1535,20 @@ filescanner_init(void)
   int ret;
 
   ret = inofd_event_set();
+  if (ret < 0)
+    {
+      return -1;
+    }
 
-  return ret;
+  updateev = evtimer_new(evbase_lib, update_trigger_cb, NULL);
+  if (!updateev)
+    {
+      DPRINTF(E_FATAL, L_SCAN, "Could not create library update event\n");
+      close(inofd);
+      return -1;
+    }
+
+  return 0;
 }
 
 /* Thread: main */

src/library/filescanner.h

@@ -31,4 +31,7 @@ void
 scan_itunes_itml(char *file);
 #endif
 
+void
+library_update_trigger(void); // TODO Move to library abstraction
+
 #endif /* !__FILESCANNER_H__ */