From 732ec9239a59525d179beac35bad5f56c5db1ced Mon Sep 17 00:00:00 2001
From: Craig Markwardt <cbmarkwardt+github@gmail.com>
Date: Wed, 24 Aug 2011 00:47:27 -0400
Subject: [PATCH] Enable dynamic library updating

Modifications to db.c to enable the DAAP server to determine when
the media library has changed, and notify clients via an update.
Updates should show up to clients within 10 seconds.

Tested on iTunes 9.2.1
---
 src/db.c         | 19 +++++++++++++++++++
 src/db.h         |  2 ++
 src/httpd_daap.c |  6 ------
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/src/db.c b/src/db.c
index 57a93dea..4a682e75 100644
--- a/src/db.c
+++ b/src/db.c
@@ -268,6 +268,15 @@ static const char *sort_clause[] =
 static char *db_path;
 static __thread sqlite3 *hdl;
 
+/*
+ * Starting database revision.  A number of 2 ensures that remote clients
+ * always get a fresh update. (they start with 1)
+ */
+static int db_rev = 2;
+/* Update the database revision number.  Don't worry about multiple threads,
+   we don't care about an accurate count of the number of revisions, just
+   that revisions have occurred or not.  */
+#define db_rev_increment() { db_rev ++; }
 
 /* Forward */
 static int
@@ -279,6 +288,14 @@ db_smartpl_count_items(const char *smartpl_query);
 struct playlist_info *
 db_pl_fetch_byid(int id);
 
+/*
+ * db_revision_number - return current database revision number to external modules
+ */
+int 
+db_revision_number()
+{
+  return db_rev;
+}
 
 char *
 db_escape_string(const char *str)
@@ -2007,6 +2024,7 @@ db_file_add(struct media_file_info *mfi)
     }
 
   sqlite3_free(query);
+  db_rev_increment();
 
   return 0;
 
@@ -2081,6 +2099,7 @@ db_file_update(struct media_file_info *mfi)
     }
 
   sqlite3_free(query);
+  db_rev_increment();
 
   return 0;
 
diff --git a/src/db.h b/src/db.h
index b3468a3b..87c1493f 100644
--- a/src/db.h
+++ b/src/db.h
@@ -470,6 +470,8 @@ db_watch_enum_end(struct watch_enum *we);
 int
 db_watch_enum_fetchwd(struct watch_enum *we, uint32_t *wd);
 
+int 
+db_revision_number(void);
 
 int
 db_perthread_init(void);
diff --git a/src/httpd_daap.c b/src/httpd_daap.c
index 637c0b8f..d3af6270 100644
--- a/src/httpd_daap.c
+++ b/src/httpd_daap.c
@@ -65,12 +65,6 @@ extern struct event_base *evbase_httpd;
 /* How often we poll for database changes */
 #define DAAP_UPDATE_MONITOR_TIMEOUT 10
 
-/* XXX Workaround before adding revision support in db.c;
-   Client will not get dynamic updates.  The state of the
-   database at the time of connection is all the client
-   gets. */
-#define db_revision_number() (2)
-
 struct uri_map {
   regex_t preg;
   char *regexp;