[rygel] media-export: Avoid extra database query

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit d588393e11194761ae26e9548d6f39e80e492915
Author: Jens Georg <mail jensge org>
Date:   Sun Aug 1 15:37:56 2010 +0200

    media-export: Avoid extra database query
    
    When checking for change conditions, avoid extra query for size-check.
    Since push_if_changed_or_unknown will be called for MediaItems only,
    there is no need for a left-outer join in the query.

 .../rygel-media-export-harvesting-task.vala        |   19 ++++---------------
 .../rygel-media-export-media-cache.vala            |    6 +++++-
 .../rygel-media-export-sql-factory.vala            |    4 +++-
 3 files changed, 12 insertions(+), 17 deletions(-)
---
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 d9d6410..ffe38aa 100644
--- a/src/plugins/media-export/rygel-media-export-harvesting-task.vala
+++ b/src/plugins/media-export/rygel-media-export-harvesting-task.vala
@@ -126,28 +126,17 @@ public class Rygel.MediaExport.HarvestingTask : Rygel.StateMachine, GLib.Object
                                              FileInfo   info) {
         var id = MediaCache.get_id (file);
         int64 timestamp;
+        int64 size;
         try {
-            if (this.cache.exists (id, out timestamp)) {
+            if (this.cache.exists (id, out timestamp, out size)) {
                 int64 mtime = (int64) info.get_attribute_uint64 (
                                         FILE_ATTRIBUTE_TIME_MODIFIED);
 
-                // Doing the check for mtime here first because the check for
-                // size involves a database query and if the size has changed,
-                // the mtime probably has as well (unfortunatly enough
-                // exceptions exist)
-                if (mtime > timestamp) {
+                if (mtime > timestamp ||
+                    info.get_size () != size) {
                     this.files.offer (file);
 
                     return true;
-                } else {
-                    // check size
-                    var size = info.get_size ();
-                    var item = cache.get_item (id);
-                    if (item.size != size) {
-                        this.files.offer (file);
-
-                        return true;
-                    }
                 }
             } else {
                 this.files.offer (file);
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 8aedae7..54c427a 100644
--- a/src/plugins/media-export/rygel-media-export-media-cache.vala
+++ b/src/plugins/media-export/rygel-media-export-media-cache.vala
@@ -154,22 +154,26 @@ public class Rygel.MediaExport.MediaCache : Object {
     }
 
     public bool exists (string    object_id,
-                        out int64 timestamp) throws DatabaseError {
+                        out int64 timestamp,
+                        out int64 size) throws DatabaseError {
         bool exists = false;
         GLib.Value[] values = { object_id };
         int64 tmp_timestamp = 0;
+        int64 tmp_size = 0;
 
         this.db.exec (this.sql.make (SQLString.EXISTS),
                       values,
                       (statement) => {
                           exists = statement.column_int (0) == 1;
                           tmp_timestamp = statement.column_int64 (1);
+                          tmp_size = statement.column_int64 (2);
 
                           return false;
                       });
 
         // out parameters are not allowed to be captured
         timestamp = tmp_timestamp;
+        size = tmp_size;
 
         return exists;
     }
diff --git a/src/plugins/media-export/rygel-media-export-sql-factory.vala b/src/plugins/media-export/rygel-media-export-sql-factory.vala
index 25eefd4..06c387f 100644
--- a/src/plugins/media-export/rygel-media-export-sql-factory.vala
+++ b/src/plugins/media-export/rygel-media-export-sql-factory.vala
@@ -143,7 +143,9 @@ internal class Rygel.MediaExport.SQLFactory : Object {
     "SELECT COUNT(upnp_id) FROM Object WHERE Object.parent = ?";
 
     private const string OBJECT_EXISTS_STRING =
-    "SELECT COUNT(upnp_id), timestamp FROM Object WHERE Object.upnp_id = ?";
+    "SELECT COUNT(upnp_id), timestamp, m.size FROM Object " +
+        "JOIN meta_data m ON m.object_fk = upnp_id " +
+        "WHERE Object.upnp_id = ?";
 
     private const string GET_CHILD_ID_STRING =
     "SELECT upnp_id FROM OBJECT WHERE parent = ?";