Better detection if a full history sync is needed in a multi-process …

…environment

If our stored 'last_sync' timestamp is newer than the logged 'sync'
action in the history database, the last history update aborted for some reason.

If the 'sync' action from the history database is newer, it means
our in-memory version of the data_cache was outdated
and already updated by another process.

framework/Kolab_Storage/lib/Horde/Kolab/Storage/Data/Query/History/Cache.php

@@ -46,13 +46,27 @@ public function synchronize($params = array())
     {
         $timestamp_key = 'Kolab_History_Sync:'.$this->data->getId();
 
+        /**
+         * Check if we need to do a full synchronization. If our stored 'last_sync'
+         * timestamp is newer than the logged 'sync' action in the history database,
+         * the last history update aborted for some reason.
+         *
+         * If the 'sync' action from the history database is newer, it means
+         * our in-memory version of the data_cache was outdated
+         * and already updated by another process.
+         */
         if (isset($params['last_sync']) &&
             ($params['last_sync'] === false ||
-             $params['last_sync'] !== $this->history->getActionTimestamp($timestamp_key, 'sync'))) {
-            /**
-             * Ignore current changeset and do a full synchronization as we are
-             * out of sync
-             */
+             $params['last_sync'] > $this->history->getActionTimestamp($timestamp_key, 'sync')))
+        {
+            $folder_id = $this->data->getIdParameters();
+            unset($folder_id['type']);
+
+            Horde::log(sprintf('Resyncing Horde_History for Kolab: last_sync: %d, logged sync: %d, folder. %s',
+                           $params['last_sync'],
+                           $this->history->getActionTimestamp($timestamp_key, 'sync'),
+                           print_r($folder_id, true)), 'WARN');
+
             unset($params['changes']);
         }
         // Sync. Base class takes care of UIDVALIDITY changes.