Merge pull request #1329 from Alfresco/feature/MNT-22712_MetadataTrackerNPE_20x

MNT-22712 Fix metadata tracker NPE

search-services/alfresco-search/src/main/java/org/alfresco/solr/tracker/AbstractTracker.java

@@ -222,18 +222,7 @@ public abstract class AbstractTracker implements Tracker
                 assert(assertTrackerStateRemainsNull());
             }
 
-            if(this.state == null)
+            updateTrackerState(iterationId);
-            {
-                this.state = getTrackerState();
-
-                LOGGER.debug("[{} / {} / {}]  Global Tracker State set to: {}", coreName, trackerId, iterationId, this.state.toString());
-                this.state.setRunning(true);
-            }
-            else
-            {
-                continueState();
-                this.state.setRunning(true);
-            }
 
             infoSrv.registerTrackerThread();
 
@@ -275,6 +264,21 @@ public abstract class AbstractTracker implements Tracker
         }
     }
 
+    private synchronized void updateTrackerState(String iterationId) {
+        if(this.state == null)
+        {
+            this.state = getTrackerState();
+
+            LOGGER.debug("[{} / {} / {}]  Global Tracker State set to: {}", coreName, trackerId, iterationId, this.state.toString());
+        }
+        else
+        {
+            continueState();
+        }
+
+        this.state.setRunning(true);
+    }
+
     /**
      * At the end of the tracking method, the {@link TrackerState} should be turned off.
      * However, during a rollback (that could be started by another tracker) the {@link TrackerState} instance