Turn gtasks sync v2 provider into a real singleton, and synchronize on the instance for certain methods

astrid/plugin-src/com/todoroo/astrid/gtasks/GtasksBackgroundService.java

@@ -14,7 +14,7 @@ public class GtasksBackgroundService extends SyncV2BackgroundService {
 
     @Override
     protected SyncV2Provider getSyncProvider() {
-        return new GtasksSyncV2Provider();
+        return GtasksSyncV2Provider.getInstance();
     }
 
     @Override

astrid/plugin-src/com/todoroo/astrid/gtasks/GtasksPreferences.java

@@ -50,7 +50,7 @@ public class GtasksPreferences extends SyncProviderPreferences {
 
     @Override
     public void logOut() {
-        new GtasksSyncV2Provider().signOut();
+        GtasksSyncV2Provider.getInstance().signOut();
     }
 
     @Override

astrid/plugin-src/com/todoroo/astrid/gtasks/sync/GtasksSyncV2Provider.java

@@ -60,6 +60,18 @@ public class GtasksSyncV2Provider extends SyncV2Provider {
         AstridDependencyInjector.initialize();
     }
 
+    private static GtasksSyncV2Provider instance = null;
+
+    protected GtasksSyncV2Provider() {
+        // prevent multiple sync providers
+    }
+
+    public synchronized static GtasksSyncV2Provider getInstance() {
+        if(instance == null)
+            instance = new GtasksSyncV2Provider();
+        return instance;
+    }
+
     @Override
     public String getName() {
         return ContextManager.getString(R.string.gtasks_GPr_header);
@@ -122,8 +134,9 @@ public class GtasksSyncV2Provider extends SyncV2Provider {
         }).start();
     }
 
-    private void pushUpdated(GtasksInvoker invoker, SyncResultCallback callback) {
-        TodorooCursor<Task> queued = taskService.query(Query.select(Task.PROPERTIES).join(Join.left(Metadata.TABLE, Task.ID.eq(Metadata.TASK))).where(
+    private synchronized void pushUpdated(GtasksInvoker invoker, SyncResultCallback callback) {
+        TodorooCursor<Task> queued = taskService.query(Query.select(Task.PROPERTIES).
+                join(Join.left(Metadata.TABLE, Task.ID.eq(Metadata.TASK))).where(
                 Criterion.or(
                         Criterion.and(MetadataCriteria.withKey(GtasksMetadata.METADATA_KEY),
                                 Task.MODIFICATION_DATE.gt(GtasksMetadata.LAST_SYNC)),

astrid/src/com/todoroo/astrid/service/SyncV2Service.java

@@ -23,9 +23,9 @@ public class SyncV2Service {
      * there is enough interest, the Astrid team could create an interface
      * for responding to sync requests through this new API.
      */
-    private final SyncV2Provider[] providers = new SyncV2Provider[] {
+    private static final SyncV2Provider[] providers = new SyncV2Provider[] {
             new ActFmSyncV2Provider(),
-            new GtasksSyncV2Provider()
+            GtasksSyncV2Provider.getInstance()
     };
 
     /**

tests-sync/src/com/todoroo/astrid/gtasks/GtasksNewSyncTest.java

@@ -473,7 +473,7 @@ public class GtasksNewSyncTest extends DatabaseTestCase {
 
     //Perform a synchronization
     private void whenInvokeSync() {
-        new GtasksSyncV2Provider().synchronizeActiveTasks(true, new SyncResultCallbackAdapter() {
+        GtasksSyncV2Provider.getInstance().synchronizeActiveTasks(true, new SyncResultCallbackAdapter() {
         	@Override
         	public void finished() {
         		synchronized(GtasksNewSyncTest.this) {