Add progress indicator to batch execution.

Also disable Execute button immediately when clicked.

tailbone/views/batch.py

@@ -647,13 +647,64 @@ class BatchCrud(BaseCrud):
         return self.request.route_url('{0}.refresh'.format(self.route_prefix), uuid=uuid)
 
     def execute(self):
+        """
+        Execute a batch.  Starts a separate thread for the execution, and
+        displays a progress indicator page.
+        """
         batch = self.current_batch()
-        if self.handler.execute(batch):
-            batch.executed = datetime.datetime.utcnow()
-            batch.executed_by = self.request.user
-            self.request.session.flash("Batch was executed successfully.")
-        return HTTPFound(location=self.view_url(batch.uuid))
 
+        key = '{0}.execute'.format(self.batch_class.__tablename__)
+        progress = SessionProgress(self.request, key)
+        thread = Thread(target=self.execute_thread, args=(batch.uuid, progress))
+        thread.start()
+
+        kwargs = {
+            'key': key,
+            'cancel_url': self.view_url(batch.uuid),
+            'cancel_msg': "Batch execution was canceled.",
+            }
+        return render_to_response('/progress.mako', kwargs, request=self.request)
+
+    def execute_thread(self, batch_uuid, progress=None):
+        """
+        Thread target for executing a batch with progress indicator.
+        """
+        # Execute the batch, with progress.  Note that we must use the rattail
+        # session here; can't use tailbone because it has web request
+        # transaction binding etc.
+        session = RatSession()
+        batch = session.query(self.batch_class).get(batch_uuid)
+        try:
+            result = self.handler.execute(batch, progress=progress)
+
+        # If anything goes wrong, rollback and log the error etc.
+        except Exception as error:
+            session.rollback()
+            log.exception("execution failed for batch: {0}".format(batch))
+            session.close()
+            if progress:
+                progress.session.load()
+                progress.session['error'] = True
+                progress.session['error_msg'] = "Batch execution failed: {0}".format(error)
+                progress.session.save()
+
+        # If no error, check result flag (false means user canceled).
+        else:
+            if result:
+                batch.executed = datetime.datetime.utcnow()
+                batch.executed_by = self.request.user
+                session.commit()
+            else:
+                session.rollback()
+            session.refresh(batch)
+            session.close()
+
+            if progress:
+                progress.session.load()
+                progress.session['complete'] = True
+                progress.session['success_url'] = self.view_url(batch.uuid)
+                progress.session.save()
+        
 
 class FileBatchCrud(BatchCrud):
     """