1 files changed, 41 insertions, 0 deletions
diff --git a/java/com/google/gerrit/server/update/BatchUpdateOp.java b/java/com/google/gerrit/server/update/BatchUpdateOp.java
new file mode 100644
index 0000000000..87a43a354c
--- /dev/null
+++ b/java/com/google/gerrit/server/update/BatchUpdateOp.java
@@ -0,0 +1,41 @@
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.update;
+
+/**
+ * Interface for {@link BatchUpdate} operations that touch a change.
+ *
+ * <p>Each operation has {@link #updateChange(ChangeContext)} called once the change is read in a
+ * transaction. Ops are associated with updates via {@link
+ * BatchUpdate#addOp(com.google.gerrit.reviewdb.client.Change.Id, BatchUpdateOp)}.
+ *
+ * <p>Usually, a single {@code BatchUpdateOp} instance is only associated with a single change, i.e.
+ * {@code addOp} is only called once with that instance. Additionally, each method in {@code
+ * BatchUpdateOp} is called at most once per {@link BatchUpdate} execution.
+ *
+ * <p>Taken together, these two properties mean an instance may communicate between phases by
+ * storing data in private fields, and a single instance must not be reused.
+ */
+public interface BatchUpdateOp extends RepoOnlyOp {
+  /**
+   * Override this method to modify a change.
+   *
+   * @param ctx context
+   * @return whether anything was changed that might require a write to the metadata storage.
+   */
+  default boolean updateChange(ChangeContext ctx) throws Exception {
+    return false;
+  }
+}