[GitHub] [samza] xinyuiscool commented on a diff in pull request #1642: SAMZA-2769: [PipelineDrain] Add drainMode to DrainNotification

[GitBox <gi...@apache.org>]

xinyuiscool commented on code in PR #1642:
URL: https://github.com/apache/samza/pull/1642#discussion_r1024576429


##########
samza-api/src/main/java/org/apache/samza/drain/DrainMode.java:
##########
@@ -0,0 +1,31 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.samza.drain;
+
+/**
+ * Defines the type of drain operation.
+ * */
+public enum DrainMode {
+  /**
+   * Simple drain mode is the default behavior of the drain operation.
+   * All intermediate streams and any samza managed state will be drained and the pipeline will be gracefully shutdown
+   * as a result. User state will not be drained.
+   * */
+  SIMPLE;

Review Comment:
   As your javadoc suggests, let's call it default?



##########
samza-api/src/main/java/org/apache/samza/drain/DrainNotification.java:
##########
@@ -35,9 +35,23 @@ public class DrainNotification {
    */
   private final String runId;
 
-  public DrainNotification(UUID uuid, String runId) {
+  /***/
+  private final DrainMode drainMode;
+
+  public DrainNotification(UUID uuid, String runId, DrainMode drainMode) {
+    Preconditions.checkNotNull(uuid);
+    Preconditions.checkNotNull(runId);
+    Preconditions.checkNotNull(drainMode);
     this.uuid = uuid;
     this.runId = runId;
+    this.drainMode = drainMode;
+  }
+
+  /**
+   * Creates a DrainNotification in {@link DrainMode#SIMPLE} mode.
+   * */
+  public static DrainNotification simple(UUID uuid, String runId) {

Review Comment:
   let's just call it create(). We can have another variant factory method for create with other mode.



##########
samza-core/src/main/java/org/apache/samza/drain/DrainUtils.java:
##########
@@ -54,44 +74,34 @@ private DrainUtils() {
    * @return generated uuid for the DrainNotification
    */
   @VisibleForTesting
-  public static UUID writeDrainNotification(MetadataStore metadataStore, String runId) {
+  public static UUID writeSimpleDrainNotification(MetadataStore metadataStore, String runId) {

Review Comment:
   If this is only used for testing, we should be able to test the variant of using DrainNotification. If not user-facing, let's get rid of it.



##########
samza-core/src/main/java/org/apache/samza/drain/DrainUtils.java:
##########
@@ -54,44 +74,34 @@ private DrainUtils() {
    * @return generated uuid for the DrainNotification
    */
   @VisibleForTesting
-  public static UUID writeDrainNotification(MetadataStore metadataStore, String runId) {
+  public static UUID writeSimpleDrainNotification(MetadataStore metadataStore, String runId) {
     Preconditions.checkArgument(metadataStore != null, "MetadataStore cannot be null.");
     Preconditions.checkArgument(!Strings.isNullOrEmpty(runId), "runId should be non-null.");
     LOG.info("Attempting to write DrainNotification to metadata-store for the deployment ID {}", runId);
+    final UUID uuid = UUID.randomUUID();
+    final DrainNotification message = DrainNotification.simple(uuid, runId);
+    return writeDrainNotification(metadataStore, message);
+  }
+
+  /**
+   * Writes a {@link DrainNotification} to an underlying metadata store.
+   * */
+  @VisibleForTesting
+  public static UUID writeDrainNotification(MetadataStore metadataStore, DrainNotification drainNotification) {

Review Comment:
   If it's only used for testing, please make it package private.



##########
samza-core/src/main/java/org/apache/samza/drain/DrainUtils.java:
##########
@@ -45,6 +45,26 @@ public class DrainUtils {
   private DrainUtils() {
   }
 
+  /**
+   * Writes a {@link DrainNotification} to the underlying metastore. This method should be used by external controllers
+   * to issue a DrainNotification to the JobCoordinator and Samza Containers.
+   * @param metadataStore Metadata store to write drain notification to.
+   *
+   * @return generated uuid for the DrainNotification
+   */
+  public static UUID writeSimpleDrainNotification(MetadataStore metadataStore) {

Review Comment:
   Let's just use writeDrainNotification(). We can overload it with other parameters later.



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