[GitHub] [rocketmq] aaron-ai commented on a diff in pull request #4019: [RIP-37] Add new APIs for consumer

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

aaron-ai commented on code in PR #4019:
URL: https://github.com/apache/rocketmq/pull/4019#discussion_r851893605


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apis/src/main/java/org/apache/rocketmq/apis/consumer/MessageListener.java:
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@@ -0,0 +1,38 @@
+/*
+ * 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.rocketmq.apis.consumer;
+
+import java.util.Collection;
+import org.apache.rocketmq.apis.message.MessageView;
+
+/**
+ * MessageListener is used only for push consumer to process message consumption synchronously.
+ *
+ * <p> Refer to {@link PushConsumer}, push consumer will get message from server
+ * and dispatch the message to backend thread pool which control by parameter threadCount to consumer message concurrently.
+ */
+public interface MessageListener {
+    /**
+     * The callback interface for consume message. Your should process the collection of messageViews
+     * and put committed messageViews to committedList. Push consumer will commit the committedList to server.
+     * If consume message throw unexpected exception, Push consumer also commit the committedList.
+     * @param messageViews are batch of messages which need consume. this message in the collection may come from different topics and the collection size control by setBatchSize(int batchSize) in {@link PushConsumerBuilder}
+     * @param ackList are collection of messages which already consume success and need ack to server.
+     */
+    void consume(Collection<MessageView> messageViews, Collection<MessageView> ackList);

Review Comment:
   > Do we consider replacing `ackList` with `failedList`? The code will look cleaner if all messages succeed.
   
   How do we define this behavior that exception is thrown during the invocation of `MessageListener`? Agree with your opinion to some degree, I feel anxious about user forget to put message into the `ackList` explicitly, which may cause a bulk of retry-messages.



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