[GitHub] Jaskey commented on a change in pull request #149: [ROCKETMQ-136]Provide a handy message queue producer for order message sharding

[gi...@git.apache.org]

Jaskey commented on a change in pull request #149: [ROCKETMQ-136]Provide a handy message queue producer for order message sharding
URL: https://github.com/apache/incubator-rocketmq/pull/149#discussion_r140944262
 
 

 ##########
 File path: client/src/main/java/org/apache/rocketmq/client/producer/OrderMQProducer.java
 ##########
 @@ -0,0 +1,118 @@
+/*
+ * 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.client.producer;
+
+import org.apache.rocketmq.client.exception.MQBrokerException;
+import org.apache.rocketmq.client.exception.MQClientException;
+import org.apache.rocketmq.client.producer.selector.SelectMessageQueueByConsistentHash;
+import org.apache.rocketmq.common.MixAll;
+import org.apache.rocketmq.common.message.Message;
+import org.apache.rocketmq.remoting.RPCHook;
+import org.apache.rocketmq.remoting.exception.RemotingException;
+
+/**
+ * A simple Order message Producer Facade to send order messages, which is a subclass of DefaultMQProducer <br>
+ *
+ * The messages with the same value returned from method {@code shardingKey} will try to be sent to the same message
+ * queue, user must extend this class and implement the abstract method shardingKey.
+ *
+ * <p> Please notice that this can not be guaranteed when the numbers of messages are changed.<br> When the number of
+ * message queues change before all the messages with the same sharding key sent successfully, the messages queue picked
+ * to sent to may be changed.<br> However, only as few as messages will be influenced thanks to the default selector
+ * backed by consistent hash algorithm. </p>
+ */
+public abstract class OrderMQProducer extends DefaultMQProducer {
+    private MessageQueueSelector selector = new SelectMessageQueueByConsistentHash();
+
+    public OrderMQProducer() {
+    }
+
+    /**
+     * Constructor specifying producer group.
+     *
+     * @param producerGroup Producer group, see the name-sake field.
+     */
+    public OrderMQProducer(String producerGroup) {
+        super(producerGroup);
+    }
+
+    /**
+     * Constructor specifying both producer group and RPC hook.
+     *
+     * @param producerGroup Producer group, see the name-sake field.
+     * @param rpcHook RPC hook to execute per each remoting command execution.
+     */
+    public OrderMQProducer(final String producerGroup, RPCHook rpcHook) {
+        super(producerGroup, rpcHook);
+    }
+
+    /**
+     * Constructor specifying the RPC hook.
+     *
+     * @param rpcHook RPC hook to execute per each remoting command execution.
+     */
+    public OrderMQProducer(RPCHook rpcHook) {
+        this(MixAll.DEFAULT_PRODUCER_GROUP, rpcHook);
+    }
+
+    public MessageQueueSelector getSelector() {
+        return selector;
+    }
+
+    public void setSelector(MessageQueueSelector selector) {
+        this.selector = selector;
+    }
+
+    /**
+     * Callback method to return a unique sharding key for each messages. The sharding key will be used to pick a
+     * message queue. The messages with the same message queue will be sent to the same message queues.
+     *
+     * @param msg the message which is ready to send
+     * @return the sharding key which will be used to select message queue
+     */
+    abstract String shardingKey(Message msg);
 
 Review comment:
   hmm, this should be a way. But when user want to send order messages, which should be in a common scene, say they want to send the msgs for ordering and paying. They must have a order number for every batch of messages, actually it is easy for them to provide a instance for each kind of messages needs ordering. Say, for payment messages , they may have one instance, for another kind of messages , they may have another one.
   
   But of course, we may discuss more to make this api more friendly.
 
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services