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https://issues.apache.org/jira/browse/ROCKETMQ-136?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16174135#comment-16174135
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ASF GitHub Bot commented on ROCKETMQ-136:
-----------------------------------------
Github user dongeforever commented on a diff in the pull request:
https://github.com/apache/incubator-rocketmq/pull/149#discussion_r140136885
--- Diff:
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);
--- End diff --
Let user implement something is expensive.
How about add a method send(msg, shardingkey) or just set one specified
property "SHARDING_KEY" to msg?
@Jaskey
> Provide a handy message queue producer for order message sharding
> -----------------------------------------------------------------
>
> Key: ROCKETMQ-136
> URL: https://issues.apache.org/jira/browse/ROCKETMQ-136
> Project: Apache RocketMQ
> Issue Type: Improvement
> Components: rocketmq-client
> Affects Versions: 4.1.0-incubating
> Reporter: Jaskey Lam
> Assignee: Jaskey Lam
> Priority: Minor
> Fix For: 4.2.0-incubating
>
>
> When order message is needed, users need to provide a message queue selector
> to make sure that the messages which has the same shading key should be sent
> to the same message queue.
> Actually this is a very common scenario with a common solutions, say
> consistent hashing.
> We should provide a handy selector for them to easily do that, what they only
> need to provide is a sharding key.
> A consistent hash selector will meet most of the user's need.
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