Merge pull request #1386 from apache/litePullConsumer

[ISSUE #1388]Add lite pull consumer support for RocketMQ

client/src/main/java/org/apache/rocketmq/client/ClientConfig.java

@@ -16,7 +16,9 @@
  */
 package org.apache.rocketmq.client;
 
+import java.util.Collection;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.Set;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.rocketmq.common.UtilAll;
@@ -95,7 +97,6 @@ public class ClientConfig {
         }
     }
 
-
     public String withNamespace(String resource) {
         return NamespaceUtil.wrapNamespace(this.getNamespace(), resource);
     }
@@ -124,9 +125,21 @@ public class ClientConfig {
         if (StringUtils.isEmpty(this.getNamespace())) {
             return queue;
         }
-
         return new MessageQueue(withNamespace(queue.getTopic()), queue.getBrokerName(), queue.getQueueId());
     }
+
+    public Collection<MessageQueue> queuesWithNamespace(Collection<MessageQueue> queues) {
+        if (StringUtils.isEmpty(this.getNamespace())) {
+            return queues;
+        }
+        Iterator<MessageQueue> iter = queues.iterator();
+        while (iter.hasNext()) {
+            MessageQueue queue = iter.next();
+            queue.setTopic(withNamespace(queue.getTopic()));
+        }
+        return queues;
+    }
+
     public void resetClientConfig(final ClientConfig cc) {
         this.namesrvAddr = cc.namesrvAddr;
         this.clientIP = cc.clientIP;
@@ -170,6 +183,7 @@ public class ClientConfig {
 
     /**
      * Domain name mode access way does not support the delimiter(;), and only one domain name can be set.
+     *
      * @param namesrvAddr name server address
      */
     public void setNamesrvAddr(String namesrvAddr) {

client/src/main/java/org/apache/rocketmq/client/Validators.java

@@ -53,14 +53,17 @@ public class Validators {
         if (UtilAll.isBlank(group)) {
             throw new MQClientException("the specified group is blank", null);
         }
+
+        if (group.length() > CHARACTER_MAX_LENGTH) {
+            throw new MQClientException("the specified group is longer than group max length 255.", null);
+        }
+
         if (!regularExpressionMatcher(group, PATTERN)) {
             throw new MQClientException(String.format(
                 "the specified group[%s] contains illegal characters, allowing only %s", group,
                 VALID_PATTERN_STR), null);
         }
-        if (group.length() > CHARACTER_MAX_LENGTH) {
-            throw new MQClientException("the specified group is longer than group max length 255.", null);
-        }
+
     }
 
     /**

client/src/main/java/org/apache/rocketmq/client/consumer/DefaultLitePullConsumer.java

+/*
+ * 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.consumer;
+
+import java.util.Collection;
+import java.util.List;
+
+import org.apache.rocketmq.client.ClientConfig;
+import org.apache.rocketmq.client.consumer.rebalance.AllocateMessageQueueAveragely;
+import org.apache.rocketmq.client.consumer.store.OffsetStore;
+import org.apache.rocketmq.client.exception.MQClientException;
+import org.apache.rocketmq.client.impl.consumer.DefaultLitePullConsumerImpl;
+import org.apache.rocketmq.common.MixAll;
+import org.apache.rocketmq.common.message.MessageExt;
+import org.apache.rocketmq.common.message.MessageQueue;
+import org.apache.rocketmq.common.protocol.heartbeat.MessageModel;
+import org.apache.rocketmq.remoting.RPCHook;
+
+public class DefaultLitePullConsumer extends ClientConfig implements LitePullConsumer {
+
+    private final DefaultLitePullConsumerImpl defaultLitePullConsumerImpl;
+
+    /**
+     * Consumers belonging to the same consumer group share a group id. The consumers in a group then
+     * divides the topic as fairly amongst themselves as possible by establishing that each queue is only
+     * consumed by a single consumer from the group. If all consumers are from the same group, it functions
+     * as a traditional message queue. Each message would be consumed by one consumer of the group only.
+     * When multiple consumer groups exist, the flow of the data consumption model aligns with the traditional
+     * publish-subscribe model. The messages are broadcast to all consumer groups.
+     */
+    private String consumerGroup;
+
+    /**
+     * Long polling mode, the Consumer connection max suspend time, it is not recommended to modify
+     */
+    private long brokerSuspendMaxTimeMillis = 1000 * 20;
+
+    /**
+     * Long polling mode, the Consumer connection timeout(must greater than brokerSuspendMaxTimeMillis), it is not
+     * recommended to modify
+     */
+    private long consumerTimeoutMillisWhenSuspend = 1000 * 30;
+
+    /**
+     * The socket timeout in milliseconds
+     */
+    private long consumerPullTimeoutMillis = 1000 * 10;
+
+    /**
+     * Consumption pattern,default is clustering
+     */
+    private MessageModel messageModel = MessageModel.CLUSTERING;
+    /**
+     * Message queue listener
+     */
+    private MessageQueueListener messageQueueListener;
+    /**
+     * Offset Storage
+     */
+    private OffsetStore offsetStore;
+
+    /**
+     * Queue allocation algorithm
+     */
+    private AllocateMessageQueueStrategy allocateMessageQueueStrategy = new AllocateMessageQueueAveragely();
+    /**
+     * Whether the unit of subscription group
+     */
+    private boolean unitMode = false;
+
+    /**
+     * The flag for auto commit offset
+     */
+    private boolean autoCommit = true;
+
+    /**
+     * Pull thread number
+     */
+    private int pullThreadNums = 20;
+
+    /**
+     * Maximum commit offset interval time in milliseconds.
+     */
+    private long autoCommitIntervalMillis = 5 * 1000;
+
+    /**
+     * Maximum number of messages pulled each time.
+     */
+    private int pullBatchSize = 10;
+
+    /**
+     * Flow control threshold for consume request, each consumer will cache at most 10000 consume requests by default.
+     * Consider the {@code pullBatchSize}, the instantaneous value may exceed the limit
+     */
+    private long pullThresholdForAll = 10000;
+
+    /**
+     * Consume max span offset.
+     */
+    private int consumeMaxSpan = 2000;
+
+    /**
+     * Flow control threshold on queue level, each message queue will cache at most 1000 messages by default, Consider
+     * the {@code pullBatchSize}, the instantaneous value may exceed the limit
+     */
+    private int pullThresholdForQueue = 1000;
+
+    /**
+     * Limit the cached message size on queue level, each message queue will cache at most 100 MiB messages by default,
+     * Consider the {@code pullBatchSize}, the instantaneous value may exceed the limit
+     *
+     * <p>
+     * The size of a message only measured by message body, so it's not accurate
+     */
+    private int pullThresholdSizeForQueue = 100;
+
+    /**
+     * The poll timeout in milliseconds
+     */
+    private long pollTimeoutMillis = 1000 * 5;
+
+    /**
+     * Interval time in in milliseconds for checking changes in topic metadata.
+     */
+    private long topicMetadataCheckIntervalMillis = 30 * 1000;
+
+    /**
+     * Default constructor.
+     */
+    public DefaultLitePullConsumer() {
+        this(null, MixAll.DEFAULT_CONSUMER_GROUP, null);
+    }
+
+    /**
+     * Constructor specifying consumer group.
+     *
+     * @param consumerGroup Consumer group.
+     */
+    public DefaultLitePullConsumer(final String consumerGroup) {
+        this(null, consumerGroup, null);
+    }
+
+    /**
+     * Constructor specifying RPC hook.
+     *
+     * @param rpcHook RPC hook to execute before each remoting command.
+     */
+    public DefaultLitePullConsumer(RPCHook rpcHook) {
+        this(null, MixAll.DEFAULT_CONSUMER_GROUP, rpcHook);
+    }
+
+    /**
+     * Constructor specifying consumer group, RPC hook
+     *
+     * @param consumerGroup Consumer group.
+     * @param rpcHook RPC hook to execute before each remoting command.
+     */
+    public DefaultLitePullConsumer(final String consumerGroup, RPCHook rpcHook) {
+        this(null, consumerGroup, rpcHook);
+    }
+
+    /**
+     * Constructor specifying namespace, consumer group and RPC hook.
+     *
+     * @param consumerGroup Consumer group.
+     * @param rpcHook RPC hook to execute before each remoting command.
+     */
+    public DefaultLitePullConsumer(final String namespace, final String consumerGroup, RPCHook rpcHook) {
+        this.namespace = namespace;
+        this.consumerGroup = consumerGroup;
+        defaultLitePullConsumerImpl = new DefaultLitePullConsumerImpl(this, rpcHook);
+    }
+
+    @Override
+    public void start() throws MQClientException {
+        this.defaultLitePullConsumerImpl.start();
+    }
+
+    @Override
+    public void shutdown() {
+        this.defaultLitePullConsumerImpl.shutdown();
+    }
+
+    @Override
+    public void subscribe(String topic, String subExpression) throws MQClientException {
+        this.defaultLitePullConsumerImpl.subscribe(withNamespace(topic), subExpression);
+    }
+
+    @Override
+    public void subscribe(String topic, MessageSelector messageSelector) throws MQClientException {
+        this.defaultLitePullConsumerImpl.subscribe(withNamespace(topic), messageSelector);
+    }
+
+    @Override
+    public void unsubscribe(String topic) {
+        this.defaultLitePullConsumerImpl.unsubscribe(withNamespace(topic));
+    }
+
+    @Override
+    public void assign(Collection<MessageQueue> messageQueues) {
+        defaultLitePullConsumerImpl.assign(queuesWithNamespace(messageQueues));
+    }
+
+    @Override
+    public List<MessageExt> poll() {
+        return defaultLitePullConsumerImpl.poll(this.getPollTimeoutMillis());
+    }
+
+    @Override
+    public List<MessageExt> poll(long timeout) {
+        return defaultLitePullConsumerImpl.poll(timeout);
+    }
+
+    @Override
+    public void seek(MessageQueue messageQueue, long offset) throws MQClientException {
+        this.defaultLitePullConsumerImpl.seek(queueWithNamespace(messageQueue), offset);
+    }
+
+    @Override
+    public void pause(Collection<MessageQueue> messageQueues) {
+        this.defaultLitePullConsumerImpl.pause(queuesWithNamespace(messageQueues));
+    }
+
+    @Override
+    public void resume(Collection<MessageQueue> messageQueues) {
+        this.defaultLitePullConsumerImpl.resume(queuesWithNamespace(messageQueues));
+    }
+
+    @Override
+    public Collection<MessageQueue> fetchMessageQueues(String topic) throws MQClientException {
+        return this.defaultLitePullConsumerImpl.fetchMessageQueues(withNamespace(topic));
+    }
+
+    @Override
+    public Long offsetForTimestamp(MessageQueue messageQueue, Long timestamp) throws MQClientException {
+        return this.defaultLitePullConsumerImpl.searchOffset(queueWithNamespace(messageQueue), timestamp);
+    }
+
+    @Override
+    public void registerTopicMessageQueueChangeListener(String topic,
+        TopicMessageQueueChangeListener topicMessageQueueChangeListener) throws MQClientException {
+        this.defaultLitePullConsumerImpl.registerTopicMessageQueueChangeListener(withNamespace(topic), topicMessageQueueChangeListener);
+    }
+
+    @Override
+    public void commitSync() {
+        this.defaultLitePullConsumerImpl.commitSync();
+    }
+
+    @Override
+    public Long committed(MessageQueue messageQueue) throws MQClientException {
+        return this.defaultLitePullConsumerImpl.committed(messageQueue);
+    }
+
+    @Override
+    public boolean isAutoCommit() {
+        return autoCommit;
+    }
+
+    @Override
+    public void setAutoCommit(boolean autoCommit) {
+        this.autoCommit = autoCommit;
+    }
+
+    public int getPullThreadNums() {
+        return pullThreadNums;
+    }
+
+    public void setPullThreadNums(int pullThreadNums) {
+        this.pullThreadNums = pullThreadNums;
+    }
+
+    public long getAutoCommitIntervalMillis() {
+        return autoCommitIntervalMillis;
+    }
+
+    public void setAutoCommitIntervalMillis(long autoCommitIntervalMillis) {
+        this.autoCommitIntervalMillis = autoCommitIntervalMillis;
+    }
+
+    public int getPullBatchSize() {
+        return pullBatchSize;
+    }
+
+    public void setPullBatchSize(int pullBatchSize) {
+        this.pullBatchSize = pullBatchSize;
+    }
+
+    public long getPullThresholdForAll() {
+        return pullThresholdForAll;
+    }
+
+    public void setPullThresholdForAll(long pullThresholdForAll) {
+        this.pullThresholdForAll = pullThresholdForAll;
+    }
+
+    public int getConsumeMaxSpan() {
+        return consumeMaxSpan;
+    }
+
+    public void setConsumeMaxSpan(int consumeMaxSpan) {
+        this.consumeMaxSpan = consumeMaxSpan;
+    }
+
+    public int getPullThresholdForQueue() {
+        return pullThresholdForQueue;
+    }
+
+    public void setPullThresholdForQueue(int pullThresholdForQueue) {
+        this.pullThresholdForQueue = pullThresholdForQueue;
+    }
+
+    public int getPullThresholdSizeForQueue() {
+        return pullThresholdSizeForQueue;
+    }
+
+    public void setPullThresholdSizeForQueue(int pullThresholdSizeForQueue) {
+        this.pullThresholdSizeForQueue = pullThresholdSizeForQueue;
+    }
+
+    public AllocateMessageQueueStrategy getAllocateMessageQueueStrategy() {
+        return allocateMessageQueueStrategy;
+    }
+
+    public void setAllocateMessageQueueStrategy(AllocateMessageQueueStrategy allocateMessageQueueStrategy) {
+        this.allocateMessageQueueStrategy = allocateMessageQueueStrategy;
+    }
+
+    public long getBrokerSuspendMaxTimeMillis() {
+        return brokerSuspendMaxTimeMillis;
+    }
+
+    public long getPollTimeoutMillis() {
+        return pollTimeoutMillis;
+    }
+
+    public void setPollTimeoutMillis(long pollTimeoutMillis) {
+        this.pollTimeoutMillis = pollTimeoutMillis;
+    }
+
+    public OffsetStore getOffsetStore() {
+        return offsetStore;
+    }
+
+    public void setOffsetStore(OffsetStore offsetStore) {
+        this.offsetStore = offsetStore;
+    }
+
+    public boolean isUnitMode() {
+        return unitMode;
+    }
+
+    public void setUnitMode(boolean isUnitMode) {
+        this.unitMode = isUnitMode;
+    }
+
+    public MessageModel getMessageModel() {
+        return messageModel;
+    }
+
+    public void setMessageModel(MessageModel messageModel) {
+        this.messageModel = messageModel;
+    }
+
+    public String getConsumerGroup() {
+        return consumerGroup;
+    }
+
+    public MessageQueueListener getMessageQueueListener() {
+        return messageQueueListener;
+    }
+
+    public void setMessageQueueListener(MessageQueueListener messageQueueListener) {
+        this.messageQueueListener = messageQueueListener;
+    }
+
+    public long getConsumerPullTimeoutMillis() {
+        return consumerPullTimeoutMillis;
+    }
+
+    public void setConsumerPullTimeoutMillis(long consumerPullTimeoutMillis) {
+        this.consumerPullTimeoutMillis = consumerPullTimeoutMillis;
+    }
+
+    public long getConsumerTimeoutMillisWhenSuspend() {
+        return consumerTimeoutMillisWhenSuspend;
+    }
+
+    public void setConsumerTimeoutMillisWhenSuspend(long consumerTimeoutMillisWhenSuspend) {
+        this.consumerTimeoutMillisWhenSuspend = consumerTimeoutMillisWhenSuspend;
+    }
+
+    public long getTopicMetadataCheckIntervalMillis() {
+        return topicMetadataCheckIntervalMillis;
+    }
+
+    public void setTopicMetadataCheckIntervalMillis(long topicMetadataCheckIntervalMillis) {
+        this.topicMetadataCheckIntervalMillis = topicMetadataCheckIntervalMillis;
+    }
+}

client/src/main/java/org/apache/rocketmq/client/consumer/DefaultMQPullConsumer.java

@@ -35,9 +35,13 @@ import org.apache.rocketmq.remoting.RPCHook;
 import org.apache.rocketmq.remoting.exception.RemotingException;
 
 /**
- * Default pulling consumer
+ * Default pulling consumer.
+ * This class will be removed in 2022, and a better implementation {@link DefaultLitePullConsumer} is recommend to use
+ * in the scenario of actively pulling messages.
  */
+@Deprecated
 public class DefaultMQPullConsumer extends ClientConfig implements MQPullConsumer {
+
     protected final transient DefaultMQPullConsumerImpl defaultMQPullConsumerImpl;
 
     /**

client/src/main/java/org/apache/rocketmq/client/consumer/LitePullConsumer.java

+/*
+ * 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.consumer;
+
+import java.util.Collection;
+import java.util.List;
+
+import org.apache.rocketmq.client.exception.MQClientException;
+import org.apache.rocketmq.common.message.MessageExt;
+import org.apache.rocketmq.common.message.MessageQueue;
+
+public interface LitePullConsumer {
+
+    /**
+     * Start the consumer
+     */
+    void start() throws MQClientException;
+
+    /**
+     * Shutdown the consumer
+     */
+    void shutdown();
+
+    /**
+     * Subscribe some topic with subExpression
+     *
+     * @param subExpression subscription expression.it only support or operation such as "tag1 || tag2 || tag3" <br> if
+     * null or * expression,meaning subscribe all
+     * @throws MQClientException if there is any client error.
+     */
+    void subscribe(final String topic, final String subExpression) throws MQClientException;
+
+    /**
+     * Subscribe some topic with selector.
+     *
+     * @param selector message selector({@link MessageSelector}), can be null.
+     * @throws MQClientException if there is any client error.
+     */
+    void subscribe(final String topic, final MessageSelector selector) throws MQClientException;
+
+    /**
+     * Unsubscribe consumption some topic
+     *
+     * @param topic Message topic that needs to be unsubscribe.
+     */
+    void unsubscribe(final String topic);
+
+    /**
+     * Manually assign a list of message queues to this consumer. This interface does not allow for incremental
+     * assignment and will replace the previous assignment (if there is one).
+     *
+     * @param messageQueues Message queues that needs to be assigned.
+     */
+    void assign(Collection<MessageQueue> messageQueues);
+
+    /**
+     * Fetch data for the topics or partitions specified using assign API
+     *
+     * @return list of message, can be null.
+     */
+    List<MessageExt> poll();
+
+    /**
+     * Fetch data for the topics or partitions specified using assign API
+     *
+     * @param timeout The amount time, in milliseconds, spent waiting in poll if data is not available. Must not be
+     * negative
+     * @return list of message, can be null.
+     */
+    List<MessageExt> poll(long timeout);
+
+    /**
+     * Overrides the fetch offsets that the consumer will use on the next poll. If this API is invoked for the same
+     * message queue more than once, the latest offset will be used on the next poll(). Note that you may lose data if
+     * this API is arbitrarily used in the middle of consumption.
+     *
+     * @param messageQueue
+     * @param offset
+     */
+    void seek(MessageQueue messageQueue, long offset) throws MQClientException;
+
+    /**
+     * Suspend pulling from the requested message queues.
+     *
+     * Because of the implementation of pre-pull, fetch data in {@link #poll()} will not stop immediately until the
+     * messages of the requested message queues drain.
+     *
+     * Note that this method does not affect message queue subscription. In particular, it does not cause a group
+     * rebalance.
+     *
+     * @param messageQueues Message queues that needs to be paused.
+     */
+    void pause(Collection<MessageQueue> messageQueues);
+
+    /**
+     * Resume specified message queues which have been paused with {@link #pause(Collection)}.
+     *
+     * @param messageQueues Message queues that needs to be resumed.
+     */
+    void resume(Collection<MessageQueue> messageQueues);
+
+    /**
+     * Whether to enable auto-commit consume offset.
+     *
+     * @return true if enable auto-commit, false if disable auto-commit.
+     */
+    boolean isAutoCommit();
+
+    /**
+     * Set whether to enable auto-commit consume offset.
+     *
+     * @param autoCommit Whether to enable auto-commit.
+     */
+    void setAutoCommit(boolean autoCommit);
+
+    /**
+     * Get metadata about the message queues for a given topic.
+     *
+     * @param topic The topic that need to get metadata.
+     * @return collection of message queues
+     * @throws MQClientException if there is any client error.
+     */
+    Collection<MessageQueue> fetchMessageQueues(String topic) throws MQClientException;
+
+    /**
+     * Look up the offsets for the given message queue by timestamp. The returned offset for each message queue is the
+     * earliest offset whose timestamp is greater than or equal to the given timestamp in the corresponding message
+     * queue.
+     *
+     * @param messageQueue Message queues that needs to get offset by timestamp.
+     * @param timestamp
+     * @return offset
+     * @throws MQClientException if there is any client error.
+     */
+    Long offsetForTimestamp(MessageQueue messageQueue, Long timestamp) throws MQClientException;
+
+    /**
+     * Manually commit consume offset.
+     */
+    void commitSync();
+
+    /**
+     * Get the last committed offset for the given message queue.
+     *
+     * @param messageQueue
+     * @return offset, if offset equals -1 means no offset in broker.
+     * @throws MQClientException if there is any client error.
+     */
+    Long committed(MessageQueue messageQueue) throws MQClientException;
+
+    /**
+     * Register a callback for sensing topic metadata changes.
+     *
+     * @param topic The topic that need to monitor.
+     * @param topicMessageQueueChangeListener Callback when topic metadata changes, refer {@link
+     * TopicMessageQueueChangeListener}
+     * @throws MQClientException if there is any client error.
+     */
+    void registerTopicMessageQueueChangeListener(String topic,
+        TopicMessageQueueChangeListener topicMessageQueueChangeListener) throws MQClientException;
+}

client/src/main/java/org/apache/rocketmq/client/consumer/MQPullConsumer.java

@@ -169,4 +169,5 @@ public interface MQPullConsumer extends MQConsumer {
      */
     void sendMessageBack(MessageExt msg, int delayLevel, String brokerName, String consumerGroup)
         throws RemotingException, MQBrokerException, InterruptedException, MQClientException;
+
 }

client/src/main/java/org/apache/rocketmq/client/consumer/MQPullConsumerScheduleService.java

@@ -32,7 +32,9 @@ import org.apache.rocketmq.logging.InternalLogger;
 import org.apache.rocketmq.remoting.RPCHook;
 
 /**
- * Schedule service for pull consumer
+ * Schedule service for pull consumer.
+ * This Consumer will be removed in 2022, and a better implementation {@link
+ * DefaultLitePullConsumer} is recommend to use in the scenario of actively pulling messages.
  */
 public class MQPullConsumerScheduleService {
     private final InternalLogger log = ClientLogger.getLog();
@@ -157,7 +159,7 @@ public class MQPullConsumerScheduleService {
         }
     }
 
-    class PullTaskImpl implements Runnable {
+    public class PullTaskImpl implements Runnable {
         private final MessageQueue messageQueue;
         private volatile boolean cancelled = false;
 

client/src/main/java/org/apache/rocketmq/client/consumer/TopicMessageQueueChangeListener.java

+/*
+ * 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.consumer;
+
+import java.util.Set;
+import org.apache.rocketmq.common.message.MessageQueue;
+
+public interface TopicMessageQueueChangeListener {
+    /**
+     * This method will be invoked in the condition of queue numbers changed, These scenarios occur when the topic is
+     * expanded or shrunk.
+     *
+     * @param messageQueues
+     */
+    void onChanged(String topic, Set<MessageQueue> messageQueues);
+}

client/src/main/java/org/apache/rocketmq/client/consumer/store/RemoteBrokerOffsetStore.java

@@ -117,7 +117,7 @@ public class RemoteBrokerOffsetStore implements OffsetStore {
             return;
 
         final HashSet<MessageQueue> unusedMQ = new HashSet<MessageQueue>();
-        if (!mqs.isEmpty()) {
+
         for (Map.Entry<MessageQueue, AtomicLong> entry : this.offsetTable.entrySet()) {
             MessageQueue mq = entry.getKey();
             AtomicLong offset = entry.getValue();
@@ -138,7 +138,6 @@ public class RemoteBrokerOffsetStore implements OffsetStore {
                 }
             }
         }
-        }
 
         if (!unusedMQ.isEmpty()) {
             for (MessageQueue mq : unusedMQ) {
@@ -187,8 +186,7 @@ public class RemoteBrokerOffsetStore implements OffsetStore {
     }
 
     /**
-     * Update the Consumer Offset in one way, once the Master is off, updated to Slave,
-     * here need to be optimized.
+     * Update the Consumer Offset in one way, once the Master is off, updated to Slave, here need to be optimized.
      */
     private void updateConsumeOffsetToBroker(MessageQueue mq, long offset) throws RemotingException,
         MQBrokerException, InterruptedException, MQClientException {
@@ -196,15 +194,13 @@ public class RemoteBrokerOffsetStore implements OffsetStore {
     }
 
     /**
-     * Update the Consumer Offset synchronously, once the Master is off, updated to Slave,
-     * here need to be optimized.
+     * Update the Consumer Offset synchronously, once the Master is off, updated to Slave, here need to be optimized.
      */
     @Override
     public void updateConsumeOffsetToBroker(MessageQueue mq, long offset, boolean isOneway) throws RemotingException,
         MQBrokerException, InterruptedException, MQClientException {
         FindBrokerResult findBrokerResult = this.mQClientFactory.findBrokerAddressInAdmin(mq.getBrokerName());
         if (null == findBrokerResult) {
-
             this.mQClientFactory.updateTopicRouteInfoFromNameServer(mq.getTopic());
             findBrokerResult = this.mQClientFactory.findBrokerAddressInAdmin(mq.getBrokerName());
         }

client/src/main/java/org/apache/rocketmq/client/impl/consumer/AssignedMessageQueue.java

+/*
+ * 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.impl.consumer;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import org.apache.rocketmq.common.message.MessageQueue;
+
+public class AssignedMessageQueue {
+
+    private final ConcurrentHashMap<MessageQueue, MessageQueueState> assignedMessageQueueState;
+
+    private RebalanceImpl rebalanceImpl;
+
+    public AssignedMessageQueue() {
+        assignedMessageQueueState = new ConcurrentHashMap<MessageQueue, MessageQueueState>();
+    }
+
+    public void setRebalanceImpl(RebalanceImpl rebalanceImpl) {
+        this.rebalanceImpl = rebalanceImpl;
+    }
+
+    public Set<MessageQueue> messageQueues() {
+        return assignedMessageQueueState.keySet();
+    }
+
+    public boolean isPaused(MessageQueue messageQueue) {
+        MessageQueueState messageQueueState = assignedMessageQueueState.get(messageQueue);
+        if (messageQueueState != null) {
+            return messageQueueState.isPaused();
+        }
+        return true;
+    }
+
+    public void pause(Collection<MessageQueue> messageQueues) {
+        for (MessageQueue messageQueue : messageQueues) {
+            MessageQueueState messageQueueState = assignedMessageQueueState.get(messageQueue);
+            if (assignedMessageQueueState.get(messageQueue) != null) {
+                messageQueueState.setPaused(true);
+            }
+        }
+    }
+
+    public void resume(Collection<MessageQueue> messageQueueCollection) {
+        for (MessageQueue messageQueue : messageQueueCollection) {
+            MessageQueueState messageQueueState = assignedMessageQueueState.get(messageQueue);
+            if (assignedMessageQueueState.get(messageQueue) != null) {
+                messageQueueState.setPaused(false);
+            }
+        }
+    }
+
+    public ProcessQueue getProcessQueue(MessageQueue messageQueue) {
+        MessageQueueState messageQueueState = assignedMessageQueueState.get(messageQueue);
+        if (messageQueueState != null) {
+            return messageQueueState.getProcessQueue();
+        }
+        return null;
+    }
+
+    public long getPullOffset(MessageQueue messageQueue) {
+        MessageQueueState messageQueueState = assignedMessageQueueState.get(messageQueue);
+        if (messageQueueState != null) {
+            return messageQueueState.getPullOffset();
+        }
+        return -1;
+    }
+
+    public void updatePullOffset(MessageQueue messageQueue, long offset) {
+        MessageQueueState messageQueueState = assignedMessageQueueState.get(messageQueue);
+        if (messageQueueState != null) {
+            messageQueueState.setPullOffset(offset);
+        }
+    }
+
+    public long getConusmerOffset(MessageQueue messageQueue) {
+        MessageQueueState messageQueueState = assignedMessageQueueState.get(messageQueue);
+        if (messageQueueState != null) {
+            return messageQueueState.getConsumeOffset();
+        }
+        return -1;
+    }
+
+    public void updateConsumeOffset(MessageQueue messageQueue, long offset) {
+        MessageQueueState messageQueueState = assignedMessageQueueState.get(messageQueue);
+        if (messageQueueState != null) {
+            messageQueueState.setConsumeOffset(offset);
+        }
+    }
+
+    public void setSeekOffset(MessageQueue messageQueue, long offset) {
+        MessageQueueState messageQueueState = assignedMessageQueueState.get(messageQueue);
+        if (messageQueueState != null) {
+            messageQueueState.setSeekOffset(offset);
+        }
+    }
+
+    public long getSeekOffset(MessageQueue messageQueue) {
+        MessageQueueState messageQueueState = assignedMessageQueueState.get(messageQueue);
+        if (messageQueueState != null) {
+            return messageQueueState.getSeekOffset();
+        }
+        return -1;
+    }
+
+    public void updateAssignedMessageQueue(String topic, Collection<MessageQueue> assigned) {
+        synchronized (this.assignedMessageQueueState) {
+            Iterator<Map.Entry<MessageQueue, MessageQueueState>> it = this.assignedMessageQueueState.entrySet().iterator();
+            while (it.hasNext()) {
+                Map.Entry<MessageQueue, MessageQueueState> next = it.next();
+                if (next.getKey().getTopic().equals(topic)) {
+                    if (!assigned.contains(next.getKey())) {
+                        next.getValue().getProcessQueue().setDropped(true);
+                        it.remove();
+                    }
+                }
+            }
+            addAssignedMessageQueue(assigned);
+        }
+    }
+
+    public void updateAssignedMessageQueue(Collection<MessageQueue> assigned) {
+        synchronized (this.assignedMessageQueueState) {
+            Iterator<Map.Entry<MessageQueue, MessageQueueState>> it = this.assignedMessageQueueState.entrySet().iterator();
+            while (it.hasNext()) {
+                Map.Entry<MessageQueue, MessageQueueState> next = it.next();
+                if (!assigned.contains(next.getKey())) {
+                    next.getValue().getProcessQueue().setDropped(true);
+                    it.remove();
+                }
+            }
+            addAssignedMessageQueue(assigned);
+        }
+    }
+
+    private void addAssignedMessageQueue(Collection<MessageQueue> assigned) {
+        for (MessageQueue messageQueue : assigned) {
+            if (!this.assignedMessageQueueState.containsKey(messageQueue)) {
+                MessageQueueState messageQueueState;
+                if (rebalanceImpl != null && rebalanceImpl.getProcessQueueTable().get(messageQueue) != null) {
+                    messageQueueState = new MessageQueueState(messageQueue, rebalanceImpl.getProcessQueueTable().get(messageQueue));
+                } else {
+                    ProcessQueue processQueue = new ProcessQueue();
+                    messageQueueState = new MessageQueueState(messageQueue, processQueue);
+                }
+                this.assignedMessageQueueState.put(messageQueue, messageQueueState);
+            }
+        }
+    }
+
+    public void removeAssignedMessageQueue(String topic) {
+        synchronized (this.assignedMessageQueueState) {
+            Iterator<Map.Entry<MessageQueue, MessageQueueState>> it = this.assignedMessageQueueState.entrySet().iterator();
+            while (it.hasNext()) {
+                Map.Entry<MessageQueue, MessageQueueState> next = it.next();
+                if (next.getKey().getTopic().equals(topic)) {
+                    it.remove();
+                }
+            }
+        }
+    }
+
+    private class MessageQueueState {
+        private MessageQueue messageQueue;
+        private ProcessQueue processQueue;
+        private volatile boolean paused = false;
+        private volatile long pullOffset = -1;
+        private volatile long consumeOffset = -1;
+        private volatile long seekOffset = -1;
+
+        private MessageQueueState(MessageQueue messageQueue, ProcessQueue processQueue) {
+            this.messageQueue = messageQueue;
+            this.processQueue = processQueue;
+        }
+
+        public MessageQueue getMessageQueue() {
+            return messageQueue;
+        }
+
+        public void setMessageQueue(MessageQueue messageQueue) {
+            this.messageQueue = messageQueue;
+        }
+
+        public boolean isPaused() {
+            return paused;
+        }
+
+        public void setPaused(boolean paused) {
+            this.paused = paused;
+        }
+
+        public long getPullOffset() {
+            return pullOffset;
+        }
+
+        public void setPullOffset(long pullOffset) {
+            this.pullOffset = pullOffset;
+        }
+
+        public ProcessQueue getProcessQueue() {
+            return processQueue;
+        }
+
+        public void setProcessQueue(ProcessQueue processQueue) {
+            this.processQueue = processQueue;
+        }
+
+        public long getConsumeOffset() {
+            return consumeOffset;
+        }
+
+        public void setConsumeOffset(long consumeOffset) {
+            this.consumeOffset = consumeOffset;
+        }
+
+        public long getSeekOffset() {
+            return seekOffset;
+        }
+
+        public void setSeekOffset(long seekOffset) {
+            this.seekOffset = seekOffset;
+        }
+    }
+}

client/src/main/java/org/apache/rocketmq/client/impl/consumer/DefaultMQPullConsumerImpl.java

@@ -66,6 +66,11 @@ import org.apache.rocketmq.remoting.RPCHook;
 import org.apache.rocketmq.remoting.common.RemotingHelper;
 import org.apache.rocketmq.remoting.exception.RemotingException;
 
+/**
+ * This class will be removed in 2022, and a better implementation {@link DefaultLitePullConsumerImpl} is recommend to use
+ * in the scenario of actively pulling messages.
+ */
+@Deprecated
 public class DefaultMQPullConsumerImpl implements MQConsumerInner {
     private final InternalLogger log = ClientLogger.getLog();
     private final DefaultMQPullConsumer defaultMQPullConsumer;
@@ -74,7 +79,7 @@ public class DefaultMQPullConsumerImpl implements MQConsumerInner {
     private final ArrayList<ConsumeMessageHook> consumeMessageHookList = new ArrayList<ConsumeMessageHook>();
     private final ArrayList<FilterMessageHook> filterMessageHookList = new ArrayList<FilterMessageHook>();
     private volatile ServiceState serviceState = ServiceState.CREATE_JUST;
-    private MQClientInstance mQClientFactory;
+    protected MQClientInstance mQClientFactory;
     private PullAPIWrapper pullAPIWrapper;
     private OffsetStore offsetStore;
     private RebalanceImpl rebalanceImpl = new RebalancePullImpl(this);

client/src/main/java/org/apache/rocketmq/client/impl/consumer/ProcessQueue.java

@@ -26,6 +26,7 @@ import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
+
 import org.apache.rocketmq.client.consumer.DefaultMQPushConsumer;
 import org.apache.rocketmq.client.log.ClientLogger;
 import org.apache.rocketmq.logging.InternalLogger;
@@ -431,4 +432,5 @@ public class ProcessQueue {
     public void setLastConsumeTimestamp(long lastConsumeTimestamp) {
         this.lastConsumeTimestamp = lastConsumeTimestamp;
     }
+
 }

client/src/main/java/org/apache/rocketmq/client/impl/consumer/RebalanceImpl.java

@@ -41,8 +41,10 @@ import org.apache.rocketmq.common.protocol.heartbeat.MessageModel;
 import org.apache.rocketmq.common.protocol.heartbeat.SubscriptionData;
 
 /**
- * Base class for rebalance algorithm
+ * This class will be removed in 2022, and a better implementation {@link RebalanceLitePullImpl} is recommend to use
+ * in the scenario of actively pulling messages.
  */
+@Deprecated
 public abstract class RebalanceImpl {
     protected static final InternalLogger log = ClientLogger.getLog();
     protected final ConcurrentMap<MessageQueue, ProcessQueue> processQueueTable = new ConcurrentHashMap<MessageQueue, ProcessQueue>(64);

client/src/main/java/org/apache/rocketmq/client/impl/consumer/RebalanceLitePullImpl.java

+/*
+ * 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.impl.consumer;
+
+import org.apache.rocketmq.client.consumer.AllocateMessageQueueStrategy;
+import org.apache.rocketmq.client.consumer.MessageQueueListener;
+import org.apache.rocketmq.client.impl.factory.MQClientInstance;
+import org.apache.rocketmq.common.message.MessageQueue;
+import org.apache.rocketmq.common.protocol.heartbeat.ConsumeType;
+import org.apache.rocketmq.common.protocol.heartbeat.MessageModel;
+
+import java.util.List;
+import java.util.Set;
+
+public class RebalanceLitePullImpl extends RebalanceImpl {
+
+    private final DefaultLitePullConsumerImpl litePullConsumerImpl;
+
+    public RebalanceLitePullImpl(DefaultLitePullConsumerImpl litePullConsumerImpl) {
+        this(null, null, null, null, litePullConsumerImpl);
+    }
+
+    public RebalanceLitePullImpl(String consumerGroup, MessageModel messageModel,
+        AllocateMessageQueueStrategy allocateMessageQueueStrategy,
+        MQClientInstance mQClientFactory, DefaultLitePullConsumerImpl litePullConsumerImpl) {
+        super(consumerGroup, messageModel, allocateMessageQueueStrategy, mQClientFactory);
+        this.litePullConsumerImpl = litePullConsumerImpl;
+    }
+
+    @Override
+    public void messageQueueChanged(String topic, Set<MessageQueue> mqAll, Set<MessageQueue> mqDivided) {
+        MessageQueueListener messageQueueListener = this.litePullConsumerImpl.getDefaultLitePullConsumer().getMessageQueueListener();
+        if (messageQueueListener != null) {
+            try {
+                messageQueueListener.messageQueueChanged(topic, mqAll, mqDivided);
+            } catch (Throwable e) {
+                log.error("messageQueueChanged exception", e);
+            }
+        }
+    }
+
+    @Override
+    public boolean removeUnnecessaryMessageQueue(MessageQueue mq, ProcessQueue pq) {
+        this.litePullConsumerImpl.getOffsetStore().persist(mq);
+        this.litePullConsumerImpl.getOffsetStore().removeOffset(mq);
+        return true;
+    }
+
+    @Override
+    public ConsumeType consumeType() {
+        return ConsumeType.CONSUME_ACTIVELY;
+    }
+
+    @Override
+    public void removeDirtyOffset(final MessageQueue mq) {
+        this.litePullConsumerImpl.getOffsetStore().removeOffset(mq);
+    }
+
+    @Override
+    public long computePullFromWhere(MessageQueue mq) {
+        return 0;
+    }
+
+    @Override
+    public void dispatchPullRequest(List<PullRequest> pullRequestList) {
+    }
+
+}

client/src/main/java/org/apache/rocketmq/client/impl/factory/MQClientInstance.java

@@ -246,10 +246,6 @@ public class MQClientInstance {
                     log.info("the client factory [{}] start OK", this.clientId);
                     this.serviceState = ServiceState.RUNNING;
                     break;
-                case RUNNING:
-                    break;
-                case SHUTDOWN_ALREADY:
-                    break;
                 case START_FAILED:
                     throw new MQClientException("The Factory object[" + this.getClientId() + "] has been created before, and failed.", null);
                 default:

example/src/main/java/org/apache/rocketmq/example/simple/LitePullConsumerAssign.java

+/*
+ * 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.example.simple;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import org.apache.rocketmq.client.consumer.DefaultLitePullConsumer;
+import org.apache.rocketmq.common.message.MessageExt;
+import org.apache.rocketmq.common.message.MessageQueue;
+
+public class LitePullConsumerAssign {
+
+    public static volatile boolean running = true;
+
+    public static void main(String[] args) throws Exception {
+        DefaultLitePullConsumer litePullConsumer = new DefaultLitePullConsumer("please_rename_unique_group_name");
+        litePullConsumer.setAutoCommit(false);
+        litePullConsumer.start();
+        Collection<MessageQueue> mqSet = litePullConsumer.fetchMessageQueues("TopicTest");
+        List<MessageQueue> list = new ArrayList<>(mqSet);
+        List<MessageQueue> assignList = new ArrayList<>();
+        for (int i = 0; i < list.size() / 2; i++) {
+            assignList.add(list.get(i));
+        }
+        litePullConsumer.assign(assignList);
+        litePullConsumer.seek(assignList.get(0), 10);
+        try {
+            while (running) {
+                List<MessageExt> messageExts = litePullConsumer.poll();
+                System.out.printf("%s %n", messageExts);
+                litePullConsumer.commitSync();
+            }
+        } finally {
+            litePullConsumer.shutdown();
+        }
+
+    }
+}

example/src/main/java/org/apache/rocketmq/example/simple/LitePullConsumerSubscribe.java

+/*
+ * 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.example.simple;
+
+import java.util.List;
+import org.apache.rocketmq.client.consumer.DefaultLitePullConsumer;
+import org.apache.rocketmq.common.message.MessageExt;
+
+public class LitePullConsumerSubscribe {
+
+    public static volatile boolean running = true;
+
+    public static void main(String[] args) throws Exception {
+        DefaultLitePullConsumer litePullConsumer = new DefaultLitePullConsumer("please_rename_unique_group_name");
+        litePullConsumer.subscribe("TopicTest", "*");
+        litePullConsumer.start();
+        try {
+            while (running) {
+                List<MessageExt> messageExts = litePullConsumer.poll();
+                System.out.printf("%s%n", messageExts);
+            }
+        } finally {
+            litePullConsumer.shutdown();
+        }
+    }
+}