聊聊rocketmq的LitePullConsumer

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本文主要研究一下rocketmq的LitePullConsumer

LitePullConsumer

rocketmq-all-4.6.0-source-release/client/src/main/java/org/apache/rocketmq/client/consumer/LitePullConsumer.java

public interface LitePullConsumer {

    void start() throws MQClientException;

    void shutdown();

    void subscribe(final String topic, final String subExpression) throws MQClientException;

    void subscribe(final String topic, final MessageSelector selector) throws MQClientException;

    void unsubscribe(final String topic);

    void assign(Collection<MessageQueue> messageQueues);

    List<MessageExt> poll();

    List<MessageExt> poll(long timeout);

    void seek(MessageQueue messageQueue, long offset) throws MQClientException;

    void pause(Collection<MessageQueue> messageQueues);

    void resume(Collection<MessageQueue> messageQueues);

    boolean isAutoCommit();

    void setAutoCommit(boolean autoCommit);

    Collection<MessageQueue> fetchMessageQueues(String topic) throws MQClientException;

    Long offsetForTimestamp(MessageQueue messageQueue, Long timestamp) throws MQClientException;

    void commitSync();

    Long committed(MessageQueue messageQueue) throws MQClientException;

    void registerTopicMessageQueueChangeListener(String topic,
        TopicMessageQueueChangeListener topicMessageQueueChangeListener) throws MQClientException;
}

• LitePullConsumer接口定义了start、shutdown、subscribe、unsubscribe、assign、poll、seek、pause、resume、isAutoCommit、setAutoCommit、fetchMessageQueues、offsetForTimestamp、commitSync、committed、registerTopicMessageQueueChangeListener方法

DefaultLitePullConsumer

rocketmq-all-4.6.0-source-release/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultLitePullConsumer.java

public class DefaultLitePullConsumer extends ClientConfig implements LitePullConsumer {

    private final DefaultLitePullConsumerImpl defaultLitePullConsumerImpl;

    private String consumerGroup;

    private long brokerSuspendMaxTimeMillis = 1000 * 20;

    private long consumerTimeoutMillisWhenSuspend = 1000 * 30;

    private long consumerPullTimeoutMillis = 1000 * 10;

    private MessageModel messageModel = MessageModel.CLUSTERING;

    private MessageQueueListener messageQueueListener;

    private OffsetStore offsetStore;

    private AllocateMessageQueueStrategy allocateMessageQueueStrategy = new AllocateMessageQueueAveragely();

    private boolean unitMode = false;

    private boolean autoCommit = true;

    private int pullThreadNums = 20;

    private long autoCommitIntervalMillis = 5 * 1000;

    private int pullBatchSize = 10;

    private long pullThresholdForAll = 10000;

    private int consumeMaxSpan = 2000;

    private int pullThresholdForQueue = 1000;

    private int pullThresholdSizeForQueue = 100;

    private long pollTimeoutMillis = 1000 * 5;

    private long topicMetadataCheckIntervalMillis = 30 * 1000;

    public DefaultLitePullConsumer() {
        this(null, MixAll.DEFAULT_CONSUMER_GROUP, null);
    }

    public DefaultLitePullConsumer(final String consumerGroup) {
        this(null, consumerGroup, null);
    }

    public DefaultLitePullConsumer(RPCHook rpcHook) {
        this(null, MixAll.DEFAULT_CONSUMER_GROUP, rpcHook);
    }

    public DefaultLitePullConsumer(final String consumerGroup, RPCHook rpcHook) {
        this(null, consumerGroup, rpcHook);
    }

    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;
    }

    //......
}

• DefaultLitePullConsumer继承了ClientConfig，实现了LitePullConsumer接口，其构造器会创建DefaultLitePullConsumerImpl，LitePullConsumer接口定义的方法，其内部实现都委托给了DefaultLitePullConsumerImpl

小结

rocketmq6.0引入了LitePullConsumer，解决Add lite pull consumer support for RocketMQ #1388，提供了如下功能：

(1) Support consume messages in subscribe way with auto rebalance.
(2) Support consume messages in assign way with no auto rebalance support.
(3) Add seek/commit offset for a specified message queue.

doc

• Add lite pull consumer support for RocketMQ #1388
• [ISSUE #1388]Add lite pull consumer support for RocketMQ #1386
• LitePullConsumer