Package org.apache.pulsar.client.api

Interface Consumer<T>

  • All Superinterfaces:
    java.lang.AutoCloseable, java.io.Closeable
    @Public
@Stable
public interface Consumer<T>
extends java.io.Closeable
    An interface that abstracts behavior of Pulsar's consumer.

    All the operations on the consumer instance are thread safe.

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      void acknowledge​(java.util.List<MessageId> messageIdList)
      Acknowledge the consumption of a list of message.
      void acknowledge​(Message<?> message)
      Acknowledge the consumption of a single message.
      void acknowledge​(MessageId messageId)
      Acknowledge the consumption of a single message, identified by its MessageId.
      void acknowledge​(Messages<?> messages)
      Acknowledge the consumption of Messages.
      java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeAsync​(java.util.List<MessageId> messageIdList)
      Asynchronously acknowledge the consumption of a list of message.
      java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeAsync​(Message<?> message)
      Asynchronously acknowledge the consumption of a single message.
      java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeAsync​(MessageId messageId)
      Asynchronously acknowledge the consumption of a single message.
      java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeAsync​(MessageId messageId, Transaction txn)
      Asynchronously acknowledge the consumption of a single message, it will store in pending ack.
      java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeAsync​(Messages<?> messages)
      Asynchronously acknowledge the consumption of Messages.
      void acknowledgeCumulative​(Message<?> message)
      Acknowledge the reception of all the messages in the stream up to (and including) the provided message.
      void acknowledgeCumulative​(MessageId messageId)
      Acknowledge the reception of all the messages in the stream up to (and including) the provided message.
      java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeCumulativeAsync​(Message<?> message)
      Asynchronously Acknowledge the reception of all the messages in the stream up to (and including) the provided message.
      java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeCumulativeAsync​(MessageId messageId)
      Asynchronously Acknowledge the reception of all the messages in the stream up to (and including) the provided message.
      java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeCumulativeAsync​(MessageId messageId, Transaction txn)
      Acknowledge the reception of all the messages in the stream up to (and including) the provided message with this transaction, it will store in transaction pending ack.
      Messages<T> batchReceive()
      Batch receiving messages.
      java.util.concurrent.CompletableFuture<Messages<T>> batchReceiveAsync()
      Batch receiving messages.
      void close()
      Close the consumer and stop the broker to push more messages.
      java.util.concurrent.CompletableFuture<java.lang.Void> closeAsync()
      Asynchronously close the consumer and stop the broker to push more messages.
      java.lang.String getConsumerName()
      Get the name of consumer.
      long getLastDisconnectedTimestamp()  
      MessageId getLastMessageId()
      Get the last message id available for consume.
      java.util.concurrent.CompletableFuture<MessageId> getLastMessageIdAsync()
      Get the last message id available for consume.
      ConsumerStats getStats()
      Get statistics for the consumer.
      java.lang.String getSubscription()
      Get a subscription for the consumer.
      java.lang.String getTopic()
      Get a topic for the consumer.
      boolean hasReachedEndOfTopic()
      Return true if the topic was terminated and this consumer has already consumed all the messages in the topic.
      boolean isConnected()  
      void negativeAcknowledge​(Message<?> message)
      Acknowledge the failure to process a single message.
      void negativeAcknowledge​(MessageId messageId)
      Acknowledge the failure to process a single message.
      void negativeAcknowledge​(Messages<?> messages)
      Acknowledge the failure to process Messages.
      void pause()
      Stop requesting new messages from the broker until resume() is called.
      Message<T> receive()
      Receives a single message.
      Message<T> receive​(int timeout, java.util.concurrent.TimeUnit unit)
      Receive a single message.
      java.util.concurrent.CompletableFuture<Message<T>> receiveAsync()
      Receive a single message
      void reconsumeLater​(Message<?> message, long delayTime, java.util.concurrent.TimeUnit unit)
      reconsumeLater the consumption of Messages.
      void reconsumeLater​(Messages<?> messages, long delayTime, java.util.concurrent.TimeUnit unit)
      reconsumeLater the consumption of Messages.
      java.util.concurrent.CompletableFuture<java.lang.Void> reconsumeLaterAsync​(Message<?> message, long delayTime, java.util.concurrent.TimeUnit unit)
      Asynchronously reconsumeLater the consumption of a single message.
      java.util.concurrent.CompletableFuture<java.lang.Void> reconsumeLaterAsync​(Messages<?> messages, long delayTime, java.util.concurrent.TimeUnit unit)
      Asynchronously reconsumeLater the consumption of Messages.
      void reconsumeLaterCumulative​(Message<?> message, long delayTime, java.util.concurrent.TimeUnit unit)
      reconsumeLater the reception of all the messages in the stream up to (and including) the provided message.
      java.util.concurrent.CompletableFuture<java.lang.Void> reconsumeLaterCumulativeAsync​(Message<?> message, long delayTime, java.util.concurrent.TimeUnit unit)
      Asynchronously ReconsumeLater the reception of all the messages in the stream up to (and including) the provided message.
      void redeliverUnacknowledgedMessages()
      Redelivers all the unacknowledged messages.
      void resume()
      Resume requesting messages from the broker.
      void seek​(long timestamp)
      Reset the subscription associated with this consumer to a specific message publish time.
      void seek​(java.util.function.Function<java.lang.String,​java.lang.Object> function)
      Reset the subscription associated with this consumer to a specific message ID or message publish time.
      void seek​(MessageId messageId)
      Reset the subscription associated with this consumer to a specific message id.
      java.util.concurrent.CompletableFuture<java.lang.Void> seekAsync​(long timestamp)
      Reset the subscription associated with this consumer to a specific message publish time.
      java.util.concurrent.CompletableFuture<java.lang.Void> seekAsync​(java.util.function.Function<java.lang.String,​java.lang.Object> function)
      Reset the subscription associated with this consumer to a specific message ID or message publish time asynchronously.
      java.util.concurrent.CompletableFuture<java.lang.Void> seekAsync​(MessageId messageId)
      Reset the subscription associated with this consumer to a specific message id.
      void unsubscribe()
      Unsubscribe the consumer.
      java.util.concurrent.CompletableFuture<java.lang.Void> unsubscribeAsync()
      Asynchronously unsubscribe the consumer.

    • Method Detail

      • getTopic

        java.lang.String getTopic()
        Get a topic for the consumer.
        Returns:
        topic for the consumer

      • getSubscription

        java.lang.String getSubscription()
        Get a subscription for the consumer.
        Returns:
        subscription for the consumer

      • unsubscribe

        void unsubscribe()
          throws PulsarClientException
        Unsubscribe the consumer.

        This call blocks until the consumer is unsubscribed.

        Unsubscribing will the subscription to be deleted and all the data retained can potentially be deleted as well.

        The operation will fail when performed on a shared subscription where multiple consumers are currently connected.

        Throws:
        PulsarClientException - if the operation fails

      • unsubscribeAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> unsubscribeAsync()
        Asynchronously unsubscribe the consumer.
        Returns:
        CompletableFuture to track the operation
        See Also:
        unsubscribe()

      • receiveAsync

        java.util.concurrent.CompletableFuture<Message<T>> receiveAsync()
        Receive a single message

        Retrieves a message when it will be available and completes CompletableFuture with received message.

        receiveAsync() should be called subsequently once returned CompletableFuture gets complete with received message. Else it creates backlog of receive requests in the application.

        The returned future can be cancelled before completion by calling .cancel(false) (CompletableFuture.cancel(boolean)) to remove it from the the backlog of receive requests. Another choice for ensuring a proper clean up of the returned future is to use the CompletableFuture.orTimeout method which is available on JDK9+. That would remove it from the backlog of receive requests if receiving exceeds the timeout.

        Returns:
        CompletableFuture<Message> will be completed when message is available

      • batchReceiveAsync

        java.util.concurrent.CompletableFuture<Messages<T>> batchReceiveAsync()
        Batch receiving messages.

        Retrieves messages when has enough messages or wait timeout and completes CompletableFuture with received messages.

        batchReceiveAsync() should be called subsequently once returned CompletableFuture gets complete with received messages. Else it creates backlog of receive requests in the application.

        The returned future can be cancelled before completion by calling .cancel(false) (CompletableFuture.cancel(boolean)) to remove it from the the backlog of receive requests. Another choice for ensuring a proper clean up of the returned future is to use the CompletableFuture.orTimeout method which is available on JDK9+. That would remove it from the backlog of receive requests if receiving exceeds the timeout.

        Returns:
        messages
        Throws:
        PulsarClientException
        Since:
        2.4.1

      • negativeAcknowledge

        void negativeAcknowledge​(Message<?> message)
        Acknowledge the failure to process a single message.

        When a message is "negatively acked" it will be marked for redelivery after some fixed delay. The delay is configurable when constructing the consumer with ConsumerBuilder.negativeAckRedeliveryDelay(long, TimeUnit).

        This call is not blocking.

        Example of usage: 

        
 while (true) {
     Message<String> msg = consumer.receive();

     try {
          // Process message...

          consumer.acknowledge(msg);
     } catch (Throwable t) {
          log.warn("Failed to process message");
          consumer.negativeAcknowledge(msg);
     }
 }
        Parameters:
        message - The Message to be acknowledged

      • negativeAcknowledge

        void negativeAcknowledge​(MessageId messageId)
        Acknowledge the failure to process a single message.

        When a message is "negatively acked" it will be marked for redelivery after some fixed delay. The delay is configurable when constructing the consumer with ConsumerBuilder.negativeAckRedeliveryDelay(long, TimeUnit).

        This call is not blocking.

        This variation allows to pass a MessageId rather than a Message object, in order to avoid keeping the payload in memory for extended amount of time

        Parameters:
        messageId - The MessageId to be acknowledged
        See Also:
        negativeAcknowledge(Message)

      • negativeAcknowledge

        void negativeAcknowledge​(Messages<?> messages)
        Acknowledge the failure to process Messages.

        When messages is "negatively acked" it will be marked for redelivery after some fixed delay. The delay is configurable when constructing the consumer with ConsumerBuilder.negativeAckRedeliveryDelay(long, TimeUnit).

        This call is not blocking.

        Example of usage: 

        
 while (true) {
     Messages<String> msgs = consumer.batchReceive();

     try {
          // Process message...

          consumer.acknowledge(msgs);
     } catch (Throwable t) {
          log.warn("Failed to process message");
          consumer.negativeAcknowledge(msgs);
     }
 }
        Parameters:
        messages - The Message to be acknowledged

      • reconsumeLater

        void reconsumeLater​(Message<?> message,
                    long delayTime,
                    java.util.concurrent.TimeUnit unit)
             throws PulsarClientException
        reconsumeLater the consumption of Messages.

        When a message is "reconsumeLater" it will be marked for redelivery after some custom delay.

        Example of usage: 

        
 while (true) {
     Message<String> msg = consumer.receive();

     try {
          // Process message...

          consumer.acknowledge(msg);
     } catch (Throwable t) {
          log.warn("Failed to process message");
          consumer.reconsumeLater(msg, 1000 , TimeUnit.MILLISECONDS);
     }
 }
        Parameters:
        message - the Message to be reconsumeLater
        delayTime - the amount of delay before the message will be delivered
        unit - the time unit for the delay
        Throws:
        PulsarClientException.AlreadyClosedException - if the consumer was already closed
        PulsarClientException

      • acknowledgeCumulative

        void acknowledgeCumulative​(Message<?> message)
                    throws PulsarClientException
        Acknowledge the reception of all the messages in the stream up to (and including) the provided message.

        This method will block until the acknowledge has been sent to the broker. After that, the messages will not be re-delivered to this consumer.

        Cumulative acknowledge cannot be used when the consumer type is set to ConsumerShared.

        It's equivalent to calling asyncAcknowledgeCumulative(Message) and waiting for the callback to be triggered.

        Parameters:
        message - The Message to be cumulatively acknowledged
        Throws:
        PulsarClientException.AlreadyClosedException - if the consumer was already closed
        PulsarClientException

      • acknowledgeCumulative

        void acknowledgeCumulative​(MessageId messageId)
                    throws PulsarClientException
        Acknowledge the reception of all the messages in the stream up to (and including) the provided message.

        This method will block until the acknowledge has been sent to the broker. After that, the messages will not be re-delivered to this consumer.

        Cumulative acknowledge cannot be used when the consumer type is set to ConsumerShared.

        It's equivalent to calling asyncAcknowledgeCumulative(MessageId) and waiting for the callback to be triggered.

        Parameters:
        messageId - The MessageId to be cumulatively acknowledged
        Throws:
        PulsarClientException.AlreadyClosedException - if the consumer was already closed
        PulsarClientException

      • acknowledgeCumulativeAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeCumulativeAsync​(MessageId messageId,
                                                                                  Transaction txn)
        Acknowledge the reception of all the messages in the stream up to (and including) the provided message with this transaction, it will store in transaction pending ack.

        After the transaction commit, the end of previous transaction acked message until this transaction acked message will actually ack.

        After the transaction abort, the end of previous transaction acked message until this transaction acked message will be redelivered to this consumer.

        Cumulative acknowledge with transaction only support cumulative ack and now have not support individual and cumulative ack sharing.

        If cumulative ack with a transaction success, we can cumulative ack messageId with the same transaction more than previous messageId.

        It will not be allowed to cumulative ack with a transaction different from the previous one when the previous transaction haven't commit or abort.

        Cumulative acknowledge cannot be used when the consumer type is set to ConsumerShared.

        Parameters:
        messageId - The MessageId to be cumulatively acknowledged
        txn - Transaction the transaction to cumulative ack
        Returns:
        CompletableFuture the future of the ack result
        Throws:
        PulsarClientException.AlreadyClosedException - if the consumer was already closed
        PulsarClientException.TransactionConflictException - if the ack with messageId is less than the messageId in pending ack state or ack with transaction is different from the transaction in pending ack.
        PulsarClientException.NotAllowedException - broker don't support transaction
        Since:
        2.7.0

      • reconsumeLaterCumulative

        void reconsumeLaterCumulative​(Message<?> message,
                              long delayTime,
                              java.util.concurrent.TimeUnit unit)
                       throws PulsarClientException
        reconsumeLater the reception of all the messages in the stream up to (and including) the provided message.
        Parameters:
        message - The message to be cumulatively reconsumeLater
        delayTime - the amount of delay before the message will be delivered
        unit - the time unit for the delay
        Throws:
        PulsarClientException.AlreadyClosedException - if the consumer was already closed
        PulsarClientException

      • acknowledgeAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeAsync​(Message<?> message)
        Asynchronously acknowledge the consumption of a single message.
        Parameters:
        message - The Message to be acknowledged
        Returns:
        a future that can be used to track the completion of the operation

      • acknowledgeAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeAsync​(MessageId messageId)
        Asynchronously acknowledge the consumption of a single message.
        Parameters:
        messageId - The MessageId to be acknowledged
        Returns:
        a future that can be used to track the completion of the operation

      • acknowledgeAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeAsync​(Messages<?> messages)
        Asynchronously acknowledge the consumption of Messages.
        Parameters:
        messages - The Messages to be acknowledged
        Returns:
        a future that can be used to track the completion of the operation

      • acknowledgeAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeAsync​(java.util.List<MessageId> messageIdList)
        Asynchronously acknowledge the consumption of a list of message.
        Parameters:
        messageIdList -
        Returns:

      • reconsumeLaterAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> reconsumeLaterAsync​(Message<?> message,
                                                                           long delayTime,
                                                                           java.util.concurrent.TimeUnit unit)
        Asynchronously reconsumeLater the consumption of a single message.
        Parameters:
        message - The Message to be reconsumeLater
        delayTime - the amount of delay before the message will be delivered
        unit - the time unit for the delay
        Returns:
        a future that can be used to track the completion of the operation

      • reconsumeLaterAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> reconsumeLaterAsync​(Messages<?> messages,
                                                                           long delayTime,
                                                                           java.util.concurrent.TimeUnit unit)
        Asynchronously reconsumeLater the consumption of Messages.
        Parameters:
        messages - The Messages to be reconsumeLater
        delayTime - the amount of delay before the message will be delivered
        unit - the time unit for the delay
        Returns:
        a future that can be used to track the completion of the operation

      • acknowledgeCumulativeAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeCumulativeAsync​(Message<?> message)
        Asynchronously Acknowledge the reception of all the messages in the stream up to (and including) the provided message.

        Cumulative acknowledge cannot be used when the consumer type is set to ConsumerShared.

        Parameters:
        message - The Message to be cumulatively acknowledged
        Returns:
        a future that can be used to track the completion of the operation

      • acknowledgeCumulativeAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> acknowledgeCumulativeAsync​(MessageId messageId)
        Asynchronously Acknowledge the reception of all the messages in the stream up to (and including) the provided message.

        Cumulative acknowledge cannot be used when the consumer type is set to ConsumerShared.

        Parameters:
        messageId - The MessageId to be cumulatively acknowledged
        Returns:
        a future that can be used to track the completion of the operation

      • reconsumeLaterCumulativeAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> reconsumeLaterCumulativeAsync​(Message<?> message,
                                                                                     long delayTime,
                                                                                     java.util.concurrent.TimeUnit unit)
        Asynchronously ReconsumeLater the reception of all the messages in the stream up to (and including) the provided message.

        Cumulative reconsumeLater cannot be used when the consumer type is set to ConsumerShared.

        Parameters:
        message - The message to be cumulatively reconsumeLater
        delayTime - the amount of delay before the message will be delivered
        unit - the time unit for the delay
        Returns:
        a future that can be used to track the completion of the operation

      • getStats

        ConsumerStats getStats()
        Get statistics for the consumer.
        • numMsgsReceived : Number of messages received in the current interval
        • numBytesReceived : Number of bytes received in the current interval
        • numReceiveFailed : Number of messages failed to receive in the current interval
        • numAcksSent : Number of acks sent in the current interval
        • numAcksFailed : Number of acks failed to send in the current interval
        • totalMsgsReceived : Total number of messages received
        • totalBytesReceived : Total number of bytes received
        • totalReceiveFailed : Total number of messages failed to receive
        • totalAcksSent : Total number of acks sent
        • totalAcksFailed : Total number of acks failed to sent
        Returns:
        statistic for the consumer

      • close

        void close()
    throws PulsarClientException
        Close the consumer and stop the broker to push more messages.
        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface java.io.Closeable
        Throws:
        PulsarClientException

      • closeAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> closeAsync()
        Asynchronously close the consumer and stop the broker to push more messages.
        Returns:
        a future that can be used to track the completion of the operation

      • hasReachedEndOfTopic

        boolean hasReachedEndOfTopic()
        Return true if the topic was terminated and this consumer has already consumed all the messages in the topic.

        Please note that this does not simply mean that the consumer is caught up with the last message published by producers, rather the topic needs to be explicitly "terminated".

      • redeliverUnacknowledgedMessages

        void redeliverUnacknowledgedMessages()
        Redelivers all the unacknowledged messages. In Failover mode, the request is ignored if the consumer is not active for the given topic. In Shared mode, the consumers messages to be redelivered are distributed across all the connected consumers. This is a non blocking call and doesn't throw an exception. In case the connection breaks, the messages are redelivered after reconnect.

      • seek

        void seek​(MessageId messageId)
   throws PulsarClientException
        Reset the subscription associated with this consumer to a specific message id.

        The message id can either be a specific message or represent the first or last messages in the topic.

        • MessageId.earliest : Reset the subscription on the earliest message available in the topic
        • MessageId.latest : Reset the subscription on the latest message in the topic

        Note: this operation can only be done on non-partitioned topics. For these, one can rather perform the seek() on the individual partitions.

        Parameters:
        messageId - the message id where to reposition the subscription
        Throws:
        PulsarClientException

      • seek

        void seek​(long timestamp)
   throws PulsarClientException
        Reset the subscription associated with this consumer to a specific message publish time.
        Parameters:
        timestamp - the message publish time where to reposition the subscription
        Throws:
        PulsarClientException

      • seek

        void seek​(java.util.function.Function<java.lang.String,​java.lang.Object> function)
   throws PulsarClientException
        Reset the subscription associated with this consumer to a specific message ID or message publish time.

        The Function input is topic+partition. It returns only timestamp or MessageId.

        The return value is the seek position/timestamp of the current partition. Exception is thrown if other object types are returned.

        If returns null, the current partition will not do any processing. Exception in a partition may affect other partitions.

        Parameters:
        function -
        Throws:
        PulsarClientException

      • seekAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> seekAsync​(java.util.function.Function<java.lang.String,​java.lang.Object> function)
        Reset the subscription associated with this consumer to a specific message ID or message publish time asynchronously.

        The Function input is topic+partition. It returns only timestamp or MessageId.

        The return value is the seek position/timestamp of the current partition. Exception is thrown if other object types are returned.

        If returns null, the current partition will not do any processing. Exception in a partition may affect other partitions.

        Parameters:
        function -
        Returns:

      • seekAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> seekAsync​(MessageId messageId)
        Reset the subscription associated with this consumer to a specific message id.

        The message id can either be a specific message or represent the first or last messages in the topic.

        • MessageId.earliest : Reset the subscription on the earliest message available in the topic
        • MessageId.latest : Reset the subscription on the latest message in the topic

        Note: this operation can only be done on non-partitioned topics. For these, one can rather perform the seek() on the individual partitions.

        Parameters:
        messageId - the message id where to reposition the subscription
        Returns:
        a future to track the completion of the seek operation

      • seekAsync

        java.util.concurrent.CompletableFuture<java.lang.Void> seekAsync​(long timestamp)
        Reset the subscription associated with this consumer to a specific message publish time.
        Parameters:
        timestamp - the message publish time where to reposition the subscription
        Returns:
        a future to track the completion of the seek operation

      • getLastMessageIdAsync

        java.util.concurrent.CompletableFuture<MessageId> getLastMessageIdAsync()
        Get the last message id available for consume.
        Returns:
        a future that can be used to track the completion of the operation.

      • isConnected

        boolean isConnected()
        Returns:
        Whether the consumer is connected to the broker

      • getConsumerName

        java.lang.String getConsumerName()
        Get the name of consumer.
        Returns:
        consumer name.

      • pause

        void pause()
        Stop requesting new messages from the broker until resume() is called. Note that this might cause receive() to block until resume() is called and new messages are pushed by the broker.

      • resume

        void resume()
        Resume requesting messages from the broker.

      • getLastDisconnectedTimestamp

        long getLastDisconnectedTimestamp()
        Returns:
        The last disconnected timestamp of the consumer