Package org.apache.pulsar.client.api

Interface Consumer<T>

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

All the operations on the consumer instance are thread safe.

  • Method Details

    • getTopic

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

    • getSubscription

      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

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

    • receive

      Message<T> receive() throws PulsarClientException
      Receives a single message.

      This calls blocks until a message is available.

      Returns:
      the received message
      Throws:
      PulsarClientException.AlreadyClosedException - if the consumer was already closed
      PulsarClientException.InvalidConfigurationException - if a message listener was defined in the configuration
      PulsarClientException

    • receiveAsync

      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

    • receive

      Message<T> receive(int timeout, TimeUnit unit) throws PulsarClientException
      Receive a single message.

      Retrieves a message, waiting up to the specified wait time if necessary.

      Parameters:
      timeout - 0 or less means immediate rather than infinite
      unit -
      Returns:
      the received Message or null if no message available before timeout
      Throws:
      PulsarClientException.AlreadyClosedException - if the consumer was already closed
      PulsarClientException.InvalidConfigurationException - if a message listener was defined in the configuration
      PulsarClientException

    • batchReceive

      Messages<T> batchReceive() throws PulsarClientException
      Batch receiving messages.

      This calls blocks until has enough messages or wait timeout, more details to see BatchReceivePolicy.

      Returns:
      messages
      Throws:
      PulsarClientException
      Since:
      2.4.1

    • batchReceiveAsync

      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

    • acknowledge

      void acknowledge(Message<?> message) throws PulsarClientException
      Acknowledge the consumption of a single message.
      Parameters:
      message - The Message to be acknowledged
      Throws:
      PulsarClientException.AlreadyClosedException - if the consumer was already closed
      PulsarClientException

    • acknowledge

      void acknowledge(MessageId messageId) throws PulsarClientException
      Acknowledge the consumption of a single message, identified by its MessageId.
      Parameters:
      messageId - The MessageId to be acknowledged
      Throws:
      PulsarClientException.AlreadyClosedException - if the consumer was already closed
      PulsarClientException

    • acknowledge

      void acknowledge(Messages<?> messages) throws PulsarClientException
      Acknowledge the consumption of Messages.
      Parameters:
      messages - messages
      Throws:
      PulsarClientException.AlreadyClosedException - if the consumer was already closed
      PulsarClientException

    • acknowledge

      void acknowledge(List<MessageId> messageIdList) throws PulsarClientException
      Acknowledge the consumption of a list of message.
      Parameters:
      messageIdList -
      Throws:
      PulsarClientException

    • 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

      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, 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

    • reconsumeLater

      void reconsumeLater(Message<?> message, Map<String,String> customProperties, long delayTime, 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
      customProperties - the custom properties 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

    • reconsumeLater

      void reconsumeLater(Messages<?> messages, long delayTime, TimeUnit unit) throws PulsarClientException
      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
      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

      CompletableFuture<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, 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

      CompletableFuture<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

      CompletableFuture<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

      CompletableFuture<Void> acknowledgeAsync(MessageId messageId, Transaction txn)
      Asynchronously acknowledge the consumption of a single message, it will store in pending ack.

      After the transaction commit, the message will actually ack.

      After the transaction abort, the message will be redelivered.

      Parameters:
      messageId - MessageId to be individual 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 has been acked by another transaction
      PulsarClientException.NotAllowedException - broker don't support transaction don't find batch size in consumer pending ack
      Since:
      2.7.0

    • acknowledgeAsync

      CompletableFuture<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

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

    • reconsumeLaterAsync

      CompletableFuture<Void> reconsumeLaterAsync(Message<?> message, long delayTime, 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

      CompletableFuture<Void> reconsumeLaterAsync(Message<?> message, Map<String,String> customProperties, long delayTime, TimeUnit unit)
      Asynchronously reconsumeLater the consumption of a single message.
      Parameters:
      message - The Message to be reconsumeLater
      customProperties - The custom properties 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

      CompletableFuture<Void> reconsumeLaterAsync(Messages<?> messages, long delayTime, 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

      CompletableFuture<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

      CompletableFuture<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

      CompletableFuture<Void> reconsumeLaterCumulativeAsync(Message<?> message, long delayTime, 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

    • reconsumeLaterCumulativeAsync

      CompletableFuture<Void> reconsumeLaterCumulativeAsync(Message<?> message, Map<String,String> customProperties, long delayTime, 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
      customProperties - The custom properties 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 AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      PulsarClientException

    • closeAsync

      CompletableFuture<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(Function<String,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

      CompletableFuture<Void> seekAsync(Function<String,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

      CompletableFuture<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

      CompletableFuture<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

    • getLastMessageId

      MessageId getLastMessageId() throws PulsarClientException
      Get the last message id available for consume.
      Returns:
      the last message id.
      Throws:
      PulsarClientException

    • getLastMessageIdAsync

      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

      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