Interface MessageEvictionStrategy

All Known Implementing Classes:
MessageEvictionStrategySupport, OldestMessageEvictionStrategy, OldestMessageWithLowestPriorityEvictionStrategy, UniquePropertyMessageEvictionStrategy
public interface MessageEvictionStrategy
A strategy for evicting messages from slow consumers.

  • Method Summary

    Modifier and Type
    Method
    Description
    org.apache.activemq.broker.region.MessageReference[]
    evictMessages(LinkedList messages)
    Find the message reference in the given list with oldest messages at the front and newer messages at the end
    int
    getEvictExpiredMessagesHighWatermark()
    REturns the high water mark on which we will eagerly evict expired messages from RAM
    boolean
    isExpiryCheckEnabled()
    Returns whether the eager expired-message scan is enabled.

  • Method Details

    • evictMessages

      org.apache.activemq.broker.region.MessageReference[] evictMessages(LinkedList messages) throws IOException
      Find the message reference in the given list with oldest messages at the front and newer messages at the end
      Returns:
      the message that has been evicted.
      Throws:
      IOException - if an exception occurs such as reading a message content (but should not ever happen as usually all the messages will be in RAM when this method is called).

    • getEvictExpiredMessagesHighWatermark

      int getEvictExpiredMessagesHighWatermark()
      REturns the high water mark on which we will eagerly evict expired messages from RAM

    • isExpiryCheckEnabled

      boolean isExpiryCheckEnabled()
      Returns whether the eager expired-message scan is enabled.

      When false, the O(n) scan inside TopicSubscription.add(MessageReference) is skipped entirely. Set to false when messages carry no TTL, or when the scan cost outweighs the benefit of eagerly evicting expired messages from slow-consumer buffers.

      See MessageEvictionStrategySupport for the default implementation that returns true.

      Returns:
      true if the expiry scan is enabled (default), false if skipped