Package org.apache.qpid.protonj2.client

Enum NextReceiverPolicy

java.lang.Object
java.lang.Enum<NextReceiverPolicy>
org.apache.qpid.protonj2.client.NextReceiverPolicy
All Implemented Interfaces:
Serializable, Comparable<NextReceiverPolicy>
public enum NextReceiverPolicy extends Enum<NextReceiverPolicy>
Determines the behavior of a Session when the next receiver method is called on that session. Each policy provides a contract on the ordering of returned receivers from the next receiver API when there are receivers with locally queued deliveries. When there are no Receiver instances that have locally queued deliveries the next receive API will return the next receiver to receive a complete incoming delivery unless a timeout was given and that time period expires in which case it will return null.

Should the user perform receive calls on a Receiver directly in multiple threads the behavior of the next receiver API is undefined and it becomes possible that the resulting receiver returned from that API will have no actual pending deliveries due to a race. In most cases the caller can mitigate some risk by using the Receiver.tryReceive() API and accounting for a null result.

  • Enum Constant Summary

    Enum Constants
    Enum Constant
    Description
    FIRST_AVAILABLE
    Examines the list of currently open receivers in the session and returns the first receiver found with an available delivery.
    LARGEST_BACKLOG
    Examines the list of currently open receivers in the session and returns the receiver with the largest backlog of available deliveries.
    RANDOM
    Examines the list of currently open receivers in the session and returns a random selection from the set of receivers that have a pending delivery immediately available.
    ROUND_ROBIN
    Examines the list of currently open receivers in the session and returns the next receiver that has a pending delivery that follows the previously returned receiver (if any) otherwise the first receiver in the session with a pending delivery is returned.
    SMALLEST_BACKLOG
    Examines the list of currently open receivers in the session and returns the receiver with the smallest backlog of available deliveries.

  • Method Summary

    Modifier and Type
    Method
    Description
    static NextReceiverPolicy
    valueOf(String name)
    Returns the enum constant of this type with the specified name.
    static NextReceiverPolicy[]
    values()
    Returns an array containing the constants of this enum type, in the order they are declared.

    Methods inherited from class java.lang.Enum

    clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

    Methods inherited from class java.lang.Object

    getClass, notify, notifyAll, wait, wait, wait

  • Enum Constant Details

    • ROUND_ROBIN

      public static final NextReceiverPolicy ROUND_ROBIN
      Examines the list of currently open receivers in the session and returns the next receiver that has a pending delivery that follows the previously returned receiver (if any) otherwise the first receiver in the session with a pending delivery is returned. The order of receivers returned will likely be creation order however the implementation is not required to follow this pattern so the caller should not be coded to rely on that ordering.

    • RANDOM

      public static final NextReceiverPolicy RANDOM
      Examines the list of currently open receivers in the session and returns a random selection from the set of receivers that have a pending delivery immediately available. This provides a means of selecting receivers which is not prone to sticking to a highly active receiver which can starve out other receivers which receive only limited traffic.

    • FIRST_AVAILABLE

      public static final NextReceiverPolicy FIRST_AVAILABLE
      Examines the list of currently open receivers in the session and returns the first receiver found with an available delivery. This can result in starvation if that receiver has a continuous feed of new deliveries from the remote as it will be repeatedly selected by the next receiver API.

    • LARGEST_BACKLOG

      public static final NextReceiverPolicy LARGEST_BACKLOG
      Examines the list of currently open receivers in the session and returns the receiver with the largest backlog of available deliveries. This can result in starvation if that receiver has a continuous feed of new deliveries from the remote as it will likely be repeatedly selected by the next receiver API.

    • SMALLEST_BACKLOG

      public static final NextReceiverPolicy SMALLEST_BACKLOG
      Examines the list of currently open receivers in the session and returns the receiver with the smallest backlog of available deliveries.

  • Method Details

    • values

      public static NextReceiverPolicy[] values()
      Returns an array containing the constants of this enum type, in the order they are declared.
      Returns:
      an array containing the constants of this enum type, in the order they are declared

    • valueOf

      public static NextReceiverPolicy valueOf(String name)
      Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
      Parameters:
      name - the name of the enum constant to be returned.
      Returns:
      the enum constant with the specified name
      Throws:
      IllegalArgumentException - if this enum type has no constant with the specified name
      NullPointerException - if the argument is null