Class ConcurrencyThrottleSupport

java.lang.Object
org.springframework.util.ConcurrencyThrottleSupport
All Implemented Interfaces:
Serializable
Direct Known Subclasses:
ConcurrencyThrottleInterceptor, SyncTaskExecutor
public abstract class ConcurrencyThrottleSupport extends Object implements Serializable
Support class for throttling concurrent access to a specific resource.

Designed for use as a base class, with the subclass invoking the beforeAccess() and afterAccess() methods at appropriate points of its workflow. Note that afterAccess should usually be called in a finally block!

The default concurrency limit of this support class is UNBOUNDED_CONCURRENCY. Subclasses may override this default; check the javadoc of the concrete class that you're using.

Since:
1.2.5
Author:
Juergen Hoeller
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected org.apache.commons.logging.Log
    logger
    Transient to optimize serialization.
    static final int
    NO_CONCURRENCY
    Concurrency limit which signals that concurrency throttling has been disabled: 0.
    static final int
    UNBOUNDED_CONCURRENCY
    Concurrency limit which signals unbounded concurrency: -1.

  • Constructor Summary

    Constructors
    Constructor
    Description
    ConcurrencyThrottleSupport()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    protected void
    afterAccess()
    To be invoked after the main execution logic of concrete subclasses.
    protected void
    beforeAccess()
    To be invoked before the main execution logic of concrete subclasses.
    int
    getConcurrencyLimit()
    Return the maximum number of concurrent access attempts allowed.
    boolean
    isThrottleActive()
    Return whether this throttle is currently active.
    protected void
    onAccessRejected(String msg)
    Triggered when access has been rejected due to the concurrency policy or due to interruption.
    protected void
    onLimitReached()
    Triggered by beforeAccess() when the concurrency limit has been reached.
    void
    setConcurrencyLimit(int concurrencyLimit)
    Set the maximum number of concurrent access attempts allowed.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • UNBOUNDED_CONCURRENCY

      public static final int UNBOUNDED_CONCURRENCY
      Concurrency limit which signals unbounded concurrency: -1.

      Setting the limit to this value permits unbounded concurrent access: that is, concurrency will not be throttled.

      See Also:

    • NO_CONCURRENCY

      public static final int NO_CONCURRENCY
      Concurrency limit which signals that concurrency throttling has been disabled: 0.

      Setting the limit to this value prevents all access.

      See Also:

    • logger

      protected transient org.apache.commons.logging.Log logger
      Transient to optimize serialization.

  • Constructor Details

    • ConcurrencyThrottleSupport

      public ConcurrencyThrottleSupport()

  • Method Details

    • setConcurrencyLimit

      public void setConcurrencyLimit(int concurrencyLimit)
      Set the maximum number of concurrent access attempts allowed. The default of -1 indicates no concurrency limit at all.

      In principle, this limit can be changed at runtime, although it is generally designed as a config time setting.

      NOTE: Do not switch between -1 and any concrete limit at runtime, as this will lead to inconsistent concurrency counts. A limit of -1 effectively turns off concurrency counting completely.

    • getConcurrencyLimit

      public int getConcurrencyLimit()
      Return the maximum number of concurrent access attempts allowed.

    • isThrottleActive

      public boolean isThrottleActive()
      Return whether this throttle is currently active.
      Returns:
      true if the concurrency limit for this instance is active
      See Also:

    • beforeAccess

      protected void beforeAccess()
      To be invoked before the main execution logic of concrete subclasses.

      This implementation applies the concurrency throttle.

      See Also:

    • onLimitReached

      protected void onLimitReached()
      Triggered by beforeAccess() when the concurrency limit has been reached. The default implementation blocks until the concurrency count allows for entering.
      Since:
      6.2.6

    • onAccessRejected

      protected void onAccessRejected(String msg)
      Triggered when access has been rejected due to the concurrency policy or due to interruption.

      Implementations will typically throw a corresponding exception. When returning normally, regular access will still be attempted.

      The default implementation throws an IllegalStateException.

      Parameters:
      msg - the rejection message (common exception messages are designed so that they can be appended with an identifier separated by a space in custom subclasses)
      Since:
      7.0.4

    • afterAccess

      protected void afterAccess()
      To be invoked after the main execution logic of concrete subclasses.
      See Also: