Spring Framework

org.springframework.util
Class ConcurrencyThrottleSupport

java.lang.Object
  extended by org.springframework.util.ConcurrencyThrottleSupport
All Implemented Interfaces:
java.io.Serializable
Direct Known Subclasses:
ConcurrencyThrottleInterceptor

public abstract class ConcurrencyThrottleSupport
extends java.lang.Object
implements java.io.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 -1 ("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:
setConcurrencyLimit(int), beforeAccess(), afterAccess(), ConcurrencyThrottleInterceptor, Serializable, Serialized Form

Field Summary
protected  org.apache.commons.logging.Log logger
          Transient to optimize serialization
static int NO_CONCURRENCY
          Switch concurrency 'off': that is, don't allow any concurrent invocations.
static int UNBOUNDED_CONCURRENCY
          Permit any number of concurrent invocations: that is, don't throttle concurrency.
 
Constructor Summary
ConcurrencyThrottleSupport()
           
 
Method Summary
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.
 void setConcurrencyLimit(int concurrencyLimit)
          Set the maximum number of concurrent access attempts allowed.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

UNBOUNDED_CONCURRENCY

public static final int UNBOUNDED_CONCURRENCY
Permit any number of concurrent invocations: that is, don't throttle concurrency.

See Also:
Constant Field Values

NO_CONCURRENCY

public static final int NO_CONCURRENCY
Switch concurrency 'off': that is, don't allow any concurrent invocations.

See Also:
Constant Field Values

logger

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

Constructor Detail

ConcurrencyThrottleSupport

public ConcurrencyThrottleSupport()
Method Detail

setConcurrencyLimit

public void setConcurrencyLimit(int concurrencyLimit)
Set the maximum number of concurrent access attempts allowed. -1 indicates unbounded concurrency.

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:
getConcurrencyLimit()

beforeAccess

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

This implementation applies the concurrency throttle.

See Also:
afterAccess()

afterAccess

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

See Also:
beforeAccess()

Spring Framework