org.springframework.util
Class ConcurrencyThrottleSupport

java.lang.Object
  org.springframework.util.ConcurrencyThrottleSupport

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

ConcurrencyThrottleInterceptor, SimpleAsyncTaskExecutor.ConcurrencyThrottleAdapter

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

private int	concurrencyCount
private int	concurrencyLimit
protected Log	logger Transient to optimize serialization
private java.lang.Object	monitor
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.
private void	readObject(java.io.ObjectInputStream ois)
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 Log logger

Transient to optimize serialization

monitor

private transient java.lang.Object monitor

concurrencyLimit

private int concurrencyLimit

concurrencyCount

private int concurrencyCount

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()

readObject

private void readObject(java.io.ObjectInputStream ois)
                 throws java.io.IOException,
                        java.lang.ClassNotFoundException

Throws:

java.io.IOException

java.lang.ClassNotFoundException