Package org.apache.commons.pool2.impl

Class EvictionTimer

java.lang.Object

org.apache.commons.pool2.impl.EvictionTimer

final class EvictionTimer
extends java.lang.Object

Provides a shared idle object eviction timer for all pools.

This class is currently implemented using ScheduledThreadPoolExecutor. This implementation may change in any future release. This class keeps track of how many pools are using it. If no pools are using the timer, it is canceled. This prevents a thread being left running which, in application server environments, can lead to memory leads and/or prevent applications from shutting down or reloading cleanly.

This class has package scope to prevent its inclusion in the pool public API. The class declaration below should *not* be changed to public.

This class is intended to be thread-safe.

Since:

2.0

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	EvictionTimer.EvictorThreadFactory	Thread factory that creates a daemon thread, with the context class loader from this class.
private static class	EvictionTimer.Reaper	Task that removes references to abandoned tasks and shuts down the executor if there are no live tasks left.
private static class	EvictionTimer.WeakRunner<R extends java.lang.Runnable>	Runnable that runs the referent of a weak reference.

Field Summary

Fields

Modifier and Type	Field	Description
private static java.util.concurrent.ScheduledThreadPoolExecutor	executor	Executor instance
private static java.util.HashMap<java.lang.ref.WeakReference<BaseGenericObjectPool.Evictor>,EvictionTimer.WeakRunner<BaseGenericObjectPool.Evictor>>	TASK_MAP	Keys are weak references to tasks, values are runners managed by executor.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	EvictionTimer()	Prevents instantiation

Method Summary

Modifier and Type	Method	Description
(package private) static void	cancel(BaseGenericObjectPool.Evictor evictor, java.time.Duration timeout, boolean restarting)	Removes the specified eviction task from the timer.
(package private) static java.util.concurrent.ScheduledThreadPoolExecutor	getExecutor()	For testing only.
(package private) static int	getNumTasks()
(package private) static java.util.HashMap<java.lang.ref.WeakReference<BaseGenericObjectPool.Evictor>,EvictionTimer.WeakRunner<BaseGenericObjectPool.Evictor>>	getTaskMap()	Gets the task map.
private static void	remove(BaseGenericObjectPool.Evictor evictor)	Removes evictor from the task set and executor.
(package private) static void	schedule(BaseGenericObjectPool.Evictor task, java.time.Duration delay, java.time.Duration period)	Adds the specified eviction task to the timer.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

executor

private static java.util.concurrent.ScheduledThreadPoolExecutor executor

Executor instance

TASK_MAP

private static final java.util.HashMap<java.lang.ref.WeakReference<BaseGenericObjectPool.Evictor>,EvictionTimer.WeakRunner<BaseGenericObjectPool.Evictor>> TASK_MAP

Keys are weak references to tasks, values are runners managed by executor.

Constructor Detail

EvictionTimer

private EvictionTimer()

Prevents instantiation

Method Detail

cancel

static void cancel(BaseGenericObjectPool.Evictor evictor,
                   java.time.Duration timeout,
                   boolean restarting)

Removes the specified eviction task from the timer.

Parameters:

evictor - Task to be canceled.

timeout - If the associated executor is no longer required, how long should this thread wait for the executor to terminate?

restarting - The state of the evictor.

getExecutor

static java.util.concurrent.ScheduledThreadPoolExecutor getExecutor()

For testing only.

Returns:

The executor.

getNumTasks

static int getNumTasks()

Returns:

the number of eviction tasks under management.

getTaskMap

static java.util.HashMap<java.lang.ref.WeakReference<BaseGenericObjectPool.Evictor>,EvictionTimer.WeakRunner<BaseGenericObjectPool.Evictor>> getTaskMap()

Gets the task map. Keys are weak references to tasks, values are runners managed by executor.

Returns:

the task map.

remove

private static void remove(BaseGenericObjectPool.Evictor evictor)

Removes evictor from the task set and executor. Only called when holding the class lock.

Parameters:

evictor - Eviction task to remove

schedule

static void schedule(BaseGenericObjectPool.Evictor task,
                     java.time.Duration delay,
                     java.time.Duration period)

Adds the specified eviction task to the timer. Tasks that are added with a call to this method *must* call cancel(BaseGenericObjectPool.Evictor, Duration, boolean) to cancel the task to prevent memory and/or thread leaks in application server environments.

Parameters:

task - Task to be scheduled.

delay - Duration before task is executed.

period - Duration between executions.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

Since:

2.4.3