com.stoyanr.evictor.scheduler

Class DelayedTaskEvictionScheduler<K,V>

java.lang.Object

com.stoyanr.evictor.scheduler.AbstractQueueEvictionScheduler<K,V>

com.stoyanr.evictor.scheduler.DelayedTaskEvictionScheduler<K,V>

Type Parameters:

K - the type of keys maintained by this map

V - the type of mapped values

All Implemented Interfaces:

EvictionScheduler<K,V>

public class DelayedTaskEvictionScheduler<K,V>
extends AbstractQueueEvictionScheduler<K,V>

A concrete implementation of AbstractQueueEvictionScheduler which uses a single delayed task scheduled in an ScheduledExecutorService to manage the automated eviction. The task is rescheduled appropriately each time an entry is added or removed from the queue to ensure that it will always fire at the time of the next scheduled eviction, not sooner or later. If the queue is empty, the task is cancelled until an entry is added.

Author:

Stoyan Rachev

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_THREAD_POOL_SIZE

Constructor Summary

Constructors

Constructor and Description
DelayedTaskEvictionScheduler() Creates a delayed task eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler) and a ScheduledThreadPoolExecutor.
DelayedTaskEvictionScheduler(EvictionQueue<K,V> queue) Creates a delayed task eviction scheduler with the specified queue and a ScheduledThreadPoolExecutor.
DelayedTaskEvictionScheduler(EvictionQueue<K,V> queue, ScheduledExecutorService executorService) Creates a delayed task eviction scheduler with the specified queue and scheduled executor service.
DelayedTaskEvictionScheduler(ScheduledExecutorService ses) Creates a delayed task eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler) and the specified scheduled executor service.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	onCancelEviction(EvictibleEntry<K,V> e) Actually cancels the eviction of the specified entry.
protected void	onEvictEntries() Performs additional activities upon automated eviction of entries, if needed.
protected void	onScheduleEviction(EvictibleEntry<K,V> e) Actually schedules the eviction of the specified entry.
void	shutdown() Immediately shuts down the scheduler and cancels all pending evictions.

Methods inherited from class com.stoyanr.evictor.scheduler.AbstractQueueEvictionScheduler

cancelEviction, evictEntries, getNextEvictionTime, hasScheduledEvictions, scheduleEviction

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_THREAD_POOL_SIZE

public static final int DEFAULT_THREAD_POOL_SIZE

See Also:

Constant Field Values

Constructor Detail

DelayedTaskEvictionScheduler

public DelayedTaskEvictionScheduler()

Creates a delayed task eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler) and a ScheduledThreadPoolExecutor.

DelayedTaskEvictionScheduler

public DelayedTaskEvictionScheduler(ScheduledExecutorService ses)

Creates a delayed task eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler) and the specified scheduled executor service.

Parameters:

ses - the scheduled executor service to be used

Throws:

NullPointerException - if the scheduled executor service is null

DelayedTaskEvictionScheduler

public DelayedTaskEvictionScheduler(EvictionQueue<K,V> queue)

Creates a delayed task eviction scheduler with the specified queue and a ScheduledThreadPoolExecutor.

Parameters:

queue - the queue to be used

Throws:

NullPointerException - if the queue is null

DelayedTaskEvictionScheduler

public DelayedTaskEvictionScheduler(EvictionQueue<K,V> queue,
                            ScheduledExecutorService executorService)

Creates a delayed task eviction scheduler with the specified queue and scheduled executor service.

Parameters:

queue - the queue to be used

executorService - the scheduled executor service to be used

Throws:

NullPointerException - if either the queue or the scheduled executor service is null

Method Detail

shutdown

public void shutdown()

Immediately shuts down the scheduler and cancels all pending evictions. After it has been shut down, the scheduler cannot be used any more. This method is never called by the associated instances of ConcurrentMapWithTimedEvictionDecorator. Instead, it is intended to be called by the client that has created the scheduler to properly shut it down when it's not needed any more.

This implementation simply invokes the shutdownNow method on the scheduled executor service.

onScheduleEviction

protected void onScheduleEviction(EvictibleEntry<K,V> e)

Actually schedules the eviction of the specified entry. It is guaranteed that this entry is evictible. Subclasses should override this method to provide the actual scheduling functionality.

This implementation checks if the current next eviction time is different from the last next eviction time, and if so (re)schedules the task.

Specified by:

onScheduleEviction in class AbstractQueueEvictionScheduler<K,V>

Parameters:

e - the entry for which the eviction should be scheduled

Throws:

RejectedExecutionException - if the task cannot be scheduled for execution

onCancelEviction

protected void onCancelEviction(EvictibleEntry<K,V> e)

Actually cancels the eviction of the specified entry. It is guaranteed that this entry is evictible. Subclasses should override this method to provide the actual cancellation functionality.

This implementation checks if the current next eviction time is different from the last next eviction time, and if so (re)schedules the task.

Specified by:

onCancelEviction in class AbstractQueueEvictionScheduler<K,V>

Parameters:

e - the entry for which the eviction should be cancelled

Throws:

RejectedExecutionException - if the task cannot be scheduled for execution

onEvictEntries

protected void onEvictEntries()

Performs additional activities upon automated eviction of entries, if needed. Subclasses should override this method if they need to perform such activities.

This implementation simply always schedules the task.

Specified by:

onEvictEntries in class AbstractQueueEvictionScheduler<K,V>

Throws:

RejectedExecutionException - if the task cannot be scheduled for execution