com.stoyanr.evictor.scheduler

Class SingleThreadEvictionScheduler<K,V>

java.lang.Object

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

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

A concrete implementation of AbstractQueueEvictionScheduler which uses a single thread to manage the automated eviction. The thread waits until the next scheduled eviction time before trying to perform an automated eviction. It is notified appropriately each time an entry is added or removed from the queue to ensure that it will always wake-up at the time of the next scheduled eviction, not sooner or later. If the queue is empty, the thread is waiting until notified when an entry is added. The behavior is similar to that of DelayedTaskEvictionScheduler, but it is implemented at a lower level, using a specially crafted thread rather than a scheduled executor service.

Author:

Stoyan Rachev

Constructor Summary

Constructors

Constructor and Description
SingleThreadEvictionScheduler() Creates a single thread eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler).
SingleThreadEvictionScheduler(EvictionQueue<K,V> queue) Creates a single thread eviction scheduler with the specified queue.

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

Constructor Detail

SingleThreadEvictionScheduler

public SingleThreadEvictionScheduler()

Creates a single thread eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler). This constructor starts the eviction thread, which will remain active until the shutdown method is called.

SingleThreadEvictionScheduler

public SingleThreadEvictionScheduler(EvictionQueue<K,V> queue)

Creates a single thread eviction scheduler with the specified queue. This constructor starts the eviction thread, which will remain active until the shutdown method is called.

Parameters:

queue - the queue to be used

Throws:

NullPointerException - if the queue 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 causes the eviction thread to terminate.

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 notifies the eviction thread, causing it to wake-up and recalculate its waiting time.

Specified by:

onScheduleEviction in class AbstractQueueEvictionScheduler<K,V>

Parameters:

e - the entry for which the eviction should be scheduled

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 notifies the eviction thread, causing it to wake-up and recalculate its waiting time.

Specified by:

onCancelEviction in class AbstractQueueEvictionScheduler<K,V>

Parameters:

e - the entry for which the eviction should be cancelled

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 does nothing.

Specified by:

onEvictEntries in class AbstractQueueEvictionScheduler<K,V>