com.stoyanr.evictor.scheduler

Class RegularTaskEvictionScheduler<K,V>

java.lang.Object

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

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

A concrete implementation of AbstractQueueEvictionScheduler which uses a single regular task scheduled in an ScheduledExecutorService to manage the automated eviction. The task is scheduled with a fixed delay, independently of the time of the next scheduled eviction. 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 long	DEFAULT_DELAY
static int	DEFAULT_THREAD_POOL_SIZE
static TimeUnit	DEFAULT_TIME_UNIT

Constructor Summary

Constructors

Constructor and Description
RegularTaskEvictionScheduler() Creates a regular task eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler), a ScheduledThreadPoolExecutor, and a default delay of 1 millisecond.
RegularTaskEvictionScheduler(EvictionQueue<K,V> queue) Creates a regular task eviction scheduler with the specified queue, a ScheduledThreadPoolExecutor, and a default delay of 1 millisecond.
RegularTaskEvictionScheduler(EvictionQueue<K,V> queue, ScheduledExecutorService ses, long delay, TimeUnit timeUnit) Creates a regular task eviction scheduler with the specified queue, scheduled executor service, and delay.
RegularTaskEvictionScheduler(long delay, TimeUnit timeUnit) Creates a regular task eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler), a ScheduledThreadPoolExecutor, and the specified delay.
RegularTaskEvictionScheduler(ScheduledExecutorService executorService, long delay, TimeUnit timeUnit) Creates a regular task eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler) and the specified scheduled executor service and delay.

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

DEFAULT_DELAY

public static final long DEFAULT_DELAY

See Also:

Constant Field Values

DEFAULT_TIME_UNIT

public static final TimeUnit DEFAULT_TIME_UNIT

Constructor Detail

RegularTaskEvictionScheduler

public RegularTaskEvictionScheduler()

Creates a regular task eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler), a ScheduledThreadPoolExecutor, and a default delay of 1 millisecond.

RegularTaskEvictionScheduler

public RegularTaskEvictionScheduler(long delay,
                            TimeUnit timeUnit)

Creates a regular task eviction scheduler with the default queue implementation (see AbstractQueueEvictionScheduler), a ScheduledThreadPoolExecutor, and the specified delay.

Parameters:

delay - the delay between the termination of one execution and the commencement of the next

timeUnit - the time unit of the delay parameter

Throws:

IllegalArgumentException - if delay is less than or equal to zero

RegularTaskEvictionScheduler

public RegularTaskEvictionScheduler(ScheduledExecutorService executorService,
                            long delay,
                            TimeUnit timeUnit)

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

Parameters:

executorService - the scheduled executor service to be used

delay - the delay between the termination of one execution and the commencement of the next

timeUnit - the time unit of the delay parameter

Throws:

NullPointerException - if the scheduled executor service is null

IllegalArgumentException - if delay is less than or equal to zero

RegularTaskEvictionScheduler

public RegularTaskEvictionScheduler(EvictionQueue<K,V> queue)

Creates a regular task eviction scheduler with the specified queue, a ScheduledThreadPoolExecutor, and a default delay of 1 millisecond.

Parameters:

queue - the queue to be used

RegularTaskEvictionScheduler

public RegularTaskEvictionScheduler(EvictionQueue<K,V> queue,
                            ScheduledExecutorService ses,
                            long delay,
                            TimeUnit timeUnit)

Creates a regular task eviction scheduler with the specified queue, scheduled executor service, and delay.

Parameters:

queue - the queue to be used

ses - the scheduled executor service to be used

delay - the delay between the termination of one execution and the commencement of the next

timeUnit - the time unit of the delay parameter

Throws:

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

IllegalArgumentException - if delay is less than or equal to zero

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 executor has scheduled evictions and the current state of the task is not active, and if so schedules the regular 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 executor does not have scheduled evictions and the current state of the task is active, and if so cancels the regular task.

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 checks if the executor does not have scheduled evictions and the current state of the task is active, and if so cancels the regular task.

Specified by:

onEvictEntries in class AbstractQueueEvictionScheduler<K,V>