echopoint.util.collections
Class TimerExpiryCache

java.lang.Object
  echopoint.util.collections.ExpiryCache
      echopoint.util.collections.TimerExpiryCache

All Implemented Interfaces:

Map

public class TimerExpiryCache
extends ExpiryCache

TimerExpiryCache is an a implementation of ExpiryCache that can contain objects that "expire". A shared background task will periodically "reap" objects that have "expired".

By default, soft references are used to the cached data so that they can be reclaimed in low memory conditions regardless of whether they have expired or not.

The time-to-live and access-timeout is used to decide when an object has expired and needs to be removed from the cache.

Time-to-live is simple. Once the specified period elapses, the object is removed from the cache, regardless of how many times its been accessed.

Access-timeout is a little more complicated. Each time the object is taken from the cache, its lastAccessTime is tracked. If the access-timeout has expired (since its last access) then the object is taken from the cache.

If both the time-to-live and access-timeout is -1, then the object will never expire from the cache.

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Field Summary

static long

DEFAULT_REAPER_INTERVAL The reaper interval is 2 minutes.

Fields inherited from class echopoint.util.collections.ExpiryCache

DEFAULT_ACCESS_TIMEOUT, DEFAULT_TIME_TO_LIVE

Constructor Summary

TimerExpiryCache()
Constructs a default TimerExpiryCache

TimerExpiryCache(long timeToLive, long accessTimeout)
Constructs a TimerExpiryCache

TimerExpiryCache(long timeToLive, long accessTimeout, boolean softReferences)
Constructs a TimerExpiryCache with all the parameters

Method Summary

Methods inherited from class echopoint.util.collections.ExpiryCache

clear, containsKey, containsValue, entrySet, get, get, hasExpired, howManyTimesAccessed, isEmpty, isSoftReferences, keySet, onExpiredObject, put, put, put, put, putAll, remove, setAccessTimeout, setSoftReferences, setTimeToLive, size, values, whenCached, whenLastAccessed, whenVersion

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

equals, hashCode

Field Detail

DEFAULT_REAPER_INTERVAL

public static final long DEFAULT_REAPER_INTERVAL

The reaper interval is 2 minutes. Therefore the cached object life span granulairty is +/- 1 minute.

See Also:

Constant Field Values

Constructor Detail

TimerExpiryCache

public TimerExpiryCache()

Constructs a default TimerExpiryCache

TimerExpiryCache

public TimerExpiryCache(long timeToLive,
                        long accessTimeout)

Constructs a TimerExpiryCache

Parameters:

timeToLive - - the default time-to-live for a cache entry

accessTimeout - - the default access timeout for a cache entry

TimerExpiryCache

public TimerExpiryCache(long timeToLive,
                        long accessTimeout,
                        boolean softReferences)

Constructs a TimerExpiryCache with all the parameters

Parameters:

timeToLive - - the default time-to-live for a cache entry

accessTimeout - - the default access timeout for a cache entry

softReferences - - whether soft refernces are used to cached data