com.stormpath.sdk.impl.cache

Class DefaultCache<K,V>

java.lang.Object

com.stormpath.sdk.impl.cache.DefaultCache<K,V>

All Implemented Interfaces:

Cache<K,V>

public class DefaultCache<K,V>
extends Object
implements Cache<K,V>

A DefaultCache is a Cache implementation that uses a backing Map instance to store and retrieve cached data.

Thread Safety

This implementation is thread-safe only if the backing map is thread-safe.

Since:

1.0

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DefaultCache.Entry<V> An Entry is a wrapper that encapsulates the actual value stored in the cache as well as creationTimeMillis and lastAccessTimeMillis metadata about the entry itself.

Constructor Summary

Constructors

Constructor and Description
DefaultCache(String name) Creates a new DefaultCache instance with the specified name, expected to be unique among all other caches in the parent CacheManager.
DefaultCache(String name, Map<K,DefaultCache.Entry<V>> backingMap) Creates a new DefaultCache instance with the specified name, storing entries in the specified backingMap.
DefaultCache(String name, Map<K,DefaultCache.Entry<V>> backingMap, Duration timeToLive, Duration timeToIdle) Creates a new DefaultCache instance with the specified name, storing entries in the specified backingMap, using the specified timeToLive and timeToIdle settings.

Method Summary

Methods

Modifier and Type	Method and Description
protected static void	assertTti(Duration tti)
protected static void	assertTtl(Duration ttl)
void	clear() Removes all entries from this cache.
V	get(K key)
long	getAccessCount() Returns the number of attempts to return a cache entry.
long	getHitCount() Returns the total number of times an access attempt successfully returned a cache entry.
double	getHitRatio() Returns the ratio of hitCount to accessCount.
long	getMissCount() Returns the total number of times an access attempt did not return a cache entry.
String	getName() Returns this cache instance's name.
Duration	getTimeToIdle() Returns the amount of time a cache entry may be idle - unused (not accessed) - before it will expire and no longer be available.
Duration	getTimeToLive() Returns the amount of time a cache entry may exist after first being created before it will expire and no longer be available.
V	put(K key, V value)
V	remove(K key)
void	setTimeToIdle(Duration timeToIdle) Sets the amount of time a cache entry may be idle - unused (not accessed) - before it will expire and no longer be available.
void	setTimeToLive(Duration timeToLive) Sets the amount of time a cache entry may exist after first being created before it will expire and no longer be available.
int	size() Returns the total number of cache entries currently available in this cache.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultCache

public DefaultCache(String name)

Creates a new DefaultCache instance with the specified name, expected to be unique among all other caches in the parent CacheManager.

This constructor uses a SoftHashMap instance as the cache's backing map, which is thread-safe and auto-sizes itself based on the application's memory constraints.

Finally, the timeToIdle and timeToLive settings are both null, indicating that cache entries will live indefinitely (except due to memory constraints as managed by the SoftHashMap).

Parameters:

name - the name to assign to this instance, expected to be unique among all other caches in the parent CacheManager.

See Also:

SoftHashMap, setTimeToIdle(com.stormpath.sdk.impl.util.Duration), setTimeToLive(com.stormpath.sdk.impl.util.Duration)

DefaultCache

public DefaultCache(String name,
            Map<K,DefaultCache.Entry<V>> backingMap)

Creates a new DefaultCache instance with the specified name, storing entries in the specified backingMap. It is expected that the backingMap implementation be thread-safe and preferrably auto-sizing based on memory constraints (see SoftHashMap for such an implementation).

The timeToIdle and timeToLive settings are both null, indicating that cache entries will live indefinitely (except due to memory constraints as managed by the backingMap instance).

Parameters:

name - name to assign to this instance, expected to be unique among all other caches in the parent CacheManager.

backingMap - the (ideally thread-safe) map instance to store the Cache entries.

See Also:

SoftHashMap, setTimeToIdle(com.stormpath.sdk.impl.util.Duration), setTimeToLive(com.stormpath.sdk.impl.util.Duration)

DefaultCache

public DefaultCache(String name,
            Map<K,DefaultCache.Entry<V>> backingMap,
            Duration timeToLive,
            Duration timeToIdle)
             throws IllegalArgumentException

Creates a new DefaultCache instance with the specified name, storing entries in the specified backingMap, using the specified timeToLive and timeToIdle settings.

It is expected that the backingMap implementation be thread-safe and preferrably auto-sizing based on memory constraints (see SoftHashMap for such an implementation).

Parameters:

name - name to assign to this instance, expected to be unique among all other caches in the parent CacheManager.

backingMap - the (ideally thread-safe) map instance to store the Cache entries.

timeToIdle - the amount of time cache entries may remain idle until they should be removed from the cache.

timeToLive - the amount of time cache entries may exist until they should be removed from the cache.

Throws:

IllegalArgumentException - if either timeToLive or timeToIdle are non-null and represent a non-positive (zero or negative) value. This is only enforced for non-null values - null values are allowed for either argument.

See Also:

setTimeToIdle(com.stormpath.sdk.impl.util.Duration), setTimeToLive(com.stormpath.sdk.impl.util.Duration)

Method Detail

assertTtl

protected static void assertTtl(Duration ttl)
                         throws IllegalArgumentException

Throws:

IllegalArgumentException

assertTti

protected static void assertTti(Duration tti)
                         throws IllegalArgumentException

Throws:

IllegalArgumentException

get

public V get(K key)

Specified by:

get in interface Cache<K,V>

put

public V put(K key,
    V value)

Specified by:

put in interface Cache<K,V>

remove

public V remove(K key)

Specified by:

remove in interface Cache<K,V>

getTimeToLive

public Duration getTimeToLive()

Returns the amount of time a cache entry may exist after first being created before it will expire and no longer be available. If a cache entry ever becomes older than this amount of time (regardless of how often it is accessed), it will be removed from the cache as soon as possible.

Returns:

the amount of time a cache entry may exist after first being created before it will expire and no longer be available.

setTimeToLive

public void setTimeToLive(Duration timeToLive)

Sets the amount of time a cache entry may exist after first being created before it will expire and no longer be available. If a cache entry ever becomes older than this amount of time (regardless of how often it is accessed), it will be removed from the cache as soon as possible.

Parameters:

timeToLive - the amount of time a cache entry may exist after first being created before it will expire and no longer be available.

getTimeToIdle

public Duration getTimeToIdle()

Returns the amount of time a cache entry may be idle - unused (not accessed) - before it will expire and no longer be available. If a cache entry is not accessed at all after this amount of time, it will be removed from the cache as soon as possible.

Returns:

the amount of time a cache entry may be idle - unused (not accessed) - before it will expire and no longer be available.

setTimeToIdle

public void setTimeToIdle(Duration timeToIdle)

Sets the amount of time a cache entry may be idle - unused (not accessed) - before it will expire and no longer be available. If a cache entry is not accessed at all after this amount of time, it will be removed from the cache as soon as possible.

Parameters:

timeToIdle - the amount of time a cache entry may be idle - unused (not accessed) - before it will expire and no longer be available.

getAccessCount

public long getAccessCount()

Returns the number of attempts to return a cache entry. Note that because remove(Object) will return a value, calls to both get(Object) and remove(Object) will increment this number.

Returns:

the number of attempts to return a cache entry

See Also:

getHitCount(), getMissCount(), getHitRatio()

getHitCount

public long getHitCount()

Returns the total number of times an access attempt successfully returned a cache entry.

Returns:

the total number of times an access attempt successfully returned a cache entry.

See Also:

getMissCount(), getHitRatio()

getMissCount

public long getMissCount()

Returns the total number of times an access attempt did not return a cache entry.

Returns:

the total number of times an access attempt successfully returned a cache entry.

See Also:

getHitCount(), getHitRatio()

getHitRatio

public double getHitRatio()

Returns the ratio of hitCount to accessCount. The closer this number is to 1.0, the more effectively the cache is being used. The closer this number is to {code 0.0}, the less effectively the cache is being used.

Returns:

the ratio of hitCount to accessCount.

clear

public void clear()

Removes all entries from this cache.

size

public int size()

Returns the total number of cache entries currently available in this cache.

Returns:

the total number of cache entries currently available in this cache.

getName

public String getName()

Returns this cache instance's name.

Returns:

this cache instance's name.

toString

public String toString()

Overrides:

toString in class Object