org.zkoss.util

Class MultiCache<K,V>

java.lang.Object

org.zkoss.util.MultiCache<K,V>

All Implemented Interfaces:

Serializable, Cloneable, Cache<K,V>

public class MultiCache<K,V>
extends Object
implements Cache<K,V>, Serializable, Cloneable

A CacheMap that uses multiple instanceof CacheMap to speed up the performance. It creates multiple instances of CacheMap, called the internal caches, and then distributes the access across them. Thus, the performance is proportional to the number of internal caches.

Thread safe.

Since:

3.0.0

Author:

tomyeh

See Also:

Serialized Form

Field Summary

Fields inherited from interface org.zkoss.util.Cache

DEFAULT_LIFETIME, DEFAULT_MAX_SIZE

Constructor Summary

Constructors

Constructor and Description
MultiCache() Constructs a multi cache with 17 initial caches.
MultiCache(int nCache) Constructs a multi cache with the specified number of internal caches.
MultiCache(int nCache, int maxSize, int lifetime) Constructs a multi cache with the specified number of internal caches, the max size and the lifetime.

Method Summary

Modifier and Type	Method and Description
void	clear() Clears all objects being cached.
Object	clone()
boolean	containsKey(Object key) Returns whether the specified key is stored.
V	get(Object key) Returns the object of the specified key, or null if not found.
protected int	getInnerCacheHashCode(Object key) Returns an integer used to identify the instance of inner caches to use.
int	getLifetime() Returns the minimal lifetime, unit=milliseconds.
int	getMaxSize() Returns the maximal allowed size.
V	put(K key, V value) Stores an object to the cache.
V	remove(Object key) Removes an object from the cache.
void	setLifetime(int lifetime) Sets the minimal lifetime.
void	setMaxSize(int maxsize) Sets the maximal allowed size.

Methods inherited from class java.lang.Object

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

Constructor Detail

MultiCache

public MultiCache()

Constructs a multi cache with 17 initial caches.

MultiCache

public MultiCache(int nCache,
                  int maxSize,
                  int lifetime)

Constructs a multi cache with the specified number of internal caches, the max size and the lifetime.

Parameters:

nCache - the positive number of the internal caches. The large the number the fast the performance.

maxSize - the maximal allowed size of each cache

MultiCache

public MultiCache(int nCache)

Constructs a multi cache with the specified number of internal caches.

The default lifetime is Cache.DEFAULT_LIFETIME, and the default maximal allowed size of each cache is (Cache.DEFAULT_MAX_SIZE / 10).

Parameters:

nCache - the positive number of the internal caches. The large the number the fast the performance.

Method Detail

containsKey

public boolean containsKey(Object key)

Description copied from interface: Cache

Returns whether the specified key is stored.

Specified by:

containsKey in interface Cache<K,V>

get

public V get(Object key)

Description copied from interface: Cache

Returns the object of the specified key, or null if not found.

Specified by:

get in interface Cache<K,V>

put

public V put(K key,
             V value)

Description copied from interface: Cache

Stores an object to the cache.

Specified by:

put in interface Cache<K,V>

Returns:

the previous value of the same, or null if no such value

remove

public V remove(Object key)

Description copied from interface: Cache

Removes an object from the cache.

Specified by:

remove in interface Cache<K,V>

Returns:

the object if found.

clear

public void clear()

Description copied from interface: Cache

Clears all objects being cached.

Specified by:

clear in interface Cache<K,V>

getInnerCacheHashCode

protected int getInnerCacheHashCode(Object key)

Returns an integer used to identify the instance of inner caches to use. By default, this method returns the hash code of the given key and the current thread. It means the value of the same key might be stored in different cache (in favor of performance). If different threads of your application usually access different keys, you can override this method to return the hash code of the given key only.

Since:

6.0.0

getLifetime

public int getLifetime()

Description copied from interface: Cache

Returns the minimal lifetime, unit=milliseconds. An mapping won't be removed by GC unless the minimal lifetime or the maximal allowed size exceeds.

Specified by:

getLifetime in interface Cache<K,V>

See Also:

Cache.getMaxSize()

setLifetime

public void setLifetime(int lifetime)

Description copied from interface: Cache

Sets the minimal lifetime. Default: Cache.DEFAULT_LIFETIME.

Specified by:

setLifetime in interface Cache<K,V>

Parameters:

lifetime - the lifetime, unit=milliseconds; if non-positive, they will be removed immediately.

See Also:

Cache.getLifetime()

getMaxSize

public int getMaxSize()

Description copied from interface: Cache

Returns the maximal allowed size. Default: Cache.DEFAULT_MAX_SIZE. An mapping won't be removed by GC unless the minimal lifetime or the maximal allowed size exceeds.

Specified by:

getMaxSize in interface Cache<K,V>

See Also:

Cache.getLifetime()

setMaxSize

public void setMaxSize(int maxsize)

Description copied from interface: Cache

Sets the maximal allowed size.

Specified by:

setMaxSize in interface Cache<K,V>

See Also:

Cache.getMaxSize()

clone

public Object clone()

Overrides:

clone in class Object