com.codename1.io

Class CacheMap

java.lang.Object

com.codename1.io.CacheMap

public class CacheMap
extends Object

A cache map is essentially a hashtable that indexes entries based on age and is limited to a fixed size. Hence when an entry is placed into the cache map and the cache size needs to increase, the least referenced entry is removed. A cache hit is made both on fetching and putting, hence frequently fetched elements will never be removed from a sufficiently large cache. Cache can work purely in memory or swap data into storage based on user definitions. Notice that this class isn't threadsafe.

Author:

Shai Almog

Constructor Summary

Constructors

Constructor and Description
CacheMap() Default constructor
CacheMap(String prefix) Creates a cache map with a prefix string

Method Summary

Modifier and Type	Method and Description
void	clearAllCache() Clears the caches for this cache object
void	clearMemoryCache() Clears the memory cache
void	clearStorageCache() Clears the storage cache
void	delete(Object key) Deletes a cached entry
Object	get(Object key) Returns the object matching the given key
String	getCachePrefix() A prefix prepended to storage entries to differentiate them
int	getCacheSize() Indicates the size of the memory cache after which the cache won't grow further Size is indicated by number of elements stored and not by KB or similar benchmark!
Vector	getKeysInCache() Returns the keys for all the objects currently in cache, this is useful to traverse all the objects and refresh them without actually deleting the cache and fetching them from scratch. Important this vector is a copy of a current state, keys might not exist anymore or might change, others might be added in the interim.
int	getStorageCacheSize() Indicates the size of the storage cache after which the cache won't grow further Size is indicated by number of elements stored and not by KB or similar benchmark!
boolean	isAlwaysStore() When set to true indicates that all entries should be persisted to storage for a constantly persisting cache
void	put(Object key, Object value) Puts the given key/value pair in the cache
void	setAlwaysStore(boolean alwaysStore) When set to true indicates that all entries should be persisted to storage for a constantly persisting cache
void	setCachePrefix(String cachePrefix) A prefix prepended to storage entries to differentiate them
void	setCacheSize(int cacheSize) Indicates the size of the memory cache after which the cache won't grow further Size is indicated by number of elements stored and not by KB or similar benchmark!
void	setStorageCacheSize(int storageCacheSize) Indicates the size of the storage cache after which the cache won't grow further Size is indicated by number of elements stored and not by KB or similar benchmark!

Methods inherited from class java.lang.Object

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

Constructor Detail

CacheMap

public CacheMap()

Default constructor

CacheMap

public CacheMap(String prefix)

Creates a cache map with a prefix string

Parameters:

prefix - string to prepend to the cache entries in storage

Method Detail

getCacheSize

public int getCacheSize()

Indicates the size of the memory cache after which the cache won't grow further Size is indicated by number of elements stored and not by KB or similar benchmark!

Returns:

the cacheSize

setCacheSize

public void setCacheSize(int cacheSize)

Indicates the size of the memory cache after which the cache won't grow further Size is indicated by number of elements stored and not by KB or similar benchmark!

Parameters:

cacheSize - the cacheSize to set

put

public void put(Object key,
                Object value)

Puts the given key/value pair in the cache

Parameters:

key - the key

value - the value

delete

public void delete(Object key)

Deletes a cached entry

Parameters:

key - entry to remove from the cache

get

public Object get(Object key)

Returns the object matching the given key

Parameters:

key - key object

Returns:

value from a previous put or null

clearAllCache

public void clearAllCache()

Clears the caches for this cache object

clearMemoryCache

public void clearMemoryCache()

Clears the memory cache

getKeysInCache

public Vector getKeysInCache()

Returns the keys for all the objects currently in cache, this is useful to traverse all the objects and refresh them without actually deleting the cache and fetching them from scratch.
Important this vector is a copy of a current state, keys might not exist anymore or might change, others might be added in the interim.

Returns:

a vector containing a snapshot of the current elements within the cache.

clearStorageCache

public void clearStorageCache()

Clears the storage cache

getStorageCacheSize

public int getStorageCacheSize()

Indicates the size of the storage cache after which the cache won't grow further Size is indicated by number of elements stored and not by KB or similar benchmark!

Returns:

the storageCacheSize

setStorageCacheSize

public void setStorageCacheSize(int storageCacheSize)

Indicates the size of the storage cache after which the cache won't grow further Size is indicated by number of elements stored and not by KB or similar benchmark!

Parameters:

storageCacheSize - the storageCacheSize to set

getCachePrefix

public String getCachePrefix()

A prefix prepended to storage entries to differentiate them

Returns:

the cachePrefix

setCachePrefix

public void setCachePrefix(String cachePrefix)

A prefix prepended to storage entries to differentiate them

Parameters:

cachePrefix - the cachePrefix to set

isAlwaysStore

public boolean isAlwaysStore()

When set to true indicates that all entries should be persisted to storage for a constantly persisting cache

Returns:

the alwaysStore

setAlwaysStore

public void setAlwaysStore(boolean alwaysStore)

When set to true indicates that all entries should be persisted to storage for a constantly persisting cache

Parameters:

alwaysStore - the alwaysStore to set