Package org.greenrobot.essentials

Class ObjectCache<KEY,VALUE>

java.lang.Object

org.greenrobot.essentials.ObjectCache<KEY,VALUE>

public class ObjectCache<KEY,VALUE>
extends java.lang.Object

An in-memory object cache supporting soft/weak/strong references, maximum size (clearing the entries that were put first), and time-based expiration.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	ObjectCache.CacheEntry<V>
static class	ObjectCache.ReferenceType

Field Summary

Fields

Modifier and Type	Field	Description
private int	countEvicted
private int	countExpired
private int	countHit
private int	countMiss
private int	countPut
private int	countPutCountSinceEviction
private int	countRefCleared
private long	expirationMillis
private boolean	isExpiring
private boolean	isStrongReference
private int	maxSize
private long	nextCleanUpTimestamp
private ObjectCache.ReferenceType	referenceType
private java.util.Map<KEY,ObjectCache.CacheEntry<VALUE>>	values

Constructor Summary

Constructors

Constructor	Description
ObjectCache(ObjectCache.ReferenceType referenceType, int maxSize, long expirationMillis)	Create a cache according to the given configuration.

Method Summary

Modifier and Type	Method	Description
(package private) void	checkCleanUpObsoleteEntries()
int	cleanUpObsoleteEntries()	Iterates over all entries to check for obsolete ones (time expired or reference cleared).
void	clear()	Clears all cached entries.
boolean	containsKey(KEY key)
boolean	containsKeyWithValue(KEY key)
void	evictToTargetSize(int targetSize)
VALUE	get(KEY key)	Get the cached entry or null if no valid cached entry is found.
int	getCountEvicted()
int	getCountExpired()
int	getCountHit()
int	getCountMiss()
int	getCountPut()
int	getCountRefCleared()
int	getMaxSize()
java.lang.String	getStatsStringRemoved()	Often used in addition to toString() to print out states: details why entries were removed.
private VALUE	getValue(KEY keyForRemoval, ObjectCache.CacheEntry<VALUE> entry)
private VALUE	getValueForRemoved(ObjectCache.CacheEntry<VALUE> entry)
java.util.Set<KEY>	keySet()
VALUE	put(KEY key, VALUE object)	Stores an new entry in the cache.
void	putAll(java.util.Map<KEY,VALUE> mapDataToPut)	Stores all entries contained in the given map in the cache.
VALUE	remove(KEY key)	Removes an entry from the cache.
int	size()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

values

private final java.util.Map<KEY,ObjectCache.CacheEntry<VALUE>> values

referenceType

private final ObjectCache.ReferenceType referenceType

isStrongReference

private final boolean isStrongReference

maxSize

private final int maxSize

expirationMillis

private final long expirationMillis

isExpiring

private final boolean isExpiring

nextCleanUpTimestamp

private volatile long nextCleanUpTimestamp

countPutCountSinceEviction

private volatile int countPutCountSinceEviction

countPut

private volatile int countPut

countHit

private volatile int countHit

countMiss

private volatile int countMiss

countExpired

private volatile int countExpired

countRefCleared

private volatile int countRefCleared

countEvicted

private volatile int countEvicted

Constructor Detail

ObjectCache

public ObjectCache(ObjectCache.ReferenceType referenceType,
                   int maxSize,
                   long expirationMillis)

Create a cache according to the given configuration.

Parameters:

referenceType - SOFT is usually a good choice allowing the VM to clear caches when running low on memory. STRONG may also be preferred, e.g. when the required space is granted.

maxSize - The maximum number of entries stored by this cache

expirationMillis -

Method Detail

put

public VALUE put(KEY key,
                 VALUE object)

Stores an new entry in the cache.

getValueForRemoved

private VALUE getValueForRemoved(ObjectCache.CacheEntry<VALUE> entry)

getValue

private VALUE getValue(KEY keyForRemoval,
                       ObjectCache.CacheEntry<VALUE> entry)

putAll

public void putAll(java.util.Map<KEY,VALUE> mapDataToPut)

Stores all entries contained in the given map in the cache.

get

public VALUE get(KEY key)

Get the cached entry or null if no valid cached entry is found.

clear

public void clear()

Clears all cached entries.

remove

public VALUE remove(KEY key)

Removes an entry from the cache.

Returns:

The removed entry

evictToTargetSize

public void evictToTargetSize(int targetSize)

checkCleanUpObsoleteEntries

void checkCleanUpObsoleteEntries()

cleanUpObsoleteEntries

public int cleanUpObsoleteEntries()

Iterates over all entries to check for obsolete ones (time expired or reference cleared).

Note: Usually you don't need to call this method explicitly, because it is called internally in certain conditions when space has to be reclaimed.

containsKey

public boolean containsKey(KEY key)

containsKeyWithValue

public boolean containsKeyWithValue(KEY key)

keySet

public java.util.Set<KEY> keySet()

getMaxSize

public int getMaxSize()

size

public int size()

getCountPut

public int getCountPut()

getCountHit

public int getCountHit()

getCountMiss

public int getCountMiss()

getCountExpired

public int getCountExpired()

getCountRefCleared

public int getCountRefCleared()

getCountEvicted

public int getCountEvicted()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getStatsStringRemoved

public java.lang.String getStatsStringRemoved()

Often used in addition to toString() to print out states: details why entries were removed.