grails.util

Class CacheEntry<V>

java.lang.Object

grails.util.CacheEntry<V>

Direct Known Subclasses:

ReloadableResourceBundleMessageSource.PropertiesHolderCacheEntry

public class CacheEntry<V>
extends java.lang.Object

Wrapper for a value inside a cache that adds timestamp information for expiration and prevents "cache storms" with a Lock. JMM happens-before is ensured with AtomicReference. Objects in cache are assumed to not change after publication.

Since:

2.3.4

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CacheEntry.UpdateException

Constructor Summary

Constructors

Constructor and Description
CacheEntry()
CacheEntry(V value)

Method Summary

Methods

Modifier and Type	Method and Description
void	expire()
long	getCreatedMillis()
V	getValue()
static <K,V> V	getValue(java.util.concurrent.ConcurrentMap<K,CacheEntry<V>> map, K key, long timeoutMillis, java.util.concurrent.Callable<V> updater)
static <K,V> V	getValue(java.util.concurrent.ConcurrentMap<K,CacheEntry<V>> map, K key, long timeoutMillis, java.util.concurrent.Callable<V> updater, boolean returnExpiredWhileUpdating)
static <K,V> V	getValue(java.util.concurrent.ConcurrentMap<K,CacheEntry<V>> map, K key, long timeoutMillis, java.util.concurrent.Callable<V> updater, java.util.concurrent.Callable<? extends CacheEntry> cacheEntryFactory, boolean returnExpiredWhileUpdating, java.lang.Object cacheRequestObject) Gets a value from cache.
V	getValue(long timeout, java.util.concurrent.Callable<V> updater)
V	getValue(long timeout, java.util.concurrent.Callable<V> updater, boolean returnExpiredWhileUpdating, java.lang.Object cacheRequestObject) gets the current value from the entry and updates it if it's older than timeout updater is a callback for creating an updated value.
protected V	getValueWhileUpdating(java.lang.Object cacheRequestObject)
protected boolean	hasExpired(long timeout, java.lang.Object cacheRequestObject)
boolean	isInitialized()
protected void	resetTimestamp(boolean updated)
void	setInitialized(boolean initialized)
void	setValue(V val)
protected boolean	shouldUpdate(long beforeLockingCreatedMillis, java.lang.Object cacheRequestObject)
protected V	updateValue(V oldValue, java.util.concurrent.Callable<V> updater, java.lang.Object cacheRequestObject)

Methods inherited from class java.lang.Object

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

Constructor Detail

CacheEntry

public CacheEntry()

CacheEntry

public CacheEntry(V value)

Method Detail

getValue

public static <K,V> V getValue(java.util.concurrent.ConcurrentMap<K,CacheEntry<V>> map,
               K key,
               long timeoutMillis,
               java.util.concurrent.Callable<V> updater,
               java.util.concurrent.Callable<? extends CacheEntry> cacheEntryFactory,
               boolean returnExpiredWhileUpdating,
               java.lang.Object cacheRequestObject)

Gets a value from cache. If the key doesn't exist, it will create the value using the updater callback Prevents cache storms with a lock The key is always added to the cache. Null return values will also be cached. You can use this together with ConcurrentLinkedHashMap to create a bounded LRU cache

Parameters:

map - the cache map

key - the key to look up

timeoutMillis - cache entry timeout

updater - callback to create/update value

cacheEntryClass - CacheEntry implementation class to use

returnExpiredWhileUpdating - when true, return expired value while updating new value

cacheRequestObject - context object that gets passed to hasExpired, shouldUpdate and updateValue methods, not used in default implementation

Returns:

getValue

public static <K,V> V getValue(java.util.concurrent.ConcurrentMap<K,CacheEntry<V>> map,
               K key,
               long timeoutMillis,
               java.util.concurrent.Callable<V> updater)

getValue

public static <K,V> V getValue(java.util.concurrent.ConcurrentMap<K,CacheEntry<V>> map,
               K key,
               long timeoutMillis,
               java.util.concurrent.Callable<V> updater,
               boolean returnExpiredWhileUpdating)

getValue

public V getValue(long timeout,
         java.util.concurrent.Callable<V> updater)

getValue

public V getValue(long timeout,
         java.util.concurrent.Callable<V> updater,
         boolean returnExpiredWhileUpdating,
         java.lang.Object cacheRequestObject)

gets the current value from the entry and updates it if it's older than timeout updater is a callback for creating an updated value.

Parameters:

timeout -

updater -

returnExpiredWhileUpdating -

cacheRequestObject -

Returns:

the current value

getValueWhileUpdating

protected V getValueWhileUpdating(java.lang.Object cacheRequestObject)

updateValue

protected V updateValue(V oldValue,
            java.util.concurrent.Callable<V> updater,
            java.lang.Object cacheRequestObject)
                 throws java.lang.Exception

Throws:

java.lang.Exception

getValue

public V getValue()

setValue

public void setValue(V val)

hasExpired

protected boolean hasExpired(long timeout,
                 java.lang.Object cacheRequestObject)

shouldUpdate

protected boolean shouldUpdate(long beforeLockingCreatedMillis,
                   java.lang.Object cacheRequestObject)

resetTimestamp

protected void resetTimestamp(boolean updated)

getCreatedMillis

public long getCreatedMillis()

expire

public void expire()

isInitialized

public boolean isInitialized()

setInitialized

public void setInitialized(boolean initialized)