Package org.ehcache.expiry

Interface ExpiryPolicy<K,V>

Type Parameters:

K - the key type for the cache

V - the value type for the cache

public interface ExpiryPolicy<K,V>

A policy object that governs expiration for mappings in a Cache.

Previous values are not accessible directly but are rather available through a value Supplier to indicate that access can require computation (such as deserialization).

Negative durations are not supported, expiry policy implementation returning such a duration will result in immediate expiry, as if the duration was zero.

NOTE: Some cache configurations (eg. caches with eventual consistency) may use local (ie. non-consistent) state to decide whether to call getExpiryForUpdate(Object, Supplier, Object) vs. getExpiryForCreation(Object, Object). For these cache configurations it is advised to return the same value for both of these methods

Field Summary

Fields

Modifier and Type	Field	Description
static final Duration	INFINITE	A duration that represents an infinite time.
static final ExpiryPolicy<Object,Object>	NO_EXPIRY	An ExpiryPolicy that represents a no expiration policy

Method Summary

Modifier and Type	Method	Description
Duration	getExpiryForAccess(K key, Supplier<? extends V> value)	Returns the expiration duration (relative to the current time) when an existing entry is accessed from a Cache.
Duration	getExpiryForCreation(K key, V value)	Returns the lifetime of an entry when it is initially added to a Cache.
Duration	getExpiryForUpdate(K key, Supplier<? extends V> oldValue, V newValue)	Returns the expiration duration (relative to the current time) when an existing entry is updated in a Cache.

Field Details

INFINITE

static final Duration INFINITE

A duration that represents an infinite time.

NO_EXPIRY

static final ExpiryPolicy<Object,Object> NO_EXPIRY

An ExpiryPolicy that represents a no expiration policy

Method Details

getExpiryForCreation

Duration getExpiryForCreation(K key,
 V value)

Returns the lifetime of an entry when it is initially added to a Cache.

This method must not return null.

Exceptions thrown from this method will be swallowed and result in the expiry duration being ZERO.

Parameters:

key - the key of the newly added entry

value - the value of the newly added entry

Returns:

a non-null Duration

getExpiryForAccess

Duration getExpiryForAccess(K key,
 Supplier<? extends V> value)

Returns the expiration duration (relative to the current time) when an existing entry is accessed from a Cache.

Returning null indicates that the expiration time remains unchanged.

Exceptions thrown from this method will be swallowed and result in the expiry duration being ZERO.

Parameters:

key - the key of the accessed entry

value - a value supplier for the accessed entry

Returns:

an expiration Duration, null means unchanged

getExpiryForUpdate

Duration getExpiryForUpdate(K key,
 Supplier<? extends V> oldValue,
 V newValue)

Returns the expiration duration (relative to the current time) when an existing entry is updated in a Cache.

Returning null indicates that the expiration time remains unchanged.

Exceptions thrown from this method will be swallowed and result in the expiry duration being ZERO.

Parameters:

key - the key of the updated entry

oldValue - a value supplier for the previous value of the entry

newValue - the new value of the entry

Returns:

an expiration Duration, null means unchanged