Package org.cache2k.io

Interface ResiliencePolicy<K,V>

All Superinterfaces:

Customization, DataAware<K,V>, DataAwareCustomization<K,V>, ExpiryTimeValues

public interface ResiliencePolicy<K,V>
extends ExpiryTimeValues, DataAwareCustomization<K,V>

Controls how to deal with loader exceptions in a read through configuration. An exception can be cached and propagated or the cache can fall back to the currently cached value if a previous load attempt did complete successful.

Since:

2

Author:

Jens Wilke

Field Summary

Fields

Modifier and Type	Field	Description
static ResiliencePolicy<?,?>	DISABLED_POLICY	A policy always returning zero, thus disabling resilience features.

Fields inherited from interface org.cache2k.expiry.ExpiryTimeValues

ETERNAL, NEUTRAL, NOW, REFRESH

Method Summary

Modifier and Type	Method	Description
static <K,V> void	disable(Cache2kBuilder<K,V> b)
static <K,V> ResiliencePolicy<K,V>	disabledPolicy()
long	retryLoadAfter(K key, LoadExceptionInfo<K,V> loadExceptionInfo)	Called after the loader threw an exception and no previous value is available or suppressExceptionUntil(K, org.cache2k.io.LoadExceptionInfo<K, V>, org.cache2k.CacheEntry<K, V>) returned zero.
long	suppressExceptionUntil(K key, LoadExceptionInfo<K,V> loadExceptionInfo, CacheEntry<K,V> cachedEntry)	Called after the loader threw an exception and a previous value is available.

Field Detail

DISABLED_POLICY

static final ResiliencePolicy<?,?> DISABLED_POLICY

A policy always returning zero, thus disabling resilience features. This is also used as default when no resilience policy is set.

Method Detail

disabledPolicy

static <K,V> ResiliencePolicy<K,V> disabledPolicy()

disable

static <K,V> void disable(Cache2kBuilder<K,V> b)

suppressExceptionUntil

long suppressExceptionUntil(K key,
                            LoadExceptionInfo<K,V> loadExceptionInfo,
                            CacheEntry<K,V> cachedEntry)

Called after the loader threw an exception and a previous value is available. Returns a point in time determining how long the exceptions should be suppressed, or in other words, until when the previous loaded value should be returned by the cache.

The returned value is a point in time. If the currently cached content is expired, returning a future time will effectively extend the entry expiry.

If Cache2kBuilder.expireAfterWrite(long, TimeUnit) is specified, the maximum duration will be capped with the specified value.

Returning 0 or a time in the past means the exception should not be suppressed. The cache will call immediately retryLoadAfter(K, org.cache2k.io.LoadExceptionInfo<K, V>) to determine how long the exception should stay in the cache and when the next retry attempt takes place.

If the exception is not suppressed, it will be wrapped into a CacheLoaderException and propagated to the cache client. This is customizable by the ExceptionPropagator.

Parameters:

cachedEntry - The entry representing the currently cached content. It is possible that this data is already expired. This entry never contains an exception.

Returns:

Time in the future when the content should expire again. A zero or a time before the current time means the exception will not be suppressed. A ExpiryTimeValues.ETERNAL means the exception will be suppressed and the recent content will be returned eternally. If the returned time is after LoadExceptionInfo.getLoadTime() the exception will be suppressed for the ongoing operation.

retryLoadAfter

long retryLoadAfter(K key,
                    LoadExceptionInfo<K,V> loadExceptionInfo)

Called after the loader threw an exception and no previous value is available or suppressExceptionUntil(K, org.cache2k.io.LoadExceptionInfo<K, V>, org.cache2k.CacheEntry<K, V>) returned zero. Returns a point in time until then an exception will be cached.

If Cache2kBuilder.expireAfterWrite(long, TimeUnit) is specified, the maximum duration will be capped with the specified value.

Returns:

Time in the future when the exception should expire. A zero or a time before the current time means the exception will not be cached and a new load is triggered by the next get(). A ExpiryTimeValues.ETERNAL means the exception will be cached forever.