Package com.peterphi.std.guice.common.cached.util

Class SingleItemCache<T>

java.lang.Object

com.peterphi.std.guice.common.cached.util.SingleItemCache<T>

Type Parameters:

T - the type of value cached

public class SingleItemCache<T>
extends Object

Wrapper around a single item guava cache as a workaround for google not implementing the request for a single item cache made in 2012.

This is a light wrapper around Cache

Constructor Summary

Constructors

Constructor	Description
SingleItemCache(com.google.common.cache.CacheBuilder builder, Callable<T> supplier)	Create a new cache, caching the result of supplier using a cache built by builder.
SingleItemCache(com.google.common.cache.CacheBuilder builder, Callable<T> supplier, boolean useCacheManager)	Create a new cache, caching the result of supplier using a cache built by builder.
SingleItemCache(Callable<T> supplier, Timeout validity)	Create a new cache, caching the result of supplier for a maximum of validity.

Method Summary

Modifier and Type	Method	Description
T	get()	Return the cached value (or regenerate it).
T	getIfPresent()	Get the value if it's sitting in the cache, otherwise return null
String	getName()
void	invalidate()	Invalidate any cached result, such that subsequent calls to get() will re-generate the value
void	setName(String name)
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Details

SingleItemCache

public SingleItemCache(Callable<T> supplier,
 Timeout validity)

Create a new cache, caching the result of supplier for a maximum of validity. A new Cache will be constructed using CacheBuilder

Parameters:

supplier - a function that generates some cache-worthy result; see get() for information on how/when this method is called. The supplier MUST NOT return null

validity - the time after write that the cached result from supplier should expire

SingleItemCache

public SingleItemCache(com.google.common.cache.CacheBuilder builder,
 Callable<T> supplier)

Create a new cache, caching the result of supplier using a cache built by builder.

Parameters:

builder - the cache builder; will be largely untouched, although the maximum size will be set to 1 (since the cache will only store a single item)

supplier - a function that generates some cache-worthy result; see get() for information on how/when this method is called. The supplier MUST NOT return null

SingleItemCache

public SingleItemCache(com.google.common.cache.CacheBuilder builder,
 Callable<T> supplier,
 boolean useCacheManager)

Create a new cache, caching the result of supplier using a cache built by builder.

Parameters:

builder - the cache builder; will be largely untouched, although the maximum size will be set to 1 (since the cache will only store a single item)

supplier - a function that generates some cache-worthy result; see get() for information on how/when this method is called. The supplier MUST NOT return null

useCacheManager - if true, will not be registered with the CacheManager to allow cache to be cleared manually

Method Details

getIfPresent

public T getIfPresent()

Get the value if it's sitting in the cache, otherwise return null

Returns:

the value from the cache, or null if no value was cached

See Also:

• Cache.getIfPresent(Object)

get

public T get()

Return the cached value (or regenerate it).

Returns:

the cached result, or a newly-generated value if the cache had expired (or had been actively invalidated)

Throws:

RuntimeException - if the supplier function passed to the constructor throws

See Also:

• Cache.get(Object, Callable)

invalidate

public void invalidate()

Invalidate any cached result, such that subsequent calls to get() will re-generate the value

See Also:

• Cache.invalidateAll()

setName

public void setName(String name)

getName

public String getName()

toString

public String toString()

Overrides:

toString in class Object