FR-48873 Time-Invalidated Cache

This project adds a new time invalidated cache API, that will allow creating new time invalidated caches. It follows the following document: https://docs.google.com/document/d/1t5dRZbudoNyd1KxLibBp25TCdSRqMs43pC_0MQNpEjU/edit#

Wiki with usage is provided here: http://wiki.openbravo.com/wiki/Time_Invalidated_Cache

Libraries

Library	Version	Status	Comment
caffeine	3.0.6	Added	High Performance caching library

Tasks

• JDK Version: 55 (Java 11)
• License: Apache 2.0
• Size: 734 kB
• Add information to Openbravo Libraries wiki
• Add library to dependencies repo

Usage

Creation of Cache and initialization:

To initialize a cache, TimeInvalidatedCache builder should be used:

• newBuilder() static initialization method will create the TimeInvalidatedCacheBuilder.
• name("cacheName") sets the name of the cache, it is required, used for logging
• expireAfterDuration(Duration duration) method allows setting a Duration object as the duration after which all keys will be evicted and considered expired in the cache. If not invoked, it will default to 1 minute.
• build(loader) call that should contain a lambda function to compute the value for each given key, if no value, return null. This will return the initialized cache.

Usage:

TimeInvalidatedCache<KeyType, ValueType> cache = TimeInvalidatedCache
    .newBuilder()
    .name("cacheName") // Sets the name of the cache
    .expireAfterDuration(Duration.ofMinutes(5)) // Could be any Duration, not necessarily in minutes. If not executed, 1 minute default is assumed
    .build(key -> generateKeyValue(key)) // This is a lambda that initializes the key if it expired or is the first time is read

How to get value from the cache:

get will return the value given a key, and getAll will return a map(key-value) for a given collection of keys. Will return the value corresponding to the key, or null if the computed value is null.

In case of getAll, it will return a map with key-value, if the value is null, it will not appear in the returned map.

Both functions will throw the following exceptions:

• NullPointerException: if the specified key is null

Usage:

ValueType value = cache.get(key); // Returns the value corresponding to the given key. 
Map<KeyType, ValueType> values = cache.getAll(keys); // keys is a Collection of keys

Get or else default to

It is also possible to provide a default mappingFunction, this function receives a key or a set of key, depending if we are dealing with get or getAll function, and returns a value(which will be used instead if not found in cache and couldn't be computed), it will be a Map of KeyType, ValueType of values if using getAll.

cache.get("testKey", (key) -> "testDefaultValue"); // returns the value corresponding to testKey from cache or from computed cache function if not null. If that is null, it will return "testDefaultValue".

cache.getAll(testKeys,
        (keys) -> keys.stream().collect(Collectors.toMap(key -> key, key -> key + "Value")))
// Same as above, each key that's not found in the cache or couldn't be computed, is computed using the mapping function provided to the getAll as second argument

How to programatically invalidate the cache:

cache.invalidate(key); // Invalidates a single key in the cache, next time is retrieved it will be recomputed
cache.invalidateAll(); // Invalidates all the keys in the cache, next time any is retrieved it will be recomputed