soabase-cache

Simple caching proxy that integrates with Dropwizard

Features

• Proxies any Interface to cache the method return value
• Cache keys based on class name, method name, parameter values or any combination
• Supports any backing store for cached objects - default uses in-memory hash map

Usage

1. Create Interfaces that model the objects to be cached, marking cacheable methods with cache annotations
2. Create the concrete implementation of the Interface
3. Allocate a CacheBackingStore instance either directly or using CacheBackingStoreFactory
4. Create the cache proxy using CachingControllerBuilder

Simple Example

...

public interface PersonContainer {
    @Cache
    Person getPerson(@CacheKey int id);
    
    @CacheClear
    void addPerson(Person p, @CacheKey int id);
}

public class PersonContainerImpl implements PersonContainer {
    ...
}

...

CacheBackingStore store = cacheBackingStoreFactory.build(environment);
PersonContainer containerImpl = new PersonContainerImpl();
PersonContainer container = CachingControllerBuilder.build(store, containerImpl, PersonContainer.class);

...

Person p = container.get(id); // next call to container.get with the same ID will be cached

container.put(newP, id);  // clears the cache entry for id

Group/Artifact

Soabase Cache is available from Maven Central

Reference

Annotations

@Cache

Marks that the annotated method's return value is to be cached. See below for details on how the cache key is generated.

@CacheClear

Marks that the annotated method's value is cleared from the cache. See below for details on how the cache key is generated.

@CacheKey

Controls how cache keys are generated (see below). Can be applied to Interfaces, methods and/or parameters.

Key Generation

A list of "key parts" is generated and then combined to create the cache key.

• Part 0 - Part 0 is based on the Interface name. If the Interface is annotated with @CacheKey and the annotation value is not an empty string, that value is used as Part 0. Otherwise, The Interface's full name is used.
• Part 1 - Part 1 is based on the Method. If the method is annotated with @CacheKey, Part 1 is either the annotation value or the method name if the annotation value is an empty string. If the method is not annotated with @CacheKey then there is no Part 1.
• Parts 1+ - The remaining parts consist of any parameters annotated with @CacheKey. The value is a concatenation of the annotation value and the parameter value.

The key parts are combined using the configured KeyPartCombiner. The StandardKeyPartCombiner joins all the parts separated with a - (dash).

Backing Store

The actual caching of objects is done by the configured CacheBackingStore. The library comes with MemoryCacheBackingStore which stores objects in a Guava Cache Map.

CacheKeyAccessor

To get the value of a method parameter, String.valueOf() is called. However, the object can implement CacheKeyAccessor to provide a custom key value.