Provides the ability to configure DefaultPersistenceConfiguration in CacheConfigurationBuilder

[linghengqian]

• In https://www.ehcache.org/blog/2016/05/18/ehcache3_jsr107_spring.html , it provided for the initial cache of JavaConfig in one idea.

  @Component
  public static class CachingSetup implements JCacheManagerCustomizer
  {
    @Override
    public void customize(CacheManager cacheManager)
    {
      cacheManager.createCache("people", new MutableConfiguration<>()  
        .setExpiryPolicyFactory(TouchedExpiryPolicy.factoryOf(new Duration(SECONDS, 10))) 
        .setStoreByValue(false)
        .setStatisticsEnabled(true));
    }
  }

• At https://www.ehcache.org/blog/2017/03/15/spontaneous-cache-creation.html , Stéphane Nicoll (https://twitter.com/snicoll) also recommends this approach.

@Bean
public JCacheManagerCustomizer cacheManagerCustomizer() {
    return cm -> {
        Configuration<Object, Object> cacheConfiguration = createCacheConfiguration();
        cm.createCache("vets", cacheConfiguration);
    };
}

private Configuration<Object, Object> createCacheConfiguration() {
    return Eh107Configuration.fromEhcacheCacheConfiguration(CacheConfigurationBuilder
        .newCacheConfigurationBuilder(Object.class, Object.class, ResourcePoolsBuilder
            .newResourcePoolsBuilder().heap(100)));
}

• But according to the official ehcache3-example, there is a detailed process in https://github.com/ehcache/ehcache3-samples/blob/master/fullstack/src/main/java/org/ehcache/sample/config/CacheConfiguration.java . In the configuration of this case, the DefaultPersistenceConfiguration can be configured by a code snippet similar to the following. But this should not be handled well in ehcache3-example(points to https://github.com/ehcache/ehcache3-samples ) as it will result. public class CacheConfig extends CachingConfigurerSupport should be changed to public class CacheConfig implements CachingConfigurer. Refer to Deprecate CachingConfigurerSupport and AsyncConfigurerSupport spring-projects/spring-framework#27813

package com.lingh.config;

@EnableCaching
@Configuration
public class CacheConfig extends CachingConfigurerSupport {
    private javax.cache.CacheManager getCacheManager(EhcacheCachingProvider provider, DefaultConfiguration configuration) {
        return provider.getCacheManager(provider.getDefaultURI(), configuration);
    }

    @Bean 
    @Override
    public org.springframework.cache.CacheManager cacheManager() {
        return new JCacheCacheManager(createInMemoryCacheManager());
    }

    private javax.cache.CacheManager createInMemoryCacheManager() {
        CacheConfiguration<Object, Object> cacheConfiguration = CacheConfigurationBuilder.newCacheConfigurationBuilder(
                        Object.class, Object.class,
                        ResourcePoolsBuilder.newResourcePoolsBuilder().heap(123L, EntryUnit.ENTRIES)
                                .disk(123L, MemoryUnit.MB, true))
                .withExpiry(ExpiryPolicyBuilder.timeToLiveExpiration(Duration.ofDays(123L)))
                .build();
        Map<String, CacheConfiguration<?, ?>> caches = new HashMap<>();
        caches.putAll(this.createCacheConfigurations(cacheConfiguration));
        EhcacheCachingProvider provider = this.getCachingProvider();
        DefaultConfiguration configuration = new DefaultConfiguration(caches, provider.getDefaultClassLoader(), new DefaultPersistenceConfiguration(new File("./cache-data")));
        return this.getCacheManager(provider, configuration);
    }

    private Map<String, CacheConfiguration<?, ?>> createCacheConfigurations(CacheConfiguration<Object, Object> cacheConfiguration) {
        Map<String, CacheConfiguration<?, ?>> caches = new HashMap<>();
        caches.put("test", cacheConfiguration);
        return caches;
    }

     private EhcacheCachingProvider getCachingProvider() {
        return (EhcacheCachingProvider) Caching.getCachingProvider(EhcacheCachingProvider.class.getName());
    }
}

• But if you use the JCacheManagerCustomizer recommended by Stéphane Nicoll in https://www.ehcache.org/blog/2017/03/15/spontaneous-cache-creation.html , It is logically impossible to configure DefaultPersistenceConfiguration at all now. Because according to https://www.ehcache.org/documentation/3.9/107.html#cachemanager-level-configuration , configuring DefaultPersistenceConfiguration must be at the org.ehcache.jsr107.EhcacheCachingProvider level of EhCache 3 to process. Since the case used by ehcache3-example is actually jhipster, I tried to find their latest use case, and what jhipster consider best practice now has become JCacheManagerCustomizer. Refer to https://github.com/jhipster/jhipster-sample-app/blob/main/src/main/java/io/github/jhipster/sample/config/CacheConfiguration.java . Refer to Cache auto-configuration should consistently apply JSR-107 support spring-projects/spring-boot#3822 .

• To sum up, I hope EhCache 3 can provide the ability to configure DefaultPersistenceConfiguration in CacheConfigurationBuilder. Of course, if there is something I overlooked, it would be better to understand. Because https://stackoverflow.com/questions/65127520/set-ehcaches-persistence-directory-programmatically-on-spring-boot also has such doubts. Of course using XML to fully configure EhCache 3 can completely solve similar problems, but I'd much rather see the JavaConfig way.

• There is also a related issue related to this, that is, the documentation for integrating with Spring has not been relatively complete. See Add documentation about Spring and Hibernate #1910

[linghengqian]

Considering #3038 (comment) 's point of view, I don't think the issue discusses anything that needs attention anymore. So I'm going to close the issue.