From 22ff39853d7c53a4e13319729275f0e8cdae2c99 Mon Sep 17 00:00:00 2001
From: Jens Wilke <jw_github@headissue.com>
Date: Thu, 12 Jul 2018 14:14:28 +0200
Subject: [PATCH] Clarify cache configuration
See gh-335
---
.../petclinic/system/CacheConfiguration.java | 37 ++++++++++++++++++-
1 file changed, 35 insertions(+), 2 deletions(-)
diff --git a/src/main/java/org/springframework/samples/petclinic/system/CacheConfiguration.java b/src/main/java/org/springframework/samples/petclinic/system/CacheConfiguration.java
index e4d7b42..adde2be 100755
--- a/src/main/java/org/springframework/samples/petclinic/system/CacheConfiguration.java
+++ b/src/main/java/org/springframework/samples/petclinic/system/CacheConfiguration.java
@@ -7,10 +7,38 @@ import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
+/**
+ * Cache configuration intended for caches providing the JCache API. This configuration
+ * creates the used cache for the application and enables statistics that
+ * become accessible via JMX.
+ *
+ * <p>This is a minimal configuration that makes use of the JCache API to enable
+ * caching with any JCache implementation out of the box. The utilized JCache implementation
+ * is specified by the dependency in the {@code pom.xml}.
+ *
+ * <p>If the used cache implementation is configured via its specific and non standard mechanism,
+ * this example configuration might be redundant and can be removed or replaced by
+ * a programmatic configuration via the implementation specific methods.
+ *
+ * <p>In case no programmatic cache configuration is needed for the selected caching
+ * implementation this configuration class can be removed and the {@link EnableCaching}
+ * annotation can be put on the application class.
+ *
+ * @author Jens Wilke
+ */
@Configuration
@EnableCaching
class CacheConfiguration {
+ /**
+ * A customizer that creates the the cache used by the application.
+ * This implies that the cache is not existent before the application start and the
+ * cache must be created. This is the default behavior of a JCache implemenation, in case
+ * no additional configuration is present and typically will create a transient in memory cache.
+ * If a persistent cache implementation is used, creating the cache on startup
+ * may lead to a failure, when the cache was created before. If the cache life time
+ * is controlled separately, the call of {@code createCache} must be removed.
+ */
@Bean
public JCacheManagerCustomizer petclinicCacheConfigurationCustomizer() {
return cm -> {
@@ -18,9 +46,14 @@ class CacheConfiguration {
};
}
+ /**
+ * Enable statistics via the JCache programmatic configuration API.
+ * Within the configuration object that is provided by the JCache API standard, there is only
+ * a very limited set of configuration options. The really relevant configuration options
+ * (like the size limit) must be set via a configuration mechanism that is provided by the
+ * selected JCache implementation.
+ */
private javax.cache.configuration.Configuration<Object, Object> cacheConfiguration() {
- // Create a cache using infinite heap. A real application will want to use a more fine-grained configuration,
- // possibly using an implementation-dependent API
return new MutableConfiguration<>().setStatisticsEnabled(true);
}
--
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