flexible caffeine cache manager

.gitignore

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 *~
 \#*\#
 \.\#
+/.project

.settings/org.eclipse.core.resources.prefs

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+eclipse.preferences.version=1
+encoding/<project>=UTF-8

README.md

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 # Java Lessons
 
 1) [Lesson #1](springboot2-junit5-skiptest/README.md) - How to write an annotation for your JUnit5 tests and to use application.properties from Spring environment
-2) [Lesson #2](springboot2-request-logger/README.md) - How to log every request in Spring/SpringBoot web application
+
+2) [Lesson #2](springboot2-request-logger/README.md) - How to log every request in Spring/SpringBoot web application
+
+# Snippets
+
+1) [Flexible Caffeine Cache Manager](flexible-caffeine-cache/FlexibleCaffeineCacheManager.java) - How to separate different cache configurations into one application using Caffeine cache

flexible-caffeine-cache/FlexibleCaffeineCacheManager.java

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+package com.pf.core.cache;
+
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.CacheLoader;
+import com.github.benmanes.caffeine.cache.Caffeine;
+import com.github.benmanes.caffeine.cache.CaffeineSpec;
+import lombok.Getter;
+import lombok.Setter;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.cache.caffeine.CaffeineCacheManager;
+import org.springframework.util.StringUtils;
+
+import javax.annotation.Nonnull;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/** Flexible Caffeine cache manager
+ * Idea: {@see "https://dzone.com/articles/multiple-cache-configurations-with-caffeine-and-sp"}
+ *
+ * to be used in cases when you need different settings per cache name
+ *
+ */
+@Slf4j
+@ConfigurationProperties(prefix = "cache")
+public class FlexibleCaffeineCacheManager extends CaffeineCacheManager implements InitializingBean {
+
+    /**
+     * default <code>spring.cache.cache-names</code> settings
+     * will be overridden with {@link FlexibleCaffeineCacheManager#specs}
+     */
+    @Value("${spring.cache.cache-names:}")
+    private String springCacheNames;
+
+    /**
+     * default <code>spring.cache.caffeine.spec</code> settings
+     * will be overridden with {@link FlexibleCaffeineCacheManager#specs}
+     */
+    @Value("${spring.cache.caffeine.spec:}")
+    private String springCacheSpecs;
+
+    /**
+     * This field could be populated from <code>application.(yaml|properties)</code> file
+     * All features are listed into {@link CaffeineSpec}
+     */
+    @Getter @Setter
+    private Map<String, String> specs = new ConcurrentHashMap<>();
+    @Getter
+    private Map<String, Caffeine<Object, Object>> builders = new ConcurrentHashMap<>();
+
+    private CacheLoader<Object, Object> cacheLoader;
+    @Override
+    public void setCacheLoader(@Nonnull CacheLoader<Object, Object> cacheLoader) {
+        this.cacheLoader = cacheLoader;
+    }
+
+    /**
+     * reads all standard settings from application.(properties|yml) and adjust proper cache builders
+     * @throws Exception
+     */
+    @Override
+    public void afterPropertiesSet() throws Exception {
+        if (StringUtils.hasText(springCacheNames) && !springCacheNames.equals("${spring.cache.cache-names:}")) {
+            String[] cacheNames = springCacheNames.split(",");
+            if (cacheNames.length > 0) {
+                for (String cacheName : cacheNames) {
+                    if (StringUtils.hasText(cacheName)) {
+                        if (!specs.containsKey(cacheName.trim())) {
+                            specs.put(cacheName.trim(), springCacheSpecs);
+                        }
+                    }
+                }
+            }
+        }
+        for (Map.Entry<String, String> cacheSpecEntry : specs.entrySet()) {
+            log.info("Creating cache with name {} and specs: {}", cacheSpecEntry.getKey(), cacheSpecEntry.getValue());
+            builders.put(cacheSpecEntry.getKey(), Caffeine.from(cacheSpecEntry.getValue()));
+        }
+    }
+
+    @Nonnull
+    @Override
+    protected Cache<Object, Object> createNativeCaffeineCache(String name) {
+        Caffeine<Object, Object> builder = builders.get(name);
+        if (builder == null) {
+            return super.createNativeCaffeineCache(name);
+        }
+
+        if (this.cacheLoader != null) {
+            return builder.build(this.cacheLoader);
+        } else {
+            return builder.build();
+        }
+    }
+
+}