Merge pull request #35 from launchdarkly/jko/init-cache

Add caching to the Redis initialization check

Author: jkodumal

src/main/java/com/launchdarkly/client/RedisFeatureStore.java

@@ -24,7 +24,9 @@ public class RedisFeatureStore implements FeatureStore {
   private static final String DEFAULT_PREFIX = "launchdarkly";
   private final Jedis jedis;
   private LoadingCache<String, FeatureRep<?>> cache;
+  private LoadingCache<String, Boolean> initCache;
   private String prefix;
+  private static final String INIT_KEY = "$initialized$";
 
   /**
    *
@@ -37,6 +39,7 @@ public RedisFeatureStore(String host, int port, String prefix, long cacheTimeSec
     jedis = new Jedis(host, port);
     setPrefix(prefix);
     createCache(cacheTimeSecs);
+    createInitCache(cacheTimeSecs);
   }
 
   /**
@@ -50,6 +53,7 @@ public RedisFeatureStore(URI uri, String prefix, long cacheTimeSecs) {
     jedis = new Jedis(uri);
     setPrefix(prefix);
     createCache(cacheTimeSecs);
+    createInitCache(cacheTimeSecs);
   }
 
   /**
@@ -82,6 +86,18 @@ public FeatureRep<?> load(String key) throws Exception {
     }
   }
 
+  private void createInitCache(long cacheTimeSecs) {
+    if (cacheTimeSecs > 0) {
+      initCache = CacheBuilder.newBuilder().expireAfterWrite(cacheTimeSecs, TimeUnit.SECONDS).build(new CacheLoader<String, Boolean>() {
+
+        @Override
+        public Boolean load(String key) throws Exception {
+          return getInit();
+        }
+      });
+    }
+  }
+
   /**
    *
    * Returns the {@link com.launchdarkly.client.FeatureRep} to which the specified key is mapped, or
@@ -218,14 +234,26 @@ public void upsert(String key, FeatureRep<?> feature) {
    */
   @Override
   public boolean initialized() {
-    return jedis.exists(featuresKey());
+    if (initCache != null) {
+      Boolean initialized = initCache.getUnchecked(INIT_KEY);
+
+      if (initialized != null && initialized.booleanValue()) {
+        return true;
+      }
+    }
+
+    return getInit();
   }
 
 
   private String featuresKey() {
     return prefix + ":features";
   }
 
+  private Boolean getInit() {
+    return jedis.exists(featuresKey());
+  }
+
   private FeatureRep<?> getRedis(String key) {
     Gson gson = new Gson();
     String featureJson = jedis.hget(featuresKey(), key);