initial entry caching implementation

src/main/java/com/commafeed/backend/cache/CacheService.java

@@ -0,0 +1,31 @@
+package com.commafeed.backend.cache;
+
+import java.util.concurrent.TimeUnit;
+
+import com.commafeed.backend.model.Feed;
+import com.commafeed.backend.model.FeedEntry;
+import com.google.common.cache.Cache;
+import com.google.common.cache.CacheBuilder;
+
+public class CacheService {
+
+	Cache<String, Marker> entryCache = CacheBuilder.newBuilder()
+			.maximumSize(1000000).expireAfterWrite(24, TimeUnit.HOURS).build();
+
+	private static enum Marker {
+		INSTANCE
+	}
+
+	public boolean hasFeedEntry(Feed feed, FeedEntry entry) {
+		return entryCache.getIfPresent(buildKey(feed, entry)) == Marker.INSTANCE;
+	}
+
+	public void putFeedEntry(Feed feed, FeedEntry entry) {
+		entryCache.put(buildKey(feed, entry), Marker.INSTANCE);
+	}
+
+	private String buildKey(Feed feed, FeedEntry entry) {
+		return String.format("%s:%s:%s", feed.getId(), entry.getGuid(),
+				entry.getUrl());
+	}
+}

src/main/java/com/commafeed/backend/feeds/FeedRefreshUpdater.java

@@ -20,6 +20,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import com.commafeed.backend.MetricsBean;
+import com.commafeed.backend.cache.CacheService;
 import com.commafeed.backend.dao.FeedDAO;
 import com.commafeed.backend.dao.FeedEntryDAO;
 import com.commafeed.backend.dao.FeedSubscriptionDAO;
@@ -62,6 +63,9 @@ public class FeedRefreshUpdater {
 	@Inject
 	FeedEntryDAO feedEntryDAO;
 
+	@Inject
+	CacheService cache;
+
 	private ThreadPoolExecutor pool;
 	private Striped<Lock> locks;
 	private LinkedBlockingDeque<Runnable> queue;
@@ -167,7 +171,13 @@ public class FeedRefreshUpdater {
 		try {
 			locked = lock.tryLock(1, TimeUnit.MINUTES);
 			if (locked) {
-				feedUpdateService.updateEntry(feed, entry, subscriptions);
+				if (!cache.hasFeedEntry(feed, entry)) {
+					log.info("cache miss for {}", entry.getUrl());
+					feedUpdateService.updateEntry(feed, entry, subscriptions);
+					cache.putFeedEntry(feed, entry);
+				} else {
+					log.info("cache hit for {}", entry.getUrl());
+				}
 				success = true;
 			} else {
 				log.error("lock timeout for " + feed.getUrl() + " - " + key);