cache the "tree"

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

@@ -7,26 +7,37 @@ import java.util.concurrent.TimeUnit;
 import javax.enterprise.context.ApplicationScoped;
 import javax.enterprise.inject.Alternative;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import redis.clients.jedis.Jedis;
 import redis.clients.jedis.JedisPool;
 import redis.clients.jedis.JedisPoolConfig;
 import redis.clients.jedis.Pipeline;
 
 import com.commafeed.backend.model.Feed;
+import com.commafeed.backend.model.Models;
+import com.commafeed.backend.model.User;
+import com.commafeed.frontend.model.Category;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.api.client.util.Lists;
 
 @Alternative
 @ApplicationScoped
 public class RedisCacheService extends CacheService {
 
+	private static final Logger log = LoggerFactory.getLogger(RedisCacheService.class);
+
 	private JedisPool pool = new JedisPool(new JedisPoolConfig(), "localhost");
+	private ObjectMapper mapper = new ObjectMapper();
 
 	@Override
 	public List<String> getLastEntries(Feed feed) {
 		List<String> list = Lists.newArrayList();
 		Jedis jedis = pool.getResource();
 		try {
-			String key = buildKey(feed);
+			String key = buildRedisEntryKey(feed);
 			Set<String> members = jedis.smembers(key);
 			for (String member : members) {
 				list.add(member);
@@ -41,7 +52,7 @@ public class RedisCacheService extends CacheService {
 	public void setLastEntries(Feed feed, List<String> entries) {
 		Jedis jedis = pool.getResource();
 		try {
-			String key = buildKey(feed);
+			String key = buildRedisEntryKey(feed);
 
 			Pipeline pipe = jedis.pipelined();
 			pipe.del(key);
@@ -55,7 +66,64 @@ public class RedisCacheService extends CacheService {
 		}
 	}
 
-	private String buildKey(Feed feed) {
+	@Override
+	public Category getRootCategory(User user) {
+		Category cat = null;
+		Jedis jedis = pool.getResource();
+		try {
+			String key = buildRedisRootCategoryKey(user);
+			String json = jedis.get(key);
+			if (json != null) {
+				cat = mapper.readValue(json, Category.class);
+			}
+		} catch (Exception e) {
+			log.error(e.getMessage(), e);
+		} finally {
+			pool.returnResource(jedis);
+		}
+		return cat;
+	}
+
+	@Override
+	public void setRootCategory(User user, Category category) {
+		Jedis jedis = pool.getResource();
+		try {
+			String key = buildRedisRootCategoryKey(user);
+
+			Pipeline pipe = jedis.pipelined();
+			pipe.del(key);
+			pipe.set(key, mapper.writeValueAsString(category));
+			pipe.expire(key, (int) TimeUnit.MINUTES.toSeconds(30));
+			pipe.sync();
+		} catch (JsonProcessingException e) {
+			log.error(e.getMessage(), e);
+		} finally {
+			pool.returnResource(jedis);
+		}
+	}
+
+	@Override
+	public void invalidateRootCategory(User... users) {
+		Jedis jedis = pool.getResource();
+		try {
+			Pipeline pipe = jedis.pipelined();
+			if (users != null) {
+				for (User user : users) {
+					String key = buildRedisRootCategoryKey(user);
+					pipe.del(key);
+				}
+			}
+			pipe.sync();
+		} finally {
+			pool.returnResource(jedis);
+		}
+	}
+
+	private String buildRedisRootCategoryKey(User user) {
+		return "root_cat:" + Models.getId(user);
+	}
+
+	private String buildRedisEntryKey(Feed feed) {
 		return "feed:" + feed.getId();
 	}