[GitHub] [helix] pkuwm commented on a change in pull request #789: Add FederatedZkClient

[GitBox <gi...@apache.org>]

pkuwm commented on a change in pull request #789: Add FederatedZkClient
URL: https://github.com/apache/helix/pull/789#discussion_r382868650
 
 

 ##########
 File path: zookeeper-api/src/main/java/org/apache/helix/zookeeper/impl/client/FederatedZkClient.java
 ##########
 @@ -20,344 +20,486 @@
  */
 
 import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.TimeUnit;
 
+import org.apache.helix.msdcommon.datamodel.MetadataStoreRoutingData;
 import org.apache.helix.zookeeper.api.client.RealmAwareZkClient;
+import org.apache.helix.zookeeper.impl.factory.DedicatedZkClientFactory;
 import org.apache.helix.zookeeper.zkclient.DataUpdater;
 import org.apache.helix.zookeeper.zkclient.IZkChildListener;
 import org.apache.helix.zookeeper.zkclient.IZkDataListener;
+import org.apache.helix.zookeeper.zkclient.ZkConnection;
 import org.apache.helix.zookeeper.zkclient.callback.ZkAsyncCallbacks;
-import org.apache.helix.zookeeper.zkclient.deprecated.IZkStateListener;
+import org.apache.helix.zookeeper.zkclient.IZkStateListener;
+import org.apache.helix.zookeeper.zkclient.serialize.BasicZkSerializer;
 import org.apache.helix.zookeeper.zkclient.serialize.PathBasedZkSerializer;
 import org.apache.helix.zookeeper.zkclient.serialize.ZkSerializer;
 import org.apache.zookeeper.CreateMode;
 import org.apache.zookeeper.Op;
 import org.apache.zookeeper.OpResult;
+import org.apache.zookeeper.ZooDefs;
 import org.apache.zookeeper.data.ACL;
 import org.apache.zookeeper.data.Stat;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/**
+ * Implements and supports all ZK operations defined in interface {@link RealmAwareZkClient},
+ * except for session-aware operations such as creating ephemeral nodes, for which
+ * an {@link UnsupportedOperationException} will be thrown.
+ * <p>
+ * It acts as a single ZK client but will automatically route read/write/change subscription
+ * requests to the corresponding ZkClient with the help of metadata store directory service.
+ * It could connect to multiple ZK addresses and maintain a {@link ZkClient} for each ZK address.
+ */
+public class FederatedZkClient implements RealmAwareZkClient {
+  private static final Logger LOG = LoggerFactory.getLogger(FederatedZkClient.class);
 
+  private static final String FEDERATED_ZK_CLIENT = FederatedZkClient.class.getSimpleName();
+  private static final String DEDICATED_ZK_CLIENT_FACTORY =
+      DedicatedZkClientFactory.class.getSimpleName();
+
+  private final MetadataStoreRoutingData _metadataStoreRoutingData;
+  private final RealmAwareZkClient.RealmAwareZkClientConfig _clientConfig;
+
+  // ZK realm -> ZkClient
+  private final Map<String, ZkClient> _zkRealmToZkClientMap;
+
+  private volatile boolean _isClosed;
+  private PathBasedZkSerializer _pathBasedZkSerializer;
+
+  // TODO: support capacity of ZkClient number in one FederatedZkClient and do garbage collection.
+  public FederatedZkClient(RealmAwareZkClient.RealmAwareZkClientConfig clientConfig,
+      MetadataStoreRoutingData metadataStoreRoutingData) {
 
 Review comment:
   We will remove this metadata store routing data in param once http routing data reader is ready.

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