[GitHub] [helix] xyuanlu commented on a diff in pull request #2421: MetaClient LockClient Interface

["xyuanlu (via GitHub)" <gi...@apache.org>]

xyuanlu commented on code in PR #2421:
URL: https://github.com/apache/helix/pull/2421#discussion_r1151288970


##########
meta-client/src/main/java/org/apache/helix/metaclient/recipes/lock/LockClientInterface.java:
##########
@@ -0,0 +1,62 @@
+package org.apache.helix.metaclient.recipes.lock;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import org.apache.helix.metaclient.api.MetaClientInterface;
+
+public interface LockClientInterface {
+  /**
+   * Acquires a lock by creating a node at entry key and lockinfo info.
+   * Will fail and return False if path and lockinfo is invalid.
+   * @param key key to identify the entry
+   * @param info Metadata of the lock
+   * @param mode EntryMode identifying if the entry will be deleted upon client disconnect
+   * @return True if the lock is acquired. False if failed to acquire (catches exception).
+   */
+  boolean acquireLock(String key, LockInfo info, MetaClientInterface.EntryMode mode);
+
+  /**
+   * Renews lock for a TTL Node.
+   * Will fail if key is an invalid path or isn't of type TTL.
+   * @param key key to identify the entry
+   * @return True if the lock was renews. False if failed to renew (catches exception).
+   */
+  boolean renewTTLLock(String key);
+
+  /**
+   * Releases the lock by deleted the node at entry key.
+   * Will fail if key is an invalid path.
+   * @param key key to identify the entry
+   * @return True if the lock was released. False if failed to release (catches exception).
+   */
+  boolean releaseLock(String key);

Review Comment:
   +1 on qqu's comment.
   Probably we want more detail regarding what does "invalid path" mean here. 
   When releasing an lock doe second time, do we want to differentiate already released lock or non-existing lock? It is hard to do when underlying datastore does remove lock entry when released.



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