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Posted to reviews@helix.apache.org by GitBox <gi...@apache.org> on 2023/01/12 17:01:02 UTC
[GitHub] [helix] desaikomal commented on a diff in pull request #2338: Implement a thread-safe listener container for zkclient
desaikomal commented on code in PR #2338:
URL: https://github.com/apache/helix/pull/2338#discussion_r1068365894
##########
zookeeper-api/src/main/java/org/apache/helix/zookeeper/zkclient/ListenerContainer.java:
##########
@@ -0,0 +1,186 @@
+package org.apache.helix.zookeeper.zkclient;
+
+/*
+ * 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 com.google.common.annotations.VisibleForTesting;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Consumer;
+
+
+/**
+ * A thread-safe container wrapper class for Listeners registered to ZkClient.
+ * It stores 2 types of listener separately, one-time listener and persistent listener. The former ones are removed
Review Comment:
Do we have any users of one-time listener?
AFAIK there are none. can you please confirm
##########
zookeeper-api/src/main/java/org/apache/helix/zookeeper/zkclient/ListenerContainer.java:
##########
@@ -0,0 +1,186 @@
+package org.apache.helix.zookeeper.zkclient;
+
+/*
+ * 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 com.google.common.annotations.VisibleForTesting;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Consumer;
+
+
+/**
+ * A thread-safe container wrapper class for Listeners registered to ZkClient.
+ * It stores 2 types of listener separately, one-time listener and persistent listener. The former ones are removed
+ * right after its consumption, while the latter need to be explicitly removed.
+ * @param <T> the type of listener
+ */
+public class ListenerContainer<T> {
+ private final ReentrantLock _lock = new ReentrantLock(true);
+ private final Map<String, Set<T>> _persistentListener = new ConcurrentHashMap<>();
Review Comment:
ConcurrentHashMap has methods for concurrency and so i am not sure you require explicit lock.
##########
zookeeper-api/src/main/java/org/apache/helix/zookeeper/zkclient/ListenerContainer.java:
##########
@@ -0,0 +1,186 @@
+package org.apache.helix.zookeeper.zkclient;
+
+/*
+ * 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 com.google.common.annotations.VisibleForTesting;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Consumer;
+
+
+/**
+ * A thread-safe container wrapper class for Listeners registered to ZkClient.
+ * It stores 2 types of listener separately, one-time listener and persistent listener. The former ones are removed
+ * right after its consumption, while the latter need to be explicitly removed.
+ * @param <T> the type of listener
+ */
+public class ListenerContainer<T> {
+ private final ReentrantLock _lock = new ReentrantLock(true);
+ private final Map<String, Set<T>> _persistentListener = new ConcurrentHashMap<>();
+ private final Map<String, Set<T>> _onetimeListener = new ConcurrentHashMap<>();
+
+ /**
+ * Add listener to the container with specified key.
+ * @param key the key to register to
+ * @param listener the listener to register
+ * @param persistListener true if the listener is persistent
+ */
+ public void addListener(String key, T listener, boolean persistListener) {
+ addListener(key, listener, persistListener ? _persistentListener : _onetimeListener);
+ }
+
+ /**
+ * Remove listener from the container.
+ * This operation removes both one-time and persistent listener from the specified key.
+ * @param key the key to remove
+ * @param listener the listener to remove
+ */
+ public void removeListener(String key, T listener) {
Review Comment:
If we remove one-time listener, lot of the code will become simpler.
Can you first please let me know who needs one-time listener?
thanks,
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