[GitHub] leventov commented on a change in pull request #6683: fix huge number of watches in zk issue

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

leventov commented on a change in pull request #6683: fix huge number of watches in zk issue
URL: https://github.com/apache/incubator-druid/pull/6683#discussion_r239161009
 
 

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 File path: server/src/main/java/org/apache/druid/curator/announcement/NodeAnnouncer.java
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 @@ -0,0 +1,346 @@
+/*
+ * 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.
+ */
+
+package org.apache.druid.curator.announcement;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Throwables;
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.api.transaction.CuratorTransaction;
+import org.apache.curator.framework.api.transaction.CuratorTransactionFinal;
+import org.apache.curator.framework.recipes.cache.ChildData;
+import org.apache.curator.framework.recipes.cache.NodeCache;
+import org.apache.curator.framework.recipes.cache.NodeCacheListener;
+import org.apache.curator.utils.ZKPaths;
+import org.apache.druid.java.util.common.IAE;
+import org.apache.druid.java.util.common.ISE;
+import org.apache.druid.java.util.common.guava.CloseQuietly;
+import org.apache.druid.java.util.common.io.Closer;
+import org.apache.druid.java.util.common.lifecycle.LifecycleStart;
+import org.apache.druid.java.util.common.lifecycle.LifecycleStop;
+import org.apache.druid.java.util.common.logger.Logger;
+import org.apache.zookeeper.CreateMode;
+import org.apache.zookeeper.KeeperException;
+import org.apache.zookeeper.data.Stat;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+/**
+ * Announces single node on Zookeeper and only watch this node, which is different with Announcer
+ */
+public class NodeAnnouncer
+{
+  private static final Logger log = new Logger(NodeAnnouncer.class);
+
+  private final CuratorFramework curator;
+
+  private final List<Announceable> toAnnounce = new ArrayList<>();
+  private final List<Announceable> toUpdate = new ArrayList<>();
+  private final ConcurrentMap<String, NodeCache> listeners = new ConcurrentHashMap<>();
+  private final ConcurrentMap<String, byte[]> announcements = new ConcurrentHashMap<>();
+  private final List<String> parentsIBuilt = new CopyOnWriteArrayList<String>();
+
+  private boolean started = false;
+
+  public NodeAnnouncer(CuratorFramework curator)
+  {
+    this.curator = curator;
+  }
+
+  @VisibleForTesting
+  Set<String> getAddedPaths()
+  {
+    return announcements.keySet();
+  }
+
+  @LifecycleStart
+  public void start()
+  {
+    log.info("Starting announcer");
+    synchronized (toAnnounce) {
+      if (started) {
+        return;
+      }
+
+      started = true;
+
+      for (Announceable announceable : toAnnounce) {
+        announce(announceable.path, announceable.bytes, announceable.removeParentsIfCreated);
+      }
+      toAnnounce.clear();
+
+      for (Announceable announceable : toUpdate) {
+        update(announceable.path, announceable.bytes);
+      }
+      toUpdate.clear();
+    }
+  }
+
+  @LifecycleStop
+  public void stop()
+  {
+    log.info("Stopping announcer");
+    synchronized (toAnnounce) {
+      if (!started) {
+        return;
+      }
+
+      started = false;
+
+      Closer closer = Closer.create();
+      for (NodeCache cache : listeners.values()) {
+        closer.register(cache);
+      }
+      CloseQuietly.close(closer);
+
+      for (String announcementPath : announcements.keySet()) {
+        unannounce(announcementPath);
+      }
+
+      if (!parentsIBuilt.isEmpty()) {
+        CuratorTransaction transaction = curator.inTransaction();
+        for (String parent : parentsIBuilt) {
+          try {
+            transaction = transaction.delete().forPath(parent).and();
+          }
+          catch (Exception e) {
+            log.info(e, "Unable to delete parent[%s], boooo.", parent);
 
 Review comment:
   log.error maybe

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