[GitHub] [pulsar] andrasbeni commented on a diff in pull request #16062: [feat][broker] PIP-145: Notifications for faster topic discovery

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

andrasbeni commented on code in PR #16062:
URL: https://github.com/apache/pulsar/pull/16062#discussion_r902833151


##########
pulsar-client/src/main/java/org/apache/pulsar/client/impl/PulsarClientImpl.java:
##########
@@ -119,9 +119,11 @@ public enum State {
     // These sets are updated from multiple threads, so they require a threadsafe data structure
     private final Set<ProducerBase<?>> producers = Collections.newSetFromMap(new ConcurrentHashMap<>());
     private final Set<ConsumerBase<?>> consumers = Collections.newSetFromMap(new ConcurrentHashMap<>());
+    private final Set<TopicListWatcher> topicListWatchers = Collections.newSetFromMap(new ConcurrentHashMap<>());

Review Comment:
   You are right. This set is redundant to ClientCnx.topicListWatchers, so I'm going to remove this.



##########
pulsar-client/src/main/java/org/apache/pulsar/client/impl/TopicListWatcher.java:
##########
@@ -0,0 +1,287 @@
+/**
+ * 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.pulsar.client.impl;
+
+import io.netty.channel.ChannelHandlerContext;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLongFieldUpdater;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.regex.Pattern;
+import org.apache.pulsar.client.api.PulsarClientException;
+import org.apache.pulsar.common.api.proto.BaseCommand;
+import org.apache.pulsar.common.api.proto.CommandWatchTopicUpdate;
+import org.apache.pulsar.common.naming.NamespaceName;
+import org.apache.pulsar.common.protocol.Commands;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class TopicListWatcher extends HandlerState implements ConnectionHandler.Connection {
+
+    private static final Logger log = LoggerFactory.getLogger(TopicListWatcher.class);
+
+    private static final AtomicLongFieldUpdater<TopicListWatcher> CREATE_WATCHER_DEADLINE_UPDATER =
+            AtomicLongFieldUpdater
+                    .newUpdater(TopicListWatcher.class, "createWatcherDeadline");
+
+    private final PatternMultiTopicsConsumerImpl.TopicsChangedListener topicsChangeListener;
+    private final String name;
+    private final ConnectionHandler connectionHandler;
+    private final Pattern topicsPattern;
+    private final long watcherId;
+    private volatile long createWatcherDeadline = 0;
+    private final NamespaceName namespace;
+    // TODO maintain the value based on updates from broker and warn the user if inconsistent with hash from polling
+    private String topicsHash;
+    private final CompletableFuture<TopicListWatcher> watcherFuture;
+
+    private final List<Throwable> previousExceptions = new CopyOnWriteArrayList<>();
+    private final AtomicReference<ClientCnx> clientCnxUsedForWatcherRegistration = new AtomicReference<>();
+
+
+    public TopicListWatcher(PatternMultiTopicsConsumerImpl.TopicsChangedListener topicsChangeListener,
+                            PulsarClientImpl client, Pattern topicsPattern, long watcherId,
+                            NamespaceName namespace, String topicsHash,
+                            CompletableFuture<TopicListWatcher> watcherFuture) {
+        super(client, null);
+        this.topicsChangeListener = topicsChangeListener;
+        this.name = "Watcher(" + topicsPattern + ")";
+        this.connectionHandler = new ConnectionHandler(this,
+                new BackoffBuilder()
+                        .setInitialTime(client.getConfiguration().getInitialBackoffIntervalNanos(),
+                                TimeUnit.NANOSECONDS)
+                        .setMax(client.getConfiguration().getMaxBackoffIntervalNanos(), TimeUnit.NANOSECONDS)
+                        .setMandatoryStop(0, TimeUnit.MILLISECONDS)
+                        .create(),
+                this);
+        this.topicsPattern = topicsPattern;
+        this.watcherId = watcherId;
+        this.namespace = namespace;
+        this.topicsHash = topicsHash;
+        this.watcherFuture = watcherFuture;
+
+        connectionHandler.grabCnx();
+    }
+
+    @Override
+    public void connectionFailed(PulsarClientException exception) {
+        boolean nonRetriableError = !PulsarClientException.isRetriableError(exception);
+        if (nonRetriableError) {
+            exception.setPreviousExceptions(previousExceptions);
+            if (watcherFuture.completeExceptionally(exception)) {
+                setState(State.Failed);
+                log.info("[{}] Watcher creation failed for {} with non-retriable error {}",
+                        topic, name, exception);
+                deregisterFromClientCnx();
+                client.cleanupTopicListWatcher(this);
+            }
+        } else {
+            previousExceptions.add(exception);
+        }
+    }
+
+    @Override
+    public void connectionOpened(ClientCnx cnx) {
+        previousExceptions.clear();
+
+        if (getState() == State.Closing || getState() == State.Closed) {
+            setState(State.Closed);
+            deregisterFromClientCnx();
+            client.cleanupTopicListWatcher(this);
+            return;
+        }
+
+        log.info("[{}][{}] Creating topic list watcher on cnx {}, watcherId {}",
+                topic, getHandlerName(), cnx.ctx().channel(), watcherId);
+
+        long requestId = client.newRequestId();
+
+        CREATE_WATCHER_DEADLINE_UPDATER
+                .compareAndSet(this, 0L, System.currentTimeMillis()
+                        + client.getConfiguration().getOperationTimeoutMs());
+
+        // synchronized this, because redeliverUnAckMessage eliminate the epoch inconsistency between them
+        synchronized (this) {
+            setClientCnx(cnx);
+            BaseCommand watchRequest = Commands.newWatchTopicList(requestId, watcherId, namespace.toString(),
+                            topicsPattern.pattern(), topicsHash);
+
+            cnx.newWatchTopicList(watchRequest, requestId)
+
+                    .thenAccept(response -> {
+                        synchronized (TopicListWatcher.this) {
+                            if (!changeToReadyState()) {
+                                // Watcher was closed while reconnecting, close the connection to make sure the broker
+                                // drops the watcher on its side
+                                setState(State.Closed);
+                                deregisterFromClientCnx();
+                                client.cleanupTopicListWatcher(this);
+
+                                cnx.channel().close();
+                                return;
+                            }
+                        }
+
+                        this.connectionHandler.resetBackoff();
+
+                        watcherFuture.complete(this);
+
+                    }).exceptionally((e) -> {
+                        deregisterFromClientCnx();
+                        if (getState() == State.Closing || getState() == State.Closed) {
+                            // Watcher was closed while reconnecting, close the connection to make sure the broker
+                            // drops the watcher on its side
+                            cnx.channel().close();
+                            return null;
+                        }
+                        log.warn("[{}][{}] Failed to subscribe to topic on {}", topic,
+                                getHandlerName(), cnx.channel().remoteAddress());
+
+                        if (e.getCause() instanceof PulsarClientException
+                                && PulsarClientException.isRetriableError(e.getCause())
+                                && System.currentTimeMillis()
+                                    < CREATE_WATCHER_DEADLINE_UPDATER.get(TopicListWatcher.this)) {
+                            reconnectLater(e.getCause());
+                        } else if (!watcherFuture.isDone()) {
+                            // unable to create new watcher, fail operation
+                            setState(State.Failed);
+                            watcherFuture.completeExceptionally(
+                                    PulsarClientException.wrap(e, String.format("Failed to create topic list watcher %s"
+                                                    + "when connecting to the broker", getHandlerName())));
+                            client.cleanupTopicListWatcher(this);

Review Comment:
   `deregisterFromClientCnx()`, this `exceptionally` block's first call does call `ClientCnx.removeTopicListWatcher(long watcherId)`, so I think it should be fine.



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