sijie commented on a change in pull request #4955: [WIP] [PIP-39] Introduce system topic and topic policies service URL: https://github.com/apache/pulsar/pull/4955#discussion_r316410694
########## File path: pulsar-broker/src/main/java/org/apache/pulsar/broker/service/TopicPoliciesService.java ########## @@ -0,0 +1,230 @@ +/** + * 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.broker.service; + +import com.google.common.annotations.VisibleForTesting; +import com.google.common.cache.CacheBuilder; +import com.google.common.cache.CacheLoader; +import com.google.common.cache.LoadingCache; +import com.google.common.cache.RemovalListener; +import org.apache.pulsar.broker.PulsarServerException; +import org.apache.pulsar.broker.PulsarService; +import org.apache.pulsar.broker.systopic.EventType; +import org.apache.pulsar.broker.systopic.NamespaceEventsSystemTopicFactory; +import org.apache.pulsar.broker.systopic.SystemTopic; +import org.apache.pulsar.broker.systopic.TopicEvent; +import org.apache.pulsar.common.naming.NamespaceName; +import org.apache.pulsar.common.naming.TopicName; +import org.apache.pulsar.common.policies.data.TopicPolicies; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.Map; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ExecutionException; +import java.util.concurrent.TimeUnit; + +/** + * Topic policies service + */ +public class TopicPoliciesService { + + private final PulsarService pulsarService; + private NamespaceEventsSystemTopicFactory namespaceEventsSystemTopicFactory; + + private final Map<TopicName, TopicPolicies> policiesCache = new ConcurrentHashMap<>(); + + private final LoadingCache<NamespaceName, CompletableFuture<SystemTopic.Reader>> readerCache; + + public TopicPoliciesService(PulsarService pulsarService) { + this(pulsarService, 1000, 10, TimeUnit.MINUTES); + } + + public TopicPoliciesService(PulsarService pulsarService, long cacheSize, long cacheExpireDuration, TimeUnit cacheExpireUnit) { + this.pulsarService = pulsarService; + this.readerCache = CacheBuilder.newBuilder() + .maximumSize(cacheSize) + .expireAfterAccess(cacheExpireDuration, cacheExpireUnit) + .removalListener((RemovalListener<NamespaceName, CompletableFuture<SystemTopic.Reader>>) notification -> { + NamespaceName namespaceName = notification.getKey(); + if (log.isDebugEnabled()) { + log.debug("Reader cache was evicted for namespace {}, current reader cache size is {} ", namespaceName, + TopicPoliciesService.this.readerCache.asMap().size()); + } + policiesCache.entrySet().removeIf(entry -> entry.getKey().getNamespaceObject().equals(namespaceName)); + if (log.isDebugEnabled()) { + log.debug("Topic policies cache deleted success, current policies cache size is {} ", policiesCache.size()); + } + notification.getValue().whenComplete((reader, ex) -> { + if (ex == null && reader != null) { + reader.closeAsync().whenComplete((v, e) -> { + if (e != null) { + log.error("Close system topic reader error for reader cache expire", e); + } else { + if (log.isDebugEnabled()) { + log.debug("Reader for system topic {} is closed.", reader.getSystemTopic().getTopicName()); + } + } + }); + } else { + TopicPoliciesService.this.readerCache.asMap().remove(namespaceName, notification.getValue()); + } + }); + }) + .build(new CacheLoader<NamespaceName, CompletableFuture<SystemTopic.Reader>>() { + @Override + public CompletableFuture<SystemTopic.Reader> load(NamespaceName namespaceName) { + CompletableFuture<SystemTopic.Reader> readerFuture = loadSystemTopicReader(namespaceName); + readerFuture.whenComplete((r, cause) -> { + if (null != cause || r == null) { + readerCache.asMap().remove(namespaceName, readerFuture); + } + }); + return readerFuture; + } + }); + } + + public CompletableFuture<TopicPolicies> getTopicPoliciesAsync(TopicName topicName) { + CompletableFuture<SystemTopic.Reader> readerFuture = null; + try { + readerFuture = readerCache.get(topicName.getNamespaceObject()); + } catch (ExecutionException e) { + log.error("Load reader for system topic {} error.", topicName, e); + } + if (readerFuture == null) { + return CompletableFuture.completedFuture(null); + } + CompletableFuture<TopicPolicies> result = new CompletableFuture<>(); + CompletableFuture<Void> refreshFuture = new CompletableFuture<>(); + refreshFuture.whenComplete((v, ex) -> result.complete(policiesCache.get(topicName))); + readerFuture.thenAccept(reader -> refreshCacheIfNeeded(reader, refreshFuture)); + return result; + } + + public CompletableFuture<TopicPolicies> getTopicPoliciesWithoutCacheAsync(TopicName topicName) { + CompletableFuture<TopicPolicies> result = new CompletableFuture<>(); + createSystemTopicFactoryIfNeeded(); + if (namespaceEventsSystemTopicFactory == null) { + result.complete(null); + return result; + } + SystemTopic systemTopic = namespaceEventsSystemTopicFactory.createSystemTopic(topicName.getNamespaceObject() + , EventType.TOPIC_POLICY); + systemTopic.newReaderAsync().thenAccept(r -> + fetchTopicPoliciesAsyncAndCloseReader(r, topicName, null, result)); + return result; + } + + private CompletableFuture<SystemTopic.Reader> loadSystemTopicReader(NamespaceName namespaceName) { + createSystemTopicFactoryIfNeeded(); + SystemTopic systemTopic = namespaceEventsSystemTopicFactory.createSystemTopic(namespaceName + , EventType.TOPIC_POLICY); + return systemTopic.newReaderAsync(); + } + + private void createSystemTopicFactoryIfNeeded() { + if (namespaceEventsSystemTopicFactory == null) { + synchronized (this) { + if (namespaceEventsSystemTopicFactory == null) { + try { + namespaceEventsSystemTopicFactory = new NamespaceEventsSystemTopicFactory(pulsarService.getClient()); + } catch (PulsarServerException e) { + log.error("Create namespace event system topic factory error.", e); + } + } + } + } + } + + private void refreshCacheIfNeeded(SystemTopic.Reader reader, CompletableFuture<Void> refreshFuture) { + reader.hasMoreEventsAsync().whenComplete((has, ex) -> { Review comment: ```suggestion reader.hasMoreEventsAsync().whenComplete((hasMore, ex) -> { ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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