poorbarcode commented on code in PR #24833: URL: https://github.com/apache/pulsar/pull/24833#discussion_r2443607042
########## pulsar-broker-common/src/main/java/org/apache/pulsar/broker/topiclistlimit/TopicListSizeResultCache.java: ########## @@ -0,0 +1,137 @@ +/* + * 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.topiclistlimit; + +import com.github.benmanes.caffeine.cache.Cache; +import com.github.benmanes.caffeine.cache.Caffeine; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.atomic.AtomicLong; +import java.util.concurrent.atomic.AtomicReference; +import org.apache.pulsar.common.api.proto.CommandGetTopicsOfNamespace; + +/** + * A cache for storing and managing topic list size estimates in namespaces. + * This class provides functionality to: + * - Cache and retrieve topic list size estimates for different namespaces and modes + * - Handle concurrent requests for topic list sizes efficiently + * - Maintain and update size estimates based on actual topic list sizes + * - Prevent thundering herd problems when multiple concurrent requests for a namespace are made without + * a previous size estimate + * The cache uses namespace name and topic list mode (PERSISTENT/NON_PERSISTENT/ALL) as keys + * and maintains size estimates that are refined with actual usage. + */ +public class TopicListSizeResultCache { + // 10kB initial estimate for topic list heap size + private static final long INITIAL_TOPIC_LIST_HEAP_SIZE = 10 * 1024; + + private Cache<CacheKey, ResultHolder> topicListSizeCache = Caffeine.newBuilder() + .maximumSize(10000) + .build(); + + record CacheKey(String namespaceName, CommandGetTopicsOfNamespace.Mode mode) { + } + + /** + * Holds the topic list size estimate and future for the topic list size. + * The size is returned by calling {@link #getSizeAsync()} method which is asynchronous. + * The estimate is updated by calling {@link #updateSize(long)} method. + */ + public static class ResultHolder { + private final AtomicReference<CompletableFuture<Long>> topicListSizeFuture = Review Comment: The value of the topic list size seems never to be modified asynchronously, so the type being CompletableFuture is unnecessary. ########## pulsar-broker-common/src/main/java/org/apache/pulsar/broker/topiclistlimit/TopicListSizeResultCache.java: ########## @@ -0,0 +1,137 @@ +/* + * 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.topiclistlimit; + +import com.github.benmanes.caffeine.cache.Cache; +import com.github.benmanes.caffeine.cache.Caffeine; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.atomic.AtomicLong; +import java.util.concurrent.atomic.AtomicReference; +import org.apache.pulsar.common.api.proto.CommandGetTopicsOfNamespace; + +/** + * A cache for storing and managing topic list size estimates in namespaces. + * This class provides functionality to: + * - Cache and retrieve topic list size estimates for different namespaces and modes + * - Handle concurrent requests for topic list sizes efficiently + * - Maintain and update size estimates based on actual topic list sizes + * - Prevent thundering herd problems when multiple concurrent requests for a namespace are made without + * a previous size estimate + * The cache uses namespace name and topic list mode (PERSISTENT/NON_PERSISTENT/ALL) as keys + * and maintains size estimates that are refined with actual usage. + */ +public class TopicListSizeResultCache { + // 10kB initial estimate for topic list heap size + private static final long INITIAL_TOPIC_LIST_HEAP_SIZE = 10 * 1024; + + private Cache<CacheKey, ResultHolder> topicListSizeCache = Caffeine.newBuilder() + .maximumSize(10000) + .build(); + + record CacheKey(String namespaceName, CommandGetTopicsOfNamespace.Mode mode) { + } + + /** + * Holds the topic list size estimate and future for the topic list size. + * The size is returned by calling {@link #getSizeAsync()} method which is asynchronous. + * The estimate is updated by calling {@link #updateSize(long)} method. + */ + public static class ResultHolder { + private final AtomicReference<CompletableFuture<Long>> topicListSizeFuture = + new AtomicReference<>(null); + private final AtomicLong existingSizeRef = new AtomicLong(-1L); Review Comment: Since the value of the topic list size seems never to be modified asynchronously, the unnecessary field `topicListSizeFuture` can be removed. ########## pulsar-broker-common/src/main/java/org/apache/pulsar/broker/topiclistlimit/TopicListSizeResultCache.java: ########## @@ -0,0 +1,137 @@ +/* + * 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.topiclistlimit; + +import com.github.benmanes.caffeine.cache.Cache; +import com.github.benmanes.caffeine.cache.Caffeine; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.atomic.AtomicLong; +import java.util.concurrent.atomic.AtomicReference; +import org.apache.pulsar.common.api.proto.CommandGetTopicsOfNamespace; + +/** + * A cache for storing and managing topic list size estimates in namespaces. + * This class provides functionality to: + * - Cache and retrieve topic list size estimates for different namespaces and modes + * - Handle concurrent requests for topic list sizes efficiently + * - Maintain and update size estimates based on actual topic list sizes + * - Prevent thundering herd problems when multiple concurrent requests for a namespace are made without + * a previous size estimate + * The cache uses namespace name and topic list mode (PERSISTENT/NON_PERSISTENT/ALL) as keys + * and maintains size estimates that are refined with actual usage. + */ +public class TopicListSizeResultCache { + // 10kB initial estimate for topic list heap size + private static final long INITIAL_TOPIC_LIST_HEAP_SIZE = 10 * 1024; + + private Cache<CacheKey, ResultHolder> topicListSizeCache = Caffeine.newBuilder() + .maximumSize(10000) + .build(); + + record CacheKey(String namespaceName, CommandGetTopicsOfNamespace.Mode mode) { + } + + /** + * Holds the topic list size estimate and future for the topic list size. + * The size is returned by calling {@link #getSizeAsync()} method which is asynchronous. + * The estimate is updated by calling {@link #updateSize(long)} method. + */ + public static class ResultHolder { + private final AtomicReference<CompletableFuture<Long>> topicListSizeFuture = + new AtomicReference<>(null); + private final AtomicLong existingSizeRef = new AtomicLong(-1L); + + /** + * Get the topic list size estimate. The first request will return the initial estimate + * and update the estimate based on the returned size of the topic list. Other concurrent requests + * will wait for the first request to complete and use the estimate of the first request. + * Subsequent requests will use estimate which gets updated based on the returned size of the topic list + * of each request. + * @return a future that will return the topic list size estimate + */ + public CompletableFuture<Long> getSizeAsync() { + if (topicListSizeFuture.compareAndSet(null, new CompletableFuture<>())) { + // let the first request proceed with the initial estimate + return CompletableFuture.completedFuture(INITIAL_TOPIC_LIST_HEAP_SIZE); + } else { + // all other requests wait for the first one to complete + return topicListSizeFuture.get(); + } + } + + /** + * Update the topic list size estimate. The new estimated size will be updated by calculating the average + * of the existing and the new size. If the difference between the new and the existing size is less than 1, + * no update will be done. + * @param actualSize the actual size of the topic list + */ + public void updateSize(long actualSize) { Review Comment: We need to mention that the current modifying operation may be dropped at line 103 ```java if (currentFuture != null && !currentFuture.isDone()) { currentFuture.complete(existingSizeValue); } else if (currentFuture == null || currentFuture.join().longValue() != existingSizeValue) { topicListSizeFuture.compareAndSet(currentFuture, CompletableFuture.completedFuture(existingSizeValue)); } else { // The operation may be dropped here } ``` ########## pulsar-common/src/main/java/org/apache/pulsar/common/semaphore/AsyncSemaphoreImpl.java: ########## @@ -0,0 +1,328 @@ +/* + * 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.common.semaphore; + +import io.netty.util.concurrent.DefaultThreadFactory; +import java.util.Queue; +import java.util.concurrent.ArrayBlockingQueue; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.Executors; +import java.util.concurrent.LinkedBlockingQueue; +import java.util.concurrent.ScheduledExecutorService; +import java.util.concurrent.ScheduledFuture; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.atomic.AtomicLong; +import java.util.concurrent.atomic.AtomicLongFieldUpdater; +import java.util.function.BooleanSupplier; +import java.util.function.LongConsumer; +import org.apache.pulsar.common.util.Runnables; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Implementation of AsyncSemaphore with timeout and queue size limits. + */ +public class AsyncSemaphoreImpl implements AsyncSemaphore, AutoCloseable { + private static final Logger log = LoggerFactory.getLogger(AsyncSemaphoreImpl.class); + + private final AtomicLong availablePermits; + private final Queue<PendingRequest> queue; + private final long maxPermits; + private final long timeoutMillis; + private final ScheduledExecutorService executor; + private final boolean shutdownExecutor; + private final LongConsumer queueLatencyRecorder; + private final AtomicBoolean closed = new AtomicBoolean(false); + private final Runnable processQueueRunnable = Runnables.catchingAndLoggingThrowables(this::internalProcessQueue); + + /** + * Creates an AsyncSemaphoreImpl with the given parameters. + * @param maxPermits max number of permits available for acquisition, set to <= 0 for unbounded semaphore (not + * recommended) + * @param maxQueueSize max number of requests that can be queued, set to <= 0 for unbounded queue (not recommended) + * @param timeoutMillis timeout in milliseconds for acquiring permits + */ + public AsyncSemaphoreImpl(long maxPermits, int maxQueueSize, long timeoutMillis) { + this(maxPermits, maxQueueSize, timeoutMillis, maxPermits > 0 ? createExecutor() : null, maxPermits > 0, null); + } + + /** + * Creates an AsyncSemaphoreImpl with the given parameters. + * @param maxPermits max number of permits available for acquisition, set to <= 0 for unbounded semaphore (not + * recommended) + * @param maxQueueSize max number of requests that can be queued, set to <= 0 for unbounded queue (not recommended) + * @param timeoutMillis timeout in milliseconds for acquiring permits + * @param executor executor service to use for scheduling timeouts, it is expected to be single threaded + * @param queueLatencyRecorder consumer to record queue latency, Long.MAX_VALUE is used for requests that timed out + */ + public AsyncSemaphoreImpl(long maxPermits, int maxQueueSize, long timeoutMillis, + ScheduledExecutorService executor, LongConsumer queueLatencyRecorder) { + this(maxPermits, maxQueueSize, timeoutMillis, executor, false, queueLatencyRecorder); + } + + AsyncSemaphoreImpl(long maxPermits, int maxQueueSize, long timeoutMillis, ScheduledExecutorService executor, + boolean shutdownExecutor, LongConsumer queueLatencyRecorder) { + this.availablePermits = new AtomicLong(maxPermits); + this.maxPermits = maxPermits; + this.queue = maxQueueSize > 0 ? new ArrayBlockingQueue<>(maxQueueSize) : new LinkedBlockingQueue<>(); + this.timeoutMillis = timeoutMillis; + this.executor = executor; + this.shutdownExecutor = shutdownExecutor; + this.queueLatencyRecorder = queueLatencyRecorder; + } + + private static ScheduledExecutorService createExecutor() { + return Executors.newSingleThreadScheduledExecutor( + new DefaultThreadFactory("async-semaphore-executor")); + } + + @Override + public CompletableFuture<AsyncSemaphorePermit> acquire(long permits, BooleanSupplier isCancelled) { + return internalAcquire(permits, permits, isCancelled); + } + + private CompletableFuture<AsyncSemaphorePermit> internalAcquire(long permits, long acquirePermits, + BooleanSupplier isCancelled) { + if (!isPermitsValidForAcquiring(permits)) { Review Comment: We'd better separate the following two cases: - `permits <0`: it may be caused by a bug - `permits > maxPermits`: users should reset the configuration -- This is an automated message from the Apache Git Service. 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