dschneider-pivotal commented on a change in pull request #6880: URL: https://github.com/apache/geode/pull/6880#discussion_r718982609
########## File path: geode-apis-compatible-with-redis/src/main/java/org/apache/geode/redis/internal/pubsub/Publisher.java ########## @@ -0,0 +1,330 @@ +/* + * 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.geode.redis.internal.pubsub; + +import static org.apache.geode.logging.internal.executors.LoggingExecutors.newCachedThreadPool; +import static org.apache.geode.redis.internal.netty.Coder.bytesToString; + +import java.io.DataInput; +import java.io.DataOutput; +import java.io.IOException; +import java.util.ArrayList; +import java.util.List; +import java.util.Map; +import java.util.Set; +import java.util.concurrent.BlockingQueue; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.LinkedBlockingQueue; +import java.util.concurrent.TimeUnit; + +import org.apache.logging.log4j.Logger; + +import org.apache.geode.DataSerializer; +import org.apache.geode.annotations.VisibleForTesting; +import org.apache.geode.cache.execute.FunctionContext; +import org.apache.geode.cache.execute.FunctionService; +import org.apache.geode.cache.execute.ResultCollector; +import org.apache.geode.distributed.DistributedMember; +import org.apache.geode.internal.cache.execute.InternalFunction; +import org.apache.geode.internal.serialization.DataSerializableFixedID; +import org.apache.geode.internal.serialization.DeserializationContext; +import org.apache.geode.internal.serialization.KnownVersion; +import org.apache.geode.internal.serialization.SerializationContext; +import org.apache.geode.logging.internal.log4j.api.LogService; +import org.apache.geode.redis.internal.RegionProvider; +import org.apache.geode.redis.internal.netty.Client; + +/** + * This class deals with doing a redis pubsub publish operation. + * Since publish requests from the same client must have order + * preserved, and since publish requests myst be done in a thread + * other than the one the request arrived from, this class has an + * instance of ClientPublisher for any Client that does a publish. + * The ClientPublisher maintains an ordered queue of requests + * and is careful to process them in the order they arrived. + * It supports batching them which can be a significant win as + * soon as a second geode server is added to the cluster. + * WARNING: The queue on the ClientPublisher is unbounded + * which can cause the server to run out of memory if the + * client keeps sending publish requests faster than the server + * can process them. It would be nice for this queue to have + * a bound but that could cause a hang because of the way + * we use Netty. + */ +public class Publisher { + private static final Logger logger = LogService.getLogger(); + + private final ExecutorService executor; + private final RegionProvider regionProvider; + private final Subscriptions subscriptions; + private final Map<Client, ClientPublisher> clientPublishers = new ConcurrentHashMap<>(); + + public Publisher(RegionProvider regionProvider, Subscriptions subscriptions) { + this.executor = createExecutorService(); + this.regionProvider = regionProvider; + this.subscriptions = subscriptions; + registerPublishFunction(); + } + + @VisibleForTesting + Publisher(RegionProvider regionProvider, Subscriptions subscriptions, ExecutorService executor) { + this.executor = executor; + this.regionProvider = regionProvider; + this.subscriptions = subscriptions; + // no need to register function in unit tests + } + + public void publish(Client client, byte[] channel, byte[] message) { + ClientPublisher clientPublisher = + clientPublishers.computeIfAbsent(client, key -> new ClientPublisher()); + clientPublisher.publish(channel, message); + } + + public void disconnect(Client client) { + clientPublishers.remove(client); + } + + public void close() { + executor.shutdown(); + try { + if (!executor.awaitTermination(1, TimeUnit.MINUTES)) { + logger.warn("Timed out waiting for queued publish requests to be sent."); + } + } catch (InterruptedException e) { + Thread.currentThread().interrupt(); + } + } + + @VisibleForTesting + int getClientCount() { + return clientPublishers.size(); + } + + + private static ExecutorService createExecutorService() { + return newCachedThreadPool("GeodeRedisServer-Publish-", true); + } + + private void registerPublishFunction() { + FunctionService.registerFunction(new PublishFunction(this)); + } + + @SuppressWarnings("unchecked") + private void internalPublish(List<PublishRequest> batch) { + Set<DistributedMember> remoteMembers = regionProvider.getRemoteRegionMembers(); + try { + ResultCollector<?, ?> resultCollector = null; + try { + if (!remoteMembers.isEmpty()) { + // send function to remotes + resultCollector = FunctionService + .onMembers(remoteMembers) + .setArguments(batch) + .execute(PublishFunction.ID); + } + } finally { + // execute it locally + publishBatchToLocalSubscribers(batch); + if (resultCollector != null) { + // block until remote execute completes + resultCollector.getResult(); + } + } + } catch (Exception e) { + // the onMembers contract is for execute to throw an exception + // if one of the members goes down. + if (logger.isDebugEnabled()) { + logger.debug( + "Exception executing publish function on batch {}. If a server departed during the publish then an exception is expected.", + batch, e); + } + } + } + + private void publishBatchToLocalSubscribers(List<PublishRequest> batch) { + batch.forEach(request -> subscriptions.forEachSubscription(request.getChannel(), + (subscriptionName, channelToMatch, client, subscription) -> subscription.publishMessage( + channelToMatch != null, subscriptionName, + client, request.getChannel(), request.getMessage()))); + } + + public static class PublishRequest implements DataSerializableFixedID { + // note final can not be used because of DataSerializableFixedID + private byte[] channel; + private byte[] message; + + public PublishRequest(byte[] channel, byte[] message) { + this.channel = channel; + this.message = message; + } + + @SuppressWarnings("unused") + public PublishRequest() { + // needed for DataSerializableFixedID + } + + public byte[] getChannel() { + return channel; + } + + public byte[] getMessage() { + return message; + } + + @Override + public int getDSFID() { + return PUBLISH_REQUEST; + } + + @Override + public void toData(DataOutput out, SerializationContext context) throws IOException { + DataSerializer.writeByteArray(getChannel(), out); + DataSerializer.writeByteArray(getMessage(), out); + } + + @Override + public void fromData(DataInput in, DeserializationContext context) + throws IOException, ClassNotFoundException { + channel = DataSerializer.readByteArray(in); + message = DataSerializer.readByteArray(in); + } + + @Override + public KnownVersion[] getSerializationVersions() { + return null; + } + + @Override + public String toString() { + return "PublishRequest{" + + "channel=" + bytesToString(channel) + + ", message=" + bytesToString(message) + + '}'; + } + } + + /** + * Manages all the publish requests from a particular client. + * The order of these requests is maintained, and they will be + * delivered to subscribers in that order. + * Since the delivery to subscribers can be slower than the rate + * at which publish requests arrive, this publisher supports + * batching so allow multiple requests to be sent with a single Review comment: done -- This is an automated message from the Apache Git Service. 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