rschmitt commented on code in PR #428: URL: https://github.com/apache/httpcomponents-client/pull/428#discussion_r1156705619
########## httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/HappyEyeballsV2AsyncClientConnectionOperatorBuilder.java: ########## @@ -0,0 +1,272 @@ +/* + * ==================================================================== + * 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. + * ==================================================================== + * + * This software consists of voluntary contributions made by many + * individuals on behalf of the Apache Software Foundation. For more + * information on the Apache Software Foundation, please see + * <http://www.apache.org/>. + * + */ +package org.apache.hc.client5.http.impl.nio; + +import org.apache.hc.client5.http.DnsResolver; +import org.apache.hc.client5.http.SystemDefaultDnsResolver; +import org.apache.hc.client5.http.nio.AsyncClientConnectionOperator; +import org.apache.hc.client5.http.ssl.ConscryptClientTlsStrategy; +import org.apache.hc.client5.http.ssl.DefaultClientTlsStrategy; +import org.apache.hc.core5.http.URIScheme; +import org.apache.hc.core5.http.config.RegistryBuilder; +import org.apache.hc.core5.http.nio.ssl.TlsStrategy; +import org.apache.hc.core5.util.Args; +import org.apache.hc.core5.util.ReflectionUtils; +import org.apache.hc.core5.util.Timeout; + +/** + * A builder for creating instances of {@link HappyEyeballsV2AsyncClientConnectionOperator}. + * + * <p>This builder provides a fluent API for configuring various options of the + * {@link HappyEyeballsV2AsyncClientConnectionOperator}. Once all the desired options have been set, + * the {@link #build()} method can be called to create an instance of the connection operator. + * + * <p>The following options can be configured using this builder: + * <ul> + * <li>The TLS strategy to be used for establishing TLS connections</li> + * <li>The connection operator to be used for creating connections</li> + * <li>The DNS resolver to be used for resolving hostnames</li> + * <li>The timeout for establishing a connection</li> + * <li>The delay between resolution of hostnames and connection establishment attempts</li> + * <li>The minimum and maximum delays between connection establishment attempts</li> + * <li>The delay between subsequent connection establishment attempts</li> + * <li>The number of connections to be established with the first address family in the list</li> + * <li>The preferred address family to be used for establishing connections</li> + * </ul> + * + * <p>If no options are explicitly set using this builder, default options will be used for each option. + * + * <p>This class is not thread-safe. + * + * @see HappyEyeballsV2AsyncClientConnectionOperator + * @since 5.3 + */ +public class HappyEyeballsV2AsyncClientConnectionOperatorBuilder { + + private AsyncClientConnectionOperator connectionOperator; + private DnsResolver dnsResolver; + private TlsStrategy tlsStrategy; + private Timeout timeout; + private Timeout minimumConnectionAttemptDelay; + private Timeout maximumConnectionAttemptDelay; + private Timeout connectionAttemptDelay; + private Timeout resolutionDelay; + private int firstAddressFamilyCount; + private HappyEyeballsV2AsyncClientConnectionOperator.AddressFamily addressFamily; + + + public static HappyEyeballsV2AsyncClientConnectionOperatorBuilder create() { + return new HappyEyeballsV2AsyncClientConnectionOperatorBuilder(); + } + + + HappyEyeballsV2AsyncClientConnectionOperatorBuilder() { + super(); + } + + + private boolean systemProperties; + + /** + * Use system properties when creating and configuring default + * implementations. + */ + public final HappyEyeballsV2AsyncClientConnectionOperatorBuilder useSystemProperties() { + this.systemProperties = true; + return this; + } + + /** + * Sets the {@link AsyncClientConnectionOperator} to use for establishing connections. + * + * @param connectionOperator the {@link AsyncClientConnectionOperator} to use + * @return this {@link HappyEyeballsV2AsyncClientConnectionOperatorBuilder} instance + */ + public HappyEyeballsV2AsyncClientConnectionOperatorBuilder withConnectionOperator( + final AsyncClientConnectionOperator connectionOperator) { + this.connectionOperator = connectionOperator; + return this; + } + + /** + * Sets the {@link DnsResolver} to use for resolving host names to IP addresses. + * + * @param dnsResolver the {@link DnsResolver} to use + * @return this builder instance + */ + public HappyEyeballsV2AsyncClientConnectionOperatorBuilder withDnsResolver(final DnsResolver dnsResolver) { + this.dnsResolver = dnsResolver; + return this; + } + + /** + * Sets the {@link TlsStrategy} to use for creating TLS connections. + * + * @param tlsStrategy the {@link TlsStrategy} to use + * @return this {@link HappyEyeballsV2AsyncClientConnectionOperatorBuilder} instance + */ + public HappyEyeballsV2AsyncClientConnectionOperatorBuilder withTlsStrategyLookup(final TlsStrategy tlsStrategy) { + this.tlsStrategy = tlsStrategy; + return this; + } + + /** + * Set the timeout to use for connection attempts. + * + * @param timeout the timeout to use for connection attempts + * @return this builder + */ + public HappyEyeballsV2AsyncClientConnectionOperatorBuilder withTimeout(final Timeout timeout) { + this.timeout = timeout; + return this; + } + + /** + * Sets the minimum delay between connection attempts. The actual delay may be longer if a resolution delay has been + * specified, in which case the minimum connection attempt delay is added to the resolution delay. + * + * @param minimumConnectionAttemptDelay the minimum delay between connection attempts + * @return this builder instance + */ + public HappyEyeballsV2AsyncClientConnectionOperatorBuilder withMinimumConnectionAttemptDelay( + final Timeout minimumConnectionAttemptDelay) { + this.minimumConnectionAttemptDelay = minimumConnectionAttemptDelay; + return this; + } + + /** + * Sets the maximum delay between two connection attempts. + * + * @param maximumConnectionAttemptDelay the maximum delay between two connection attempts + * @return the builder instance + */ + public HappyEyeballsV2AsyncClientConnectionOperatorBuilder withMaximumConnectionAttemptDelay( + final Timeout maximumConnectionAttemptDelay) { + this.maximumConnectionAttemptDelay = maximumConnectionAttemptDelay; + return this; + } + + /** + * Sets the delay between two connection attempts. + * + * @param connectionAttemptDelay the delay between two connection attempts + * @return the builder instance + */ + public HappyEyeballsV2AsyncClientConnectionOperatorBuilder withConnectionAttemptDelay( + final Timeout connectionAttemptDelay) { + this.connectionAttemptDelay = connectionAttemptDelay; + return this; + } + + /** + * Sets the delay before attempting to resolve the next address in the list. + * + * @param resolutionDelay the delay before attempting to resolve the next address in the list + * @return the builder instance + */ + public HappyEyeballsV2AsyncClientConnectionOperatorBuilder withResolutionDelay(final Timeout resolutionDelay) { + this.resolutionDelay = resolutionDelay; + return this; + } + + /** + * Sets the number of first address families to try before falling back to the other address families. + * + * @param firstAddressFamilyCount the number of first address families to try + * @return this builder + */ + public HappyEyeballsV2AsyncClientConnectionOperatorBuilder withFirstAddressFamilyCount( + final int firstAddressFamilyCount) { + this.firstAddressFamilyCount = firstAddressFamilyCount; + return this; + } + + /** + * Sets the preferred address family to use for connections. + * + * @param addressFamily the preferred address family + * @return this builder + */ + public HappyEyeballsV2AsyncClientConnectionOperatorBuilder withAddressFamily(final HappyEyeballsV2AsyncClientConnectionOperator.AddressFamily addressFamily) { + this.addressFamily = addressFamily; + return this; + } + + /** + * Builds a {@link HappyEyeballsV2AsyncClientConnectionOperator} with the specified parameters. + * + * @return the {@link HappyEyeballsV2AsyncClientConnectionOperator} instance built with the specified parameters. + * @throws IllegalArgumentException if the connection operator is null. + */ + public HappyEyeballsV2AsyncClientConnectionOperator build() { + final TlsStrategy tlsStrategyCopy; + if (tlsStrategy != null) { + tlsStrategyCopy = tlsStrategy; + } else { + if (ReflectionUtils.determineJRELevel() <= 8 && ConscryptClientTlsStrategy.isSupported()) { + if (systemProperties) { + tlsStrategyCopy = ConscryptClientTlsStrategy.getSystemDefault(); + } else { + tlsStrategyCopy = ConscryptClientTlsStrategy.getDefault(); + } + } else { + if (systemProperties) { + tlsStrategyCopy = DefaultClientTlsStrategy.getSystemDefault(); + } else { + tlsStrategyCopy = DefaultClientTlsStrategy.getDefault(); + } + } + } + + + connectionOperator = Args.notNull(connectionOperator, "Connection operator"); + final DnsResolver dnsResolverToUse = dnsResolver != null ? dnsResolver : SystemDefaultDnsResolver.INSTANCE; + final Timeout timeoutToUse = timeout != null ? timeout : Timeout.ofMilliseconds(250); + final Timeout resolutionDelayToUse = resolutionDelay != null ? resolutionDelay : Timeout.ofMilliseconds(50); + final Timeout minimumConnectionAttemptDelayToUse = minimumConnectionAttemptDelay != null ? minimumConnectionAttemptDelay : Timeout.ofMilliseconds(100); + final Timeout maximumConnectionAttemptDelayToUse = maximumConnectionAttemptDelay != null ? maximumConnectionAttemptDelay : Timeout.ofSeconds(2); + final Timeout connectionAttemptDelayToUse = connectionAttemptDelay != null ? connectionAttemptDelay : Timeout.ofMilliseconds(250); + final int firstAddressFamilyCountToUse = Args.positive(firstAddressFamilyCount, "First Address Family"); + final HappyEyeballsV2AsyncClientConnectionOperator.AddressFamily addressFamilyToUse = addressFamily; Review Comment: These defaults are all duplicated in the `HappyEyeballsV2AsyncClientConnectionOperator` constructor. ########## httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/HappyEyeballsV2AsyncClientConnectionOperator.java: ########## @@ -0,0 +1,680 @@ +/* + * ==================================================================== + * 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. + * ==================================================================== + * + * This software consists of voluntary contributions made by many + * individuals on behalf of the Apache Software Foundation. For more + * information on the Apache Software Foundation, please see + * <http://www.apache.org/>. + * + */ + +package org.apache.hc.client5.http.impl.nio; + +import org.apache.hc.client5.http.DnsResolver; +import org.apache.hc.client5.http.SchemePortResolver; +import org.apache.hc.client5.http.SystemDefaultDnsResolver; +import org.apache.hc.client5.http.impl.ConnPoolSupport; +import org.apache.hc.client5.http.impl.DefaultSchemePortResolver; +import org.apache.hc.client5.http.nio.AsyncClientConnectionOperator; +import org.apache.hc.client5.http.nio.ManagedAsyncClientConnection; +import org.apache.hc.core5.concurrent.FutureCallback; +import org.apache.hc.core5.http.HttpHost; +import org.apache.hc.core5.http.config.Lookup; +import org.apache.hc.core5.http.nio.ssl.TlsStrategy; +import org.apache.hc.core5.http.protocol.HttpContext; +import org.apache.hc.core5.reactor.ConnectionInitiator; +import org.apache.hc.core5.reactor.ssl.TransportSecurityLayer; +import org.apache.hc.core5.util.Args; +import org.apache.hc.core5.util.Timeout; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.net.ConnectException; +import java.net.Inet4Address; +import java.net.Inet6Address; +import java.net.InetAddress; +import java.net.SocketAddress; +import java.net.UnknownHostException; +import java.time.Duration; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collections; +import java.util.List; +import java.util.concurrent.CancellationException; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.Future; + +/** + * The {@link AsyncClientConnectionOperator} implementation that uses Happy Eyeballs V2 algorithm to connect + * to the target server. Happy Eyeballs V2 (HEV2) algorithm is used to connect to the target server by concurrently + * attempting to establish multiple connections to different IP addresses. The first connection to complete + * successfully is selected and the others are closed. If all connections fail, the last error is rethrown. + * The algorithm also applies a configurable delay before subsequent connection attempts. HEV2 was introduced + * as a means to mitigate the latency issues caused by IPv4 and IPv6 co-existence in the Internet. HEV2 is defined + * in RFC 8305. + * + * <p> + * This connection operator maintains a connection pool for each unique route (combination of target host and + * target port) and selects the next connection from the pool to establish a new connection or reuse an + * existing connection. The connection pool uses a First-In-First-Out (FIFO) queue and has a configurable limit + * on the maximum number of connections that can be kept alive in the pool. Once the maximum number of connections + * has been reached, the oldest connection in the pool is closed to make room for a new one. + * </p> + * + * <p> + * This class is thread-safe and can be used in a multi-threaded environment. + * </p> + * + * <p> + * The HEV2 algorithm is configurable through the following parameters: + * <ul> + * <li>{@code dualStackEnabled}: Whether to enable dual-stack connectivity. When set to {@code true}, + * the operator attempts to connect to both IPv4 and IPv6 addresses concurrently. When set to {@code false}, + * only IPv4 or IPv6 addresses are attempted depending on the address type of the target server.</li> + * <li>{@code maxAttempts}: The maximum number of connection attempts to be made before failing. If all + * attempts fail, the last error is rethrown.</li> + * <li>{@code delay}: The delay (in milliseconds) to apply before subsequent connection attempts.</li> + * <li>{@code connectTimeout}: The connection timeout (in milliseconds) for each attempt.</li> + * </ul> + * </p> + * + * + * <p> + * This class can be used with any {@link org.apache.hc.core5.http.nio.AsyncClientEndpoint} implementation + * that supports HTTP/1.1 or HTTP/2 protocols. + * </p> + * + * @since 5.3 + */ +public class HappyEyeballsV2AsyncClientConnectionOperator implements AsyncClientConnectionOperator { + + private static final Logger LOG = LoggerFactory.getLogger(AsyncClientConnectionOperator.class); + + /** + * The underlying {@link AsyncClientConnectionOperator} that is used to establish connections + * to the target server. + */ + private final AsyncClientConnectionOperator connectionOperator; + + /** + * The DNS resolver used to resolve hostnames to IP addresses. + */ + private final DnsResolver dnsResolver; + + /** + * A lookup table used to determine the {@link TlsStrategy} to use for a given connection route. + */ + private final Lookup<TlsStrategy> tlsStrategyLookup; + + /** + * The default timeout for connection establishment attempts. If a connection cannot be established + * within this timeout, the attempt is considered failed. + */ + private final Timeout timeout; + + /** + * The minimum delay between connection establishment attempts. + */ + private final Timeout minimumConnectionAttemptDelay; + + /** + * The maximum delay between connection establishment attempts. + */ + private final Timeout maximumConnectionAttemptDelay; + + /** + * The current delay between connection establishment attempts. + */ + private final Timeout connectionAttemptDelay; + + /** + * The delay before resolution is started. + */ + private final Timeout resolution_delay; + + /** + * The number of IP addresses of each address family to include in the initial list of + * IP addresses to attempt connections to. This value is set to 2 by default, but can be + * increased to more aggressively favor a particular address family (e.g. set to 4 for IPv6). + */ + private final int firstAddressFamilyCount; + + /** + * The address family to use for establishing connections. This can be set to either + * {@link AddressFamily#IPv4} or {@link AddressFamily#IPv6}. + */ + private final AddressFamily addressFamily; + + + /** + * The AddressFamily enum represents the possible address families that can be used when attempting to establish + * <p> + * connections using the Happy Eyeballs V2 algorithm. + * + * <p> + * The Happy Eyeballs V2 algorithm allows for concurrent connection attempts to be made to different IP addresses, + * <p> + * so this enum specifies whether connections should be attempted using IPv4 or IPv6 addresses. + * + * </p> + */ + public enum AddressFamily { + IPv4, IPv6 + } + + /** + * Constructs a new {@link HappyEyeballsV2AsyncClientConnectionOperator} with the specified parameters. + * + * @param tlsStrategyLookup the lookup object used to retrieve a {@link TlsStrategy} for a given {@link Route} + * @param connectionOperator the underlying {@link AsyncClientConnectionOperator} to use for establishing connections + * @param dnsResolver the {@link DnsResolver} to use for resolving target hostnames + * @param timeout the timeout duration for establishing a connection + * @param resolution_delay the configurable delay before subsequent DNS resolution attempts + * @param minimumConnectionAttemptDelay the minimum configurable delay between connection attempts + * @param maximumConnectionAttemptDelay the maximum configurable delay between connection attempts + * @param connectionAttemptDelay the configurable delay before attempting to establish a connection + * @param firstAddressFamilyCount the number of initial address families to use for establishing a connection + * @param addressFamily the preferred address family to use for establishing a connection + * @throws IllegalArgumentException if {@code firstAddressFamilyCount} is not positive + */ + public HappyEyeballsV2AsyncClientConnectionOperator(final Lookup<TlsStrategy> tlsStrategyLookup, + final AsyncClientConnectionOperator connectionOperator, + final DnsResolver dnsResolver, + final Timeout timeout, + final Timeout resolution_delay, + final Timeout minimumConnectionAttemptDelay, + final Timeout maximumConnectionAttemptDelay, + final Timeout connectionAttemptDelay, + final int firstAddressFamilyCount, + final AddressFamily addressFamily) { + this.tlsStrategyLookup = Args.notNull(tlsStrategyLookup, "TLS strategy lookup"); + this.connectionOperator = Args.notNull(connectionOperator, "Connection operator"); + this.dnsResolver = dnsResolver != null ? dnsResolver : SystemDefaultDnsResolver.INSTANCE; + this.timeout = timeout != null ? timeout : Timeout.ofMilliseconds(250); + this.resolution_delay = resolution_delay != null ? resolution_delay : Timeout.ofMilliseconds(50); + this.minimumConnectionAttemptDelay = minimumConnectionAttemptDelay != null ? minimumConnectionAttemptDelay : Timeout.ofMilliseconds(100); + this.maximumConnectionAttemptDelay = maximumConnectionAttemptDelay != null ? maximumConnectionAttemptDelay : Timeout.ofSeconds(2); + this.connectionAttemptDelay = connectionAttemptDelay != null ? connectionAttemptDelay : Timeout.ofMilliseconds(250); + this.firstAddressFamilyCount = Args.positive(firstAddressFamilyCount, "firstAddressFamilyCount"); + this.addressFamily = addressFamily; + } + + /** + * Constructs a new instance of {@link HappyEyeballsV2AsyncClientConnectionOperator} using the specified + * {@link Lookup} for {@link TlsStrategy} and {@link SchemePortResolver} and {@link DnsResolver}. + * <p> + * The constructor internally creates a new instance of {@link DefaultAsyncClientConnectionOperator} with the + * specified {@link Lookup} for {@link TlsStrategy}, {@link SchemePortResolver} and {@link DnsResolver}. The + * created {@link AsyncClientConnectionOperator} is then passed to the main constructor along with default values + * for other parameters. + * </p> + * + * @param tlsStrategyLookup The {@link Lookup} for {@link TlsStrategy}. + * @param schemePortResolver The {@link SchemePortResolver} to use for resolving scheme ports. + * @param dnsResolver The {@link DnsResolver} to use for resolving hostnames to IP addresses. + * @throws IllegalArgumentException if the {@code tlsStrategyLookup} or {@code schemePortResolver} or {@code dnsResolver} parameter is {@code null}. + */ + public HappyEyeballsV2AsyncClientConnectionOperator( + final Lookup<TlsStrategy> tlsStrategyLookup, + final SchemePortResolver schemePortResolver, + final DnsResolver dnsResolver) { + this(tlsStrategyLookup, + new DefaultAsyncClientConnectionOperator(tlsStrategyLookup, schemePortResolver, dnsResolver), + dnsResolver, + null, + null, + null, + null, + null, + 1, + AddressFamily.IPv6); + } + + /** + * Creates a new instance of {@link HappyEyeballsV2AsyncClientConnectionOperator} using the provided TLS strategy lookup + * and scheme-port resolver. The DNS resolver will be set to the system default resolver. + * + * @param tlsStrategyLookup The lookup instance for {@link TlsStrategy} to be used for establishing connections. + * @param schemePortResolver The resolver instance for mapping scheme names to default port numbers. + * @throws IllegalArgumentException if {@code tlsStrategyLookup} is {@code null}. + */ + public HappyEyeballsV2AsyncClientConnectionOperator( + final Lookup<TlsStrategy> tlsStrategyLookup, + final SchemePortResolver schemePortResolver) { + this(tlsStrategyLookup, schemePortResolver != null ? schemePortResolver : DefaultSchemePortResolver.INSTANCE, null); + } + + /** + * Creates a new instance of {@link HappyEyeballsV2AsyncClientConnectionOperator} using the provided TLS strategy lookup. + * The scheme-port resolver and DNS resolver will be set to their default instances. + * + * @param tlsStrategyLookup The lookup instance for {@link TlsStrategy} to be used for establishing connections. + * @throws IllegalArgumentException if {@code tlsStrategyLookup} is {@code null}. + */ + public HappyEyeballsV2AsyncClientConnectionOperator( + final Lookup<TlsStrategy> tlsStrategyLookup) { + this(tlsStrategyLookup, DefaultSchemePortResolver.INSTANCE, null); + } + + + /** + * Attempts to connect to the given host and returns a Future that will be completed when the connection is established + * or when an error occurs. This method may attempt to connect to multiple IP addresses associated with the host, + * depending on the address family and the number of connection attempts to execute. The address family and number of + * connection attempts can be configured by calling the corresponding setters on this class. + * + * @param connectionInitiator the connection initiator to use when creating the connection + * @param host the host to connect to + * @param localAddress the local address to bind to when connecting, or null to use any available local address + * @param connectTimeout the timeout to use when connecting, or null to use the default timeout + * @param attachment the attachment to associate with the connection, or null if no attachment is needed + * @param callback the callback to invoke when the connection is established or an error occurs, or null if no callback is needed + * @return a Future that will be completed when the connection is established or when an error occurs + */ + @Override + public Future<ManagedAsyncClientConnection> connect( + final ConnectionInitiator connectionInitiator, + final HttpHost host, + final SocketAddress localAddress, + final Timeout connectTimeout, + final Object attachment, + final FutureCallback<ManagedAsyncClientConnection> callback) { + + final CompletableFuture<ManagedAsyncClientConnection> connectionFuture = new CompletableFuture<>(); + + final Timeout conTimeout = connectTimeout != null ? connectTimeout : timeout; + + resolveDnsAsync(host.getHostName()) + .thenCompose(inetAddresses -> { + final List<InetAddress> ipv4Addresses = new ArrayList<>(); + final List<InetAddress> ipv6Addresses = new ArrayList<>(); + + for (final InetAddress inetAddress : inetAddresses) { + if (inetAddress instanceof Inet4Address) { + ipv4Addresses.add(inetAddress); + } else if (inetAddress instanceof Inet6Address) { + ipv6Addresses.add(inetAddress); + } + } + + sortAndInterleave(inetAddresses); + + final List<CompletableFuture<ManagedAsyncClientConnection>> connectionFutures = new ArrayList<>(); + + // Create a list of connection attempts to execute + final List<CompletableFuture<ManagedAsyncClientConnection>> attempts = new ArrayList<>(); + + // Create a list of connection attempts to execute + if (addressFamily == AddressFamily.IPv4 && !ipv4Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv4Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv4Addresses.get(i)), localAddress)); + } + } else if (addressFamily == AddressFamily.IPv6 && !ipv6Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv6Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv6Addresses.get(i)), localAddress)); + } + } else { + if (!ipv4Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv4Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv4Addresses.get(i)), localAddress)); + } + } + if (!ipv6Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv6Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv6Addresses.get(i)), localAddress)); + } + } + } + + // Execute the connection attempts concurrently using CompletableFuture.anyOf + return CompletableFuture.anyOf(attempts.toArray(new CompletableFuture[0])) + .thenCompose(result -> { + if (result instanceof ManagedAsyncClientConnection) { + // If there is a result, cancel all other attempts and complete the connectionFuture + connectionFutures.forEach(future -> future.cancel(true)); + connectionFuture.complete((ManagedAsyncClientConnection) result); + } else { + // If there is an exception, complete the connectionFuture exceptionally with the exception + connectionFuture.completeExceptionally(new ConnectException("Failed to connect to any address for " + host)); + } + // Invoke the callback if provided + if (callback != null) { + connectionFuture.whenComplete((conn, ex) -> { + if (ex != null) { + callback.failed(new Exception(ex)); + } else { + callback.completed(conn); + } + }); + } + return connectionFuture; + }); + }) + .exceptionally(e -> { + connectionFuture.completeExceptionally(e); + if (callback != null) { + callback.failed(new Exception(e)); + } + return null; + }); + + return connectionFuture; + } + + /** + * Asynchronously resolves the DNS for the given host name and returns a CompletableFuture that will be completed + * with an array of InetAddress objects representing the IP addresses of the host. + * The resolution of AAAA records is delayed by the configured resolution delay to allow for a chance for A records to be + * returned first. + * + * @param host the host name to resolve DNS for + * @return a CompletableFuture that will be completed with an array of InetAddress objects representing the IP addresses + */ + private CompletableFuture<InetAddress[]> resolveDnsAsync(final String host) { + final CompletableFuture<InetAddress[]> dnsFuture = new CompletableFuture<>(); + CompletableFuture.runAsync(() -> { + try { + final InetAddress[] inetAddresses = dnsResolver.resolve(host); + // Introduce a delay before resolving AAAA records after receiving A records + resolution_delay.sleep(); + dnsFuture.complete(inetAddresses); + } catch (final UnknownHostException | InterruptedException e) { Review Comment: Shouldn't you catch `Exception` here, instead of just the checked exceptions? ########## httpclient5/src/test/java/org/apache/hc/client5/http/impl/nio/HappyEyeballsV2AsyncClientConnectionOperatorTest.java: ########## @@ -0,0 +1,309 @@ +/* + * ==================================================================== + * 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. + * ==================================================================== + * + * This software consists of voluntary contributions made by many + * individuals on behalf of the Apache Software Foundation. For more + * information on the Apache Software Foundation, please see + * <http://www.apache.org/>. + * + */ +package org.apache.hc.client5.http.impl.nio; + +import org.apache.hc.client5.http.DnsResolver; +import org.apache.hc.client5.http.config.TlsConfig; +import org.apache.hc.client5.http.nio.AsyncClientConnectionOperator; +import org.apache.hc.client5.http.nio.ManagedAsyncClientConnection; +import org.apache.hc.client5.http.ssl.ConscryptClientTlsStrategy; +import org.apache.hc.core5.concurrent.FutureCallback; +import org.apache.hc.core5.http.HttpHost; +import org.apache.hc.core5.http.URIScheme; +import org.apache.hc.core5.http.config.RegistryBuilder; +import org.apache.hc.core5.http.nio.ssl.TlsStrategy; +import org.apache.hc.core5.http.protocol.BasicHttpContext; +import org.apache.hc.core5.http.protocol.HttpContext; +import org.apache.hc.core5.reactor.ConnectionInitiator; +import org.apache.hc.core5.util.Timeout; +import org.junit.jupiter.api.BeforeEach; +import org.junit.jupiter.api.DisplayName; +import org.junit.jupiter.api.Test; +import org.mockito.Mockito; +import org.mockito.stubbing.Answer; + +import java.net.InetAddress; +import java.net.SocketAddress; +import java.net.UnknownHostException; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.ExecutionException; +import java.util.concurrent.Future; + +import static org.junit.jupiter.api.Assertions.assertFalse; +import static org.junit.jupiter.api.Assertions.assertSame; +import static org.junit.jupiter.api.Assertions.assertTrue; +import static org.mockito.ArgumentMatchers.any; +import static org.mockito.Mockito.mock; + +public class HappyEyeballsV2AsyncClientConnectionOperatorTest { + + private AsyncClientConnectionOperator happyEyeballsV2AsyncClientConnectionOperator; + + private ConnectionInitiator connectionInitiator; + + private DnsResolver dnsResolver; + + private SocketAddress socketAddress; + + private AsyncClientConnectionOperator connectionOperator; + + + @BeforeEach + public void setup() { + + dnsResolver = Mockito.mock(DnsResolver.class); + connectionOperator = Mockito.mock(AsyncClientConnectionOperator.class); + + happyEyeballsV2AsyncClientConnectionOperator = new HappyEyeballsV2AsyncClientConnectionOperator + (RegistryBuilder.<TlsStrategy>create().register(URIScheme.HTTPS.getId(), ConscryptClientTlsStrategy.getDefault()).build(), + connectionOperator, + dnsResolver, + Timeout.ofSeconds(1), + Timeout.ofSeconds(1), + Timeout.ofSeconds(1), + Timeout.ofSeconds(1), + Timeout.ofSeconds(1), + 1, + HappyEyeballsV2AsyncClientConnectionOperator.AddressFamily.IPv4); + + connectionInitiator = mock(ConnectionInitiator.class); + socketAddress = mock(SocketAddress.class); + + + } + + @DisplayName("Test that application prioritizes IPv6 over IPv4 when both are available") Review Comment: Again, the sorting rules are more complicated than this. For example, native IPv4 addresses are preferred to IPv6 addresses that use an encapsulation/tunneling transport like 6to4 or Teredo. IPv6 addresses will also be considered unusable, and therefore deprioritized, if no IPv6 _source_ address is available. ########## httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/HappyEyeballsV2AsyncClientConnectionOperator.java: ########## @@ -0,0 +1,680 @@ +/* + * ==================================================================== + * 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. + * ==================================================================== + * + * This software consists of voluntary contributions made by many + * individuals on behalf of the Apache Software Foundation. For more + * information on the Apache Software Foundation, please see + * <http://www.apache.org/>. + * + */ + +package org.apache.hc.client5.http.impl.nio; + +import org.apache.hc.client5.http.DnsResolver; +import org.apache.hc.client5.http.SchemePortResolver; +import org.apache.hc.client5.http.SystemDefaultDnsResolver; +import org.apache.hc.client5.http.impl.ConnPoolSupport; +import org.apache.hc.client5.http.impl.DefaultSchemePortResolver; +import org.apache.hc.client5.http.nio.AsyncClientConnectionOperator; +import org.apache.hc.client5.http.nio.ManagedAsyncClientConnection; +import org.apache.hc.core5.concurrent.FutureCallback; +import org.apache.hc.core5.http.HttpHost; +import org.apache.hc.core5.http.config.Lookup; +import org.apache.hc.core5.http.nio.ssl.TlsStrategy; +import org.apache.hc.core5.http.protocol.HttpContext; +import org.apache.hc.core5.reactor.ConnectionInitiator; +import org.apache.hc.core5.reactor.ssl.TransportSecurityLayer; +import org.apache.hc.core5.util.Args; +import org.apache.hc.core5.util.Timeout; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.net.ConnectException; +import java.net.Inet4Address; +import java.net.Inet6Address; +import java.net.InetAddress; +import java.net.SocketAddress; +import java.net.UnknownHostException; +import java.time.Duration; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collections; +import java.util.List; +import java.util.concurrent.CancellationException; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.Future; + +/** + * The {@link AsyncClientConnectionOperator} implementation that uses Happy Eyeballs V2 algorithm to connect + * to the target server. Happy Eyeballs V2 (HEV2) algorithm is used to connect to the target server by concurrently + * attempting to establish multiple connections to different IP addresses. The first connection to complete + * successfully is selected and the others are closed. If all connections fail, the last error is rethrown. + * The algorithm also applies a configurable delay before subsequent connection attempts. HEV2 was introduced + * as a means to mitigate the latency issues caused by IPv4 and IPv6 co-existence in the Internet. HEV2 is defined + * in RFC 8305. + * + * <p> + * This connection operator maintains a connection pool for each unique route (combination of target host and + * target port) and selects the next connection from the pool to establish a new connection or reuse an + * existing connection. The connection pool uses a First-In-First-Out (FIFO) queue and has a configurable limit + * on the maximum number of connections that can be kept alive in the pool. Once the maximum number of connections + * has been reached, the oldest connection in the pool is closed to make room for a new one. + * </p> + * + * <p> + * This class is thread-safe and can be used in a multi-threaded environment. + * </p> + * + * <p> + * The HEV2 algorithm is configurable through the following parameters: + * <ul> + * <li>{@code dualStackEnabled}: Whether to enable dual-stack connectivity. When set to {@code true}, + * the operator attempts to connect to both IPv4 and IPv6 addresses concurrently. When set to {@code false}, + * only IPv4 or IPv6 addresses are attempted depending on the address type of the target server.</li> + * <li>{@code maxAttempts}: The maximum number of connection attempts to be made before failing. If all + * attempts fail, the last error is rethrown.</li> + * <li>{@code delay}: The delay (in milliseconds) to apply before subsequent connection attempts.</li> + * <li>{@code connectTimeout}: The connection timeout (in milliseconds) for each attempt.</li> + * </ul> + * </p> + * + * + * <p> + * This class can be used with any {@link org.apache.hc.core5.http.nio.AsyncClientEndpoint} implementation + * that supports HTTP/1.1 or HTTP/2 protocols. + * </p> + * + * @since 5.3 + */ +public class HappyEyeballsV2AsyncClientConnectionOperator implements AsyncClientConnectionOperator { + + private static final Logger LOG = LoggerFactory.getLogger(AsyncClientConnectionOperator.class); + + /** + * The underlying {@link AsyncClientConnectionOperator} that is used to establish connections + * to the target server. + */ + private final AsyncClientConnectionOperator connectionOperator; + + /** + * The DNS resolver used to resolve hostnames to IP addresses. + */ + private final DnsResolver dnsResolver; + + /** + * A lookup table used to determine the {@link TlsStrategy} to use for a given connection route. + */ + private final Lookup<TlsStrategy> tlsStrategyLookup; + + /** + * The default timeout for connection establishment attempts. If a connection cannot be established + * within this timeout, the attempt is considered failed. + */ + private final Timeout timeout; + + /** + * The minimum delay between connection establishment attempts. + */ + private final Timeout minimumConnectionAttemptDelay; + + /** + * The maximum delay between connection establishment attempts. + */ + private final Timeout maximumConnectionAttemptDelay; + + /** + * The current delay between connection establishment attempts. + */ + private final Timeout connectionAttemptDelay; + + /** + * The delay before resolution is started. + */ + private final Timeout resolution_delay; + + /** + * The number of IP addresses of each address family to include in the initial list of + * IP addresses to attempt connections to. This value is set to 2 by default, but can be + * increased to more aggressively favor a particular address family (e.g. set to 4 for IPv6). + */ + private final int firstAddressFamilyCount; + + /** + * The address family to use for establishing connections. This can be set to either + * {@link AddressFamily#IPv4} or {@link AddressFamily#IPv6}. + */ + private final AddressFamily addressFamily; + + + /** + * The AddressFamily enum represents the possible address families that can be used when attempting to establish + * <p> + * connections using the Happy Eyeballs V2 algorithm. + * + * <p> + * The Happy Eyeballs V2 algorithm allows for concurrent connection attempts to be made to different IP addresses, + * <p> + * so this enum specifies whether connections should be attempted using IPv4 or IPv6 addresses. + * + * </p> + */ + public enum AddressFamily { + IPv4, IPv6 + } + + /** + * Constructs a new {@link HappyEyeballsV2AsyncClientConnectionOperator} with the specified parameters. + * + * @param tlsStrategyLookup the lookup object used to retrieve a {@link TlsStrategy} for a given {@link Route} + * @param connectionOperator the underlying {@link AsyncClientConnectionOperator} to use for establishing connections + * @param dnsResolver the {@link DnsResolver} to use for resolving target hostnames + * @param timeout the timeout duration for establishing a connection + * @param resolution_delay the configurable delay before subsequent DNS resolution attempts + * @param minimumConnectionAttemptDelay the minimum configurable delay between connection attempts + * @param maximumConnectionAttemptDelay the maximum configurable delay between connection attempts + * @param connectionAttemptDelay the configurable delay before attempting to establish a connection + * @param firstAddressFamilyCount the number of initial address families to use for establishing a connection + * @param addressFamily the preferred address family to use for establishing a connection + * @throws IllegalArgumentException if {@code firstAddressFamilyCount} is not positive + */ + public HappyEyeballsV2AsyncClientConnectionOperator(final Lookup<TlsStrategy> tlsStrategyLookup, + final AsyncClientConnectionOperator connectionOperator, + final DnsResolver dnsResolver, + final Timeout timeout, + final Timeout resolution_delay, + final Timeout minimumConnectionAttemptDelay, + final Timeout maximumConnectionAttemptDelay, + final Timeout connectionAttemptDelay, + final int firstAddressFamilyCount, + final AddressFamily addressFamily) { + this.tlsStrategyLookup = Args.notNull(tlsStrategyLookup, "TLS strategy lookup"); + this.connectionOperator = Args.notNull(connectionOperator, "Connection operator"); + this.dnsResolver = dnsResolver != null ? dnsResolver : SystemDefaultDnsResolver.INSTANCE; + this.timeout = timeout != null ? timeout : Timeout.ofMilliseconds(250); + this.resolution_delay = resolution_delay != null ? resolution_delay : Timeout.ofMilliseconds(50); + this.minimumConnectionAttemptDelay = minimumConnectionAttemptDelay != null ? minimumConnectionAttemptDelay : Timeout.ofMilliseconds(100); + this.maximumConnectionAttemptDelay = maximumConnectionAttemptDelay != null ? maximumConnectionAttemptDelay : Timeout.ofSeconds(2); + this.connectionAttemptDelay = connectionAttemptDelay != null ? connectionAttemptDelay : Timeout.ofMilliseconds(250); + this.firstAddressFamilyCount = Args.positive(firstAddressFamilyCount, "firstAddressFamilyCount"); + this.addressFamily = addressFamily; + } + + /** + * Constructs a new instance of {@link HappyEyeballsV2AsyncClientConnectionOperator} using the specified + * {@link Lookup} for {@link TlsStrategy} and {@link SchemePortResolver} and {@link DnsResolver}. + * <p> + * The constructor internally creates a new instance of {@link DefaultAsyncClientConnectionOperator} with the + * specified {@link Lookup} for {@link TlsStrategy}, {@link SchemePortResolver} and {@link DnsResolver}. The + * created {@link AsyncClientConnectionOperator} is then passed to the main constructor along with default values + * for other parameters. + * </p> + * + * @param tlsStrategyLookup The {@link Lookup} for {@link TlsStrategy}. + * @param schemePortResolver The {@link SchemePortResolver} to use for resolving scheme ports. + * @param dnsResolver The {@link DnsResolver} to use for resolving hostnames to IP addresses. + * @throws IllegalArgumentException if the {@code tlsStrategyLookup} or {@code schemePortResolver} or {@code dnsResolver} parameter is {@code null}. + */ + public HappyEyeballsV2AsyncClientConnectionOperator( + final Lookup<TlsStrategy> tlsStrategyLookup, + final SchemePortResolver schemePortResolver, + final DnsResolver dnsResolver) { + this(tlsStrategyLookup, + new DefaultAsyncClientConnectionOperator(tlsStrategyLookup, schemePortResolver, dnsResolver), + dnsResolver, + null, + null, + null, + null, + null, + 1, + AddressFamily.IPv6); + } + + /** + * Creates a new instance of {@link HappyEyeballsV2AsyncClientConnectionOperator} using the provided TLS strategy lookup + * and scheme-port resolver. The DNS resolver will be set to the system default resolver. + * + * @param tlsStrategyLookup The lookup instance for {@link TlsStrategy} to be used for establishing connections. + * @param schemePortResolver The resolver instance for mapping scheme names to default port numbers. + * @throws IllegalArgumentException if {@code tlsStrategyLookup} is {@code null}. + */ + public HappyEyeballsV2AsyncClientConnectionOperator( + final Lookup<TlsStrategy> tlsStrategyLookup, + final SchemePortResolver schemePortResolver) { + this(tlsStrategyLookup, schemePortResolver != null ? schemePortResolver : DefaultSchemePortResolver.INSTANCE, null); + } + + /** + * Creates a new instance of {@link HappyEyeballsV2AsyncClientConnectionOperator} using the provided TLS strategy lookup. + * The scheme-port resolver and DNS resolver will be set to their default instances. + * + * @param tlsStrategyLookup The lookup instance for {@link TlsStrategy} to be used for establishing connections. + * @throws IllegalArgumentException if {@code tlsStrategyLookup} is {@code null}. + */ + public HappyEyeballsV2AsyncClientConnectionOperator( + final Lookup<TlsStrategy> tlsStrategyLookup) { + this(tlsStrategyLookup, DefaultSchemePortResolver.INSTANCE, null); + } + + + /** + * Attempts to connect to the given host and returns a Future that will be completed when the connection is established + * or when an error occurs. This method may attempt to connect to multiple IP addresses associated with the host, + * depending on the address family and the number of connection attempts to execute. The address family and number of + * connection attempts can be configured by calling the corresponding setters on this class. + * + * @param connectionInitiator the connection initiator to use when creating the connection + * @param host the host to connect to + * @param localAddress the local address to bind to when connecting, or null to use any available local address + * @param connectTimeout the timeout to use when connecting, or null to use the default timeout + * @param attachment the attachment to associate with the connection, or null if no attachment is needed + * @param callback the callback to invoke when the connection is established or an error occurs, or null if no callback is needed + * @return a Future that will be completed when the connection is established or when an error occurs + */ + @Override + public Future<ManagedAsyncClientConnection> connect( + final ConnectionInitiator connectionInitiator, + final HttpHost host, + final SocketAddress localAddress, + final Timeout connectTimeout, + final Object attachment, + final FutureCallback<ManagedAsyncClientConnection> callback) { + + final CompletableFuture<ManagedAsyncClientConnection> connectionFuture = new CompletableFuture<>(); + + final Timeout conTimeout = connectTimeout != null ? connectTimeout : timeout; + + resolveDnsAsync(host.getHostName()) + .thenCompose(inetAddresses -> { + final List<InetAddress> ipv4Addresses = new ArrayList<>(); + final List<InetAddress> ipv6Addresses = new ArrayList<>(); + + for (final InetAddress inetAddress : inetAddresses) { + if (inetAddress instanceof Inet4Address) { + ipv4Addresses.add(inetAddress); + } else if (inetAddress instanceof Inet6Address) { + ipv6Addresses.add(inetAddress); + } + } + + sortAndInterleave(inetAddresses); + + final List<CompletableFuture<ManagedAsyncClientConnection>> connectionFutures = new ArrayList<>(); + + // Create a list of connection attempts to execute + final List<CompletableFuture<ManagedAsyncClientConnection>> attempts = new ArrayList<>(); + + // Create a list of connection attempts to execute + if (addressFamily == AddressFamily.IPv4 && !ipv4Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv4Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv4Addresses.get(i)), localAddress)); + } + } else if (addressFamily == AddressFamily.IPv6 && !ipv6Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv6Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv6Addresses.get(i)), localAddress)); + } + } else { + if (!ipv4Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv4Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv4Addresses.get(i)), localAddress)); + } + } + if (!ipv6Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv6Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv6Addresses.get(i)), localAddress)); + } + } + } + + // Execute the connection attempts concurrently using CompletableFuture.anyOf + return CompletableFuture.anyOf(attempts.toArray(new CompletableFuture[0])) + .thenCompose(result -> { + if (result instanceof ManagedAsyncClientConnection) { + // If there is a result, cancel all other attempts and complete the connectionFuture + connectionFutures.forEach(future -> future.cancel(true)); + connectionFuture.complete((ManagedAsyncClientConnection) result); + } else { + // If there is an exception, complete the connectionFuture exceptionally with the exception + connectionFuture.completeExceptionally(new ConnectException("Failed to connect to any address for " + host)); + } + // Invoke the callback if provided + if (callback != null) { + connectionFuture.whenComplete((conn, ex) -> { + if (ex != null) { + callback.failed(new Exception(ex)); + } else { + callback.completed(conn); + } + }); + } + return connectionFuture; + }); + }) + .exceptionally(e -> { + connectionFuture.completeExceptionally(e); + if (callback != null) { + callback.failed(new Exception(e)); + } + return null; + }); + + return connectionFuture; + } + + /** + * Asynchronously resolves the DNS for the given host name and returns a CompletableFuture that will be completed + * with an array of InetAddress objects representing the IP addresses of the host. + * The resolution of AAAA records is delayed by the configured resolution delay to allow for a chance for A records to be + * returned first. + * + * @param host the host name to resolve DNS for + * @return a CompletableFuture that will be completed with an array of InetAddress objects representing the IP addresses + */ + private CompletableFuture<InetAddress[]> resolveDnsAsync(final String host) { + final CompletableFuture<InetAddress[]> dnsFuture = new CompletableFuture<>(); + CompletableFuture.runAsync(() -> { + try { + final InetAddress[] inetAddresses = dnsResolver.resolve(host); + // Introduce a delay before resolving AAAA records after receiving A records + resolution_delay.sleep(); + dnsFuture.complete(inetAddresses); + } catch (final UnknownHostException | InterruptedException e) { + if (LOG.isDebugEnabled()) { + LOG.debug("Failed to resolve DNS for host '{}': {}", host, e.getMessage(), e); + } + dnsFuture.completeExceptionally(e); + } + }); + return dnsFuture; + } + + + /** + * Initiates an asynchronous connection attempt to the given list of IP addresses for the specified {@link HttpHost}. + * + * @param connectionInitiator the {@link ConnectionInitiator} to use for establishing the connection + * @param host the {@link HttpHost} to connect to + * @param connectTimeout the timeout for the connection attempt + * @param attachment the attachment object to pass to the connection operator + * @param addresses the list of IP addresses to attempt to connect to + * @param localAddress the local socket address to bind the connection to, or {@code null} if not binding + * @return a {@link CompletableFuture} that completes with a {@link ManagedAsyncClientConnection} if the connection attempt succeeds, + * or exceptionally with an exception if all attempts fail + */ + private CompletableFuture<ManagedAsyncClientConnection> connectAttempt( + final ConnectionInitiator connectionInitiator, + final HttpHost host, + final Timeout connectTimeout, + final Object attachment, + final List<InetAddress> addresses, + final SocketAddress localAddress) { + + final CompletableFuture<ManagedAsyncClientConnection> connectionFuture = new CompletableFuture<>(); + + // Create a list of connection attempts to execute + final List<CompletableFuture<Void>> attempts = new ArrayList<>(); + for (int i = 0; i < addresses.size(); i++) { + final InetAddress address = addresses.get(i); + + if (LOG.isDebugEnabled()) { + LOG.info("Attempting to connect to {}", address); + } + + final CompletableFuture<Void> attempt = new CompletableFuture<>(); + attempts.add(attempt); + final HttpHost currentHost = new HttpHost(host.getSchemeName(), address, host.getHostName(), host.getPort()); + + connectionOperator.connect( + connectionInitiator, + currentHost, + localAddress, + connectTimeout, + attachment, + new FutureCallback<ManagedAsyncClientConnection>() { + @Override + public void completed(final ManagedAsyncClientConnection connection) { + if (LOG.isDebugEnabled()) { + LOG.debug("Successfully connected {}", ConnPoolSupport.getId(connection)); + } + connectionFuture.complete(connection); + } + + @Override + public void failed(final Exception ex) { + if (LOG.isDebugEnabled()) { + LOG.debug("Failed to connect {}", ConnPoolSupport.getId(address), ex); + } + attempt.completeExceptionally(ex); + } + + @Override + public void cancelled() { + if (LOG.isDebugEnabled()) { + LOG.debug("Cancelled connect for {}", ConnPoolSupport.getId(address)); + } + attempt.cancel(true); + } + }); + + // Introduce a delay before executing the next connection attempt + if (i < addresses.size() - 1) { + try { + final Duration delay = calculateDelay(i); + delay.wait(); Review Comment: What thread is this code running in? This will block for up to 2,000 milliseconds. ########## httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/InetAddressComparator.java: ########## @@ -0,0 +1,89 @@ +/* + * ==================================================================== + * 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. + * ==================================================================== + * + * This software consists of voluntary contributions made by many + * individuals on behalf of the Apache Software Foundation. For more + * information on the Apache Software Foundation, please see + * <http://www.apache.org/>. + * + */ +package org.apache.hc.client5.http.impl.nio; + +import org.apache.hc.core5.annotation.Contract; +import org.apache.hc.core5.annotation.Internal; +import org.apache.hc.core5.annotation.ThreadingBehavior; + +import java.net.Inet4Address; +import java.net.Inet6Address; +import java.net.InetAddress; +import java.util.Comparator; +/** + * Comparator that orders IPv6 addresses before IPv4 addresses, and then based on their byte values. + */ +@Contract(threading = ThreadingBehavior.STATELESS) +@Internal +class InetAddressComparator implements Comparator<InetAddress> { + + /** + * Singleton instance of the comparator. + */ + public static final InetAddressComparator INSTANCE = new InetAddressComparator(); + + /** + * Compares the specified IPv4 and IPv6 addresses. + * + * @param adr1 the first address to be compared + * @param adr2 the second address to be compared + * @return a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater + * than the second + * @throws NullPointerException if either argument is null + */ + @Override + public int compare(final InetAddress adr1, final InetAddress adr2) { + if (adr1 == null && adr2 == null) { + return 0; + } + if (adr1 == null) { + return -1; + } + if (adr2 == null) { + return 1; + } + // Compare IPv6 addresses first + if (adr1 instanceof Inet6Address && adr2 instanceof Inet4Address) { + return 1; + } + if (adr1 instanceof Inet4Address && adr2 instanceof Inet6Address) { + return -1; + } + // Compare based on address bytes Review Comment: This appears to have nothing to do with the [address sorting algorithm](http://biplane.com.au/blog/?p=141) specified by [RFC 6724](https://www.rfc-editor.org/rfc/rfc6724#section-6), which is [mandated](https://www.rfc-editor.org/rfc/rfc8305#section-4) by RFC 8305. Furthermore, sorting addresses in this way is a bad idea, since it will defeat [round-robin DNS](https://en.wikipedia.org/wiki/Round-robin_DNS), an important load balancing technique. ########## httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/HappyEyeballsV2AsyncClientConnectionOperator.java: ########## @@ -0,0 +1,680 @@ +/* + * ==================================================================== + * 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. + * ==================================================================== + * + * This software consists of voluntary contributions made by many + * individuals on behalf of the Apache Software Foundation. For more + * information on the Apache Software Foundation, please see + * <http://www.apache.org/>. + * + */ + +package org.apache.hc.client5.http.impl.nio; + +import org.apache.hc.client5.http.DnsResolver; +import org.apache.hc.client5.http.SchemePortResolver; +import org.apache.hc.client5.http.SystemDefaultDnsResolver; +import org.apache.hc.client5.http.impl.ConnPoolSupport; +import org.apache.hc.client5.http.impl.DefaultSchemePortResolver; +import org.apache.hc.client5.http.nio.AsyncClientConnectionOperator; +import org.apache.hc.client5.http.nio.ManagedAsyncClientConnection; +import org.apache.hc.core5.concurrent.FutureCallback; +import org.apache.hc.core5.http.HttpHost; +import org.apache.hc.core5.http.config.Lookup; +import org.apache.hc.core5.http.nio.ssl.TlsStrategy; +import org.apache.hc.core5.http.protocol.HttpContext; +import org.apache.hc.core5.reactor.ConnectionInitiator; +import org.apache.hc.core5.reactor.ssl.TransportSecurityLayer; +import org.apache.hc.core5.util.Args; +import org.apache.hc.core5.util.Timeout; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.net.ConnectException; +import java.net.Inet4Address; +import java.net.Inet6Address; +import java.net.InetAddress; +import java.net.SocketAddress; +import java.net.UnknownHostException; +import java.time.Duration; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collections; +import java.util.List; +import java.util.concurrent.CancellationException; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.Future; + +/** + * The {@link AsyncClientConnectionOperator} implementation that uses Happy Eyeballs V2 algorithm to connect + * to the target server. Happy Eyeballs V2 (HEV2) algorithm is used to connect to the target server by concurrently + * attempting to establish multiple connections to different IP addresses. The first connection to complete + * successfully is selected and the others are closed. If all connections fail, the last error is rethrown. + * The algorithm also applies a configurable delay before subsequent connection attempts. HEV2 was introduced + * as a means to mitigate the latency issues caused by IPv4 and IPv6 co-existence in the Internet. HEV2 is defined + * in RFC 8305. + * + * <p> + * This connection operator maintains a connection pool for each unique route (combination of target host and + * target port) and selects the next connection from the pool to establish a new connection or reuse an + * existing connection. The connection pool uses a First-In-First-Out (FIFO) queue and has a configurable limit + * on the maximum number of connections that can be kept alive in the pool. Once the maximum number of connections + * has been reached, the oldest connection in the pool is closed to make room for a new one. + * </p> + * + * <p> + * This class is thread-safe and can be used in a multi-threaded environment. + * </p> + * + * <p> + * The HEV2 algorithm is configurable through the following parameters: + * <ul> + * <li>{@code dualStackEnabled}: Whether to enable dual-stack connectivity. When set to {@code true}, + * the operator attempts to connect to both IPv4 and IPv6 addresses concurrently. When set to {@code false}, + * only IPv4 or IPv6 addresses are attempted depending on the address type of the target server.</li> + * <li>{@code maxAttempts}: The maximum number of connection attempts to be made before failing. If all + * attempts fail, the last error is rethrown.</li> + * <li>{@code delay}: The delay (in milliseconds) to apply before subsequent connection attempts.</li> + * <li>{@code connectTimeout}: The connection timeout (in milliseconds) for each attempt.</li> + * </ul> + * </p> + * + * + * <p> + * This class can be used with any {@link org.apache.hc.core5.http.nio.AsyncClientEndpoint} implementation + * that supports HTTP/1.1 or HTTP/2 protocols. + * </p> + * + * @since 5.3 + */ +public class HappyEyeballsV2AsyncClientConnectionOperator implements AsyncClientConnectionOperator { + + private static final Logger LOG = LoggerFactory.getLogger(AsyncClientConnectionOperator.class); + + /** + * The underlying {@link AsyncClientConnectionOperator} that is used to establish connections + * to the target server. + */ + private final AsyncClientConnectionOperator connectionOperator; + + /** + * The DNS resolver used to resolve hostnames to IP addresses. + */ + private final DnsResolver dnsResolver; + + /** + * A lookup table used to determine the {@link TlsStrategy} to use for a given connection route. + */ + private final Lookup<TlsStrategy> tlsStrategyLookup; + + /** + * The default timeout for connection establishment attempts. If a connection cannot be established + * within this timeout, the attempt is considered failed. + */ + private final Timeout timeout; + + /** + * The minimum delay between connection establishment attempts. + */ + private final Timeout minimumConnectionAttemptDelay; + + /** + * The maximum delay between connection establishment attempts. + */ + private final Timeout maximumConnectionAttemptDelay; + + /** + * The current delay between connection establishment attempts. + */ + private final Timeout connectionAttemptDelay; + + /** + * The delay before resolution is started. + */ + private final Timeout resolution_delay; + + /** + * The number of IP addresses of each address family to include in the initial list of + * IP addresses to attempt connections to. This value is set to 2 by default, but can be + * increased to more aggressively favor a particular address family (e.g. set to 4 for IPv6). + */ + private final int firstAddressFamilyCount; + + /** + * The address family to use for establishing connections. This can be set to either + * {@link AddressFamily#IPv4} or {@link AddressFamily#IPv6}. + */ + private final AddressFamily addressFamily; + + + /** + * The AddressFamily enum represents the possible address families that can be used when attempting to establish + * <p> + * connections using the Happy Eyeballs V2 algorithm. + * + * <p> + * The Happy Eyeballs V2 algorithm allows for concurrent connection attempts to be made to different IP addresses, + * <p> + * so this enum specifies whether connections should be attempted using IPv4 or IPv6 addresses. + * + * </p> + */ + public enum AddressFamily { + IPv4, IPv6 + } + + /** + * Constructs a new {@link HappyEyeballsV2AsyncClientConnectionOperator} with the specified parameters. + * + * @param tlsStrategyLookup the lookup object used to retrieve a {@link TlsStrategy} for a given {@link Route} + * @param connectionOperator the underlying {@link AsyncClientConnectionOperator} to use for establishing connections + * @param dnsResolver the {@link DnsResolver} to use for resolving target hostnames + * @param timeout the timeout duration for establishing a connection + * @param resolution_delay the configurable delay before subsequent DNS resolution attempts + * @param minimumConnectionAttemptDelay the minimum configurable delay between connection attempts + * @param maximumConnectionAttemptDelay the maximum configurable delay between connection attempts + * @param connectionAttemptDelay the configurable delay before attempting to establish a connection + * @param firstAddressFamilyCount the number of initial address families to use for establishing a connection + * @param addressFamily the preferred address family to use for establishing a connection + * @throws IllegalArgumentException if {@code firstAddressFamilyCount} is not positive + */ + public HappyEyeballsV2AsyncClientConnectionOperator(final Lookup<TlsStrategy> tlsStrategyLookup, + final AsyncClientConnectionOperator connectionOperator, + final DnsResolver dnsResolver, + final Timeout timeout, + final Timeout resolution_delay, + final Timeout minimumConnectionAttemptDelay, + final Timeout maximumConnectionAttemptDelay, + final Timeout connectionAttemptDelay, + final int firstAddressFamilyCount, + final AddressFamily addressFamily) { + this.tlsStrategyLookup = Args.notNull(tlsStrategyLookup, "TLS strategy lookup"); + this.connectionOperator = Args.notNull(connectionOperator, "Connection operator"); + this.dnsResolver = dnsResolver != null ? dnsResolver : SystemDefaultDnsResolver.INSTANCE; + this.timeout = timeout != null ? timeout : Timeout.ofMilliseconds(250); + this.resolution_delay = resolution_delay != null ? resolution_delay : Timeout.ofMilliseconds(50); + this.minimumConnectionAttemptDelay = minimumConnectionAttemptDelay != null ? minimumConnectionAttemptDelay : Timeout.ofMilliseconds(100); + this.maximumConnectionAttemptDelay = maximumConnectionAttemptDelay != null ? maximumConnectionAttemptDelay : Timeout.ofSeconds(2); + this.connectionAttemptDelay = connectionAttemptDelay != null ? connectionAttemptDelay : Timeout.ofMilliseconds(250); + this.firstAddressFamilyCount = Args.positive(firstAddressFamilyCount, "firstAddressFamilyCount"); + this.addressFamily = addressFamily; + } + + /** + * Constructs a new instance of {@link HappyEyeballsV2AsyncClientConnectionOperator} using the specified + * {@link Lookup} for {@link TlsStrategy} and {@link SchemePortResolver} and {@link DnsResolver}. + * <p> + * The constructor internally creates a new instance of {@link DefaultAsyncClientConnectionOperator} with the + * specified {@link Lookup} for {@link TlsStrategy}, {@link SchemePortResolver} and {@link DnsResolver}. The + * created {@link AsyncClientConnectionOperator} is then passed to the main constructor along with default values + * for other parameters. + * </p> + * + * @param tlsStrategyLookup The {@link Lookup} for {@link TlsStrategy}. + * @param schemePortResolver The {@link SchemePortResolver} to use for resolving scheme ports. + * @param dnsResolver The {@link DnsResolver} to use for resolving hostnames to IP addresses. + * @throws IllegalArgumentException if the {@code tlsStrategyLookup} or {@code schemePortResolver} or {@code dnsResolver} parameter is {@code null}. + */ + public HappyEyeballsV2AsyncClientConnectionOperator( + final Lookup<TlsStrategy> tlsStrategyLookup, + final SchemePortResolver schemePortResolver, + final DnsResolver dnsResolver) { + this(tlsStrategyLookup, + new DefaultAsyncClientConnectionOperator(tlsStrategyLookup, schemePortResolver, dnsResolver), + dnsResolver, + null, + null, + null, + null, + null, + 1, + AddressFamily.IPv6); + } + + /** + * Creates a new instance of {@link HappyEyeballsV2AsyncClientConnectionOperator} using the provided TLS strategy lookup + * and scheme-port resolver. The DNS resolver will be set to the system default resolver. + * + * @param tlsStrategyLookup The lookup instance for {@link TlsStrategy} to be used for establishing connections. + * @param schemePortResolver The resolver instance for mapping scheme names to default port numbers. + * @throws IllegalArgumentException if {@code tlsStrategyLookup} is {@code null}. + */ + public HappyEyeballsV2AsyncClientConnectionOperator( + final Lookup<TlsStrategy> tlsStrategyLookup, + final SchemePortResolver schemePortResolver) { + this(tlsStrategyLookup, schemePortResolver != null ? schemePortResolver : DefaultSchemePortResolver.INSTANCE, null); + } + + /** + * Creates a new instance of {@link HappyEyeballsV2AsyncClientConnectionOperator} using the provided TLS strategy lookup. + * The scheme-port resolver and DNS resolver will be set to their default instances. + * + * @param tlsStrategyLookup The lookup instance for {@link TlsStrategy} to be used for establishing connections. + * @throws IllegalArgumentException if {@code tlsStrategyLookup} is {@code null}. + */ + public HappyEyeballsV2AsyncClientConnectionOperator( + final Lookup<TlsStrategy> tlsStrategyLookup) { + this(tlsStrategyLookup, DefaultSchemePortResolver.INSTANCE, null); + } + + + /** + * Attempts to connect to the given host and returns a Future that will be completed when the connection is established + * or when an error occurs. This method may attempt to connect to multiple IP addresses associated with the host, + * depending on the address family and the number of connection attempts to execute. The address family and number of + * connection attempts can be configured by calling the corresponding setters on this class. + * + * @param connectionInitiator the connection initiator to use when creating the connection + * @param host the host to connect to + * @param localAddress the local address to bind to when connecting, or null to use any available local address + * @param connectTimeout the timeout to use when connecting, or null to use the default timeout + * @param attachment the attachment to associate with the connection, or null if no attachment is needed + * @param callback the callback to invoke when the connection is established or an error occurs, or null if no callback is needed + * @return a Future that will be completed when the connection is established or when an error occurs + */ + @Override + public Future<ManagedAsyncClientConnection> connect( + final ConnectionInitiator connectionInitiator, + final HttpHost host, + final SocketAddress localAddress, + final Timeout connectTimeout, + final Object attachment, + final FutureCallback<ManagedAsyncClientConnection> callback) { + + final CompletableFuture<ManagedAsyncClientConnection> connectionFuture = new CompletableFuture<>(); + + final Timeout conTimeout = connectTimeout != null ? connectTimeout : timeout; + + resolveDnsAsync(host.getHostName()) + .thenCompose(inetAddresses -> { + final List<InetAddress> ipv4Addresses = new ArrayList<>(); + final List<InetAddress> ipv6Addresses = new ArrayList<>(); + + for (final InetAddress inetAddress : inetAddresses) { + if (inetAddress instanceof Inet4Address) { + ipv4Addresses.add(inetAddress); + } else if (inetAddress instanceof Inet6Address) { + ipv6Addresses.add(inetAddress); + } + } + + sortAndInterleave(inetAddresses); + + final List<CompletableFuture<ManagedAsyncClientConnection>> connectionFutures = new ArrayList<>(); + + // Create a list of connection attempts to execute + final List<CompletableFuture<ManagedAsyncClientConnection>> attempts = new ArrayList<>(); + + // Create a list of connection attempts to execute + if (addressFamily == AddressFamily.IPv4 && !ipv4Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv4Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv4Addresses.get(i)), localAddress)); + } + } else if (addressFamily == AddressFamily.IPv6 && !ipv6Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv6Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv6Addresses.get(i)), localAddress)); + } + } else { + if (!ipv4Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv4Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv4Addresses.get(i)), localAddress)); + } + } + if (!ipv6Addresses.isEmpty()) { + for (int i = 0; i < firstAddressFamilyCount && i < ipv6Addresses.size(); i++) { + attempts.add(connectAttempt(connectionInitiator, host, conTimeout, attachment, + Collections.singletonList(ipv6Addresses.get(i)), localAddress)); + } + } + } + + // Execute the connection attempts concurrently using CompletableFuture.anyOf + return CompletableFuture.anyOf(attempts.toArray(new CompletableFuture[0])) + .thenCompose(result -> { + if (result instanceof ManagedAsyncClientConnection) { + // If there is a result, cancel all other attempts and complete the connectionFuture + connectionFutures.forEach(future -> future.cancel(true)); + connectionFuture.complete((ManagedAsyncClientConnection) result); + } else { + // If there is an exception, complete the connectionFuture exceptionally with the exception + connectionFuture.completeExceptionally(new ConnectException("Failed to connect to any address for " + host)); + } + // Invoke the callback if provided + if (callback != null) { + connectionFuture.whenComplete((conn, ex) -> { + if (ex != null) { + callback.failed(new Exception(ex)); + } else { + callback.completed(conn); + } + }); + } + return connectionFuture; + }); + }) + .exceptionally(e -> { + connectionFuture.completeExceptionally(e); + if (callback != null) { + callback.failed(new Exception(e)); + } + return null; + }); + + return connectionFuture; + } + + /** + * Asynchronously resolves the DNS for the given host name and returns a CompletableFuture that will be completed + * with an array of InetAddress objects representing the IP addresses of the host. + * The resolution of AAAA records is delayed by the configured resolution delay to allow for a chance for A records to be + * returned first. + * + * @param host the host name to resolve DNS for + * @return a CompletableFuture that will be completed with an array of InetAddress objects representing the IP addresses + */ + private CompletableFuture<InetAddress[]> resolveDnsAsync(final String host) { + final CompletableFuture<InetAddress[]> dnsFuture = new CompletableFuture<>(); + CompletableFuture.runAsync(() -> { + try { + final InetAddress[] inetAddresses = dnsResolver.resolve(host); + // Introduce a delay before resolving AAAA records after receiving A records + resolution_delay.sleep(); Review Comment: I'm slightly concerned about async code, running in the shared `ForkJoinPool`, performing a blocking sleep of a configurable duration. -- This is an automated message from the Apache Git Service. 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