c0ae5e697c
Motivation: Right now to customize DNS name resolver when using DnsAddressResolverGroup one should subclass implementation and override newNameResolver method when in fact it's possible to collect all settings in a DnsNameResolverBuilder instance. Described in #7749. Modifications: - Added new constructor for DnsNameResolverBuilder in order to delay EventLoop specification - Added copy() method to DnsNameResolverBuilder to provide an immutable copy of the builder - Added new single-argument constructor for DnsAddressResolverGroup and RoundRobinDnsAddressResolverGroup accepting DnsNameResolverBuilder instance - DnsAddressResolverGroup to build a new resolver using DnsNameResolverBuilder given instead of creating a new one - Test cases to check that changing channelFactory after the builder was passed to create a DnsNameResolverGroup would not propagate to the name resolver Result: Much easier to customize DNS settings w/o subclassing DnsAddressResolverGroup
69 lines
2.8 KiB
Java
69 lines
2.8 KiB
Java
/*
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* Copyright 2016 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.resolver.dns;
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import io.netty.channel.ChannelFactory;
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import io.netty.channel.EventLoop;
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import io.netty.channel.socket.DatagramChannel;
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import io.netty.resolver.AddressResolver;
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import io.netty.resolver.AddressResolverGroup;
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import io.netty.resolver.NameResolver;
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import io.netty.resolver.RoundRobinInetAddressResolver;
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import io.netty.util.internal.UnstableApi;
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import java.net.InetAddress;
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import java.net.InetSocketAddress;
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/**
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* A {@link AddressResolverGroup} of {@link DnsNameResolver}s that supports random selection of destination addresses if
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* multiple are provided by the nameserver. This is ideal for use in applications that use a pool of connections, for
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* which connecting to a single resolved address would be inefficient.
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*/
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@UnstableApi
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public class RoundRobinDnsAddressResolverGroup extends DnsAddressResolverGroup {
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public RoundRobinDnsAddressResolverGroup(DnsNameResolverBuilder dnsResolverBuilder) {
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super(dnsResolverBuilder);
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}
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public RoundRobinDnsAddressResolverGroup(
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Class<? extends DatagramChannel> channelType,
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DnsServerAddressStreamProvider nameServerProvider) {
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super(channelType, nameServerProvider);
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}
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public RoundRobinDnsAddressResolverGroup(
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ChannelFactory<? extends DatagramChannel> channelFactory,
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DnsServerAddressStreamProvider nameServerProvider) {
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super(channelFactory, nameServerProvider);
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}
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/**
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* We need to override this method, not
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* {@link #newNameResolver(EventLoop, ChannelFactory, DnsServerAddressStreamProvider)},
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* because we need to eliminate possible caching of {@link io.netty.resolver.NameResolver#resolve}
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* by {@link InflightNameResolver} created in
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* {@link #newResolver(EventLoop, ChannelFactory, DnsServerAddressStreamProvider)}.
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*/
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@Override
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protected final AddressResolver<InetSocketAddress> newAddressResolver(EventLoop eventLoop,
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NameResolver<InetAddress> resolver)
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throws Exception {
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return new RoundRobinInetAddressResolver(eventLoop, resolver).asAddressResolver();
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}
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}
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