0cb4cc4e49
Motivation: We wish to separate these two into clearer write/read interfaces. In particular, we don't want to be able to add listeners to promises, because it makes it easy to add them out of order. We can't prevent it entirely, because any promise can be freely converted to a future where listeners can be added. We can, however, discourage this in the API. Modification: The Promise interface no longer extends the Future interface. Numerous changes to make the project compile and its tests run. Result: Clearer separation of concerns in the code.
122 lines
4.3 KiB
Java
122 lines
4.3 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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* https://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.resolver.NameResolver;
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import io.netty.util.concurrent.EventExecutor;
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import io.netty.util.concurrent.Future;
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import io.netty.util.concurrent.Promise;
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import io.netty.util.internal.StringUtil;
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import java.util.List;
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import java.util.concurrent.ConcurrentMap;
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import static java.util.Objects.requireNonNull;
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// FIXME(trustin): Find a better name and move it to the 'resolver' module.
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final class InflightNameResolver<T> implements NameResolver<T> {
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private final EventExecutor executor;
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private final NameResolver<T> delegate;
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private final ConcurrentMap<String, Promise<T>> resolvesInProgress;
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private final ConcurrentMap<String, Promise<List<T>>> resolveAllsInProgress;
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InflightNameResolver(EventExecutor executor, NameResolver<T> delegate,
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ConcurrentMap<String, Promise<T>> resolvesInProgress,
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ConcurrentMap<String, Promise<List<T>>> resolveAllsInProgress) {
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this.executor = requireNonNull(executor, "executor");
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this.delegate = requireNonNull(delegate, "delegate");
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this.resolvesInProgress = requireNonNull(resolvesInProgress, "resolvesInProgress");
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this.resolveAllsInProgress = requireNonNull(resolveAllsInProgress, "resolveAllsInProgress");
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}
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@Override
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public Future<T> resolve(String inetHost) {
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return resolve(inetHost, executor.newPromise());
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}
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@Override
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public Future<List<T>> resolveAll(String inetHost) {
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return resolveAll(inetHost, executor.newPromise());
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}
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@Override
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public void close() {
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delegate.close();
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}
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@Override
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public Future<T> resolve(String inetHost, Promise<T> promise) {
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return resolve(resolvesInProgress, inetHost, promise, false);
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}
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@Override
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public Future<List<T>> resolveAll(String inetHost, Promise<List<T>> promise) {
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return resolve(resolveAllsInProgress, inetHost, promise, true);
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}
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private <U> Future<U> resolve(
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final ConcurrentMap<String, Promise<U>> resolveMap,
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final String inetHost, final Promise<U> promise, boolean resolveAll) {
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final Promise<U> earlyPromise = resolveMap.putIfAbsent(inetHost, promise);
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if (earlyPromise != null) {
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// Name resolution for the specified inetHost is in progress already.
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Future<U> earlyFuture = promise.asFuture();
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if (earlyFuture.isDone()) {
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transferResult(earlyFuture, promise);
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} else {
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earlyFuture.addListener(f -> transferResult(f, promise));
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}
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} else {
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try {
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if (resolveAll) {
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@SuppressWarnings("unchecked")
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final Promise<List<T>> castPromise = (Promise<List<T>>) promise; // U is List<T>
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delegate.resolveAll(inetHost, castPromise);
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} else {
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@SuppressWarnings("unchecked")
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final Promise<T> castPromise = (Promise<T>) promise; // U is T
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delegate.resolve(inetHost, castPromise);
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}
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} finally {
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if (promise.isDone()) {
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resolveMap.remove(inetHost);
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} else {
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promise.asFuture().addListener(f -> resolveMap.remove(inetHost));
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}
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}
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}
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return promise.asFuture();
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}
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private static <T> void transferResult(Future<? extends T> src, Promise<T> dst) {
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if (src.isSuccess()) {
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dst.trySuccess(src.getNow());
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} else {
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dst.tryFailure(src.cause());
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}
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}
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@Override
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public String toString() {
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return StringUtil.simpleClassName(this) + '(' + delegate + ')';
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}
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}
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