org.apache.dubbo.rpc.FutureContext Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.dubbo.rpc;
import org.apache.dubbo.common.constants.CommonConstants;
import org.apache.dubbo.common.threadlocal.InternalThreadLocal;
import org.apache.dubbo.rpc.protocol.dubbo.FutureAdapter;
import java.util.concurrent.CompletableFuture;
/**
* Used for async call scenario. But if the method you are calling has a {@link CompletableFuture} signature
* you do not need to use this class since you will get a Future response directly.
*
* Remember to save the Future reference before making another call using the same thread, otherwise,
* the current Future will be override by the new one, which means you will lose the chance get the return value.
*/
public class FutureContext {
private static InternalThreadLocal futureTL = new InternalThreadLocal() {
@Override
protected FutureContext initialValue() {
return new FutureContext();
}
};
public static FutureContext getContext() {
return futureTL.get();
}
private CompletableFuture future;
private CompletableFuture compatibleFuture;
/**
* Whether clear future once get
*/
private final static boolean clearFutureAfterGet = Boolean.parseBoolean(System.getProperty(CommonConstants.CLEAR_FUTURE_AFTER_GET, "false"));
/**
* get future.
*
* @param
* @return future
*/
@SuppressWarnings("unchecked")
public CompletableFuture getCompletableFuture() {
try {
return (CompletableFuture) future;
} finally {
if (clearFutureAfterGet) {
this.future = null;
}
}
}
/**
* set future.
*
* @param future
*/
public void setFuture(CompletableFuture future) {
this.future = future;
}
@Deprecated
@SuppressWarnings("unchecked")
public CompletableFuture getCompatibleCompletableFuture() {
try {
return (CompletableFuture) compatibleFuture;
} finally {
if (clearFutureAfterGet) {
this.compatibleFuture = null;
}
}
}
/**
* Guarantee 'using org.apache.dubbo.rpc.RpcContext.getFuture() before proxy returns' can work, a typical scenario is:
* {@code
* public final class TracingFilter implements Filter {
* public Result invoke(Invoker invoker, Invocation invocation) throws RpcException {
* Result result = invoker.invoke(invocation);
* Future
*
* Start from 2.7.3, you don't have to get Future from RpcContext, we recommend using Result directly:
* {@code
* public final class TracingFilter implements Filter {
* public Result invoke(Invoker invoker, Invocation invocation) throws RpcException {
* Result result = invoker.invoke(invocation);
* result.getResponseFuture().whenComplete(new FinishSpanCallback(span));
* ......
* }
* }
* }
*
*/
@Deprecated
public void setCompatibleFuture(CompletableFuture compatibleFuture) {
this.compatibleFuture = compatibleFuture;
if (compatibleFuture != null) {
this.setFuture(new FutureAdapter(compatibleFuture));
}
}
}