取消使用WebFlux

时间：2018-03-20 11:19:21

标签： java project-reactor spring-webflux

首先，完整运行的代码示例（客户端和服务器）可在此处获取：https://github.com/kklepacz/webflux-cancel-subscription

案例描述：

我有遗留系统生成数据（我在我的github示例中用SampleEmitter模拟它。我可以提供监听器，当新数据到达时它会被通知。我想“翻译”这些监听器调用数据流。这个流需要是无限的（只要系统工作就会有新的值）。准确地说，它也需要是热源（遵循Reactor项目术语）所以每当有人将订阅，他将只收到当前值。

这里的翻译方式如下：

class ReactiveRepoImpl implements ReactiveRepo {
private static final Logger log = LoggerFactory.getLogger(ReactiveRepoImpl.class);
private final UnicastProcessor<MyObject> hotProcessor = UnicastProcessor.create();
private final FluxSink<MyObject> fluxSink = hotProcessor.sink(FluxSink.OverflowStrategy.LATEST);
private final Flux<MyObject> hotFlux = hotProcessor.publish().autoConnect();

@Override
public void save(MyObject elem) {
    fluxSink.next(elem);
}

@Override
public Flux<MyObject> findAll() {
    return hotFlux;
}
}

所以此时我可以通过RouterFunctions这样公开它：

@Bean
public RouterFunction routerFunction(ReactiveRepo repo) {
    return RouterFunctions.route(GET("/objects"), serverRequest -> {
        log.info("Subscribing for GET /objects");
        return ok()
                .contentType(MediaType.TEXT_EVENT_STREAM)
                .body(repo.findAll(), MyObject.class);
    });
}

正如您所看到的，我在这里制作服务器端事件。

现在让我们消费它：

 WebClient.create("http://localhost:8080")
                .get()
                .uri("/objects")
                .retrieve()
                .bodyToFlux(MyObject.class)
                .subscribe(n -> log.info("Next: {}", n.getId()),
                        e -> log.error("Error: {}", e),
                        () -> log.info("Completed"));

问题是： 当我要杀死客户端或致电Disposable.dispose()时，我在服务器应用程序中收到以下错误：

2018-03-20 12:00:50.926 ERROR 11944 --- [ctor-http-nio-2] o.s.w.s.adapter.HttpWebHandlerAdapter    : Unhandled failure: An established connection was aborted by the software in your host machine, response already set (status=200)
2018-03-20 12:00:50.941 ERROR 11944 --- [ctor-http-nio-2] o.s.h.s.r.ReactorHttpHandlerAdapter      : Handling completed with error

java.io.IOException: An established connection was aborted by the software in your host machine
at sun.nio.ch.SocketDispatcher.writev0(Native Method) ~[na:1.8.0_144]
at sun.nio.ch.SocketDispatcher.writev(SocketDispatcher.java:55) ~[na:1.8.0_144]
at sun.nio.ch.IOUtil.write(IOUtil.java:148) ~[na:1.8.0_144]
at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:504) ~[na:1.8.0_144]
at io.netty.channel.socket.nio.NioSocketChannel.doWrite(NioSocketChannel.java:418) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannel$AbstractUnsafe.flush0(AbstractChannel.java:934) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.flush0(AbstractNioChannel.java:360) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannel$AbstractUnsafe.flush(AbstractChannel.java:901) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.DefaultChannelPipeline$HeadContext.flush(DefaultChannelPipeline.java:1376) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:776) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:768) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:749) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.flush(CombinedChannelDuplexHandler.java:533) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.ChannelOutboundHandlerAdapter.flush(ChannelOutboundHandlerAdapter.java:115) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.CombinedChannelDuplexHandler.flush(CombinedChannelDuplexHandler.java:358) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:776) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:768) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:749) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.ChannelDuplexHandler.flush(ChannelDuplexHandler.java:117) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:776) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:768) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:749) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at reactor.ipc.netty.channel.ChannelOperationsHandler$PublisherSender.onComplete(ChannelOperationsHandler.java:535) ~[reactor-netty-0.7.5.RELEASE.jar:0.7.5.RELEASE]
at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onComplete(FluxContextStart.java:122) ~[reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.FluxMap$MapConditionalSubscriber.onComplete(FluxMap.java:245) ~[reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onComplete(FluxConcatArray.java:184) ~[reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.FluxConcatArray.subscribe(FluxConcatArray.java:80) ~[reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.FluxMap.subscribe(FluxMap.java:59) ~[reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.FluxContextStart.subscribe(FluxContextStart.java:49) ~[reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.Flux.subscribe(Flux.java:6873) ~[reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.ipc.netty.channel.ChannelOperationsHandler.drain(ChannelOperationsHandler.java:461) ~[reactor-netty-0.7.5.RELEASE.jar:0.7.5.RELEASE]
at reactor.ipc.netty.channel.ChannelOperationsHandler.flush(ChannelOperationsHandler.java:191) ~[reactor-netty-0.7.5.RELEASE.jar:0.7.5.RELEASE]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:776) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:768) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.access$1500(AbstractChannelHandlerContext.java:38) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext$WriteAndFlushTask.write(AbstractChannelHandlerContext.java:1129) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.run(AbstractChannelHandlerContext.java:1070) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163) ~[netty-common-4.1.22.Final.jar:4.1.22.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404) ~[netty-common-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:463) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:886) ~[netty-common-4.1.22.Final.jar:4.1.22.Final]
at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_144]

2018-03-20 12:00:50.957 ERROR 11944 --- [ctor-http-nio-2] r.ipc.netty.channel.ChannelOperations    : [HttpServer] Error processing connection. Requesting close the channel

java.io.IOException: An established connection was aborted by the software in your host machine
at sun.nio.ch.SocketDispatcher.writev0(Native Method) ~[na:1.8.0_144]
at sun.nio.ch.SocketDispatcher.writev(SocketDispatcher.java:55) ~[na:1.8.0_144]
at sun.nio.ch.IOUtil.write(IOUtil.java:148) ~[na:1.8.0_144]
at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:504) ~[na:1.8.0_144]
at io.netty.channel.socket.nio.NioSocketChannel.doWrite(NioSocketChannel.java:418) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannel$AbstractUnsafe.flush0(AbstractChannel.java:934) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.flush0(AbstractNioChannel.java:360) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannel$AbstractUnsafe.flush(AbstractChannel.java:901) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.DefaultChannelPipeline$HeadContext.flush(DefaultChannelPipeline.java:1376) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:776) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:768) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:749) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.flush(CombinedChannelDuplexHandler.java:533) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.ChannelOutboundHandlerAdapter.flush(ChannelOutboundHandlerAdapter.java:115) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.CombinedChannelDuplexHandler.flush(CombinedChannelDuplexHandler.java:358) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:776) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:768) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:749) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.ChannelDuplexHandler.flush(ChannelDuplexHandler.java:117) ~[netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:776) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:768) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:749) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at reactor.ipc.netty.channel.ChannelOperationsHandler$PublisherSender.onComplete(ChannelOperationsHandler.java:535) ~[reactor-netty-0.7.5.RELEASE.jar:0.7.5.RELEASE]
at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onComplete(FluxContextStart.java:122) [reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.FluxMap$MapConditionalSubscriber.onComplete(FluxMap.java:245) [reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onComplete(FluxConcatArray.java:184) [reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.FluxConcatArray.subscribe(FluxConcatArray.java:80) [reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.FluxMap.subscribe(FluxMap.java:59) [reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.FluxContextStart.subscribe(FluxContextStart.java:49) [reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.core.publisher.Flux.subscribe(Flux.java:6873) [reactor-core-3.1.5.RELEASE.jar:3.1.5.RELEASE]
at reactor.ipc.netty.channel.ChannelOperationsHandler.drain(ChannelOperationsHandler.java:461) [reactor-netty-0.7.5.RELEASE.jar:0.7.5.RELEASE]
at reactor.ipc.netty.channel.ChannelOperationsHandler.flush(ChannelOperationsHandler.java:191) [reactor-netty-0.7.5.RELEASE.jar:0.7.5.RELEASE]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:776) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:768) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext.access$1500(AbstractChannelHandlerContext.java:38) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext$WriteAndFlushTask.write(AbstractChannelHandlerContext.java:1129) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.run(AbstractChannelHandlerContext.java:1070) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163) [netty-common-4.1.22.Final.jar:4.1.22.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404) [netty-common-4.1.22.Final.jar:4.1.22.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:463) [netty-transport-4.1.22.Final.jar:4.1.22.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:886) [netty-common-4.1.22.Final.jar:4.1.22.Final]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_144]

我该如何避免它？创建此类热源流并正确处理多个客户端断开连接/流取消和连接/订阅的正确方法是什么？

为了全面了解为什么我需要这样的功能 - 我有一个带标签的Web应用程序。在一个选项卡上，我显示从我的服务器收到的所有数据当我切换标签时，我不希望我的流继续，我想在我回到此标签时再取消订阅并再次订阅。

1 个答案:

答案 0 :(得分：1)

<强> TLDR;

dispose()是取消订阅流的正确方法。

完整答案：

我无法通过互联网找到答案，所以我问过来源 - Spring团队。 这是我创建的JIRA：https://jira.spring.io/browse/SPR-16688

因此，根据那里的评论，上面的stacktrace是在使用Undertow，Tomcat和Netty时未涵盖Windows环境特定异常的结果。它们不应该出现在Linux / Unix上或使用Jetty时。 Spring团队将在下一版本中对此进行微调 - 根据JIRA，可能会5.0.6和/或5.1 RC1。

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