SpringBoot Undertow :如何调度到工作线程

Question

我目前正在查看 Springboot 暗流，并且(对我来说(不太清楚如何将传入的 HTTP 请求调度到工作线程以阻止操作处理。

查看 UndertowEmbeddedServletContainer.class 类，看起来没有办法有这种行为，因为唯一的 HttpHandler 是一个 ServletHandler，它允许@Controller配置

private Undertow createUndertowServer() {
    try {
        HttpHandler servletHandler = this.manager.start();
        this.builder.setHandler(getContextHandler(servletHandler));
        return this.builder.build();
    }
    catch (ServletException ex) {
        throw new EmbeddedServletContainerException(
                "Unable to start embdedded Undertow", ex);
    }
}
private HttpHandler getContextHandler(HttpHandler servletHandler) {
    if (StringUtils.isEmpty(this.contextPath)) {
        return servletHandler;
    }
    return Handlers.path().addPrefixPath(this.contextPath, servletHandler);
}

默认情况下，在 undertow 中，所有请求都由 IO-Thread 处理，以实现非阻塞操作。这是否意味着每个@Controller执行都将由非阻塞线程处理？或者有没有解决方案可以从IO线程或工作线程中选择？

我尝试编写一个解决方法，但这段代码非常丑陋，也许有人有更好的解决方案：

阻塞处理程序.class

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface BlockingHandler {
    String contextPath() default "/";
}

UndertowInitializer.class

public class UndertowInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
    @Override
    public void initialize(ConfigurableApplicationContext configurableApplicationContext) {
        configurableApplicationContext.addBeanFactoryPostProcessor(new UndertowHandlerPostProcessor());
    }
}

UndertowHandlerPostProcessor.class

public class UndertowHandlerPostProcessor implements BeanDefinitionRegistryPostProcessor {

    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) throws BeansException {
        ClassPathScanningCandidateComponentProvider scanner = new ClassPathScanningCandidateComponentProvider(false);
        scanner.addIncludeFilter(new AnnotationTypeFilter(BlockingHandler.class));
        for (BeanDefinition beanDefinition : scanner.findCandidateComponents("org.me.lah")){
            try{
                Class clazz = Class.forName(beanDefinition.getBeanClassName());
                beanDefinitionRegistry.registerBeanDefinition(clazz.getSimpleName(), beanDefinition);
            } catch (ClassNotFoundException e) {
                throw new BeanCreationException(format("Unable to create bean %s", beanDefinition.getBeanClassName()), e);
            }
        }
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {
        //no need to post process defined bean
    }
}

override UndertowEmbeddedServletContainerFactory.class

public class UndertowEmbeddedServletContainerFactory extends  AbstractEmbeddedServletContainerFactory implements ResourceLoaderAware, ApplicationContextAware {
    private ApplicationContext applicationContext;
    @Override
    public EmbeddedServletContainer getEmbeddedServletContainer(ServletContextInitializer... initializers) {
        DeploymentManager manager = createDeploymentManager(initializers);
        int port = getPort();
        if (port == 0) {
            port = SocketUtils.findAvailableTcpPort(40000);
        }
        Undertow.Builder builder = createBuilder(port);
        Map<String, Object> handlers = applicationContext.getBeansWithAnnotation(BlockingHandler.class);
        return new UndertowEmbeddedServletContainer(builder, manager, getContextPath(),
            port, port >= 0, handlers);
    }
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
}
...

override UndertowEmbeddedServletContainer.class

public UndertowEmbeddedServletContainer(Builder builder, DeploymentManager manager,
                                        String contextPath, int port, boolean autoStart, Map<String, Object> handlers) {
    this.builder = builder;
    this.manager = manager;
    this.contextPath = contextPath;
    this.port = port;
    this.autoStart = autoStart;
    this.handlers = handlers;
}
private Undertow createUndertowServer() {
    try {
        HttpHandler servletHandler = this.manager.start();
        String path = this.contextPath.isEmpty() ? "/" : this.contextPath;
        PathHandler pathHandler = Handlers.path().addPrefixPath(path, servletHandler);
        for(Entry<String, Object> entry : handlers.entrySet()){
            Annotation annotation = entry.getValue().getClass().getDeclaredAnnotation(BlockingHandler.class);
            System.out.println(((BlockingHandler) annotation).contextPath());
            pathHandler.addPrefixPath(((BlockingHandler) annotation).contextPath(), (HttpHandler) entry.getValue());
        }
        this.builder.setHandler(pathHandler);
        return this.builder.build();
    }
    catch (ServletException ex) {
        throw new EmbeddedServletContainerException(
                "Unable to start embdedded Undertow", ex);
    }
}

将初始值设定项设置为应用程序上下文

public static void main(String[] args) {
    new SpringApplicationBuilder(Application.class).initializers(new UndertowInitializer()).run(args);
}

finaly 创建一个调度到工作线程的 HttpHandler

@BlockingHandler(contextPath = "/blocking/test")
public class DatabaseHandler implements HttpHandler {
    @Autowired
    private EchoService echoService;
    @Override
    public void handleRequest(HttpServerExchange httpServerExchange) throws Exception {
        if(httpServerExchange.isInIoThread()){
            httpServerExchange.dispatch();
        }
        echoService.getMessage("my message");
    }

}

如您所见，我的"解决方案"真的很重，我非常感谢任何帮助来简化它。

谢谢

Answer 1

你不需要做任何事情。

Spring Boot 的默认 Undertow

配置在 Spring MVC 的DispatcherServlet前面使用 Undertow 的ServletInitialHandler。此处理程序执行exchange.isInIoThread()检查，并在必要时调用dispatch()。

如果在@Controller中放置断点，您将看到它是在名为 XNIO-1 task-n 的线程上调用的，该线程是工作线程(IO 线程名为 XNIO-1 I/O-n (。