Question

我认为此问题与Server sent event with Jersey: EventOutput is not closed after client drops不重复，但可能与Jersey Server-Sent Events - write to broken connection does not throw exception有关。

在泽西文档的chapter 15.4.2中，描述了SseBroadcaster：

但是，SseBroadcaster在内部识别并处理客户端断开连接。当客户端关闭连接时，广播公司会检测到这种情况，并从已注册的EventOutputs的内部集合中删除过时的连接，并释放与过时连接相关的所有服务器端资源。

我无法证实这一点。在下面的测试用例中，我看到永远不会调用子类SseBroadcaster的{{1}}方法：当onClose()关闭时，而不是在广播另一条消息时。

EventInput

也许public class NotificationsResourceTest extends JerseyTest { final static Logger log = LoggerFactory.getLogger(NotificationsResourceTest.class); final static CountingSseBroadcaster broadcaster = new CountingSseBroadcaster(); public static class CountingSseBroadcaster extends SseBroadcaster { final AtomicInteger connectionCounter = new AtomicInteger(0); public EventOutput createAndAttachEventOutput() { EventOutput output = new EventOutput(); if (add(output)) { int cons = connectionCounter.incrementAndGet(); log.debug("Active connection count: "+ cons); } return output; } @Override public void onClose(final ChunkedOutput<OutboundEvent> output) { int cons = connectionCounter.decrementAndGet(); log.debug("A connection has been closed. Active connection count: "+ cons); } @Override public void onException(final ChunkedOutput<OutboundEvent> chunkedOutput, final Exception exception) { log.trace("An exception has been detected", exception); } public int getConnectionCount() { return connectionCounter.get(); } } @Path("notifications") public static class NotificationsResource { @GET @Produces(SseFeature.SERVER_SENT_EVENTS) public EventOutput subscribe() { log.debug("New stream subscription"); EventOutput eventOutput = broadcaster.createAndAttachEventOutput(); return eventOutput; } } @Override protected Application configure() { ResourceConfig config = new ResourceConfig(NotificationsResource.class); config.register(SseFeature.class); return config; } @Test public void test() throws Exception { // check that there are no connections assertEquals(0, broadcaster.getConnectionCount()); // connect subscriber log.info("Connecting subscriber"); EventInput eventInput = target("notifications").request().get(EventInput.class); assertFalse(eventInput.isClosed()); // now there are connections assertEquals(1, broadcaster.getConnectionCount()); // push data log.info("Broadcasting data"); String payload = UUID.randomUUID().toString(); OutboundEvent chunk = new OutboundEvent.Builder() .mediaType(MediaType.TEXT_PLAIN_TYPE) .name("message") .data(payload) .build(); broadcaster.broadcast(chunk); // read data log.info("Reading data"); InboundEvent inboundEvent = eventInput.read(); assertNotNull(inboundEvent); assertEquals(payload, inboundEvent.readData()); // close subscription log.info("Closing subscription"); eventInput.close(); assertTrue(eventInput.isClosed()); // at this point, the subscriber has disconnected itself, // but jersey doesnt realise that assertEquals(1, broadcaster.getConnectionCount()); // wait, give TCP a chance to close the connection log.debug("Sleeping for some time"); Thread.sleep(10000); // push data again, this should really flush out the not-connected client log.info("Broadcasting data again"); broadcaster.broadcast(chunk); Thread.sleep(100); // there is no subscriber anymore assertEquals(0, broadcaster.getConnectionCount()); // FAILS! } }不是测试它的好方法。在使用JavaScript JerseyTest的较少临床设置中，我看到EventSource被调用，但仅在先前关闭的连接上广播消息之后。

我做错了什么？

为什么没有onClose()检测到客户端关闭连接？

后续

我发现JERSEY-2833已被 Works设计拒绝了：

根据15.4.1中SSE章节（https://jersey.java.net/documentation/latest/sse.html）中的泽西岛文档，它提到泽西岛没有明确关闭连接，它是资源方法或者资源方法的责任。客户端。

这究竟是什么意思？资源是否应该执行超时并终止所有活动和已关闭的客户端连接？

Answer 1

在构造函数org.glassfish.jersey.media.sse.SseBroadcaster.SseBroadcaster()的文档中，它说：

创建一个新实例。如果此子构造函数由子类调用，则它假定子类存在的原因是实现onClose(org.glassfish.jersey.server.ChunkedOutput)和onException(org.glassfish.jersey.server.ChunkedOutput, Exception)方法，因此它将新创建的实例添加为侦听器。为了避免这种情况，子类可以调用SseBroadcaster(Class)将它们的类作为参数传递。

因此，您不应该保留默认构造函数，并尝试使用您的类实现构造函数调用super：

public CountingSseBroadcaster(){
    super(CountingSseBroadcaster.class);
}

Answer 2

我认为在资源上设置超时并仅杀死该连接可能会更好，例如：

@Path("notifications")
public static class NotificationsResource {

    @GET
    @Produces(SseFeature.SERVER_SENT_EVENTS)
    public EventOutput subscribe() {
        log.debug("New stream subscription");

        EventOutput eventOutput = broadcaster.createAndAttachEventOutput();
        new Timer().schedule( new TimerTask()
        {
            @Override public void run()
            {
               eventOutput.close()
            }
        }, 10000); // 10 second timeout
        return eventOutput;
    }
}

Answer 3

我想知道通过子类化你是否可能改变了行为。

    @Override
    public void onClose(final ChunkedOutput<OutboundEvent> output) {
        int cons = connectionCounter.decrementAndGet();
        log.debug("A connection has been closed. Active connection count: "+ cons);
    }

在此，您不要关闭ChunkedOutput，以免它释放连接。这可能是问题吗？

使用Jersey SSE进行广播：检测已关闭的连接

3 个答案: