hystrix源码小贴士之之hystrix-metrics-event-stream
2024-10-09 18:05:26
hystrix-metrics-event-stream主要提供了一些servlet，可以让用户通过http请求获取metrics信息。
HystrixSampleSseServlet
继承了HttpServlet，不断从sampleStream中读取值并返回，直到sampleStream发送complete或出现异常。
private void handleRequest(HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException {
...
sampleSubscription = sampleStream
.observeOn(Schedulers.io())
.subscribe(new Subscriber<String>() {
@Override
public void onCompleted() {
logger.error("HystrixSampleSseServlet: ({}) received unexpected OnCompleted from sample stream", getClass().getSimpleName());
moreDataWillBeSent.set(false);
}
@Override
public void onError(Throwable e) {
moreDataWillBeSent.set(false);
}
@Override
public void onNext(String sampleDataAsString) {
if (sampleDataAsString != null) {
try {
writer.print("data: " + sampleDataAsString + "\n\n");
// explicitly check for client disconnect - PrintWriter does not throw exceptions
if (writer.checkError()) {
moreDataWillBeSent.set(false);
}
writer.flush();
} catch (Exception ex) {
moreDataWillBeSent.set(false);
}
}
}
});
while (moreDataWillBeSent.get() && !isDestroyed) {
try {
Thread.sleep(pausePollerThreadDelayInMs);
//in case stream has not started emitting yet, catch any clients which connect/disconnect before emits start
writer.print("ping: \n\n");
// explicitly check for client disconnect - PrintWriter does not throw exceptions
if (writer.checkError()) {
moreDataWillBeSent.set(false);
}
writer.flush();
} catch (Exception ex) {
moreDataWillBeSent.set(false);
}
}
}
} finally {
decrementCurrentConcurrentConnections();
if (sampleSubscription != null && !sampleSubscription.isUnsubscribed()) {
sampleSubscription.unsubscribe();
}
}
}
HystrixConfigSseServlet
继承HystrixSampleSseServlet，读取HystrixConfigurationStream流数据。
public HystrixConfigSseServlet() {
this(HystrixConfigurationStream.getInstance().observe(), DEFAULT_PAUSE_POLLER_THREAD_DELAY_IN_MS);
}
/* package-private */ HystrixConfigSseServlet(Observable<HystrixConfiguration> sampleStream, int pausePollerThreadDelayInMs) {
super(sampleStream.map(new Func1<HystrixConfiguration, String>() {
@Override
public String call(HystrixConfiguration hystrixConfiguration) {
return SerialHystrixConfiguration.toJsonString(hystrixConfiguration);
}
}), pausePollerThreadDelayInMs);
}
HystrixMetricsStreamServlet
继承HystrixSampleSseServlet，读取HystrixDashboardStream流数据。
public HystrixMetricsStreamServlet() {
this(HystrixDashboardStream.getInstance().observe(), DEFAULT_PAUSE_POLLER_THREAD_DELAY_IN_MS);
}
/* package-private */ HystrixMetricsStreamServlet(Observable<HystrixDashboardStream.DashboardData> sampleStream, int pausePollerThreadDelayInMs) {
super(sampleStream.concatMap(new Func1<HystrixDashboardStream.DashboardData, Observable<String>>() {
@Override
public Observable<String> call(HystrixDashboardStream.DashboardData dashboardData) {
return Observable.from(SerialHystrixDashboardData.toMultipleJsonStrings(dashboardData));
}
}), pausePollerThreadDelayInMs);
}
HystrixRequestEventsSseServlet
继承HystrixSampleSseServlet，读取HystrixRequestEventsStream流数据。
public HystrixRequestEventsSseServlet() {
this(HystrixRequestEventsStream.getInstance().observe(), DEFAULT_PAUSE_POLLER_THREAD_DELAY_IN_MS);
}
/* package-private */ HystrixRequestEventsSseServlet(Observable<HystrixRequestEvents> sampleStream, int pausePollerThreadDelayInMs) {
super(sampleStream.map(new Func1<HystrixRequestEvents, String>() {
@Override
public String call(HystrixRequestEvents requestEvents) {
return SerialHystrixRequestEvents.toJsonString(requestEvents);
}
}), pausePollerThreadDelayInMs);
}
HystrixUtilizationSseServlet
继承HystrixSampleSseServlet，读取HystrixUtilizationStream流数据。
public HystrixUtilizationSseServlet() {
this(HystrixUtilizationStream.getInstance().observe(), DEFAULT_PAUSE_POLLER_THREAD_DELAY_IN_MS);
}
/* package-private */ HystrixUtilizationSseServlet(Observable<HystrixUtilization> sampleStream, int pausePollerThreadDelayInMs) {
super(sampleStream.map(new Func1<HystrixUtilization, String>() {
@Override
public String call(HystrixUtilization hystrixUtilization) {
return SerialHystrixUtilization.toJsonString(hystrixUtilization);
}
}), pausePollerThreadDelayInMs);
}
使用hystrix-metrics-event-stream
- 引入hystrix-metrics-event-stream-*.jar包
- 添加web.xml配置
<servlet>
<description></description>
<display-name>HystrixUtilizationSseServlet</display-name>
<servlet-name>HystrixUtilizationSseServlet</servlet-name>
<servlet-class>com.netflix.hystrix.contrib.sample.stream.HystrixUtilizationSseServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HystrixUtilizationSseServlet</servlet-name>
<url-pattern>/hystrix/utilization.stream</url-pattern>
</servlet-mapping>
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