/*
* Copyright 2014 the original author or authors.
*
* Licensed 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 ratpack.hystrix;
import org.reactivestreams.Publisher;
import ratpack.handling.Context;
import ratpack.handling.Handler;
import ratpack.hystrix.internal.HystrixCommandMetricsBroadcaster;
import ratpack.hystrix.internal.HystrixCommandMetricsJsonMapper;
import ratpack.hystrix.internal.HystrixThreadPoolMetricsBroadcaster;
import ratpack.hystrix.internal.HystrixThreadPoolMetricsJsonMapper;
import static ratpack.sse.ServerSentEvents.serverSentEvents;
import static ratpack.stream.Streams.*;
/**
* A Handler that streams Hystrix metrics in text/event-stream format.
* <p>
* This handler should be bound to an application path, and most likely only for the GET method…
* <pre class="java-chain-dsl">
* import ratpack.hystrix.HystrixMetricsEventStreamHandler;
*
* chain instanceof ratpack.handling.Chain;
* chain.get("admin/hystrix.stream", new HystrixMetricsEventStreamHandler());
* </pre>
* <p>
* This handler can be used in conjunction with Server Sent Event based clients such as the
* <a href="https://github.com/Netflix/Hystrix/wiki/Dashboard">Hystrix Dashboard</a> and
* <a href="https://github.com/Netflix/Turbine/wiki">Turbine</a> to consume the metrics being reported by your
* application in realtime.
*
* @see <a href="https://github.com/Netflix/Hystrix/wiki" target="_blank">Hystrix</a>
* @see ratpack.sse.internal.ServerSentEventsRenderer
*/
public class HystrixMetricsEventStreamHandler implements Handler {
@Override
public void handle(Context context) throws Exception {
final HystrixCommandMetricsBroadcaster commandMetricsBroadcasterbroadcaster = context.get(HystrixCommandMetricsBroadcaster.class);
final HystrixCommandMetricsJsonMapper commandMetricsMapper = context.get(HystrixCommandMetricsJsonMapper.class);
final HystrixThreadPoolMetricsBroadcaster threadPoolMetricsBroadcaster = context.get(HystrixThreadPoolMetricsBroadcaster.class);
final HystrixThreadPoolMetricsJsonMapper threadPoolMetricsMapper = context.get(HystrixThreadPoolMetricsJsonMapper.class);
Publisher<String> commandStream = map(fanOut(commandMetricsBroadcasterbroadcaster), commandMetricsMapper);
Publisher<String> threadPoolStream = map(fanOut(threadPoolMetricsBroadcaster), threadPoolMetricsMapper);
@SuppressWarnings("unchecked") Publisher<String> metricsStream = merge(commandStream, threadPoolStream);
context.render(serverSentEvents(metricsStream, spec -> spec.data(spec.getItem())));
}
}