/*
* 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 com.google.inject.AbstractModule;
import com.google.inject.Singleton;
import com.netflix.hystrix.strategy.HystrixPlugins;
import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy;
import ratpack.hystrix.internal.*;
/**
* An extension module that provides support for <a href="https://github.com/Netflix/Hystrix/wiki">Hystrix</a>.
* <p>
* To use it one has to register the module.
* <p>
* By default the module registers a {@link com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy}
* with Hystrix that provides a {@link ratpack.registry.Registry} backed strategy for caching {@link com.netflix.hystrix.strategy.concurrency.HystrixRequestVariable}
* during a {@link ratpack.http.Request}. This means that Hystrix will use Ratpack's Request Registry for request caching, request collapsing and request log.
* <p>
* To enable the streaming of Hystrix metrics in text/event-stream format use the {@link #sse()} configuration option.
* For example: (Groovy DSL)
* <pre class="groovy-ratpack-dsl">
* import ratpack.hystrix.HystrixModule
* import static ratpack.groovy.Groovy.ratpack
*
* ratpack {
* bindings {
* add new HystrixModule().sse()
* }
* }
* </pre>
* <p>
* This allows 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
* {@link ratpack.hystrix.HystrixMetricsEventStreamHandler} for more details.
*
* @see <a href="https://github.com/Netflix/Hystrix/wiki" target="_blank">Hystrix</a>
* @see <a href="https://github.com/Netflix/Hystrix/wiki/Plugins#concurrency-strategy" target="_blank">Hystrix Plugins - Concurrency Strategy</a>
* @see <a href="https://github.com/Netflix/Hystrix/wiki/How-To-Use#request-cache" target="_blank">Hystrix - Request Cache</a>
* @see <a href="https://github.com/Netflix/Hystrix/wiki/How-To-Use#request-collapsing" target="_blank">Hystrix - Request Collapsing</a>
*/
public class HystrixModule extends AbstractModule {
private boolean reportMetricsToSse;
@Override
protected void configure() {
try {
HystrixPlugins.getInstance().registerConcurrencyStrategy(new HystrixRegistryBackedConcurrencyStrategy());
} catch (IllegalStateException e) {
HystrixConcurrencyStrategy existingStrategy = HystrixPlugins.getInstance().getConcurrencyStrategy();
if (!(existingStrategy instanceof HystrixRegistryBackedConcurrencyStrategy)) {
throw new IllegalStateException("Cannot install Hystrix integration because another concurrency strategy (" + existingStrategy.getClass() + ") is already installed");
}
}
if (reportMetricsToSse) {
bind(HystrixCommandMetricsPeriodicPublisher.class).in(Singleton.class);
bind(HystrixCommandMetricsBroadcaster.class).in(Singleton.class);
bind(HystrixCommandMetricsJsonMapper.class).in(Singleton.class);
bind(HystrixThreadPoolMetricsPeriodicPublisher.class).in(Singleton.class);
bind(HystrixThreadPoolMetricsBroadcaster.class).in(Singleton.class);
bind(HystrixThreadPoolMetricsJsonMapper.class).in(Singleton.class);
}
}
/**
* Enable the reporting of Hystrix metrics via SSE.
* <p>
* To stream metrics within an application see {@link HystrixMetricsEventStreamHandler}.
*
* @return this {@code HystrixModule}
*/
public HystrixModule sse() {
this.reportMetricsToSse = true;
return this;
}
}