/*
* The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
* (the "License"). You may not use this work except in compliance with the License, which is
* available at www.apache.org/licenses/LICENSE-2.0
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied, as more fully set forth in the License.
*
* See the NOTICE file distributed with this work for information regarding copyright ownership.
*/
package alluxio.metrics.sink;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.json.MetricsModule;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;
import java.io.IOException;
import java.util.Properties;
import java.util.concurrent.TimeUnit;
import javax.annotation.concurrent.NotThreadSafe;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* A sink that exposes metrics data in JSON format by HTTP.
*/
@NotThreadSafe
public class MetricsServlet implements Sink {
private static final String SERVLET_PATH = "/metrics/json";
private MetricRegistry mMetricsRegistry;
private ObjectMapper mObjectMapper;
/**
* Creates a new {@link MetricsServlet} with a {@link Properties} and {@link MetricRegistry}.
*
* @param registry the metric registry to register
*/
public MetricsServlet(MetricRegistry registry) {
mMetricsRegistry = registry;
mObjectMapper =
new ObjectMapper().registerModule(new MetricsModule(TimeUnit.SECONDS,
TimeUnit.MILLISECONDS, false));
}
private HttpServlet createServlet() {
return new HttpServlet() {
private static final long serialVersionUID = -2761243531478788172L;
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/json;charset=utf-8");
response.setStatus(HttpServletResponse.SC_OK);
response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate");
String result = mObjectMapper.writeValueAsString(mMetricsRegistry);
response.getWriter().println(result);
}
};
}
/**
* Gets the {@link ServletContextHandler} of the metrics servlet.
*
* @return the {@link ServletContextHandler} object
*/
public ServletContextHandler getHandler() {
ServletContextHandler contextHandler = new ServletContextHandler();
contextHandler.setContextPath(SERVLET_PATH);
contextHandler.addServlet(new ServletHolder(createServlet()), "/");
return contextHandler;
}
@Override
public void start() {}
@Override
public void stop() {}
@Override
public void report() {}
}