package com.tinkerpop.rexster.kibbles.sample;
import com.codahale.metrics.Counter;
import com.codahale.metrics.MetricRegistry;
import com.tinkerpop.rexster.RexsterResourceContext;
import com.tinkerpop.rexster.extension.ExtensionDefinition;
import com.tinkerpop.rexster.extension.ExtensionDescriptor;
import com.tinkerpop.rexster.extension.ExtensionNaming;
import com.tinkerpop.rexster.extension.ExtensionPoint;
import com.tinkerpop.rexster.extension.ExtensionResponse;
import com.tinkerpop.rexster.extension.RexsterContext;
/**
* An extension that shows how to register custom metrics to extensions to expose via reporters.
*
* Rexster utilizes "Metrics":http://metrics.codahale.com/ for gathering and reporting measurements on internal
* activity. Rexster already tracks and reports many measurements on its internal operations and extension activity
* can be generally measured through existing REST metrics. For a greater level of control and flexibility, as
* well as a finer degree of granularity to measurements within a specific extension, there are options to
* register new metrics within the extension itself.
*
* To try this extension after deployment of the samples to the packaged "emtpygraph", resolve this url:
*
* http://localhost:8182/graphs/emptygraph/tp-sample/metric
*
* and then view the reported metrics by going here:
*
* http://localhost:8182/metrics
*
* This url will resolve to a JSON file that contains a key for "counters" that looks something like this:
*
* counters: { http.rest.extension.sample.counter: { count: 3 } }
*/
@ExtensionNaming(namespace = AbstractSampleExtension.EXTENSION_NAMESPACE, name = MetricExtension.EXTENSION_NAME)
public class MetricExtension extends AbstractSampleExtension {
public static final String EXTENSION_NAME = "metric";
@ExtensionDefinition(extensionPoint = ExtensionPoint.GRAPH)
@ExtensionDescriptor(description = "a counter extension.")
public ExtensionResponse evaluateCounter(@RexsterContext RexsterResourceContext context) {
// get or create a sample counter metric
final Counter counter = context.getMetricRegistry().counter(
MetricRegistry.name("http", "rest", "extension", "sample", "counter"));
// increment the counter for each request.
counter.inc();
return ExtensionResponse.noContent();
}
}