What it does

This library uses Jersey 1, Metrics and Guice to simplify gathering performance metrics for your JAX-RS resource methods.

If you have a resource class like this:

@Path("whatever")
public class SomeResource {
    @GET
    public String get() {
        return "some data";
    }
}

then by using this library you will get a Timer metric generated for the get() method, as well as Counters for each status code returned by get(). In this case, get() only returns 200, so you would have one counter for status code 200.

Installation

The first step is to add this library's module and its prerequisites.

• ResourceMethodMetricsModule is the module for this library.
• ResourceMethodWrappedDispatchModule is needed so that method invocation times can be captured without resorting to thread locals or other such unpleasantness.
• ConfigModuleBuilder is used to assemble the config sources for config-inject. If you just want the defaults used, you need not provide any config sources, so you can just call build() as shown. See JerseyMetricsConfig for more.
• We also bind a MetricRegistry instance. The binding uses a binding annotation because it's impolite for a library to insist on an un-qualified binding of a common type like MetricRegistry. This MetricRegistry instance is what will be used to house all metrics generated by the library.

// in your Guice module
@Override
protected void configure() {
    install(new ResourceMethodMetricsModule());

    // required for resource method metrics
    install(new ResourceMethodWrappedDispatchModule());
    install(new ConfigModuleBuilder().build());

    MetricRegistry registry = new MetricRegistry();
    bind(MetricRegistry.class).annotatedWith(JerseyResourceMetrics.class).toInstance(registry);

    ...

Next, you'll want to make sure you're providing init params to the GuiceContainer servlet that provides Jersey/Guice integration so that http status codes can be captured. HttpStatusCodeCounterResourceFilterFactory registers a Jersey container response filter that feeds outgoing HTTP status codes to the appropriate counters.

// in your Guice module
...
final Map<String, String> initParams = new HashMap<>();
initParams.put(ResourceConfig.PROPERTY_RESOURCE_FILTER_FACTORIES,
    HttpStatusCodeCounterResourceFilterFactory.class.getCanonicalName());

install(new ServletModule() {
    @Override
    protected void configureServlets() {
        serve("/*").with(GuiceContainer.class, initParams);
    }
}
...
});

Configuration

At this point, you should now be getting metrics generated for every resource method. If you want to use annotations to have more control, you can use @ResourceMetrics to turn both timing and status code counters off and on for a class or method. In this case below, the method would end up having a timer metric but no status code counters.

@Path("somewhere")
@ResourceMetrics(statusCodeCounter = true, timer = false)
public class EnabledOnClassDisabledOnMethod {
    // method annotation overrides class annotation
    @GET
    @ResourceMetrics(statusCodeCounter = false, timer = true)
    public String get() {
        return "ok";
    }
}

You can also make it so that the default is to not create metrics for un-annotated classes and methods by setting the properties used in JerseyMetricsConfig. You can do this via the ConfigModuleBuilder's config stack. Here, we'll use a simple in-code Map to define properties.

Map<String, Object> config = new HashMap<>();
config.put("com.palominolabs.jersey.metrics.resourceMethod.timer.enabledByDefault", "false");

ConfigModuleBuilder builder = new ConfigModuleBuilder();
// read from a map
builder.addConfiguration(new MapConfiguration(config));