Quick Start

Get the artifacts

Artifacts are released in Bintray. For gradle, use the jcenter() repository. For maven, go here and click "Set me up".

Maven:

<dependency>
  <groupId>com.palominolabs.metrics</groupId>
  <artifactId>metrics-guice</artifactId>
  <version>[the latest version]</version>
</dependency>

Gradle:

compile 'com.palominolabs.metrics:metrics-guice:[the latest version]'

Install the Guice module

// somewhere in your Guice module setup
install(MetricsInstrumentationModule.builder().withRegistry(yourFavoriteMetricRegistry).build());

Use it

The MetricsInstrumentationModule you installed above will create and appropriately invoke a Timer for @Timed methods, a Meter for @Metered methods, a Counter for @Counted methods, and a Gauge for @Gauge methods. @ExceptionMetered is also supported; this creates a Meter that measures how often a method throws exceptions.

The annotations have some configuration options available for metric name, etc. You can also provide a custom MetricNamer implementation if the default name scheme does not work for you.

Type level annotations

By default MetricsInstrumentationModule will provide metrics only for annotated methods, it is possible to enable type level annotation checks to get metrics for all declared methods of the class. To enable type level checks, you should provide AnnotationMatcher. ClassAnnotationMatcher for matching class level annotations and MethodAnnotationMatcher for method level annotations are provided.

// somewhere in your Guice module setup
install(
    MetricsInstrumentationModule.builder()
        .withRegistry(yourFavoriteMetricRegistry)
        .withAnnotationMatcher(new ClassAnnotationMatcher())
        .withAnnotationMatcher(new MethodAnnotationMatcher())
        .build()
);

Metric namer

Custom metric namers can be applied by providing MetricNamer implementations. By default DefaultMetricNamer is used.

Example

If you have a method like this:

class SuperCriticalFunctionality {
    public void doSomethingImportant() {
        // critical business logic
    }
}

and you want to use a Timer to measure duration, etc, you could always do it by hand:

public void doSomethingImportant() {
    // timer is some Timer instance
    Timer.Context context = timer.time();
    try {
        // critical business logic
    } finally {
        context.stop();
    }
}

However, if you're instantiating that class with Guice, you could just do this:

@Timed
public void doSomethingImportant() {
    // critical business logic
}

Limitations

Since this uses Guice AOP, instances must be created by Guice; see the Guice wiki. This means that using a Provider where you create the instance won't work, or binding a singleton to an instance, etc.

Guice AOP doesn't allow us to intercept method calls to annotated methods in supertypes, so @Counted, etc, will not have metrics generated for them if they are in supertypes of the injectable class. One small consolation is that @Gauge methods can be anywhere in the type hierarchy since they work differently from the other metrics (the generated Gauge object invokes the java.lang.reflect.Method directly, so we can call the supertype method unambiguously).

History

This module started from the state of metrics-guice immediately before it was removed from the main metrics repo in dropwizard/metrics@e058f76dabf3f805d1c220950a4f42c2ec605ecd.