metrics-spring: A Java repository from ozoli

#Metrics for Spring

##About

The metrics-spring module integrates Dropwizard Metrics library with Spring, and provides XML and Java configuration.

This module does the following:

Creates metrics and proxies beans which contain methods annotated with @Timed, @Metered, @ExceptionMetered, and @Counted
Registers a Gauge for beans which have members annotated with @Gauge and @CachedGauge
Autowires Timers, Meters, Counters and Histograms into fields annotated with @Metric
Registers with the HealthCheckRegistry any beans which extend the class HealthCheck
Creates reporters from XML config and binds them to the Spring lifecycle
Registers metrics and metric sets in XML

###Maven

Current version is 3.1.3, which is compatible with Metrics 3.1.2

<dependency>
    <groupId>com.ryantenney.metrics</groupId>
    <artifactId>metrics-spring</artifactId>
    <version>3.1.3</version>
</dependency>

###Basic Usage

As of version 3, metrics-spring may be configured using XML or Java, depending on your personal preference.

Spring Context XML:

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:metrics="http://www.ryantenney.com/schema/metrics"
       xsi:schemaLocation="
           http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd
           http://www.ryantenney.com/schema/metrics
           http://www.ryantenney.com/schema/metrics/metrics.xsd">

    <!-- Creates a MetricRegistry bean -->
    <metrics:metric-registry id="metricRegistry" />

    <!-- Creates a HealthCheckRegistry bean (Optional) -->
    <metrics:health-check-registry id="health" />

    <!-- Registers BeanPostProcessors with Spring which proxy beans and capture metrics -->
    <!-- Include this once per context (once in the parent context and in any subcontexts) -->
    <metrics:annotation-driven metric-registry="metricRegistry" />

    <!-- Example reporter definiton. Supported reporters include jmx, slf4j, graphite, and others. -->
    <!-- Reporters should be defined only once, preferably in the parent context -->
    <metrics:reporter type="console" metric-registry="metricRegistry" period="1m" />

    <!-- Register metric beans (Optional) -->
    <!-- The metrics in this example require metrics-jvm -->
    <metrics:register metric-registry="metricRegistry">
        <bean metrics:name="jvm.gc" class="com.codahale.metrics.jvm.GarbageCollectorMetricSet" />
        <bean metrics:name="jvm.memory" class="com.codahale.metrics.jvm.MemoryUsageGaugeSet" />
        <bean metrics:name="jvm.thread-states" class="com.codahale.metrics.jvm.ThreadStatesGaugeSet" />
        <bean metrics:name="jvm.fd.usage" class="com.codahale.metrics.jvm.FileDescriptorRatioGauge" />
    </metrics:register>

    <!-- Beans and other Spring config -->

</beans>

Java Annotation Config:

import java.util.concurrent.TimeUnit;
import org.springframework.context.annotation.Configuration;
import com.codahale.metrics.ConsoleReporter;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.SharedMetricRegistries;
import com.ryantenney.metrics.spring.config.annotation.EnableMetrics;
import com.ryantenney.metrics.spring.config.annotation.MetricsConfigurerAdapter;

@Configuration
@EnableMetrics
public class SpringConfiguringClass extends MetricsConfigurerAdapter {

    @Override
    public void configureReporters(MetricRegistry metricRegistry) {
        // registerReporter allows the MetricsConfigurerAdapter to
        // shut down the reporter when the Spring context is closed
        registerReporter(ConsoleReporter
            .forRegistry(metricRegistry)
            .build())
            .start(1, TimeUnit.MINUTES);
    }

}

###XML Config Documentation

The <metrics:annotation-driven /> element is required, and has 4 optional arguments:

Attributes
metric-registry - the id of the MetricRegsitry bean with which the generated metrics should be registered. If omitted a new MetricRegistry bean is created.
health-check-registry - the id of the HealthCheckRegsitry bean with which to register any beans which extend the class HealthCheck. If omitted a new HealthCheckRegistry bean is created.
proxy-target-class - if set to true, always creates CGLIB proxies instead of defaulting to JDK proxies. This may be necessary if you use class-based autowiring.
expose-proxy - if set to true, the target can access the proxy which wraps it by calling AopContext.currentProxy().

The <metrics:metric-registry /> element constructs a new MetricRegistry or retrieves a shared registry:

Attributes
id - the bean name with which to register the MetricRegistry bean
name - the name of the MetricRegistry, if present, this calls SharedMetricRegistries.getOrCreate(name)

The <metrics:health-check-registry /> element constructs a new HealthCheckRegistry:

Attributes
id - the bean name with which to register the HealthCheckRegistry bean

The <metrics:reporter /> element creates and starts a reporter:

Attributes
id - the bean name
metric-registry - the id of the MetricRegsitry bean for which the reporter should retrieve metrics
type - the type of the reporter. Additional types may be registered through SPI (more on this later).
console: ConsoleReporter
jmx: JmxReporter
slf4j: Slf4jReporter
ganglia: GangliaReporter (requires metrics-ganglia)
graphite: GraphiteReporter (requires metrics-graphite)

The <metrics:register /> element registers with the MetricRegistry a bean which extends implements Metric or MetricSet

Attributes
metric-registry - the id of the MetricRegsitry bean with which the metrics are to be registered
Child elements
<bean /> - The beans to register with the specified registry.
metrics:name attribute on the bean element - specifies the name with which the metric will be registered. Optional if the bean is a MetricSet.

###Java Config Documentation

A @Configuration class annotated with @EnableMetrics is functionally equivalent to using the <metrics:annotation-driven /> element.

proxyTargetClass - if set to true, always creates CGLIB proxies instead of defaulting to JDK proxies. This may be necessary if you use class-based autowiring.
exposeProxy - if set to true, the target can access the proxy which wraps it by calling AopContext.currentProxy().

The class may also implement the interface MetricsConfigurer, or extend the abstract class MetricsConfigurerAdapter

getMetricRegistry() - return the MetricRegsitry instance with which metrics should be registered. If omitted a new MetricRegistry instance is created.
getHealthCheckRegistry() - return the HealthCheckRegsitry instance with which to register any beans which extend the class HealthCheck. If omitted a new HealthCheckRegistry instance is created.
configureReporters(MetricRegistry) - configure reporters

###A Note on the Limitations of Spring AOP

Due to limitations of Spring AOP only public methods can be proxied, so @Timed, @Metered, @ExceptionMetered, and @Counted have no effect on non-public methods. Additionally, calling an annotated method from within the same class will not go through the proxy.

public class Foo {
	
    @Timed
    public void bar() { /* … */ }
	
    public void baz() {
        this.bar(); // doesn't pass through the proxy
		
        // fix: reengineer
        // workaround: enable `expose-proxy` and change to:
        ((Foo) AopContext.currentProxy()).bar(); // hideous, but it works
    }
}

As @Gauge doesn’t involve a proxy, it may be used on non-public fields and methods. Additionally, @InjectMetric may be used on non-public, non-final fields.

###Users of the Maven Shade plugin

Please see the Shade Readme

###Documentation

Javadocs are hosted at http://ryantenney.github.io/metrics-spring/docs/

Acknowledgements

YourKit is kindly supporting this open source project with its full-featured Java Profiler. YourKit, LLC is the creator of innovative and intelligent tools for profiling Java and .NET applications. Take a look at YourKit's leading software products: YourKit Java Profiler and YourKit .NET Profiler.

License

Published under Apache Software License 2.0, see LICENSE

ozoli/metrics-spring

Acknowledgements

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