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Spring integration for Coda Hale's Metrics Library

There is a newer version: 3.1.3

/**
 * Copyright (C) 2012 Ryan W Tenney ([email protected])
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.ryantenney.metrics.spring;

import java.lang.reflect.Method;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.aop.support.AopUtils;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.core.Ordered;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.MethodCallback;

import com.codahale.metrics.MetricRegistry;
import com.ryantenney.metrics.annotation.CachedGauge;

class CachedGaugeAnnotationBeanPostProcessor implements BeanPostProcessor, Ordered {

	private static final Logger LOG = LoggerFactory.getLogger(CachedGaugeAnnotationBeanPostProcessor.class);

	private static final AnnotationFilter FILTER = new AnnotationFilter(CachedGauge.class);

	private final MetricRegistry metrics;

	public CachedGaugeAnnotationBeanPostProcessor(final MetricRegistry metrics) {
		this.metrics = metrics;
	}

	@Override
	public Object postProcessBeforeInitialization(Object bean, String beanName) {
		return bean;
	}

	@Override
	public Object postProcessAfterInitialization(final Object bean, String beanName) {
		final Class targetClass = AopUtils.getTargetClass(bean);

		ReflectionUtils.doWithMethods(targetClass, new MethodCallback() {
			@Override
			public void doWith(final Method method) throws IllegalAccessException {
				if (method.getParameterTypes().length > 0) {
					throw new IllegalStateException("Method " + method.getName() +
						" is annotated with @CachedGauge but requires parameters.");
				}

				final CachedGauge annotation = method.getAnnotation(CachedGauge.class);
				final String metricName = Util.forCachedGauge(targetClass, method, annotation);

				metrics.register(metricName, new com.codahale.metrics.CachedGauge