com.ryantenney.metrics.spring.AbstractMetricMethodInterceptor.java Source code

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Here is the source code for com.ryantenney.metrics.spring.AbstractMetricMethodInterceptor.java

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/**
 * Copyright (C) 2012 Ryan W Tenney (ryan@10e.us)
 *
 * 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.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.MethodCallback;
import org.springframework.util.ReflectionUtils.MethodFilter;

import com.codahale.metrics.MetricRegistry;

abstract class AbstractMetricMethodInterceptor<A extends Annotation, M>
        implements MethodInterceptor, MethodCallback {

    protected final Logger LOG = LoggerFactory.getLogger(getClass());

    private final MetricRegistry metricRegistry;
    private final Class<?> targetClass;
    private final Class<A> annotationClass;
    private final Map<MethodKey, AnnotationMetricPair<A, M>> metrics;

    AbstractMetricMethodInterceptor(final MetricRegistry metricRegistry, final Class<?> targetClass,
            final Class<A> annotationClass, final MethodFilter methodFilter) {
        this.metricRegistry = metricRegistry;
        this.targetClass = targetClass;
        this.annotationClass = annotationClass;
        this.metrics = new HashMap<MethodKey, AnnotationMetricPair<A, M>>();

        LOG.debug("Creating method interceptor for class {}", targetClass.getCanonicalName());
        LOG.debug("Scanning for @{} annotated methods", annotationClass.getSimpleName());

        ReflectionUtils.doWithMethods(targetClass, this, methodFilter);
    }

    @Override
    public Object invoke(MethodInvocation invocation) throws Throwable {
        final AnnotationMetricPair<A, M> annotationMetricPair = metrics
                .get(MethodKey.forMethod(invocation.getMethod()));
        if (annotationMetricPair != null) {
            return invoke(invocation, annotationMetricPair.getMeter(), annotationMetricPair.getAnnotation());
        } else {
            return invocation.proceed();
        }
    }

    @Override
    public void doWith(Method method) throws IllegalAccessException {
        final A annotation = method.getAnnotation(annotationClass);
        if (annotation != null) {
            final MethodKey methodKey = MethodKey.forMethod(method);
            final String metricName = buildMetricName(targetClass, method, annotation);
            final M metric = buildMetric(metricRegistry, metricName, annotation);

            if (metric != null) {
                metrics.put(methodKey, new AnnotationMetricPair<A, M>(annotation, metric));

                if (LOG.isDebugEnabled()) {
                    LOG.debug("Created {} {} for method {}", metric.getClass().getSimpleName(), metricName,
                            methodKey);
                }
            }
        }
    }

    protected abstract String buildMetricName(Class<?> targetClass, Method method, A annotation);

    protected abstract M buildMetric(MetricRegistry metricRegistry, String metricName, A annotation);

    protected abstract Object invoke(MethodInvocation invocation, M metric, A annotation) throws Throwable;

    public static final class AnnotationMetricPair<A extends Annotation, M> {

        private final A annotation;
        private final M meter;

        public AnnotationMetricPair(final A annotation, final M meter) {
            this.annotation = annotation;
            this.meter = meter;
        }

        public A getAnnotation() {
            return annotation;
        }

        public M getMeter() {
            return meter;
        }

    }

}