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

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

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/*
 * Copyright 2012 Ryan W Tenney (http://ryan.10e.us)
 *            and Martello Technologies (http://martellotech.com)
 *
 * 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 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.aop.Pointcut;
import org.springframework.aop.support.annotation.AnnotationMatchingPointcut;
import org.springframework.core.Ordered;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.MethodCallback;
import org.springframework.util.ReflectionUtils.MethodFilter;

import com.codahale.metrics.Meter;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.annotation.ExceptionMetered;

class ExceptionMeteredMethodInterceptor implements MethodInterceptor, MethodCallback, Ordered {

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

    public static final Pointcut POINTCUT = new AnnotationMatchingPointcut(null, ExceptionMetered.class);
    public static final MethodFilter METHOD_FILTER = new AnnotationFilter(ExceptionMetered.class);

    private final MetricRegistry metrics;
    private final Class<?> targetClass;
    private final Map<MethodKey, ExceptionMeter> meters;

    public ExceptionMeteredMethodInterceptor(final MetricRegistry metrics, final Class<?> targetClass) {
        this.metrics = metrics;
        this.targetClass = targetClass;
        this.meters = new HashMap<MethodKey, ExceptionMeter>();

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

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

    @Override
    public Object invoke(MethodInvocation invocation) throws Throwable {
        try {
            return invocation.proceed();
        } catch (Throwable t) {
            final MethodKey key = MethodKey.forMethod(invocation.getMethod());
            final ExceptionMeter exceptionMeter = meters.get(key);
            if (exceptionMeter != null && exceptionMeter.getCause().isAssignableFrom(t.getClass())) {
                exceptionMeter.getMeter().mark();
            }
            throw t;
        }
    }

    @Override
    public void doWith(Method method) throws IllegalAccessException {
        final ExceptionMetered annotation = method.getAnnotation(ExceptionMetered.class);
        final String metricName = Util.forExceptionMeteredMethod(targetClass, method, annotation);
        final MethodKey methodKey = MethodKey.forMethod(method);
        final Meter meter = metrics.meter(metricName);

        meters.put(methodKey, new ExceptionMeter(meter, annotation.cause()));

        LOG.debug("Created Meter {} for method {}", metricName, methodKey);
    }

    @Override
    public int getOrder() {
        return HIGHEST_PRECEDENCE;
    }

    private static class ExceptionMeter {

        private final Meter meter;
        private final Class<? extends Throwable> cause;

        public ExceptionMeter(final Meter meter, final Class<? extends Throwable> cause) {
            this.meter = meter;
            this.cause = cause;
        }

        public Meter getMeter() {
            return meter;
        }

        public Class<? extends Throwable> getCause() {
            return cause;
        }

    }

}