001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.monitoring.aop;
019
020 import org.apache.commons.monitoring.Role;
021 import org.apache.commons.monitoring.counters.Counter;
022 import org.apache.commons.monitoring.repositories.Repository;
023 import org.apache.commons.monitoring.stopwatches.StopWatch;
024
025 import java.io.ByteArrayOutputStream;
026 import java.io.PrintStream;
027 import java.lang.reflect.Method;
028
029 /**
030 * A method interceptor that compute method invocation performances.
031 * <p/>
032 * Concrete implementation will adapt the method interception API to
033 * this class requirement.
034 *
035 * @author <a href="mailto:nicolas@apache.org">Nicolas De Loof</a>
036 */
037 public abstract class AbstractPerformanceInterceptor<T> {
038
039 protected MonitorNameExtractor monitorNameExtractor;
040
041 public AbstractPerformanceInterceptor() {
042 setMonitorNameExtractor(DefaultMonitorNameExtractor.INSTANCE);
043 }
044
045 /**
046 * API neutral method invocation
047 */
048 protected Object doInvoke(final T invocation) throws Throwable {
049 final String name = getCounterName(invocation);
050 if (name == null) {
051 return proceed(invocation);
052 }
053
054 final Counter monitor = Repository.INSTANCE.getCounter(new Counter.Key(Role.PERFORMANCES, name));
055 final StopWatch stopwatch = Repository.INSTANCE.start(monitor);
056 Throwable error = null;
057 try {
058 return proceed(invocation);
059 } catch (final Throwable t) {
060 error = t;
061 throw t;
062 } finally {
063 stopwatch.stop();
064 if (error != null) {
065 final ByteArrayOutputStream writer = new ByteArrayOutputStream();
066 error.printStackTrace(new PrintStream(writer));
067 Repository.INSTANCE.getCounter(new Counter.Key(Role.FAILURES, writer.toString())).add(stopwatch.getElapsedTime());
068 }
069 }
070 }
071
072 protected abstract Object proceed(T invocation) throws Throwable;
073
074 protected abstract String getCounterName(T invocation);
075
076 /**
077 * Compute the counter name associated to this method invocation
078 *
079 * @param method method being invoked
080 * @return counter name. If <code>null</code>, nothing will be monitored
081 */
082 protected String getCounterName(final Object instance, final Method method) {
083 return monitorNameExtractor.getMonitorName(instance, method);
084 }
085
086 public void setMonitorNameExtractor(final MonitorNameExtractor monitorNameExtractor) {
087 this.monitorNameExtractor = monitorNameExtractor;
088 }
089 }