001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  You may obtain a copy of the License at                                                              *
006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
009// * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.rest.stats;
014
015import java.lang.reflect.*;
016
017import org.apache.juneau.cp.*;
018import org.apache.juneau.reflect.*;
019
020/**
021 * A wrapper around a {@link Method#invoke(Object, Object...)} method that allows for basic instrumentation.
022 */
023public class MethodInvoker {
024   private final MethodInfo m;
025   private final MethodExecStats stats;
026
027   /**
028    * Constructor.
029    *
030    * @param m The method being wrapped.
031    * @param stats The instrumentor.
032    */
033   public MethodInvoker(Method m, MethodExecStats stats) {
034      this.m = MethodInfo.of(m);
035      this.stats = stats;
036   }
037
038   /**
039    * Returns the inner method.
040    *
041    * @return The inner method.
042    */
043   public MethodInfo inner() {
044      return m;
045   }
046
047   /**
048    * Invokes the underlying method.
049    *
050    * @param o  The object the underlying method is invoked from.
051    * @param args  The arguments used for the method call.
052    * @return  The result of dispatching the method represented by this object on {@code obj} with parameters {@code args}
053    * @throws IllegalAccessException If method cannot be accessed.
054    * @throws IllegalArgumentException If wrong arguments were passed to method.
055    * @throws InvocationTargetException If method threw an exception.
056    */
057   public Object invoke(Object o, Object...args) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {
058      long startTime = System.nanoTime();
059      stats.started();
060      try {
061         return m.inner().invoke(o, args);
062      } catch (IllegalAccessException|IllegalArgumentException e) {
063         stats.error(e);
064         throw e;
065      } catch (InvocationTargetException e) {
066         stats.error(e.getTargetException());
067         throw e;
068      } finally {
069         stats.finished(System.nanoTime() - startTime);
070      }
071   }
072
073   /**
074    * Invokes the wrapped method using parameters from the specified bean store.
075    *
076    * @param beanStore The bean store to use to resolve parameters.
077    * @param o The object to invoke the method on.
078    * @return The result of invoking the method.
079    * @throws IllegalAccessException If method cannot be accessed.
080    * @throws IllegalArgumentException If wrong arguments were passed to method.
081    * @throws InvocationTargetException If method threw an exception.
082    */
083   public Object invoke(BeanStore beanStore, Object o) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {
084      if (beanStore.hasAllParams(m))
085         return invoke(o, beanStore.getParams(m));
086      throw new IllegalArgumentException("Could not find prerequisites to invoke method '"+getFullName()+"': "+beanStore.getMissingParams(m));
087   }
088
089   /**
090    * Convenience method for calling <c>inner().getDeclaringClass()</c>
091    *
092    * @return The declaring class of the method.
093    */
094   public ClassInfo getDeclaringClass() {
095      return m.getDeclaringClass();
096   }
097
098   /**
099    * Convenience method for calling <c>inner().getName()</c>
100    *
101    * @return The name of the method.
102    */
103   public String getFullName() {
104      return m.getFullName();
105   }
106
107   /**
108    * Returns the stats of this method invoker.
109    *
110    * @return The stats of this method invoker.
111    */
112   public MethodExecStats getStats() {
113      return stats;
114   }
115}