Coverage Report - org.apache.turbine.services.BaseInitableBroker
 
Classes in this File Line Coverage Branch Coverage Complexity
BaseInitableBroker
0%
0/62
0%
0/22
5,6
 
 1  
 package org.apache.turbine.services;
 2  
 
 3  
 
 4  
 /*
 5  
  * Licensed to the Apache Software Foundation (ASF) under one
 6  
  * or more contributor license agreements.  See the NOTICE file
 7  
  * distributed with this work for additional information
 8  
  * regarding copyright ownership.  The ASF licenses this file
 9  
  * to you under the Apache License, Version 2.0 (the
 10  
  * "License"); you may not use this file except in compliance
 11  
  * with the License.  You may obtain a copy of the License at
 12  
  *
 13  
  *   http://www.apache.org/licenses/LICENSE-2.0
 14  
  *
 15  
  * Unless required by applicable law or agreed to in writing,
 16  
  * software distributed under the License is distributed on an
 17  
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 18  
  * KIND, either express or implied.  See the License for the
 19  
  * specific language governing permissions and limitations
 20  
  * under the License.
 21  
  */
 22  
 
 23  
 
 24  
 import java.util.Hashtable;
 25  
 import java.util.Stack;
 26  
 
 27  
 import org.apache.logging.log4j.LogManager;
 28  
 import org.apache.logging.log4j.Logger;
 29  
 
 30  
 /**
 31  
  * A generic implementation of <code>InitableBroker</code>.
 32  
  * Functionality provided by the broker includes:
 33  
  *
 34  
  * <ul>
 35  
  *
 36  
  * <li>Maintaining single instance of each <code>Initable</code> in
 37  
  * the system.</li>
 38  
  *
 39  
  * <li>Early initialization of <code>Initables</code> during system
 40  
  * startup.</li>
 41  
  *
 42  
  * <li>Late initialization of <code>Initables</code> before they are
 43  
  * used.</li>
 44  
  *
 45  
  * <li>Providing instances of <code>Initables</code> to requesting
 46  
  * parties.</li>
 47  
  *
 48  
  * <li>Maintaining dependencies between <code>Initables</code> during
 49  
  * early initialization phases, including circular dependencies
 50  
  * detection.</li>
 51  
  *
 52  
  * </ul>
 53  
  *
 54  
  * @author <a href="mailto:burton@apache.org">Kevin Burton</a>
 55  
  * @author <a href="mailto:krzewski@e-point.pl">Rafal Krzewski</a>
 56  
  * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
 57  
  * @version $Id: BaseInitableBroker.java 1854688 2019-03-03 10:36:42Z tv $
 58  
  */
 59  
 public abstract class BaseInitableBroker
 60  
         implements InitableBroker
 61  
 {
 62  
     /** A repository of Initable instances. */
 63  0
     protected Hashtable<String, Initable> initables = new Hashtable<String, Initable>();
 64  
 
 65  
     /**
 66  
      * Names of classes being early-initialized are pushed onto this
 67  
      * stack.  A name appearing twice indicates a circular dependency
 68  
      * chain.
 69  
      */
 70  0
     protected Stack<String> stack = new Stack<String>();
 71  
 
 72  
     /** Logging */
 73  0
     private final Logger log = LogManager.getLogger(this.getClass());
 74  
 
 75  
     /**
 76  
      * Default constructor of InitableBroker.
 77  
      *
 78  
      * This constructor does nothing. Your brokers should be
 79  
      * singletons, therefore their constructors should be
 80  
      * private. They should also have public YourBroker getInstance()
 81  
      * methods.
 82  
      */
 83  
     protected BaseInitableBroker()
 84  0
     {
 85  
         // empty
 86  0
     }
 87  
 
 88  
     /**
 89  
      * Performs early initialization of an Initable class.
 90  
      *
 91  
      * @param className The name of the class to be initialized.
 92  
      * @param data An Object to be used for initialization activities.
 93  
      * @throws InitializationException Initialization was not successful.
 94  
      */
 95  
     @Override
 96  
     public void initClass(String className, Object data)
 97  
             throws InitializationException
 98  
     {
 99  
         // make sure that only one thread calls this method recursively
 100  0
         synchronized (stack)
 101  
         {
 102  0
             int pos = stack.search(className);
 103  0
             if (pos != -1)
 104  
             {
 105  0
                 StringBuilder msg = new StringBuilder().append(className)
 106  0
                         .append(" couldn't be initialized because of circular dependency chain:\n");
 107  0
                 for (int i = pos; i > 0; i--)
 108  
                 {
 109  0
                     msg.append(stack.elementAt(stack.size() - i - 1) + "->");
 110  
                 }
 111  0
                 msg.append(className).append('\n');
 112  
 
 113  0
                 throw new InitializationException(msg.toString());
 114  
             }
 115  
             try
 116  
             {
 117  0
                 stack.push(className);
 118  0
                 Initable instance = getInitableInstance(className);
 119  0
                 if (!instance.getInit())
 120  
                 {
 121  
                     // this call might result in an indirect recursion
 122  0
                     instance.init(data);
 123  
                 }
 124  
             }
 125  
             finally
 126  
             {
 127  
                 // Succeeded or not, make sure the name gets off the stack.
 128  0
                 stack.pop();
 129  0
             }
 130  0
         }
 131  0
     }
 132  
 
 133  
     /**
 134  
      * Shuts down an <code>Initable</code>.
 135  
      *
 136  
      * This method is used to release resources allocated by an
 137  
      * <code>Initable</code>, and return it to its initial (uninitialized)
 138  
      * state.
 139  
      *
 140  
      * @param className The name of the class to be uninitialized.
 141  
      */
 142  
     @Override
 143  
     public void shutdownClass(String className)
 144  
     {
 145  
         try
 146  
         {
 147  0
             Initable initable = getInitableInstance(className);
 148  0
             if (initable.getInit())
 149  
             {
 150  0
                 initable.shutdown();
 151  0
                 ((BaseInitable) initable).setInit(false);
 152  
             }
 153  
         }
 154  0
         catch (InstantiationException e)
 155  
         {
 156  
             // Shutdown of a nonexistent class was requested.
 157  
             // This does not hurt anything, so we log the error and continue.
 158  0
             log.error("Shutdown of a nonexistent class {} was requested", className, e);
 159  0
         }
 160  0
     }
 161  
 
 162  
     /**
 163  
      * Provides an instance of Initable class ready to work.
 164  
      *
 165  
      * If the requested class couldn't be instantiated or initialized,
 166  
      * an InstantiationException will be thrown. You needn't handle
 167  
      * this exception in your code, since it indicates fatal
 168  
      * misconfiguration of the system.
 169  
      *
 170  
      * @param className The name of the Initable requested.
 171  
      * @return An instance of the requested Initable.
 172  
      * @throws InstantiationException if there was a problem
 173  
      * during instantiation or initialization of the Initable.
 174  
      */
 175  
     @Override
 176  
     public Initable getInitable(String className)
 177  
             throws InstantiationException
 178  
     {
 179  
         Initable initable;
 180  
         try
 181  
         {
 182  0
             initable = getInitableInstance(className);
 183  0
             if (!initable.getInit())
 184  
             {
 185  0
                 synchronized (initable.getClass())
 186  
                 {
 187  0
                     if (!initable.getInit())
 188  
                     {
 189  0
                         initable.init();
 190  
                     }
 191  0
                     if (!initable.getInit())
 192  
                     {
 193  
                         // this exception will be caught & rethrown by this
 194  
                         // very method. getInit() returning false indicates
 195  
                         // some initialization issue, which in turn prevents
 196  
                         // the InitableBroker from passing a working
 197  
                         // instance of the initable to the client.
 198  0
                         throw new InitializationException(
 199  
                                 "init() failed to initialize class "
 200  
                                 + className);
 201  
                     }
 202  0
                 }
 203  
             }
 204  0
             return initable;
 205  
         }
 206  0
         catch (InitializationException e)
 207  
         {
 208  0
             throw new InstantiationException("Class " + className +
 209  
                     " failed to initialize", e);
 210  
         }
 211  
     }
 212  
 
 213  
     /**
 214  
      * Retrieves an instance of an Initable from the repository.
 215  
      *
 216  
      * If the requested class is not present in the repository, it is
 217  
      * instantiated and passed a reference to the broker, saved and
 218  
      * then returned.
 219  
      *
 220  
      * @param className The name of the class to be instantiated.
 221  
      *
 222  
      * @return an instance of the requested class
 223  
      *
 224  
      * @throws InstantiationException if the requested class can't
 225  
      * be instantiated.
 226  
      */
 227  
     protected Initable getInitableInstance(String className)
 228  
             throws InstantiationException
 229  
     {
 230  0
         Initable initable = initables.get(className);
 231  
 
 232  0
         if (initable == null)
 233  
         {
 234  
             try
 235  
             {
 236  0
                 initable = (Initable) Class.forName(className).newInstance();
 237  
             }
 238  
 
 239  
                     // those two errors must be passed to the VM
 240  0
             catch (ThreadDeath t)
 241  
             {
 242  0
                 throw t;
 243  
             }
 244  0
             catch (OutOfMemoryError t)
 245  
             {
 246  0
                 throw t;
 247  
             }
 248  
 
 249  0
             catch (Throwable t)
 250  
             {
 251  
                 // Used to indicate error condition.
 252  0
                 String msg = null;
 253  
 
 254  0
                 if (t instanceof NoClassDefFoundError)
 255  
                 {
 256  0
                     msg = "A class referenced by " + className +
 257  
                             " is unavailable. Check your jars and classes.";
 258  
                 }
 259  0
                 else if (t instanceof ClassNotFoundException)
 260  
                 {
 261  0
                     msg = "Class " + className +
 262  
                             " is unavailable. Check your jars and classes.";
 263  
                 }
 264  0
                 else if (t instanceof ClassCastException)
 265  
                 {
 266  0
                     msg = "Class " + className +
 267  
                             " doesn't implement Initable.";
 268  
                 }
 269  
                 else
 270  
                 {
 271  0
                     msg = "Failed to instantiate " + className;
 272  
                 }
 273  
 
 274  0
                 throw new InstantiationException(msg, t);
 275  0
             }
 276  
 
 277  0
             initable.setInitableBroker(this);
 278  0
             initables.put(className, initable);
 279  
         }
 280  
 
 281  0
         return initable;
 282  
     }
 283  
 
 284  
 }