package org.apache.maven.plugin.coreit;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.
   */
  
  import org.apache.maven.plugin.AbstractMojo;
  import org.apache.maven.plugin.MojoExecutionException;
  import org.apache.maven.plugin.MojoFailureException;
  
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Properties;
  import java.util.Vector;
  
  /**
   * Checks the thread-safe retrieval of components from active component collections.
   * 
   * @goal check-thread-safety
   * @phase validate
   * 
   * @author Benjamin Bentmann
   */
  public class CheckThreadSafetyMojo
      extends AbstractMojo
  {
  
      /**
       * Project base directory used for manual path alignment.
       * 
       * @parameter default-value="${basedir}"
       * @readonly
       */
      private File basedir;
  
      /**
       * The available components, as a map.
       * 
       * @component role="org.apache.maven.plugin.coreit.Component"
       */
      private Map componentMap;
  
      /**
       * The available components, as a list.
       * 
       * @component role="org.apache.maven.plugin.coreit.Component"
       */
      private List componentList;
  
      /**
       * The path to the properties file to create.
       * 
       * @parameter expression="${collections.outputFile}"
       */
      private File outputFile;
  
      /**
       * Runs this mojo.
       * 
       * @throws MojoFailureException If the output file could not be created.
       */
      public void execute()
          throws MojoExecutionException
      {
          Properties componentProperties = new Properties();
  
          getLog().info( "[MAVEN-CORE-IT-LOG] Testing concurrent component access" );
  
          ClassLoader pluginRealm = getClass().getClassLoader();
          ClassLoader coreRealm = MojoExecutionException.class.getClassLoader();
  
          final Map map = componentMap;
          final List list = componentList;
          final List go = new Vector();
          final List exceptions = new Vector();
  
          Thread[] threads = new Thread[2];
          for ( int i = 0; i < threads.length; i++ )
          {
             // NOTE: The threads need to use different realms to trigger changes of the collections
             final ClassLoader cl = ( i % 2 ) == 0 ? pluginRealm : coreRealm;
             threads[i] = new Thread()
             {
                 private final ClassLoader tccl = cl;
 
                 public void run()
                 {
                     getLog().info( "[MAVEN-CORE-IT-LOG] Thread " + this + " uses " + tccl );
                     Thread.currentThread().setContextClassLoader( tccl );
                     while ( go.isEmpty() )
                     {
                         // wait for start
                     }
                     for ( int j = 0; j < 10000; j++ )
                     {
                         try
                         {
                             for ( Iterator it = map.values().iterator(); it.hasNext(); )
                             {
                                 it.next().toString();
                             }
                             for ( Iterator it = list.iterator(); it.hasNext(); )
                             {
                                 it.next().toString();
                             }
                         }
                         catch ( Exception e )
                         {
                             getLog().warn( "[MAVEN-CORE-IT-LOG] Thread " + this + " encountered concurrency issue", e );
                             exceptions.add( e );
                         }
                     }
                 }
             };
             threads[i].start();
         }
 
         go.add( null );
         for ( int i = 0; i < threads.length; i++ )
         {
             try
             {
                 threads[i].join();
             }
             catch ( InterruptedException e )
             {
                 getLog().warn( "[MAVEN-CORE-IT-LOG] Interrupted while joining " + threads[i] );
             }
         }
 
         componentProperties.setProperty( "components", Integer.toString( componentList.size() ) );
         componentProperties.setProperty( "exceptions", Integer.toString( exceptions.size() ) );
 
         if ( !outputFile.isAbsolute() )
         {
             outputFile = new File( basedir, outputFile.getPath() );
         }
 
         getLog().info( "[MAVEN-CORE-IT-LOG] Creating output file " + outputFile );
 
         OutputStream out = null;
         try
         {
             outputFile.getParentFile().mkdirs();
             out = new FileOutputStream( outputFile );
             componentProperties.store( out, "MAVEN-CORE-IT-LOG" );
         }
         catch ( IOException e )
         {
             throw new MojoExecutionException( "Output file could not be created: " + outputFile, e );
         }
         finally
         {
             if ( out != null )
             {
                 try
                 {
                     out.close();
                 }
                 catch ( IOException e )
                 {
                     // just ignore
                 }
             }
         }
 
         getLog().info( "[MAVEN-CORE-IT-LOG] Created output file " + outputFile );
     }
 
 }