package org.apache.maven.plugin.surefire.booterclient.lazytestprovider;
   
   /*
    * 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.surefire.booter.Command;
  import org.apache.maven.surefire.booter.Shutdown;
  
  import java.io.IOException;
  import java.util.Queue;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.Semaphore;
  import java.util.concurrent.atomic.AtomicBoolean;
  
  import static org.apache.maven.surefire.booter.Command.BYE_ACK;
  import static org.apache.maven.surefire.booter.Command.NOOP;
  import static org.apache.maven.surefire.booter.Command.SKIP_SINCE_NEXT_TEST;
  import static org.apache.maven.surefire.booter.Command.toRunClass;
  import static org.apache.maven.surefire.booter.Command.toShutdown;
  
  /**
   * An {@link java.io.InputStream} that, when read, provides test class names out of a queue.
   * <br>
   * The Stream provides only one test at a time, but only after {@link #provideNewTest()} has been invoked.
   * <br>
   * After providing each test class name, followed by a newline character, a flush is performed on the
   * {@link FlushReceiver} provided by the {@link FlushReceiverProvider} that can be set using
   * {@link #setFlushReceiverProvider(FlushReceiverProvider)}.
   * <br>
   * The instance is used only in reusable forks in {@link org.apache.maven.plugin.surefire.booterclient.ForkStarter}
   * by one Thread.
   *
   * @author Andreas Gudian
   * @author Tibor Digana (tibor17)
   */
  public final class TestProvidingInputStream
      extends AbstractCommandStream
  {
      private final Semaphore barrier = new Semaphore( 0 );
  
      private final Queue<Command> commands = new ConcurrentLinkedQueue<>();
  
      private final AtomicBoolean closed = new AtomicBoolean();
  
      private final Queue<String> testClassNames;
  
      /**
       * C'tor
       *
       * @param testClassNames source of the tests to be read from this stream
       */
      public TestProvidingInputStream( Queue<String> testClassNames )
      {
          this.testClassNames = testClassNames;
      }
  
      /**
       * For testing purposes.
       */
      void testSetFinished()
      {
          if ( canContinue() )
          {
              commands.add( Command.TEST_SET_FINISHED );
              barrier.release();
          }
      }
  
      @Override
      public void skipSinceNextTest()
      {
          if ( canContinue() )
          {
              commands.add( SKIP_SINCE_NEXT_TEST );
              barrier.release();
          }
      }
  
      @Override
      public void shutdown( Shutdown shutdownType )
      {
          if ( canContinue() )
          {
             commands.add( toShutdown( shutdownType ) );
             barrier.release();
         }
     }
 
     @Override
     public void noop()
     {
         if ( canContinue() )
         {
             commands.add( NOOP );
             barrier.release();
         }
     }
 
     @Override
     public void acknowledgeByeEventReceived()
     {
         if ( canContinue() )
         {
             commands.add( BYE_ACK );
             barrier.release();
         }
     }
 
     @Override
     protected Command nextCommand()
     {
         Command cmd = commands.poll();
         if ( cmd == null )
         {
             String cmdData = testClassNames.poll();
             return cmdData == null ? Command.TEST_SET_FINISHED : toRunClass( cmdData );
         }
         else
         {
             return cmd;
         }
     }
 
     @Override
     protected void beforeNextCommand()
         throws IOException
     {
         awaitNextTest();
     }
 
     @Override
     protected boolean isClosed()
     {
         return closed.get();
     }
 
     /**
      * Signal that a new test is to be provided.
      */
     @Override
     public void provideNewTest()
     {
         if ( canContinue() )
         {
             barrier.release();
         }
     }
 
     @Override
     public void close()
     {
         if ( closed.compareAndSet( false, true ) )
         {
             invalidateInternalBuffer();
             barrier.drainPermits();
             barrier.release();
         }
     }
 
     private void awaitNextTest()
         throws IOException
     {
         try
         {
             barrier.acquire();
         }
         catch ( InterruptedException e )
         {
             // help GC to free this object because StreamFeeder Thread cannot read it anyway after IOE
             invalidateInternalBuffer();
             throw new IOException( e.getLocalizedMessage() );
         }
     }
 }