content: package org.apache.cassandra.concurrent;
  /*
   * 
   * 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.cassandra.Util;
  import org.apache.cassandra.utils.concurrent.WaitQueue;
  import org.junit.*;
  
  import java.util.concurrent.ThreadLocalRandom;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import static org.apache.cassandra.utils.concurrent.WaitQueue.newWaitQueue;
  import static org.junit.Assert.*;
  
  public class WaitQueueTest
  {
  
      @Test
      public void testSerial() throws InterruptedException
      {
          testSerial(newWaitQueue());
      }
      public void testSerial(final WaitQueue queue) throws InterruptedException
      {
          final AtomicInteger ready = new AtomicInteger();
          Thread[] ts = new Thread[4];
          for (int i = 0 ; i < ts.length ; i++)
              ts[i] = NamedThreadFactory.createAnonymousThread(new Runnable()
          {
              @Override
              public void run()
              {
                  WaitQueue.Signal wait = queue.register();
                  ready.incrementAndGet();
                  try
                  {
                      wait.await();
                  } catch (InterruptedException e)
                  {
                      e.printStackTrace();
                  }
              }
          });
          for (Thread t : ts)
              t.start();
          final ThreadLocalRandom random = ThreadLocalRandom.current();
          while (ready.get() < ts.length)
              random.nextLong();
          for (Thread t : ts)
              queue.signal();
          for (Thread t : ts)
          {
              Util.joinThread(t);
              assertFalse(queue.getClass().getName(), t.isAlive());
          }
      }
  
      @Test
      public void testCondition() throws InterruptedException
      {
          testCondition(newWaitQueue());
      }
      public void testCondition(final WaitQueue queue) throws InterruptedException
      {
          final AtomicBoolean ready = new AtomicBoolean(false);
          final AtomicBoolean condition = new AtomicBoolean(false);
          final AtomicBoolean fail = new AtomicBoolean(false);
          Thread t = NamedThreadFactory.createAnonymousThread(new Runnable()
          {
              @Override
              public void run()
              {
                  WaitQueue.Signal wait = queue.register();
                  if (condition.get())
                  {
                      System.err.println("");
                      fail.set(true);
                      ready.set(true);
                      return;
                  }
  
                  ready.set(true);
                  wait.awaitUninterruptibly();
                  if (!condition.get())
                  {
                      System.err.println("Woke up when condition not met");
                      fail.set(true);
                  }
              }
          });
          t.start();
          final ThreadLocalRandom random = ThreadLocalRandom.current();
          while (!ready.get())
              random.nextLong();
          condition.set(true);
          queue.signal();
          Util.joinThread(t);
          assertFalse(queue.getClass().getName(), t.isAlive());
          assertFalse(fail.get());
      }
  
      @Test
      public void testInterruptOfSignalAwaitingThread() throws InterruptedException
      {
          final WaitQueue waitQueue = newWaitQueue();
          Thread writerAwaitThread = createThread(() -> {
              Thread.currentThread().interrupt();
              WaitQueue.Signal signal = waitQueue.register();
              signal.awaitUninterruptibly();
  
          }, "writer.await");
  
          writerAwaitThread.start();
  
          Thread.sleep(1_000); // wait to enter signal.awaitUninterruptibly()
          waitQueue.signalAll();
  
          writerAwaitThread.join(4_000);
          if (writerAwaitThread.isAlive())
          {
              printThreadStackTrace(writerAwaitThread);
              fail("signal.awaitUninterruptibly() is stuck");
          }
      }
  
      @Test
      public void testInterruptOfSignalAwaitingWithTimeoutThread() throws InterruptedException
      {
          final WaitQueue waitQueue = newWaitQueue();
          Thread writerAwaitThread = createThread(() -> {
              Thread.currentThread().interrupt();
              WaitQueue.Signal signal = waitQueue.register();
              signal.awaitUninterruptibly(100_000, TimeUnit.MILLISECONDS);
          }, "writer.await");
  
          writerAwaitThread.start();
  
          Thread.sleep(1_000); // wait to enter signal.awaitUninterruptibly()
          waitQueue.signalAll();
  
          writerAwaitThread.join(4_000);
          if (writerAwaitThread.isAlive())
          {
              printThreadStackTrace(writerAwaitThread);
              fail("signal.awaitUninterruptibly() is stuck");
          }
      }
  
      private static Thread createThread(Runnable job, String name)
      {
          Thread thread = new Thread(job, name);
          thread.setDaemon(true);
          return thread;
      }
  
      private static void printThreadStackTrace(Thread thread)
      {
          System.out.println("Stack trace for thread: " + thread.getName());
          StackTraceElement[] stackTrace = thread.getStackTrace();
          if (stackTrace.length == 0)
          {
              System.out.println("The thread is not currently running or has no stack trace.");
          } else
          {
              for (StackTraceElement element : stackTrace)
              {
                  System.out.println("\tat " + element);
              }
          }
      }
  }
  