content: /**
   * 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.
   */
  package org.apache.activemq.usage;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertNotNull;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Random;
  import java.util.concurrent.ArrayBlockingQueue;
  import java.util.concurrent.BlockingQueue;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.LinkedBlockingQueue;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicBoolean;
  
  import org.junit.Test;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class MemoryUsageConcurrencyTest {
  
      private static final Logger LOG = LoggerFactory.getLogger(MemoryUsageConcurrencyTest.class);
  
      @Test
      public void testCycle() throws Exception {
          Random r = new Random(0xb4a14);
          for (int i = 0; i < 30000; i++) {
              checkPercentage(i, i, r.nextInt(100) + 10, i % 2 == 0, i % 5 == 0);
          }
      }
  
      private void checkPercentage(int attempt, int seed, int operations, boolean useArrayBlocking, boolean useWaitForSpaceThread) throws InterruptedException {
  
          final BlockingQueue<Integer> toAdd;
          final BlockingQueue<Integer> toRemove;
          final BlockingQueue<Integer> removed;
  
          if (useArrayBlocking) {
              toAdd = new ArrayBlockingQueue<Integer>(operations);
              toRemove = new ArrayBlockingQueue<Integer>(operations);
              removed = new ArrayBlockingQueue<Integer>(operations);
          } else {
              toAdd = new LinkedBlockingQueue<Integer>();
              toRemove = new LinkedBlockingQueue<Integer>();
              removed = new LinkedBlockingQueue<Integer>();
          }
  
          final AtomicBoolean running = new AtomicBoolean(true);
          final CountDownLatch startLatch = new CountDownLatch(1);
  
          final MemoryUsage memUsage = new MemoryUsage();
          memUsage.setLimit(1000);
          memUsage.start();
  
          Thread addThread = new Thread(new Runnable() {
              @Override
              public void run() {
                  try {
                      startLatch.await();
  
                      while (true) {
                          Integer add = toAdd.poll(1, TimeUnit.MILLISECONDS);
                          if (add == null) {
                              if (!running.get()) {
                                  break;
                              }
                          } else {
                              // add to other queue before removing
                              toRemove.add(add);
                              memUsage.increaseUsage(add);
                          }
                      }
                  } catch (Exception e) {
                      e.printStackTrace();
                  }
              }
          });
  
          Thread removeThread = new Thread(new Runnable() {
              @Override
              public void run() {
                  try {
                      startLatch.await();
  
                      while (true) {
                          Integer remove = toRemove.poll(1, TimeUnit.MILLISECONDS);
                          if (remove == null) {
                              if (!running.get()) {
                                  break;
                              }
                          } else {
                              memUsage.decreaseUsage(remove);
                              removed.add(remove);
                          }
                      }
                  } catch (Exception e) {
                      e.printStackTrace();
                  }
              }
          });
  
          Thread waitForSpaceThread = new Thread(new Runnable() {
              @Override
              public void run() {
                  try {
                      startLatch.await();
  
                      while (running.get()) {
                          memUsage.waitForSpace();
                      }
                  } catch (Exception e) {
                      e.printStackTrace();
                  }
              }
          });
  
          removeThread.start();
          addThread.start();
          if (useWaitForSpaceThread) {
              waitForSpaceThread.start();
          }
  
          Random r = new Random(seed);
  
          startLatch.countDown();
  
          for (int i = 0; i < operations; i++) {
              toAdd.add(r.nextInt(100) + 1);
          }
  
          // we expect the failure percentage to be related to the last operation
          List<Integer> ops = new ArrayList<Integer>(operations);
          for (int i = 0; i < operations; i++) {
              Integer op = removed.poll(1000, TimeUnit.MILLISECONDS);
              assertNotNull(op);
              ops.add(op);
          }
  
          running.set(false);
  
          if (useWaitForSpaceThread) {
              try {
                  waitForSpaceThread.join(1000);
              } catch (InterruptedException e) {
                  LOG.debug("Attempt: {} : {} waitForSpace never returned", attempt, memUsage);
                  waitForSpaceThread.interrupt();
                  waitForSpaceThread.join();
              }
          }
  
          removeThread.join();
          addThread.join();
  
          if (memUsage.getPercentUsage() != 0 || memUsage.getUsage() != memUsage.getPercentUsage()) {
              LOG.debug("Attempt: {} : {}", attempt, memUsage);
              LOG.debug("Operations: {}", ops);
              assertEquals(0, memUsage.getPercentUsage());
          }
      }
  }
  