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 java.util.concurrent.TimeUnit;
  
  /**
   * Used to keep track of how much of something is being used so that a
   * productive working set usage can be controlled. Main use case is manage
   * memory usage.
   *
   * @org.apache.xbean.XBean
   *
   */
  public class MemoryUsage extends Usage<MemoryUsage> {
  
      private long usage;
  
      public MemoryUsage() {
          this(null, null);
      }
  
      /**
       * Create the memory manager linked to a parent. When the memory manager is
       * linked to a parent then when usage increased or decreased, the parent's
       * usage is also increased or decreased.
       *
       * @param parent
       */
      public MemoryUsage(MemoryUsage parent) {
          this(parent, "default");
      }
  
      public MemoryUsage(String name) {
          this(null, name);
      }
  
      public MemoryUsage(MemoryUsage parent, String name) {
          this(parent, name, 1.0f);
      }
  
      public MemoryUsage(MemoryUsage parent, String name, float portion) {
          super(parent, name, portion);
      }
  
      /**
       * @throws InterruptedException
       */
      @Override
      public void waitForSpace() throws InterruptedException {
          if (parent != null) {
              parent.waitForSpace();
          }
          usageLock.readLock().lock();
          try {
              if (percentUsage >= 100 && isStarted()) {
                  usageLock.readLock().unlock();
                  usageLock.writeLock().lock();
                  try {
                      while (percentUsage >= 100 && isStarted()) {
                          waitForSpaceCondition.await();
                      }
                  } finally {
                      usageLock.writeLock().unlock();
                      usageLock.readLock().lock();
                  }
              }
  
              if (percentUsage >= 100 && !isStarted()) {
                  throw new InterruptedException("waitForSpace stopped during wait.");
              }
          } finally {
              usageLock.readLock().unlock();
          }
      }
  
      /**
       * @param timeout
       * @throws InterruptedException
       * @return true if space
       */
      @Override
      public boolean waitForSpace(final long timeout) throws InterruptedException {
          if (parent != null) {
              if (!parent.waitForSpace(timeout)) {
                  return false;
              }
          }
          usageLock.readLock().lock();
          try {
              if (percentUsage >= 100) {
                  usageLock.readLock().unlock();
                  usageLock.writeLock().lock();
                  try {
                      final long deadline = timeout > 0 ? System.currentTimeMillis() + timeout : Long.MAX_VALUE;
                      long timeleft = deadline;
                      while (percentUsage >= 100 && timeleft > 0) {
                          waitForSpaceCondition.await(Math.min(getPollingTime(), timeleft), TimeUnit.MILLISECONDS);
                          timeleft = deadline - System.currentTimeMillis();
                      }
                  } finally {
                      usageLock.writeLock().unlock();
                      usageLock.readLock().lock();
                  }
              }
  
              return percentUsage < 100;
          } finally {
              usageLock.readLock().unlock();
          }
      }
  
      @Override
      public boolean isFull() {
          if (parent != null && parent.isFull()) {
              return true;
          }
          usageLock.readLock().lock();
          try {
              return percentUsage >= 100;
          } finally {
              usageLock.readLock().unlock();
          }
      }
  
      /**
       * Tries to increase the usage by value amount but blocks if this object is
       * currently full.
       *
       * @param value
       * @throws InterruptedException
       */
      public void enqueueUsage(long value) throws InterruptedException {
          waitForSpace();
          increaseUsage(value);
      }
  
      /**
       * Increases the usage by the value amount.
       *
       * @param value
       */
      public void increaseUsage(long value) {
          if (value == 0) {
              return;
          }
  
          usageLock.writeLock().lock();
          try {
              usage += value;
              setPercentUsage(caclPercentUsage());
          } finally {
              usageLock.writeLock().unlock();
          }
  
          if (parent != null) {
              parent.increaseUsage(value);
          }
      }
  
      /**
       * Decreases the usage by the value amount.
       *
       * @param value
       */
      public void decreaseUsage(long value) {
          if (value == 0) {
              return;
          }
  
          usageLock.writeLock().lock();
          try {
              usage -= value;
              setPercentUsage(caclPercentUsage());
          } finally {
              usageLock.writeLock().unlock();
          }
  
          if (parent != null) {
              parent.decreaseUsage(value);
          }
      }
  
      @Override
      protected long retrieveUsage() {
          return usage;
      }
  
      @Override
      public long getUsage() {
          return usage;
      }
  
      public void setUsage(long usage) {
          this.usage = usage;
      }
  
      public void setPercentOfJvmHeap(int percentOfJvmHeap) {
          if (percentOfJvmHeap > 0) {
              setLimit(Math.round(Runtime.getRuntime().maxMemory() * percentOfJvmHeap / 100.0));
          }
      }
  }
  