lang/java/reef-runtime-yarn/src/main/java/org/apache/reef/runtime/yarn/driver/ContainerRequestCounter.java

/*
 * 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.reef.runtime.yarn.driver;

import org.apache.reef.annotations.audience.DriverSide;
import org.apache.reef.annotations.audience.Private;

import javax.inject.Inject;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Used to keep track of resource requests.
 */
@Private
@DriverSide
final class ContainerRequestCounter {
  private static final Logger LOG = Logger.getLogger(ContainerRequestCounter.class.getName());

  private int counter = 0;

  @Inject
  ContainerRequestCounter() {
    LOG.log(Level.FINEST, "Instantiated 'ContainerRequestCounter'");
  }

  /**
   * Increment the counter by the given amount.
   *
   * @param number
   */
  synchronized void incrementBy(final int number) {
    this.counter += number;
  }

  /**
   * @return the current value of the counter.
   */
  synchronized int get() {
    return this.counter;
  }

  /**
   * Decrement the counter by 1.
   */
  synchronized void decrement() {
    if (this.counter <= 0) {
      LOG.log(Level.WARNING, "requestedContainerCount cannot go below 0");
      this.counter = 0;
    } else {
      this.counter -= 1;
    }
  }

}