/**
* 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.hadoop.yarn.util;


public class ControlledClock implements Clock {
  private long time = -1;
  private final Clock actualClock;
  // Convenience for getting a controlled clock with overridden time
  public ControlledClock() {
    this(new SystemClock());
    setTime(0);
  }
  public ControlledClock(Clock actualClock) {
    this.actualClock = actualClock;
  }
  public synchronized void setTime(long time) {
    this.time = time;
  }
  public synchronized void reset() {
    time = -1;
  }
  public synchronized void tickSec(int seconds) {
    tickMsec(seconds * 1000L);
  }
  public synchronized void tickMsec(long millisec) {
    if (time == -1) {
      throw new IllegalStateException("ControlledClock setTime should be " +
          "called before incrementing time");
    }
    time = time + millisec;
  }

  @Override
  public synchronized long getTime() {
    if (time != -1) {
      return time;
    }
    return actualClock.getTime();
  }

}
