/**
* 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;
import org.apache.hadoop.classification.InterfaceAudience.Public;
import org.apache.hadoop.classification.InterfaceStability.Evolving;
import org.apache.hadoop.util.Time;
/**
* A monotonic clock from some arbitrary time base in the past, counting in
* milliseconds, and not affected by settimeofday or similar system clock
* changes.
* This is appropriate to use when computing how much longer to wait for an
* interval to expire.
* This function can return a negative value and it must be handled correctly
* by callers. See the documentation of System#nanoTime for caveats.
*/
@Public
@Evolving
public class MonotonicClock implements Clock {
/**
* Get current time from some arbitrary time base in the past, counting in
* milliseconds, and not affected by settimeofday or similar system clock
* changes.
* @return a monotonic clock that counts in milliseconds.
*/
public long getTime() {
return Time.monotonicNow();
}
}