| /** |
| * 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(); |
| } |
| } |