1/* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18package org.apache.spark.util 19 20/** 21 * An interface to represent clocks, so that they can be mocked out in unit tests. 22 */ 23private[spark] trait Clock { 24 def getTimeMillis(): Long 25 def waitTillTime(targetTime: Long): Long 26} 27 28/** 29 * A clock backed by the actual time from the OS as reported by the `System` API. 30 */ 31private[spark] class SystemClock extends Clock { 32 33 val minPollTime = 25L 34 35 /** 36 * @return the same time (milliseconds since the epoch) 37 * as is reported by `System.currentTimeMillis()` 38 */ 39 def getTimeMillis(): Long = System.currentTimeMillis() 40 41 /** 42 * @param targetTime block until the current time is at least this value 43 * @return current system time when wait has completed 44 */ 45 def waitTillTime(targetTime: Long): Long = { 46 var currentTime = 0L 47 currentTime = System.currentTimeMillis() 48 49 var waitTime = targetTime - currentTime 50 if (waitTime <= 0) { 51 return currentTime 52 } 53 54 val pollTime = math.max(waitTime / 10.0, minPollTime).toLong 55 56 while (true) { 57 currentTime = System.currentTimeMillis() 58 waitTime = targetTime - currentTime 59 if (waitTime <= 0) { 60 return currentTime 61 } 62 val sleepTime = math.min(waitTime, pollTime) 63 Thread.sleep(sleepTime) 64 } 65 -1 66 } 67} 68