org.apache.spark.util.Clock.scala Maven / Gradle / Ivy
/*
* 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.spark.util
/**
* An interface to represent clocks, so that they can be mocked out in unit tests.
*/
private[spark] trait Clock {
def getTimeMillis(): Long
def waitTillTime(targetTime: Long): Long
}
/**
* A clock backed by the actual time from the OS as reported by the `System` API.
*/
private[spark] class SystemClock extends Clock {
val minPollTime = 25L
/**
* @return the same time (milliseconds since the epoch)
* as is reported by `System.currentTimeMillis()`
*/
def getTimeMillis(): Long = System.currentTimeMillis()
/**
* @param targetTime block until the current time is at least this value
* @return current system time when wait has completed
*/
def waitTillTime(targetTime: Long): Long = {
var currentTime = 0L
currentTime = System.currentTimeMillis()
var waitTime = targetTime - currentTime
if (waitTime <= 0) {
return currentTime
}
val pollTime = math.max(waitTime / 10.0, minPollTime).toLong
while (true) {
currentTime = System.currentTimeMillis()
waitTime = targetTime - currentTime
if (waitTime <= 0) {
return currentTime
}
val sleepTime = math.min(waitTime, pollTime)
Thread.sleep(sleepTime)
}
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}
}