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/*
* Copyright 2016-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
*/
package kotlinx.coroutines
import java.io.*
import java.util.concurrent.*
import java.util.concurrent.locks.*
private const val SHUTDOWN_TIMEOUT = 1000L
internal inline fun withVirtualTimeSource(log: PrintStream? = null, block: () -> Unit) {
DefaultExecutor.shutdown(SHUTDOWN_TIMEOUT) // shutdown execution with old time source (in case it was working)
val testTimeSource = VirtualTimeSource(log)
timeSource = testTimeSource
DefaultExecutor.ensureStarted() // should start with new time source
try {
block()
} finally {
DefaultExecutor.shutdown(SHUTDOWN_TIMEOUT)
testTimeSource.shutdown()
timeSource = null // restore time source
}
}
private const val NOT_PARKED = -1L
private class ThreadStatus {
@Volatile @JvmField
var parkedTill = NOT_PARKED
@Volatile @JvmField
var permit = false
var registered = 0
override fun toString(): String = "parkedTill = ${TimeUnit.NANOSECONDS.toMillis(parkedTill)} ms, permit = $permit"
}
private const val MAX_WAIT_NANOS = 10_000_000_000L // 10s
private const val REAL_TIME_STEP_NANOS = 200_000_000L // 200 ms
private const val REAL_PARK_NANOS = 10_000_000L // 10 ms -- park for a little to better track real-time
@Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
internal class VirtualTimeSource(
private val log: PrintStream?
) : TimeSource {
private val mainThread: Thread = Thread.currentThread()
private var checkpointNanos: Long = System.nanoTime()
@Volatile
private var isShutdown = false
@Volatile
private var time: Long = 0
private var trackedTasks = 0
private val threads = ConcurrentHashMap<Thread, ThreadStatus>()
override fun currentTimeMillis(): Long = TimeUnit.NANOSECONDS.toMillis(time)
override fun nanoTime(): Long = time
override fun wrapTask(block: Runnable): Runnable {
trackTask()
return Runnable {
try { block.run() }
finally { unTrackTask() }
}
}
@Synchronized
override fun trackTask() {
trackedTasks++
}
@Synchronized
override fun unTrackTask() {
assert(trackedTasks > 0)
trackedTasks--
}
@Synchronized
override fun registerTimeLoopThread() {
val status = threads.getOrPut(Thread.currentThread()) { ThreadStatus() }!!
status.registered++
}
@Synchronized
override fun unregisterTimeLoopThread() {
val currentThread = Thread.currentThread()
val status = threads[currentThread]!!
if (--status.registered == 0) {
threads.remove(currentThread)
wakeupAll()
}
}
override fun parkNanos(blocker: Any, nanos: Long) {
if (nanos <= 0) return
val status = threads[Thread.currentThread()]!!
assert(status.parkedTill == NOT_PARKED)
status.parkedTill = time + nanos.coerceAtMost(MAX_WAIT_NANOS)
while (true) {
checkAdvanceTime()
if (isShutdown || time >= status.parkedTill || status.permit) {
status.parkedTill = NOT_PARKED
status.permit = false
break
}
LockSupport.parkNanos(blocker, REAL_PARK_NANOS)
}
}
override fun unpark(thread: Thread) {
val status = threads[thread] ?: return
status.permit = true
LockSupport.unpark(thread)
}
@Synchronized
private fun checkAdvanceTime() {
if (isShutdown) return
val realNanos = System.nanoTime()
if (realNanos > checkpointNanos + REAL_TIME_STEP_NANOS) {
checkpointNanos = realNanos
val minParkedTill = minParkedTill()
time = (time + REAL_TIME_STEP_NANOS).coerceAtMost(if (minParkedTill < 0) Long.MAX_VALUE else minParkedTill)
logTime("R")
wakeupAll()
return
}
if (threads[mainThread] == null) return
if (trackedTasks != 0) return
val minParkedTill = minParkedTill()
if (minParkedTill <= time) return
time = minParkedTill
logTime("V")
wakeupAll()
}
private fun logTime(s: String) {
log?.println("[$s: Time = ${TimeUnit.NANOSECONDS.toMillis(time)} ms]")
}
private fun minParkedTill(): Long =
threads.values.map { if (it.permit) NOT_PARKED else it.parkedTill }.min() ?: NOT_PARKED
@Synchronized
fun shutdown() {
isShutdown = true
wakeupAll()
while (!threads.isEmpty()) (this as Object).wait()
}
private fun wakeupAll() {
threads.keys.forEach { LockSupport.unpark(it) }
(this as Object).notifyAll()
}
}
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