鍓嶈█
鍦ㄥ紑鍙戦」鐩湡闂?Kotlin 鍗忕▼鏄粡甯镐娇鐢ㄧ殑寮傛&骞跺彂缂栫▼妗嗘灦銆傚湪鍗忕▼浣跨敤杩囩▼涓紝鏃跺父浼氱敤鍒版寕璧峰嚱鏁帮紝鑰?delay 灏辨槸涓€涓寕璧峰嚱鏁帮紝鍦ㄥ緢澶氫笟鍔″満鏅腑浼氫娇鐢ㄥ埌锛屾湰鏂囬€氳繃婧愮爜鍒嗘瀽浜嗚В鍏惰儗鍚庣殑瀹炵幇鍘熺悊
鍒嗘瀽
涓句釜馃尠
閫氬父鎴戜滑鐨勪笟鍔″満鏅湁杩欑鎯呭喌锛岄渶瑕佸欢鏃舵墽琛屾煇浜涗换鍔?/p>
private suspend fun test() {
findViewLifecycleOwner()?.lifecycleScope?.launch() {
print("before delay")
//寤舵椂3s
delay(3000)
print("after delay")
}
}
delay 鍑芥暟鍒欎細鎸傝捣褰撳墠鍗忕▼锛屽苟涓斾細鍦?s鍚庤繘琛屾仮澶?br> 鍐嶆潵鐪嬬湅 delay 鍑芥暟鐨勫疄鐜?/p>
/**
* Delays coroutine for a given time without blocking a thread and resumes it after a specified time.
*
*/
public suspend fun delay(timeMillis: Long) {
if (timeMillis <= 0) return // don't delay
return suspendCancellableCoroutine sc@ { cont: CancellableContinuation<Unit> ->
// if timeMillis == Long.MAX_VALUE then just wait forever like awaitCancellation, don't schedule.
if (timeMillis < Long.MAX_VALUE) {
cont.context.delay.scheduleResumeAfterDelay(timeMillis, cont)
}
}
}
suspendCancellableCoroutine
鎴戜滑鍏堟潵鐪嬬湅 suspendCancellableCoroutine 鍑芥暟锛屽畠鏄?Kotlin 鍗忕▼搴撲腑鐨勪竴涓嚱鏁帮紝瀹冩槸涓€涓寕璧峰嚱鏁帮紝鐢ㄤ簬鍒涘缓涓€涓彲浠ヨ鍙栨秷鐨勬寕璧风偣銆?br> 杩欎釜鍑芥暟涔熸槸鍗忕▼涓粡甯镐娇鐢紝瀹冨彲浠ュ皢寮傛鐨勫洖璋冪敤鍚屾鐨勬柟寮忚〃杈惧嚭鏉ワ紝鍑忓皯鍥炶皟宓屽
public suspend inline fun <T> suspendCancellableCoroutine(
crossinline block: (CancellableContinuation<T>) -> Unit
): T =
suspendCoroutineUninterceptedOrReturn { uCont ->
val cancellable = CancellableContinuationImpl(uCont.intercepted(), resumeMode = MODE_CANCELLABLE)
/*
* For non-atomic cancellation we setup parent-child relationship immediately
* in case when `block` blocks the current thread (e.g. Rx2 with trampoline scheduler), but
* properly supports cancellation.
*/
cancellable.initCancellability()
block(cancellable)
cancellable.getResult()
}
鐒惰€?suspendCancellableCoroutine 鍑芥暟鍐呴儴鏄娇鐢ㄤ簡suspendCoroutineUninterceptedOrReturn 鍑芥暟瀹炵幇鐨勶紝鑰屼笖涔熸槸涓€涓寕璧峰嚱鏁?/p>
public suspend inline fun <T> suspendCoroutineUninterceptedOrReturn(crossinline block: (Continuation<T>) -> Any?): T {
contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) }
throw NotImplementedError("Implementation of suspendCoroutineUninterceptedOrReturn is intrinsic")
}
suspendCoroutineUninterceptedOrReturn 鍑芥暟娌℃湁瀹為檯鍐呭锛屾槸鍥犱负瀹冩槸缂栬瘧鍣ㄥ唴寤哄嚱鏁帮紝瀹冩槸鐢?Kotlin 缂栬瘧鍣ㄦ潵瀹炵幇鐨勩€備富瑕佷綔鐢ㄦ槸浼犻€掑崗绋嬩笂涓嬫枃锛屼互鍙婂垽鏂槸鍚︽寕璧风殑锛屾垨鑰呯洿鎺ヨ繑鍥炵粨鏋?br> 鍐嶄妇涓煂?br> 鍐欎釜馃憞鏂规硶锛岀劧鍚庤繘琛屽弽缂栬瘧鐪嬬湅
private suspend fun test2(){
suspendCancellableCoroutine<String> {
print("suspendCancellableCoroutine test")
}
}
鍙嶇紪璇戝悗
// 浼犻€掍簡 Continuation 涓婁笅鏂?
private final Object test2(Continuation $completion) {
int $i$f$suspendCancellableCoroutine = false;
int var4 = false;
//灏佽瀹炰綋
CancellableContinuationImpl cancellable$iv = new CancellableContinuationImpl(IntrinsicsKt.intercepted($completion), 1);
cancellable$iv.initCancellability();
CancellableContinuation it = (CancellableContinuation)cancellable$iv;
int var7 = false;
//鎵цblock浠ｇ爜
String var8 = "suspendCancellableCoroutine test";
System.out.print(var8);
//鑾峰彇鍗忕▼浣撹繑鍥炲€?
Object var10000 = cancellable$iv.getResult();
if (var10000 == IntrinsicsKt.getCOROUTINE_SUSPENDED()) {
DebugProbesKt.probeCoroutineSuspended($completion);
}
//鍒ゆ柇鏄惁鏄寕璧凤紝鏄殑璇濊繑鍥炴寕璧风姸鎬?
return var10000 == IntrinsicsKt.getCOROUTINE_SUSPENDED() var10000 : Unit.INSTANCE;
}
姝ｅ涓婇潰鎵€璇寸殑锛宻uspendCoroutineUninterceptedOrReturn 鍑芥暟鏄?strong>鏂板浜嗕紶閫掑崗绋嬩笂涓嬫枃锛屼互鍙婂垽鏂槸鍚︽寕璧风殑锛屾垨鑰呯洿鎺ヨ繑鍥炵粨鏋滅殑閫昏緫
鐭ラ亾浜?suspendCancellableCoroutine 鍑芥暟鐨勪綔鐢ㄥ悗锛屽啀鍥炶繃澶寸湅 delay 鍑芥暟
/**
* Delays coroutine for a given time without blocking a thread and resumes it after a specified time.
*
*/
public suspend fun delay(timeMillis: Long) {
if (timeMillis <= 0) return // don't delay
return suspendCancellableCoroutine sc@ { cont: CancellableContinuation<Unit> ->
// if timeMillis == Long.MAX_VALUE then just wait forever like awaitCancellation, don't schedule.
if (timeMillis < Long.MAX_VALUE) {
cont.context.delay.scheduleResumeAfterDelay(timeMillis, cont)
}
}
}
suspendCancellableCoroutine 鍑芥暟浼犻€掍簡灏佽鍚庣殑鍗忕▼瀵硅薄 cont锛屼互鍙婂垽鏂?cont 鏄惁浼氭墽琛屾寕璧?/p>
DefaultExecutor
鐪嬬湅 cont.context.delay鏄暐
//鑾峰彇delay
internal val CoroutineContext.delay: Delay get() = get(ContinuationInterceptor) asDelay ?: DefaultDelay
//榛樿瀹炵幇
internal actual val DefaultDelay: Delay = DefaultExecutor
@Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
internal actual object DefaultExecutor : EventLoopImplBase(), Runnable {
init {
incrementUseCount() // this event loop is never completed
}
... 鐪佺暐寰堝浠ｇ爜 ...
}
鍙互鐪嬭 cont.context.delay 鏈€缁堢殑瀹炵幇鏄?DefaultExecutor 锛屽畠缁ф壙浜咵ventLoopImplBase 鍜?Runnable
DefaultExecutor 鏄釜鍗曚緥锛岄噷杈瑰紑鍚簡绾跨▼锛屽苟涓旀娴嬮槦鍒楅噷浠诲姟鐨勬儏鍐垫潵鍐冲畾鏄惁闇€瑕佹寕璧风嚎绋嬭繘琛岀瓑寰?br>
鑰?scheduleResumeAfterDelay 鍑芥暟鏄?EventLoopImplBase 閲屽疄鐜扮殑
public override fun scheduleResumeAfterDelay(timeMillis: Long, continuation: CancellableContinuation<Unit>) {
val timeNanos = delayToNanos(timeMillis)
if (timeNanos < MAX_DELAY_NS) {
val now = nanoTime()
DelayedResumeTask(now + timeNanos, continuation).also { task ->
continuation.disposeOnCancellation(task)
schedule(now, task)
}
}
}
濡傛灉婊¤冻鏃堕棿鏉′欢锛屽垯鍒涘缓涓€涓欢杩熺殑task锛孌elayedResumeTask
鍏ラ槦鍒?/h3>
鐪?schedule 鍑芥暟
public fun schedule(now: Long, delayedTask: DelayedTask) {
when (scheduleImpl(now, delayedTask)) {
//unpark() 浼氬惎鍔ㄧ嚎绋?
SCHEDULE_OK -> if (shouldUnpark(delayedTask)) unpark()
SCHEDULE_COMPLETED -> reschedule(now, delayedTask)
SCHEDULE_DISPOSED -> {} // do nothing -- task was already disposed
else -> error("unexpected result")
}
}
private fun scheduleImpl(now: Long, delayedTask: DelayedTask): Int {
if (isCompleted) return SCHEDULE_COMPLETED
val delayedQueue = _delayed.value ?: run {
_delayed.compareAndSet(null, DelayedTaskQueue(now))
_delayed.value!!
}
//鍏ラ槦鍒?
return delayedTask.scheduleTask(now, delayedQueue, this)
}
瀹為檯灏辨槸鎶?DelayedResumeTask 鏀捐繘 _delayed 闃熷垪閲岄潰锛屽苟涓斿惎鍔?DefaultExecutor 閲岀殑绾跨▼锛堝鏋滄病鏈夊紑鍚殑璇濓級
_delayed 鏄瓨鍌ㄥ欢杩熸墽琛?task 鐨勯槦鍒?br>
杩樻湁涓€涓?_queue 鏄槸瀛樺偍姝ｅ父浠诲姟鐨勯槦鍒?/p>
internal abstract class EventLoopImplBase: EventLoopImplPlatform(), Delay {
// null | CLOSED_EMPTY | task | Queue<Runnable>
private val _queue = atomic<Any?>(null)
// Allocated only only once
private val _delayed = atomic<DelayedTaskQueue?>(null)
...
}
鏃㈢劧涓婇潰鏈夊叆闃熷垪锛屽氨鏈夊嚭闃熷垪
鍑洪槦鍒?/h3>
鍥炲埌鍒氬垰璇寸殑鍚姩浜?DefaultExecutor 閲岀殑绾跨▼锛岀湅鐪嬪畠鐨?run 鏂规硶
override fun run() {
ThreadLocalEventLoop.setEventLoop(this)
registerTimeLoopThread()
try {
var shutdownNanos = Long.MAX_VALUE
if (!notifyStartup()) return
while (true) {
Thread.interrupted() // just reset interruption flag
//鍙栭槦鍒楁牳蹇冧唬鐮?
var parkNanos = processNextEvent()
if (parkNanos == Long.MAX_VALUE) {
// nothing to do, initialize shutdown timeout
val now = nanoTime()
if (shutdownNanos == Long.MAX_VALUE) shutdownNanos = now + KEEP_ALIVE_NANOS
val tillShutdown = shutdownNanos - now
if (tillShutdown <= 0) return // shut thread down
parkNanos = parkNanos.coerceAtMost(tillShutdown)
} else
shutdownNanos = Long.MAX_VALUE
//濡傛灉杩斿洖鐨勬椂闂村ぇ浜?
if (parkNanos > 0) {
// check if shutdown was requested and bail out in this case
if (isShutdownRequested) return
//鎸傝捣绾跨▼涓€娈垫椂闂?
parkNanos(this, parkNanos)
}
}
} finally {
_thread = null // this thread is dead
acknowledgeShutdownIfNeeded()
unregisterTimeLoopThread()
// recheck if queues are empty after _thread reference was set to null (!!!)
if (!isEmpty) thread // recreate thread if it is needed
}
}
鍙栧嚭闃熷垪閲岀殑 task 閫昏緫鏄湪 processNextEvent() 鍑芥暟涓紝鐪嬬湅瀹冪殑瀹炵幇
override fun processNextEvent(): Long {
// unconfined events take priority
if (processUnconfinedEvent()) return 0
// queue all delayed tasks that are due to be executed
val delayed = _delayed.value
if (delayed != null && !delayed.isEmpty) {
val now = nanoTime()
while (true) {
// make sure that moving from delayed to queue removes from delayed only after it is added to queue
// to make sure that 'isEmpty' and `nextTime` that check both of them
// do not transiently report that both delayed and queue are empty during move
delayed.removeFirstIf {
if (it.timeToExecute(now)) {
// 鍔犲叆姝ｅ父浠诲姟闃熷垪
enqueueImpl(it)
} else
false
} ?: break // quit loop when nothing more to remove or enqueueImpl returns false on "isComplete"
}
}
// then process one event from queue
val task = dequeue()
if (task != null) {
task.run()
return 0
}
//杩斿洖绾跨▼闇€瑕佹寕璧风殑鏃堕棿
return nextTime
}
protected override val nextTime: Long
get() {
if (super.nextTime == 0L) return 0L
val queue = _queue.value
when {
queue === null -> {} // empty queue -- proceed
queue is Queue<*> -> if (!queue.isEmpty) return 0 // non-empty queue
queue === CLOSED_EMPTY -> return Long.MAX_VALUE // no more events -- closed
else -> return 0 // non-empty queue
}
val nextDelayedTask = _delayed.value?.peek() ?: return Long.MAX_VALUE
return (nextDelayedTask.nanoTime - nanoTime()).coerceAtLeast(0)
鍏朵腑娴佺▼鏄細
- 鏈変釜姝诲惊鐜竴鐩村湪浠?_delayed 闃熷垪閲屽彇寤惰繜 task锛屽鏋滃垽鏂欢杩熸椂闂村凡缁忓埌浜嗘墠浼氬姞鍏ユ甯镐换鍔￠槦鍒楅噷涓旂Щ闄?/li>
- 鐩村埌鍙栦笉鍑哄欢杩?task 浜嗘墠璺冲嚭寰幆
- 鐒跺悗浠庢甯搁槦鍒楅噷鍙栧嚭浠诲姟杩涜鎵ц
- 鎵ц浠诲姟灏辨槸鍦ㄦ墽琛?DelayedResumeTask 绫婚噷鐨?run 鏂规硶
private inner class DelayedResumeTask(
nanoTime: Long,
private val cont: CancellableContinuation<Unit>
) : DelayedTask(nanoTime) {
override fun run() { with(cont) { resumeUndispatched(Unit) } }
override fun toString(): String = super.toString() + cont.toString()
}
- 鍙互鏄湅瑙佽皟鐢ㄤ簡 resumeUndispatched() 鍑芥暟锛屼娇鐢ㄥ崗绋嬭兘缁忓父鐪嬭鎴栬€呬娇鐢?resumexxx 鍑芥暟锛屽畠灏辨槸鍗忕▼涓殑鎭㈠锛屽搴斾簬鎸傝捣锛屽畠浠悊搴旀槸鎴愬鍑虹幇鐨?/li>
- resumeUndispatched() 鍑芥暟鏈€缁堢殑瀹炵幇灏辨槸涓€寮€濮嬪皝瑁?Continuation 鍗忕▼涓?CancellableContinuationImpl 鐨勫疄鐜帮紝鍗虫槸 cont 瀵硅薄锛屾渶缁堟仮澶嶄簡鍗忕▼鐨勮繍琛?/li>
//鎭㈠鍗忕▼
override fun CoroutineDispatcher.resumeUndispatched(value: T) {
val dc = delegate asDispatchedContinuation
resumeImpl(value, if (dc?.dispatcher === this) MODE_UNDISPATCHED else resumeMode)
}
processNextEvent() 鍑芥暟鐨勮繑鍥炲€?/h3>
- 鏈€鍚庤繑鍥炰笅涓€涓?nextDelayedTask 鐨勫欢杩熸椂闂达紝鍗虫槸绾跨▼鎸傝捣鏃堕棿
- 濡傛灉杩斿洖鐨勬椂闂村ぇ浜?锛屽垯鏈€缁堜細璋冪敤 LockSupport.parkNanos()锛屽皢绾跨▼鎸傝捣涓€娈垫椂闂达紝鐩村埌寤惰繜鏃堕棿缁撴潫銆?br>
婧愮爜鐪嬪埌杩欓噷灏辫兘鐭ラ亾 delay 鍑芥暟鐨勮儗鍚庤繍琛屽師鐞嗕簡锛屾渶缁堟槸鐢?DefaultExecutor 绾跨▼鏁翠綋鎺у埗鎸傝捣鍜屾仮澶嶏紝鑰屼笖涓嶄細闃诲褰撳墠璋冪敤鏂圭殑绾跨▼銆?/li>
鎬荤粨
delay 鍑芥暟鐨勬€讳綋娴佺▼鏄?/p>
- 鍒涘缓涓€涓欢杩熶换鍔★紙DelayedResumeTask锛夛紝瀹冨寘鍚渶瑕佸欢杩熸墽琛岀殑閫昏緫鍜屾墽琛屾椂闂翠俊鎭€?/li>
- 灏嗗欢杩熶换鍔℃坊鍔犲埌寤惰繜闃熷垪锛坃delayed锛変腑銆?/li>
- 鍦ㄧ瓑寰呭欢杩熶换鍔℃墽琛屼箣鍓嶏紝鍗忕▼浼氳鏆傚仠锛堟寕璧凤級銆?/li>
- 鏈変竴涓崟鐙殑 DefaultExecutor 绾跨▼瀹氭湡妫€鏌ュ欢杩熼槦鍒椾腑鐨勪换鍔★紝濡傛灉浠诲姟鐨勫欢杩熸椂闂村埌浜嗭紝灏变細灏嗕换鍔′粠寤惰繜闃熷垪涓Щ闄わ紝骞跺皢鍏舵斁鍏ユ墽琛岄槦鍒椾腑銆?/li>
- 鎵ц闃熷垪涓彇鍑轰换鍔★紝骞惰皟鐢ㄥ叾鎵ц閫昏緫銆?/li>
- 鎵ц浠诲姟鐨勮繃绋嬩篃灏辨槸鍗忕▼鐨勬仮澶嶈繃绋嬶紝涓€鏃︿换鍔″紑濮嬫墽琛岋紝鍗忕▼浼氳鎭㈠锛岀户缁墽琛屽叾鍚庣画鐨勯€昏緫銆?/li>