Kotlin 协程的取消机制详细解读

suspend fun main(): Unit = coroutineScope {
    val job = launch {
        repeat(1000) { i ->
            println("job: I'm sleeping $i ...")
            delay(500L)
        }
    }
    delay(1300L) // delay a bit
    println("main: I'm tired of waiting!")
    job.cancel() // cancels the job
    job.join() // waits for job's completion 
    println("main: Now I can quit.")
}

suspend fun main(): Unit = coroutineScope {
    val startTime = System.currentTimeMillis()
    val job = launch(Dispatchers.Default) {
        var nextPrintTime = startTime
        var i = 0
        while (i < 5) { // computation loop, just wastes CPU
            // print a message twice a second
            if (System.currentTimeMillis() >= nextPrintTime) {
                println("job: I'm sleeping ${i++} ...")
                nextPrintTime += 500L
            }
        }
    }
    delay(1300L) // delay a bit
    println("main: I'm tired of waiting!")
    job.cancelAndJoin() // cancels the job and waits for its completion
    println("main: Now I can quit.")
}

suspend fun main(): Unit = coroutineScope {
    val job = launch(Dispatchers.Default) {
        repeat(5) { i ->
            try {
                // print a message twice a second
                println("job: I'm sleeping $i ...")
                delay(500)
            } catch (e: Exception) {
                // log the exception
                println(e)
            }
        }
    }
    delay(1300L) // delay a bit
    println("main: I'm tired of waiting!")
    job.cancelAndJoin() // cancels the job and waits for its completion
    println("main: Now I can quit.")
}

suspend fun main(): Unit = coroutineScope {
    val job = launch(Dispatchers.Default) {
        repeat(5) { i ->
            // print a message twice a second
            println("job: I'm sleeping $i ...")
            delay(500)
        }
    }
    delay(1300L) // delay a bit
    println("main: I'm tired of waiting!")
    job.cancelAndJoin() // cancels the job and waits for its completion
    println("main: Now I can quit.")
}

suspend fun main(): Unit = coroutineScope {
    val startTime = System.currentTimeMillis()
    val job = launch(Dispatchers.Default) {
        var nextPrintTime = startTime
        var i = 0
        while (isActive) { // cancellable computation loop
            // print a message twice a second
            if (System.currentTimeMillis() >= nextPrintTime) {
                println("job: I'm sleeping ${i++} ...")
                nextPrintTime += 500L
            }
        }
    }
    delay(1300L) // delay a bit
    println("main: I'm tired of waiting!")
    job.cancelAndJoin() // cancels the job and waits for its completion
    println("main: Now I can quit.")
}

val job = launch {
    try {
        repeat(1000) { i ->
            println("job: I'm sleeping $i ...")
            delay(500L)
        }
    } finally {
        println("job: I'm running finally")
    }
}
delay(1300L) // delay a bit
println("main: I'm tired of waiting!")
job.cancelAndJoin() // cancels the job and waits for its completion
println("main: Now I can quit.")

val job = launch {
    try {
        repeat(1000) { i ->
            println("job: I'm sleeping $i ...")
            delay(500L)
        }
    } finally {
        withContext(NonCancellable) {
            println("job: I'm running finally")
            delay(1000L)
            println("job: And I've just delayed for 1 sec because I'm non-cancellable")
        }
    }
}
delay(1300L) // delay a bit
println("main: I'm tired of waiting!")
job.cancelAndJoin() // cancels the job and waits for its completion
println("main: Now I can quit.")

public actual typealias CancellationException = java.util.concurrent.CancellationException

public interface CoroutineExceptionHandler : CoroutineContext.Element {
    /**
     * Key for [CoroutineExceptionHandler] instance in the coroutine context.
     */
    public companion object Key : CoroutineContext.Key<CoroutineExceptionHandler>
    /**
     * Handles uncaught [exception] in the given [context]. It is invoked
     * if coroutine has an uncaught exception.
     */
    public fun handleException(context: CoroutineContext, exception: Throwable)
}

withTimeout(1300L) {
    repeat(1000) { i ->
        println("I'm sleeping $i ...")
        delay(500L)
    }
}

val result = withTimeoutOrNull(1300L) {
    repeat(1000) { i ->
        println("I'm sleeping $i ...")
        delay(500L)
    }
    "Done" // will get cancelled before it produces this result
}
println("Result is $result")

var acquired = 0
class Resource {
    init { acquired++ } // Acquire the resource
    fun close() { acquired-- } // Release the resource
}
fun main() {
    runBlocking {
        repeat(100_000) { // Launch 100K coroutines
            launch { 
                val resource = withTimeout(60) { // Timeout of 60 ms
                    delay(50) // Delay for 50 ms
                    Resource() // Acquire a resource and return it from withTimeout block     
                }
                resource.close() // Release the resource
            }
        }
    }
    // Outside of runBlocking all coroutines have completed
    println(acquired) // Print the number of resources still acquired
}

fun main() {
    runBlocking {
        repeat(100_000) { // Launch 100K coroutines
            launch {
                var resource: Resource? = null // Not acquired yet
                try {
                    withTimeout(60) { // Timeout of 60 ms
                        delay(50) // Delay for 50 ms
                        resource = Resource() // Store a resource to the variable if acquired
                    }
                    // We can do something else with the resource here
                } finally {
                    resource?.close() // Release the resource if it was acquired
                }
            }
        }
    }
// Outside of runBlocking all coroutines have completed
    println(acquired) // Print the number of resources still acquired
}

class Solution {
    suspend fun func(): String {
        return "测试 suspend 关键字"
    }
}

class Solution {
    fun func(): String {
        return "测试 suspend 关键字"
    }
}

// 普通的方法
public final class Solution {
    public static final int $stable = LiveLiterals$SolutionKt.INSTANCE.Int$class-Solution();
    @NotNull
    public final String func() {
        return LiveLiterals$SolutionKt.INSTANCE.String$fun-func$class-Solution();
    }
}
// 带有 suspend 关键字的方法
public final class Solution {
    public static final int $stable = LiveLiterals$SolutionKt.INSTANCE.Int$class-Solution();
    @Nullable
    public final Object func(@NotNull Continuation<? super String> $completion) {
        return LiveLiterals$SolutionKt.INSTANCE.String$fun-func$class-Solution();
    }
}

val a: String = func()
print(a)

func { a ->
    print(a)
}

生成的函数 {
    if(!当前协程.isActive) {
        throw CancellationException()
    }
    // ... 这里是函数真实逻辑
}

public interface Continuation<in T> {
    /**
     * The context of the coroutine that corresponds to this continuation.
     */
    public val context: CoroutineContext
    /**
     * 恢复相应协程的执行，将成功或失败的结果作为最后一个挂起点的返回值传递。
     */
    public fun resumeWith(result: Result<T>)
}

        Function1 lambda = (Function1)(new Function1((Continuation)null) {
            int label;
            @Nullable
            public final Object invokeSuspend(@NotNull Object $result) {
                byte text;
                @BlockTag1: {
                    Object result;
                    @BlockTag2: {
                        result = IntrinsicsKt.getCOROUTINE_SUSPENDED();
                        switch(this.label) {
                            case 0:
                                ResultKt.throwOnFailure($result);
                                this.label = 1;
                                if (SuspendTestKt.dummy(this) == result) {
                                    return result;
                                }
                                break;
                            case 1:
                                ResultKt.throwOnFailure($result);
                                break;
                            case 2:
                                ResultKt.throwOnFailure($result);
                                break @BlockTag2;
                            case 3:
                                ResultKt.throwOnFailure($result);
                                break @BlockTag1;
                            default:
                                throw new IllegalStateException("call to 'resume' before 'invoke' with coroutine");
                        }
                        text = 1;
                        System.out.println(text);
                        this.label = 2;
                        if (SuspendTestKt.dummy(this) == result) {
                            return result;
                        }
                    }
                    text = 2;
                    System.out.println(text);
                    this.label = 3;
                    if (SuspendTestKt.dummy(this) == result) {
                        return result;
                    }
                }
                text = 3;
                System.out.println(text);
                return Unit.INSTANCE;
            }
            @NotNull
            public final Continuation create(@NotNull Continuation completion) {
                Intrinsics.checkNotNullParameter(completion, "completion");
                Function1 funcation = new <anonymous constructor>(completion);
                return funcation;
            }
            public final Object invoke(Object object) {
                return ((<undefinedtype>)this.create((Continuation)object)).invokeSuspend(Unit.INSTANCE);
            }
        });

@PublishedApi
@SinceKotlin("1.3")
internal fun Result<*>.throwOnFailure() {
    if (value is Result.Failure) throw value.exception
}

        @Suppress("INAPPLICABLE_JVM_NAME")
        @InlineOnly
        @JvmName("success")
        public inline fun <T> success(value: T): Result<T> =
            Result(value)
        /**
         * Returns an instance that encapsulates the given [Throwable] [exception] as failure.
         */
        @Suppress("INAPPLICABLE_JVM_NAME")
        @InlineOnly
        @JvmName("failure")
        public inline fun <T> failure(exception: Throwable): Result<T> =
            Result(createFailure(exception))