1 /* <lambda>null2 * Copyright 2016-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license. 3 */ 4 @file:OptIn(ExperimentalContracts::class) 5 @file:Suppress("DEPRECATION_ERROR") 6 7 package kotlinx.coroutines 8 9 import kotlinx.coroutines.internal.* 10 import kotlinx.coroutines.intrinsics.* 11 import kotlin.contracts.* 12 import kotlin.coroutines.* 13 import kotlin.coroutines.intrinsics.* 14 import kotlin.jvm.* 15 16 /** 17 * Creates a _supervisor_ job object in an active state. 18 * Children of a supervisor job can fail independently of each other. 19 * 20 * A failure or cancellation of a child does not cause the supervisor job to fail and does not affect its other children, 21 * so a supervisor can implement a custom policy for handling failures of its children: 22 * 23 * * A failure of a child job that was created using [launch][CoroutineScope.launch] can be handled via [CoroutineExceptionHandler] in the context. 24 * * A failure of a child job that was created using [async][CoroutineScope.async] can be handled via [Deferred.await] on the resulting deferred value. 25 * 26 * If [parent] job is specified, then this supervisor job becomes a child job of its parent and is cancelled when its 27 * parent fails or is cancelled. All this supervisor's children are cancelled in this case, too. The invocation of 28 * [cancel][Job.cancel] with exception (other than [CancellationException]) on this supervisor job also cancels parent. 29 * 30 * @param parent an optional parent job. 31 */ 32 @Suppress("FunctionName") 33 public fun SupervisorJob(parent: Job? = null) : CompletableJob = SupervisorJobImpl(parent) 34 35 /** @suppress Binary compatibility only */ 36 @Suppress("FunctionName") 37 @Deprecated(level = DeprecationLevel.HIDDEN, message = "Since 1.2.0, binary compatibility with versions <= 1.1.x") 38 @JvmName("SupervisorJob") 39 public fun SupervisorJob0(parent: Job? = null) : Job = SupervisorJob(parent) 40 41 /** 42 * Creates a [CoroutineScope] with [SupervisorJob] and calls the specified suspend block with this scope. 43 * The provided scope inherits its [coroutineContext][CoroutineScope.coroutineContext] from the outer scope, but overrides 44 * context's [Job] with [SupervisorJob]. 45 * 46 * A failure of a child does not cause this scope to fail and does not affect its other children, 47 * so a custom policy for handling failures of its children can be implemented. See [SupervisorJob] for details. 48 * A failure of the scope itself (exception thrown in the [block] or cancellation) fails the scope with all its children, 49 * but does not cancel parent job. 50 */ 51 public suspend fun <R> supervisorScope(block: suspend CoroutineScope.() -> R): R { 52 contract { 53 callsInPlace(block, InvocationKind.EXACTLY_ONCE) 54 } 55 return suspendCoroutineUninterceptedOrReturn { uCont -> 56 val coroutine = SupervisorCoroutine(uCont.context, uCont) 57 coroutine.startUndispatchedOrReturn(coroutine, block) 58 } 59 } 60 61 private class SupervisorJobImpl(parent: Job?) : JobImpl(parent) { childCancellednull62 override fun childCancelled(cause: Throwable): Boolean = false 63 } 64 65 private class SupervisorCoroutine<in T>( 66 context: CoroutineContext, 67 uCont: Continuation<T> 68 ) : ScopeCoroutine<T>(context, uCont) { 69 override fun childCancelled(cause: Throwable): Boolean = false 70 } 71