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Coroutines support libraries for Kotlin
/*
* Copyright 2016-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
*/
@file:Suppress("DEPRECATION_ERROR")
package kotlinx.coroutines
import kotlinx.coroutines.CoroutineStart.*
import kotlinx.coroutines.intrinsics.*
import kotlin.coroutines.*
import kotlin.jvm.*
/**
* Abstract base class for implementation of coroutines in coroutine builders.
*
* This class implements completion [Continuation], [Job], and [CoroutineScope] interfaces.
* It stores the result of continuation in the state of the job.
* This coroutine waits for children coroutines to finish before completing and
* fails through an intermediate _failing_ state.
*
* The following methods are available for override:
*
* * [onStart] is invoked when the coroutine was created in non-active state and is being [started][Job.start].
* * [onCancelling] is invoked as soon as the coroutine starts being cancelled for any reason (or completes).
* * [onCompleted] is invoked when the coroutine completes with a value.
* * [onCancelled] in invoked when the coroutine completes with an exception (cancelled).
*
* @param parentContext the context of the parent coroutine.
* @param active when `true` (by default), the coroutine is created in the _active_ state, otherwise it is created in the _new_ state.
* See [Job] for details.
*
* @suppress **This an internal API and should not be used from general code.**
*/
@InternalCoroutinesApi
public abstract class AbstractCoroutine(
/**
* The context of the parent coroutine.
*/
@JvmField
protected val parentContext: CoroutineContext,
active: Boolean = true
) : JobSupport(active), Job, Continuation, CoroutineScope {
/**
* The context of this coroutine that includes this coroutine as a [Job].
*/
@Suppress("LeakingThis")
public final override val context: CoroutineContext = parentContext + this
/**
* The context of this scope which is the same as the [context] of this coroutine.
*/
public override val coroutineContext: CoroutineContext get() = context
override val isActive: Boolean get() = super.isActive
/**
* Initializes the parent job from the `parentContext` of this coroutine that was passed to it during construction.
* It shall be invoked at most once after construction after all other initialization.
*
* Invocation of this function may cause this coroutine to become cancelled if the parent is already cancelled,
* in which case it synchronously invokes all the corresponding handlers.
* @suppress **This is unstable API and it is subject to change.**
*/
internal fun initParentJob() {
initParentJobInternal(parentContext[Job])
}
/**
* This function is invoked once when a non-active coroutine (constructed with `active` set to `false)
* is [started][start].
*/
protected open fun onStart() {}
internal final override fun onStartInternal() {
onStart()
}
/**
* This function is invoked once when the job was completed normally with the specified [value],
* right before all the waiters for the coroutine's completion are notified.
*/
protected open fun onCompleted(value: T) {}
/**
* This function is invoked once when the job was cancelled with the specified [cause],
* right before all the waiters for coroutine's completion are notified.
*
* **Note:** the state of the coroutine might not be final yet in this function and should not be queried.
* You can use [completionCause] and [completionCauseHandled] to recover parameters that we passed
* to this `onCancelled` invocation only when [isCompleted] returns `true`.
*
* @param cause The cancellation (failure) cause
* @param handled `true` if the exception was handled by parent (always `true` when it is a [CancellationException])
*/
protected open fun onCancelled(cause: Throwable, handled: Boolean) {}
@Suppress("UNCHECKED_CAST")
protected final override fun onCompletionInternal(state: Any?) {
if (state is CompletedExceptionally)
onCancelled(state.cause, state.handled)
else
onCompleted(state as T)
}
internal open val defaultResumeMode: Int get() = MODE_ATOMIC_DEFAULT
/**
* Completes execution of this with coroutine with the specified result.
*/
public final override fun resumeWith(result: Result) {
makeCompletingOnce(result.toState(), defaultResumeMode)
}
internal final override fun handleOnCompletionException(exception: Throwable) {
handleCoroutineException(context, exception)
}
internal override fun nameString(): String {
val coroutineName = context.coroutineName ?: return super.nameString()
return "\"$coroutineName\":${super.nameString()}"
}
/**
* Starts this coroutine with the given code [block] and [start] strategy.
* This function shall be invoked at most once on this coroutine.
*
* First, this function initializes parent job from the `parentContext` of this coroutine that was passed to it
* during construction. Second, it starts the coroutine based on [start] parameter:
*
* * [DEFAULT] uses [startCoroutineCancellable].
* * [ATOMIC] uses [startCoroutine].
* * [UNDISPATCHED] uses [startCoroutineUndispatched].
* * [LAZY] does nothing.
*/
public fun start(start: CoroutineStart, block: suspend () -> T) {
initParentJob()
start(block, this)
}
/**
* Starts this coroutine with the given code [block] and [start] strategy.
* This function shall be invoked at most once on this coroutine.
*
* First, this function initializes parent job from the `parentContext` of this coroutine that was passed to it
* during construction. Second, it starts the coroutine based on [start] parameter:
*
* * [DEFAULT] uses [startCoroutineCancellable].
* * [ATOMIC] uses [startCoroutine].
* * [UNDISPATCHED] uses [startCoroutineUndispatched].
* * [LAZY] does nothing.
*/
public fun start(start: CoroutineStart, receiver: R, block: suspend R.() -> T) {
initParentJob()
start(block, receiver, this)
}
}