kotlinx.coroutines.experimental.NonCancellable.kt Maven / Gradle / Ivy
/*
* Copyright 2016-2017 JetBrains s.r.o.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package kotlinx.coroutines.experimental
import kotlinx.coroutines.experimental.NonCancellable.isActive
import kotlinx.coroutines.experimental.selects.SelectClause0
import kotlin.coroutines.experimental.AbstractCoroutineContextElement
/**
* A non-cancelable job that is always [active][isActive]. It is designed for [withContext] function
* to prevent cancellation of code blocks that need to be executed without cancellation.
*
* Use it like this:
* ```
* withContext(NonCancellable) {
* // this code will not be cancelled
* }
* ```
*/
public actual object NonCancellable : AbstractCoroutineContextElement(Job), Job {
/** Always returns `true`. */
actual override val isActive: Boolean get() = true
/** Always returns `false`. */
actual override val isCompleted: Boolean get() = false
/** Always returns `false`. */
actual override val isCancelled: Boolean get() = false
/** Always returns `false`. */
actual override fun start(): Boolean = false
/** Always throws [UnsupportedOperationException]. */
actual suspend override fun join() {
throw UnsupportedOperationException("This job is always active")
}
override val onJoin: SelectClause0
get() = throw UnsupportedOperationException("This job is always active")
/** Always throws [IllegalStateException]. */
actual override fun getCancellationException(): CancellationException = throw IllegalStateException("This job is always active")
/** Always returns [NonDisposableHandle]. */
@Suppress("OverridingDeprecatedMember")
override fun invokeOnCompletion(handler: CompletionHandler): DisposableHandle =
NonDisposableHandle
/** Always returns [NonDisposableHandle]. */
@Suppress("OverridingDeprecatedMember")
override fun invokeOnCompletion(handler: CompletionHandler, onCancelling: Boolean): DisposableHandle =
NonDisposableHandle
/** Always returns [NonDisposableHandle]. */
@Suppress("OverridingDeprecatedMember")
override fun invokeOnCompletion(onCancelling_: Boolean, handler: CompletionHandler): DisposableHandle =
NonDisposableHandle
/** Always returns [NonDisposableHandle]. */
actual override fun invokeOnCompletion(onCancelling: Boolean, invokeImmediately: Boolean, handler: CompletionHandler): DisposableHandle =
NonDisposableHandle
/** Always returns `false`. */
actual override fun cancel(cause: Throwable?): Boolean = false
/** Always returns [emptySequence]. */
actual override val children: Sequence
get() = emptySequence()
/** Always returns [NonDisposableHandle] and does not do anything. */
@Suppress("OverridingDeprecatedMember")
actual override fun attachChild(child: Job): DisposableHandle = NonDisposableHandle
/** Does not do anything. */
@Suppress("OverridingDeprecatedMember")
override fun cancelChildren(cause: Throwable?) {}
}