core/kotlinx-coroutines-core/src/main/kotlin/kotlinx/coroutines/experimental/Future.kt

/*
 * 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.
 */

@file:JvmMultifileClass
@file:JvmName("JobKt")

package kotlinx.coroutines.experimental

import java.util.concurrent.*

/**
 * Cancels a specified [future] when this job is cancelled.
 * This is a shortcut for the following code with slightly more efficient implementation (one fewer object created).
 * ```
 * invokeOnCompletion { future.cancel(false) }
 * ```
 */
public fun Job.cancelFutureOnCompletion(future: Future<*>): DisposableHandle =
    invokeOnCompletion(handler = CancelFutureOnCompletion(this, future)) // TODO make it work only on cancellation as well?

/**
 * Cancels a specified [future] when this job is cancelled.
 * This is a shortcut for the following code with slightly more efficient implementation (one fewer object created).
 * ```
 * invokeOnCompletion { future.cancel(false) }
 * ```
 */
@Deprecated(
    message = "Disposable handlers on regular completion are no longer supported",
    replaceWith = ReplaceWith("cancelFutureOnCancellation(future)"),
    level = DeprecationLevel.WARNING)
public fun CancellableContinuation<*>.cancelFutureOnCompletion(future: Future<*>): DisposableHandle {
    cancelFutureOnCancellation(future)
    return NonDisposableHandle
}

/**
 * Cancels a specified [future] when this job is cancelled.
 * This is a shortcut for the following code with slightly more efficient implementation (one fewer object created).
 * ```
 * invokeOnCancellation { future.cancel(false) }
 * ```
 */
public fun CancellableContinuation<*>.cancelFutureOnCancellation(future: Future<*>) {
    if (this is AbstractContinuation<*>) {
        invokeOnCancellation(handler = CancelFutureOnCancellation(this, future))
    } else {
        // Fallback if someone else implement CancellableContinuation
        invokeOnCancellation { future.cancel(false)  }
    }
}

private class CancelFutureOnCompletion(
    job: Job,
    private val future: Future<*>
) : JobNode<Job>(job)  {
    override fun invoke(reason: Throwable?) {
        // Don't interrupt when cancelling future on completion, because no one is going to reset this
        // interruption flag and it will cause spurious failures elsewhere
        future.cancel(false)
    }
    override fun toString() = "CancelFutureOnCompletion[$future]"
}

private class CancelFutureOnCancellation(
    continuation: CancellableContinuation<*>,
    private val future: Future<*>
) : CancellationHandlerImpl<AbstractContinuation<*>>(continuation as AbstractContinuation<*>)  {

    override fun invoke(reason: Throwable?) {
        // Don't interrupt when cancelling future on completion, because no one is going to reset this
        // interruption flag and it will cause spurious failures elsewhere
        future.cancel(false)
    }
    override fun toString() = "CancelFutureOnCancellation[$future]"
}