| /* |
| * Copyright 2022 The Android Open Source Project |
| * |
| * 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. |
| */ |
| |
| // java.util.function.Consumer was added in API 24 |
| @file:RequiresApi(24) |
| package androidx.core.util |
| |
| import androidx.annotation.RequiresApi |
| import java.util.concurrent.atomic.AtomicBoolean |
| import kotlin.coroutines.Continuation |
| import kotlin.coroutines.resume |
| |
| /** |
| * Returns a [java.util.function.Consumer] that will resume this [Continuation] when the result of |
| * an operation is [accepted][java.util.function.Consumer.accept]. |
| * |
| * Useful for writing `suspend` bindings to async methods that accept |
| * [java.util.function.Consumer] as a result callback for a one-time operation: |
| * |
| * ``` |
| * public suspend fun FancinessManager.query( |
| * query: FancinessManager.Query |
| * ): FancinessManager.QueryResult = suspendCancellableCoroutine<QueryResult> { continuation -> |
| * |
| * // Any Android API that supports cancellation should be configured to propagate |
| * // coroutine cancellation as follows: |
| * val canceller = CancellationSignal() |
| * continuation.invokeOnCancellation { canceller.cancel() } |
| * |
| * // Invoke the FancinessManager#queryAsync method as follows: |
| * queryAsync( |
| * query, |
| * canceller, |
| * // Use a direct executor to avoid extra dispatch. Resuming the continuation will |
| * // handle getting to the right thread or pool via the ContinuationInterceptor. |
| * Runnable::run, |
| * continuation.asConsumer() |
| * ) |
| * } |
| * ``` |
| */ |
| @RequiresApi(24) |
| public fun <T> Continuation<T>.asConsumer(): java.util.function.Consumer<T> = |
| ContinuationConsumer(this) |
| |
| @RequiresApi(24) |
| private class ContinuationConsumer<T>( |
| private val continuation: Continuation<T> |
| ) : java.util.function.Consumer<T>, AtomicBoolean(false) { |
| override fun accept(value: T) { |
| // Do not attempt to resume more than once, even if the caller of the returned |
| // Consumer is buggy and tries anyway. |
| if (compareAndSet(false, true)) { |
| continuation.resume(value) |
| } |
| } |
| |
| override fun toString() = "ContinuationConsumer(resultAccepted = ${get()})" |
| } |