| /* |
| * Copyright 2016-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license. |
| */ |
| |
| package kotlinx.coroutines.experimental.channels |
| |
| import kotlinx.coroutines.experimental.* |
| import kotlinx.coroutines.experimental.channels.Channel.Factory.CONFLATED |
| import kotlinx.coroutines.experimental.channels.Channel.Factory.UNLIMITED |
| import kotlinx.coroutines.experimental.intrinsics.* |
| import kotlin.coroutines.experimental.* |
| |
| /** |
| * Broadcasts all elements of the channel. |
| * |
| * @param capacity capacity of the channel's buffer (1 by default). |
| * @param start coroutine start option. The default value is [CoroutineStart.LAZY]. |
| */ |
| fun <E> ReceiveChannel<E>.broadcast( |
| capacity: Int = 1, |
| start: CoroutineStart = CoroutineStart.LAZY |
| ) : BroadcastChannel<E> = |
| broadcast(Unconfined, capacity = capacity, start = start, onCompletion = consumes()) { |
| for (e in this@broadcast) { |
| send(e) |
| } |
| } |
| |
| /** |
| * Launches new coroutine to produce a stream of values by sending them to a broadcast channel |
| * and returns a reference to the coroutine as a [BroadcastChannel]. The resulting |
| * object can be used to [subscribe][BroadcastChannel.openSubscription] to elements produced by this coroutine. |
| * |
| * The scope of the coroutine contains [ProducerScope] interface, which implements |
| * both [CoroutineScope] and [SendChannel], so that coroutine can invoke |
| * [send][SendChannel.send] directly. The channel is [closed][SendChannel.close] |
| * when the coroutine completes. |
| * |
| * The [context] for the new coroutine can be explicitly specified. |
| * See [CoroutineDispatcher] for the standard context implementations that are provided by `kotlinx.coroutines`. |
| * The [coroutineContext] of the parent coroutine may be used, |
| * in which case the [Job] of the resulting coroutine is a child of the job of the parent coroutine. |
| * The parent job may be also explicitly specified using [parent] parameter. |
| * |
| * If the context does not have any dispatcher nor any other [ContinuationInterceptor], then [DefaultDispatcher] is used. |
| * |
| * Uncaught exceptions in this coroutine close the channel with this exception as a cause and |
| * the resulting channel becomes _failed_, so that any attempt to receive from such a channel throws exception. |
| * |
| * The kind of the resulting channel depends on the specified [capacity] parameter: |
| * * when `capacity` positive (1 by default), but less than [UNLIMITED] -- uses [ArrayBroadcastChannel] |
| * * when `capacity` is [CONFLATED] -- uses [ConflatedBroadcastChannel] that conflates back-to-back sends; |
| * * otherwise -- throws [IllegalArgumentException]. |
| * |
| * **Note:** By default, the coroutine does not start until the first subscriber appears via [BroadcastChannel.openSubscription] |
| * as [start] parameter has a value of [CoroutineStart.LAZY] by default. |
| * This ensures that the first subscriber does not miss any sent elements. |
| * However, later subscribers may miss elements. |
| * |
| * See [newCoroutineContext] for a description of debugging facilities that are available for newly created coroutine. |
| * |
| * @param context context of the coroutine. The default value is [DefaultDispatcher]. |
| * @param capacity capacity of the channel's buffer (1 by default). |
| * @param start coroutine start option. The default value is [CoroutineStart.LAZY]. |
| * @param parent explicitly specifies the parent job, overrides job from the [context] (if any).* |
| * @param onCompletion optional completion handler for the producer coroutine (see [Job.invokeOnCompletion]). |
| * @param block the coroutine code. |
| */ |
| public fun <E> broadcast( |
| context: CoroutineContext = DefaultDispatcher, |
| capacity: Int = 1, |
| start: CoroutineStart = CoroutineStart.LAZY, |
| parent: Job? = null, |
| onCompletion: CompletionHandler? = null, |
| block: suspend ProducerScope<E>.() -> Unit |
| ): BroadcastChannel<E> { |
| val channel = BroadcastChannel<E>(capacity) |
| val newContext = newCoroutineContext(context, parent) |
| val coroutine = if (start.isLazy) |
| LazyBroadcastCoroutine(newContext, channel, block) else |
| BroadcastCoroutine(newContext, channel, active = true) |
| if (onCompletion != null) coroutine.invokeOnCompletion(handler = onCompletion) |
| coroutine.start(start, coroutine, block) |
| return coroutine |
| } |
| |
| private open class BroadcastCoroutine<E>( |
| parentContext: CoroutineContext, |
| protected val _channel: BroadcastChannel<E>, |
| active: Boolean |
| ) : AbstractCoroutine<Unit>(parentContext, active), ProducerScope<E>, BroadcastChannel<E> by _channel { |
| override val channel: SendChannel<E> |
| get() = this |
| |
| public override fun cancel(cause: Throwable?): Boolean = super.cancel(cause) |
| |
| override fun onCancellationInternal(exceptionally: CompletedExceptionally?) { |
| val cause = exceptionally?.cause |
| val processed = when (exceptionally) { |
| is Cancelled -> _channel.cancel(cause) // producer coroutine was cancelled -- cancel channel |
| else -> _channel.close(cause) // producer coroutine has completed -- close channel |
| } |
| if (!processed && cause != null) |
| handleCoroutineException(context, cause) |
| } |
| } |
| |
| private class LazyBroadcastCoroutine<E>( |
| parentContext: CoroutineContext, |
| channel: BroadcastChannel<E>, |
| private val block: suspend ProducerScope<E>.() -> Unit |
| ) : BroadcastCoroutine<E>(parentContext, channel, active = false) { |
| override fun openSubscription(): ReceiveChannel<E> { |
| // open subscription _first_ |
| val subscription = _channel.openSubscription() |
| // then start coroutine |
| start() |
| return subscription |
| } |
| |
| override fun onStart() { |
| block.startCoroutineCancellable(this, this) |
| } |
| } |
| |