| /* |
| * Copyright 2016-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license. |
| */ |
| |
| package kotlinx.coroutines.channels |
| |
| import kotlinx.coroutines.internal.* |
| import kotlinx.coroutines.selects.* |
| |
| /** |
| * Channel with linked-list buffer of a unlimited capacity (limited only by available memory). |
| * Sender to this channel never suspends and [offer] always returns `true`. |
| * |
| * This channel is created by `Channel(Channel.UNLIMITED)` factory function invocation. |
| * |
| * This implementation is fully lock-free. |
| * |
| * @suppress **This an internal API and should not be used from general code.** |
| */ |
| internal open class LinkedListChannel<E>(onUndeliveredElement: OnUndeliveredElement<E>?) : AbstractChannel<E>(onUndeliveredElement) { |
| protected final override val isBufferAlwaysEmpty: Boolean get() = true |
| protected final override val isBufferEmpty: Boolean get() = true |
| protected final override val isBufferAlwaysFull: Boolean get() = false |
| protected final override val isBufferFull: Boolean get() = false |
| |
| // result is always `OFFER_SUCCESS | Closed` |
| protected override fun offerInternal(element: E): Any { |
| while (true) { |
| val result = super.offerInternal(element) |
| when { |
| result === OFFER_SUCCESS -> return OFFER_SUCCESS |
| result === OFFER_FAILED -> { // try to buffer |
| when (val sendResult = sendBuffered(element)) { |
| null -> return OFFER_SUCCESS |
| is Closed<*> -> return sendResult |
| } |
| // otherwise there was receiver in queue, retry super.offerInternal |
| } |
| result is Closed<*> -> return result |
| else -> error("Invalid offerInternal result $result") |
| } |
| } |
| } |
| |
| // result is always `ALREADY_SELECTED | OFFER_SUCCESS | Closed`. |
| protected override fun offerSelectInternal(element: E, select: SelectInstance<*>): Any { |
| while (true) { |
| val result = if (hasReceiveOrClosed) |
| super.offerSelectInternal(element, select) else |
| (select.performAtomicTrySelect(describeSendBuffered(element)) ?: OFFER_SUCCESS) |
| when { |
| result === ALREADY_SELECTED -> return ALREADY_SELECTED |
| result === OFFER_SUCCESS -> return OFFER_SUCCESS |
| result === OFFER_FAILED -> {} // retry |
| result === RETRY_ATOMIC -> {} // retry |
| result is Closed<*> -> return result |
| else -> error("Invalid result $result") |
| } |
| } |
| } |
| |
| override fun onCancelIdempotentList(list: InlineList<Send>, closed: Closed<*>) { |
| var undeliveredElementException: UndeliveredElementException? = null |
| list.forEachReversed { |
| when (it) { |
| is SendBuffered<*> -> { |
| @Suppress("UNCHECKED_CAST") |
| undeliveredElementException = onUndeliveredElement?.callUndeliveredElementCatchingException(it.element as E, undeliveredElementException) |
| } |
| else -> it.resumeSendClosed(closed) |
| } |
| } |
| undeliveredElementException?.let { throw it } // throw UndeliveredElementException at the end if there was one |
| } |
| } |
| |