BroadcastChannel

interface BroadcastChannel<E> : SendChannel<E>

Broadcast channel is a non-blocking primitive for communication between the sender and multiple receivers that subscribe for the elements using openSubscription function and unsubscribe using ReceiveChannel.cancel function.

See BroadcastChannel() factory function for the description of available broadcast channel implementations.

Inherited Properties

isClosedForSend

abstract val isClosedForSend: Boolean

Returns true if this channel was closed by invocation of close and thus the send and offer attempts throws exception.

isFull

abstract val isFull: Boolean

Returns true if the channel is full (out of capacity) and the send attempt will suspend. This function returns false for isClosedForSend channel.

onSend

abstract val onSend: SelectClause2<E, SendChannel<E>>

Clause for select expression of send suspending function that selects when the element that is specified as parameter is sent to the channel. When the clause is selected the reference to this channel is passed into the corresponding block.

Functions

cancel

abstract fun cancel(cause: Throwable? = null): Boolean

Cancels reception of remaining elements from this channel. This function closes the channel with the specified cause (unless it was already closed), removes all buffered sent elements from it, and cancels all open subscriptions. This function returns true if the channel was not closed previously, or false otherwise.

openSubscription

abstract fun openSubscription(): ReceiveChannel<E>

Subscribes to this BroadcastChannel and returns a channel to receive elements from it. The resulting channel shall be cancelled to unsubscribe from this broadcast channel.

Inherited Functions

close

abstract fun close(cause: Throwable? = null): Boolean

Closes this channel with an optional exceptional cause. This is an idempotent operation – repeated invocations of this function have no effect and return false. Conceptually, its sends a special “close token” over this channel.

invokeOnClose

abstract fun invokeOnClose(
    handler: (cause: Throwable?) -> Unit
): Unit

Registers handler which is synchronously invoked once the channel is closed or receiving side of this channel is cancelled. Only one handler can be attached to the channel during channel’s lifetime. Handler is invoked when isClosedForSend starts to return true. If channel is already closed, handler is invoked immediately.

offer

abstract fun offer(element: E): Boolean

Adds element into this queue if it is possible to do so immediately without violating capacity restrictions and returns true. Otherwise, it returns false immediately or throws exception if the channel isClosedForSend (see close for details).

send

abstract suspend fun send(element: E): Unit

Adds element into to this channel, suspending the caller while this channel isFull, or throws exception if the channel isClosedForSend (see close for details).

Extension Functions

consume

fun <E, R> BroadcastChannel<E>.consume(
    block: ReceiveChannel<E>.() -> R
): R

Opens subscription to this BroadcastChannel and makes sure that the given block consumes all elements from it by always invoking cancel after the execution of the block.

consumeEach

suspend fun <E> BroadcastChannel<E>.consumeEach(
    action: (E) -> Unit
): Unit

Subscribes to this BroadcastChannel and performs the specified action for each received element.

sendBlocking

fun <E> SendChannel<E>.sendBlocking(element: E): Unit

Adds element into to this channel, blocking the caller while this channel Channel.isFull, or throws exception if the channel Channel.isClosedForSend (see Channel.close for details).

Inheritors

ArrayBroadcastChannel

class ArrayBroadcastChannel<E> : 
    AbstractSendChannel<E>,
    BroadcastChannel<E>

Broadcast channel with array buffer of a fixed capacity. Sender suspends only when buffer is full due to one of the receives being slow to consume and receiver suspends only when buffer is empty.

ConflatedBroadcastChannel

class ConflatedBroadcastChannel<E> : BroadcastChannel<E>

Broadcasts the most recently sent element (aka value) to all openSubscription subscribers.