interface SendChannel<in E> (source)

Sender’s interface to Channel.



abstract val isClosedForSend: Boolean

Returns true if this channel was closed by an invocation of close. This means that calling send will result in an exception.


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

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



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

Closes this channel. This is an idempotent operation — subsequent invocations of this function have no effect and return false. Conceptually, it sends a special “close token” over this channel.


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

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


open fun offer(element: E): Boolean

Deprecated offer method.


abstract suspend fun send(element: E): Unit

Sends the specified element to this channel, suspending the caller while the buffer of this channel is full or if it does not exist, or throws an exception if the channel is closed for send (see close for details).


abstract fun trySend(element: E): ChannelResult<Unit>

Immediately adds the specified element to this channel, if this doesn’t violate its capacity restrictions, and returns the successful result. Otherwise, returns failed or closed result. This is synchronous variant of send, which backs off in situations when send suspends or throws.

Extension Functions


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

Deprecated blocking variant of send. This method is deprecated in the favour of trySendBlocking.


fun <E> SendChannel<E>.trySendBlocking(
    element: E
): ChannelResult<Unit>

Adds element into to this channel, blocking the caller while this channel is full, and returning either successful result when the element was added, or failed result representing closed channel with a corresponding exception.



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.


interface Channel<E> : SendChannel<E>, ReceiveChannel<E>

Channel is a non-blocking primitive for communication between a sender (via SendChannel) and a receiver (via ReceiveChannel). Conceptually, a channel is similar to Java’s BlockingQueue, but it has suspending operations instead of blocking ones and can be closed.


interface ProducerScope<in E> : 

Scope for the produce coroutine builder.