tryReceive

Attempts to retrieve an element without waiting, removing it from the channel.

• When the channel is non-empty, a successful result is returned, and ChannelResult.getOrNull returns the retrieved element.

• When the channel is empty, a failed result is returned.

• When the channel is already closed for receive, returns the "channel is closed" result. If the channel was closed with a cause (for example, cancelled), ChannelResult.exceptionOrNull contains the cause.

This function is useful when implementing on-demand allocation of resources to be stored in the channel:

val resourcePool = Channel<Resource>(maxResources)

suspend fun withResource(block: (Resource) -> Unit) {
    val result = resourcePool.tryReceive()
    val resource = result.getOrNull()
        ?: tryCreateNewResource() // try to create a new resource
        ?: resourcePool.receive() // could not create: actually wait for the resource
    try {
        block(resource)
    } finally {
        resourcePool.trySend(resource)
    }
}