Module futures_channel::mpsc
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A multi-producer, single-consumer queue for sending values across asynchronous tasks.
Similarly to the std, channel creation provides Receiver and
Sender handles. Receiver implements Stream and allows a task to
read values out of the channel. If there is no message to read from the
channel, the current task will be notified when a new value is sent.
Sender implements the Sink trait and allows a task to send messages into
the channel. If the channel is at capacity, the send will be rejected and
the task will be notified when additional capacity is available. In other
words, the channel provides backpressure.
Unbounded channels are also available using the unbounded constructor.
Disconnection
When all Sender handles have been dropped, it is no longer
possible to send values into the channel. This is considered the termination
event of the stream. As such, Receiver::poll_next
will return Ok(Ready(None)).
If the Receiver handle is dropped, then messages can no longer
be read out of the channel. In this case, all further attempts to send will
result in an error.
Clean Shutdown
If the Receiver is simply dropped, then it is possible for
there to be messages still in the channel that will not be processed. As
such, it is usually desirable to perform a “clean” shutdown. To do this, the
receiver will first call close, which will prevent any further messages to
be sent into the channel. Then, the receiver consumes the channel to
completion, at which point the receiver can be dropped.
Structs
try_next.try_send.