disconnect receiving side of a channel but consume objects already pushed to the channel

[behzadnouri]

Lets say during the process shutdown I want:

• The consumer thread process all items already pushed to the channel.
• The producer thread stops pushing new items to the channel.

This requires an api which "atomically":

• disconnects the receiving side of a channel (so that the producer can no longer push new items on to the channel).
• but also returns all items which were already pushed on the channel before disconnect happens.

Something like:

impl Receiver<T> {
  fn consume(self) -> Vec<T> {
    // disconnect and return existing items.
  }
}

Does corssbeam channels have any such api that I am missing?
or, any paradigms to achieve the same functionality?

Currently what I am doing is something like this on the consumer side:

// start of shutdown process.
for item in receiver.try_iter() {
  // process item
}
drop(receiver);

Obviously this leaves some race condition between the time .try_iter() iterator returns None until drop(receiver) is invoked, where the producer may push new items into the channel.

We can send an out-of-band exit signal to producer channel using an Arc<AtomicBool> for example, but that is not ideal; because it fragments the data plane and control plane and leads to ugly code.

[ryoqun]

@behzadnouri hey, colleagues meet at upstream crate land. :) I've just submitted a pr exactly for this: #959