Signalling Queue

The signalling queue is a mutex protected queue which can signal waiting tasks/threads when new nodes have been pushed onto the queue.

lib.rs:

sigq is a FIFO queue that supports pushing and poping nodes from threads/tasks, crossing sync/async boundaries. The interface to interact with the queue is a pair of end-points. The Pusher is used to add data to the queue, and the Puller is used to pull data off the queue.

The Pusher has a push() method that is used to push new nodes onto the queue.

The Puller has a blocking pop() and a apop() that returns a Future for getting the next node off the queue. These will return immediately with the next node if available, or block and wait for a new node to be pushed onto the queue. try_pop() can be used as a non-blocking way to get the next node, if available.

let (pusher, puller) = sigq::new();
pusher.push(42).unwrap();
assert_eq!(puller.pop(), Ok(42));
assert_eq!(puller.try_pop(), Ok(None));

Semantics

• Dropping the last Pusher end-point will cause waiting Puller's to wake up and return Err(StaleErr) if there are no more nodes on the queue.
• Dropping the last Puller end-point will:
  • Immediately drop all the nodes in the queue.
  • Cause the Puller's to return Err(StaleErr) if new nodes are attempted to be added to the queue.