package saturn_lockfree

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Module Saturn_lockfree.Single_consumer_queueSource

Lock-free multi-producer, single-consumer, domain-safe queue without support for cancellation.

This makes a good data structure for a scheduler's run queue and is currently (September 2022) used for Eio's scheduler.

Sourcetype 'a t

A queue of items of type 'a.

Sourceexception Closed
Sourceval create : unit -> 'a t

create () returns a new empty queue.

Sourceval is_empty : 'a t -> bool

is_empty q is true if calling pop would return None.

  • raises Closed

    if q is closed and empty.

Sourceval close : 'a t -> unit

close q marks q as closed, preventing any further items from being pushed by the producers (i.e. with push).

  • raises Closed

    if q has already been closed.

Sourceval push : 'a t -> 'a -> unit

push q v adds the element v at the end of the queue q. This can be used safely by multiple producer domains, in parallel with the other operations.

Consumer-only functions

Sourceexception Empty

Raised when pop or peek is applied to an empty queue.

Sourceval pop : 'a t -> 'a

pop q removes and returns the first element in queue q.

  • raises Empty

    if q is empty.

  • raises Closed

    if q is closed and empty.

Sourceval pop_opt : 'a t -> 'a option

pop_opt q removes and returns the first element in queue q or returns None if the queue is empty.

  • raises Closed

    if q is closed and empty.

Sourceval peek : 'a t -> 'a

peek q returns the first element in queue q.

  • raises Empty

    if q is empty.

  • raises Closed

    if q is closed and empty.

Sourceval peek_opt : 'a t -> 'a option

peek_opt q returns the first element in queue q or returns None if the queue is empty.

  • raises Closed

    if q is closed and empty.

Sourceval push_head : 'a t -> 'a -> unit

push_head q v adds the element v at the head of the queue q. This can only be used by the consumer (if run in parallel with pop, the item might be skipped).

  • raises Closed

    if q is closed and empty.