A lock-free queue of waiters that should all be resumed at once.
This uses Cells internally.
val create : unit -> tcreate () is a fresh broadcast queue.
suspend t fn arranges for fn () to be called on resume_all.
fn () may be called from the caller's context, or by resume_all, so it needs to be able to cope with running in any context where that can run. For example, fn must be safe to call from a signal handler if resume_all can be called from one. fn must not raise.
The returned request can be used to cancel. It can be None in the (unlikely) event that t got resumed before the function returned.
val resume_all : t -> unitresume_all t calls all non-cancelled callbacks attached to t, in the order in which they were suspended.
This function is lock-free and can be used safely even from a signal handler or GC finalizer.
val cancel : request -> boolcancel request attempts to remove a pending request.
It returns true if the request was cancelled, or false if it got resumed before that could happen.
val dump : Format.formatter -> t -> unitDisplay the internal state of a queue, for debugging.