Module Await_sync.Mvar

An 'a Mvar.t is a mutable cell that is either empty or contains a single value of type 'a. One can put new values, and wait to read the value with take.

Mvars are entirely linear - every put value is taken exactly once.

create () returns a new empty mvar.

The optional padded argument specifies whether to pad the data structure to avoid false sharing. See Atomic.make for a longer explanation.

create_full v returns a new mvar filled with v.

put w t a waits using w until the mvar t is empty, and then sets the value to a. If there are multiple concurrent puts, there is no fairness guarantee (ie, puts may happen out of order or may be starved).

• raises Terminated

  if w is terminated before t becomes empty.

put_or_cancel w c t a is Completed (put w t a) if c is not canceled, otherwise it is Canceled.

try_put t a sets the value of t to a and returns Ok if it is empty, otherwise it returns Already_full.

put_exn t a sets the value of t to a.

• raises Already_full

  in case t was already full.

take w t waits using w until the mvar t is full, then clears it and returns its value. If there are multiple concurrent calls to take then only one will be fulfilled and the others will continue waiting on future values. There is no ordering guarantee for which take call will be filled first.

• raises Terminated

  if w is terminated before t becomes full.

take_or_cancel w c t a is Completed (take w t a) if c is not canceled, otherwise it is Canceled.

try_take t empties the mvar t and returns This v if it is currently full, or returns Null otherwise.

take_exn empties the mvar t and returns its value v if it is currently full.

• raises Empty

  in case t was empty.

is_full t is true if the mvar t is currently full.

wait_until_empty w t waits until the mvar t becomes empty.

• raises Terminated

  if w is terminated before t becomes empty.

wait_until_empty_or_cancel w c t is Completed (wait_until_empty w t) if c is not canceled, otherwise it is Canceled.