Module Moonpool.Lock

Mutex-protected resource.

This lock is a synchronous concurrency primitive, as a thin wrapper around Mutex that encourages proper management of the critical section in RAII style:

  let (let@) = (@@)


  …
  let compute_foo =
    (* enter critical section *)
    let@ x = Lock.with_ protected_resource in
    use_x;
    return_foo ()
    (* exit critical section *)
  in
  …

This lock does not work well with Await. A critical section that contains a call to await might cause deadlocks, or lock starvation, because it will hold onto the lock while it goes to sleep.

type 'a t

A value protected by a mutex

val create : 'a -> 'a t

Create a new protected value.

val with_ : 'a t -> ('a -> 'b) -> 'b

with_ l f runs f x where x is the value protected with the lock l, in a critical section. If f x fails, with_lock l f fails too but the lock is released.

val update : 'a t -> ('a -> 'a) -> unit

update l f replaces the content x of l with f x, while protected by the mutex.

val update_map : 'a t -> ('a -> 'a * 'b) -> 'b

update_map l f computes x', y = f (get l), then puts x' in l and returns y, while protected by the mutex.

val mutex : _ t -> Stdlib.Mutex.t

Underlying mutex.

val get : 'a t -> 'a

Atomically get the value in the lock. The value that is returned isn't protected!

val set : 'a t -> 'a -> unit

Atomically set the value.

NOTE caution: using get and set as if this were a ref is an anti pattern and will not protect data against some race conditions.