Std.AtomicRef

Process-safe mutable references backed by ETS with a lock server.

Types

AtomicMutRef

opaque type AtomicMutRef a

Opaque handle to an atomic mutable reference. Backed by an ETS ref with a lock server process that serializes access. Safe for use across concurrent actors.

LockError

type LockError =
  | LockTimeout
  deriving (Show)

Error type for timed lock acquisition.

Effects

AtomicRef

effect AtomicRef {
  fun atomic_new : a -> AtomicMutRef a
  fun atomic_lock : AtomicMutRef a -> a
  fun atomic_try_lock : AtomicMutRef a -> Int -> Result a LockError
  fun atomic_unlock : AtomicMutRef a -> a -> Unit
}

Atomic mutable reference effect. Provides lock-based access to shared mutable state that is safe across concurrent processes.

Handlers

atomic_ref

handler atomic_ref for AtomicRef needs {Process, Monitor, Ref}

Lock-based handler for AtomicRef. Uses ets_ref for storage and a serializing process for mutual exclusion. The lock server monitors the lock holder — if the holder crashes, the lock releases automatically.

Functions

lock_server

fun lock_server : Unit -> Unit needs {Process, Actor LockMsg, Monitor}

atomic_modify

fun atomic_modify : AtomicMutRef a -> a -> a -> a needs {AtomicRef}

Read-modify-write under the lock. Acquires the lock, applies the function to the current value, writes the result, and releases.

atomic_get

fun atomic_get : AtomicMutRef a -> a needs {AtomicRef}

Read the current value. Acquires and immediately releases the lock.

atomic_set

fun atomic_set : AtomicMutRef a -> a -> Unit needs {AtomicRef}

Overwrite the value. Acquires the lock, writes, and releases.