Atomics.wait()

The static Atomics.wait() method verifies that a given position in an Int32Array still contains a given value and if so sleeps, awaiting a wakeup or a timeout. It returns a string which is either "ok", "not-equal", or "timed-out".

typedArray

A shared Int32Array.

index

The position in the typedArray to wait on.

value

The expected value to test.

timeout Optional

Time to wait in milliseconds. Infinity, if no time is provided.

A string which is either "ok", "not-equal", or "timed-out".

• Throws a TypeError, if typedArray is not a shared Int32Array.
• Throws a RangeError, if index is out of bounds in the typedArray.

Given a shared Int32Array:

const sab = new SharedArrayBuffer(1024);
const int32 = new Int32Array(sab);

A reading thread is sleeping and waiting on location 0 which is expected to be 0. As long as that is true, it will not go on. However, once the writing thread has stored a new value, it will be notified by the writing thread and return the new value (123).

Atomics.wait(int32, 0, 0);
console.log(int32[0]); // 123

A writing thread stores a new value and notifies the waiting thread once it has written:

console.log(int32[0]); // 0;
Atomics.store(int32, 0, 123);
Atomics.notify(int32, 0, 1);

• Atomics
• Atomics.notify()