The Atomics.wait()
static
method verifies that a shared memory location still contains a
given value and if so sleeps, awaiting a wake-up notification or times out. It returns a string which
is either "ok"
, "not-equal"
, or "timed-out"
.
Note: This operation only works with an Int32Array or BigInt64Array that views a SharedArrayBuffer, and may not be allowed on the main thread. For a non-blocking, asynchronous version of this method, see Atomics.waitAsync.
Syntax
Atomics.wait(typedArray, index, value)
Atomics.wait(typedArray, index, value, timeout)
Parameters
typedArray
- : An Int32Array or BigInt64Array that views a SharedArrayBuffer.
index
- : The position in the
typedArray
to wait on.
- : The position in the
value
- : The expected value to test.
timeout
Return value
A string which is either "ok"
, "not-equal"
, or "timed-out"
.
Exceptions
- TypeError
- : Thrown in one of the following cases:
- If
typedArray
is not an Int32Array or BigInt64Array that views a SharedArrayBuffer. - If the current thread cannot be blocked (for example, because it's the main thread).
- If
- : Thrown in one of the following cases:
- RangeError
- : Thrown if
index
is out of bounds in thetypedArray
.
- : Thrown if
Examples
Using wait()
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);