Function advanceReadIndexCAS

apps/desktop/src/utils/shared-frame-buffer.ts:250–278

(
	controlView: Uint32Array,
	readIdx: number,
	nextIdx: number,
)

}

function advanceReadIndexCAS(
	controlView: Uint32Array,
	readIdx: number,
	nextIdx: number,
): void {
	const MAX_ADVANCE_RETRIES = 16;
	let expectedIdx = readIdx;

	for (let attempt = 0; attempt < MAX_ADVANCE_RETRIES; attempt++) {
		const exchanged = Atomics.compareExchange(
			controlView,
			CONTROL_READ_INDEX,
			expectedIdx,
			nextIdx,
		);
		if (exchanged === expectedIdx) {
			return;
		}
		const currentIdx = Atomics.load(controlView, CONTROL_READ_INDEX);
		const hasProgressed =
			currentIdx !== readIdx &&
			((nextIdx > readIdx && (currentIdx >= nextIdx || currentIdx < readIdx)) ||
				(nextIdx < readIdx && currentIdx >= nextIdx && currentIdx < readIdx));
		if (hasProgressed) {
			return;
		}
		expectedIdx = exchanged;
	}
}

export function createConsumer(buffer: SharedArrayBuffer): Consumer {
	const controlView = new Uint32Array(buffer, 0, 8);