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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 | 1x 1x 1x 16x 16x 16x 16x 16x 16x | import { getShouldUseSharedArrayBuffer } from '../init';
const SMALL_MEMORY_LIMIT = 2 * 1024 * 1024 * 1024 - 2;
const BIG_MEMORY_LIMIT = SMALL_MEMORY_LIMIT * 2;
// Wasm page size
const PAGE_SIZE = 65536;
/**
* A helper function that creates a new Float32Array that utilized a shared
* array buffer. This allows the array to be updated simultaneously in
* workers or the main thread. Depending on the system (the CPU, the OS, the Browser)
* it can take a while until the change is propagated to all contexts.
*
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer|MDN: SharedArrayBuffer}
* @remarks
* We use SharedArrayBuffers in our ImageCache class. It's what allows us to
* stream data to build a volume. It's important to note that SharedArrayBuffer
* does not work out of the box for all web browsers. In some, it is disabled
* behind a flag; in others, it has been removed entirely.
*
* @example
* Creating an array for a Volume with known dimensions:
* ```
* const dimensions = [512, 512, 25];
* const scalarData = createFloat32SharedArray(dimensions[0] * dimensions[1] * dimensions[2]);
* ```
*
* @param length - frame size * number of frames
* @returns a Float32Array with an underlying SharedArrayBuffer
* @public
*/
function createFloat32SharedArray(length: number): Float32Array {
Iif (!getShouldUseSharedArrayBuffer()) {
throw new Error(
'Your page is NOT cross-origin isolated, see https://developer.mozilla.org/en-US/docs/Web/API/crossOriginIsolated'
);
}
Iif (window.SharedArrayBuffer === undefined) {
throw new Error(
'SharedArrayBuffer is NOT supported in your browser see https://developer.chrome.com/blog/enabling-shared-array-buffer/'
);
}
const byteLength = length * 4;
if (byteLength < SMALL_MEMORY_LIMIT) {
const sharedArrayBuffer = new SharedArrayBuffer(byteLength);
return new Float32Array(sharedArrayBuffer);
} else Eif (byteLength < BIG_MEMORY_LIMIT) {
const pages = Math.ceil(byteLength / PAGE_SIZE);
const memory = new WebAssembly.Memory({
initial: pages,
maximum: pages,
shared: true,
});
return new Float32Array(memory.buffer, 0, length);
}
}
export default createFloat32SharedArray;
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