@worker-tools/html-rewriter
Version:
WASM-based implementation of Cloudflare's HTML Rewriter for use in Deno, browsers, etc.
96 lines • 2.96 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.wrap = exports.setWasmExports = exports.awaitPromise = void 0;
const asserts_js_1 = require("../deps/deno.land/std@0.134.0/testing/asserts.js");
/**
* @typedef {object} WasmExports
* @property {WebAssembly.Memory} memory
* @property {function} asyncify_get_state
* @property {function} asyncify_start_unwind
* @property {function} asyncify_stop_unwind
* @property {function} asyncify_start_rewind
* @property {function} asyncify_stop_rewind
*/
/**
* @type {WasmExports}
*/
let wasm;
/**
* @param {WasmExports} wasmExports
*/
function setWasmExports(wasmExports) {
wasm = wasmExports;
}
exports.setWasmExports = setWasmExports;
/**
* @type {Int32Array}
*/
let cachedInt32Memory = null;
/**
* @returns {Int32Array}
*/
function getInt32Memory() {
if (cachedInt32Memory === null ||
cachedInt32Memory.buffer !== wasm.memory.buffer) {
cachedInt32Memory = new Int32Array(wasm.memory.buffer);
}
return cachedInt32Memory;
}
// https://github.com/WebAssembly/binaryen/blob/fb9de9d391a7272548dcc41cd8229076189d7398/src/passes/Asyncify.cpp#L99
const State = {
NONE: 0,
UNWINDING: 1,
REWINDING: 2,
};
function assertNoneState() {
(0, asserts_js_1.assertEquals)(wasm.asyncify_get_state(), State.NONE);
}
/**
* Maps `HTMLRewriter`s (their `asyncifyStackPtr`s) to `Promise`s.
* `asyncifyStackPtr` acts as unique reference to `HTMLRewriter`.
* Each rewriter MUST have AT MOST ONE pending promise at any time.
* @type {Map<number, Promise>}
*/
const promises = new Map();
/**
* @param {number} stackPtr
* @param {Promise} promise
*/
function awaitPromise(stackPtr, promise) {
if (wasm.asyncify_get_state() === State.REWINDING) {
wasm.asyncify_stop_rewind();
return;
}
assertNoneState();
// https://github.com/WebAssembly/binaryen/blob/fb9de9d391a7272548dcc41cd8229076189d7398/src/passes/Asyncify.cpp#L106
(0, asserts_js_1.assertEquals)(stackPtr % 4, 0);
getInt32Memory().set([stackPtr + 8, stackPtr + 1024], stackPtr / 4);
wasm.asyncify_start_unwind(stackPtr);
(0, asserts_js_1.assert)(!promises.has(stackPtr));
promises.set(stackPtr, promise);
}
exports.awaitPromise = awaitPromise;
/**
* @param {HTMLRewriter} rewriter
* @param {Function} fn
* @param args
*/
async function wrap(rewriter, fn, ...args) {
const stackPtr = rewriter.asyncifyStackPtr;
assertNoneState();
let result = fn(...args);
while (wasm.asyncify_get_state() === State.UNWINDING) {
wasm.asyncify_stop_unwind();
assertNoneState();
(0, asserts_js_1.assert)(promises.has(stackPtr));
await promises.get(stackPtr);
promises.delete(stackPtr);
assertNoneState();
wasm.asyncify_start_rewind(stackPtr);
result = fn();
}
assertNoneState();
return result;
}
exports.wrap = wrap;
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