@worker-tools/html-rewriter/esm/vendor/asyncify.js

import { assert, assertEquals } from "../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;
}
/**
 * @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() {
    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
    assertEquals(stackPtr % 4, 0);
    getInt32Memory().set([stackPtr + 8, stackPtr + 1024], stackPtr / 4);
    wasm.asyncify_start_unwind(stackPtr);
    assert(!promises.has(stackPtr));
    promises.set(stackPtr, promise);
}
/**
 * @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();
        assert(promises.has(stackPtr));
        await promises.get(stackPtr);
        promises.delete(stackPtr);
        assertNoneState();
        wasm.asyncify_start_rewind(stackPtr);
        result = fn();
    }
    assertNoneState();
    return result;
}
export { awaitPromise, setWasmExports, wrap };
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