wasmer/lib/wasi-web/public/worker.js

// The purpose of this file is two-fold:
// First: Expose a function to start a web worker. This function must
// not be inlined into the Rust lib, as otherwise bundlers could not
// bundle it -- huh.
export function startWorker(module, memory, state, opts, helper) {
    const worker = new Worker(new URL('./worker.js',
        import.meta.url), opts);

    try {
        worker.postMessage([module, memory, state, helper.mainJS()]);
    } catch(err) {
        return new Promise((res, rej) => {
            rej(err);
        });
    }

    return new Promise((res, rej) => {
      worker.onmessage = async ev => {
        if (ev.data === 'started') res();
        else {
            const importFrom = (typeof __webpack_require__ === 'function') ? import('../../..') : import(mainJS);
            const {
                worker_schedule_task,
            } = await importFrom;

            let [module, memory, state] = event.data;
            worker_schedule_task(module, memory, state);
        }
      };
      worker.onerror = rej;
    });
}
export function startWasm(module, memory, ctx, opts, helper, wasm_module, wasm_memory) {
    const worker = new Worker(new URL('./worker.js',
        import.meta.url), opts);

    try {
        worker.postMessage([module, memory, ctx, helper.mainJS(), wasm_module, wasm_memory]);
    } catch(err) {
        return new Promise((res, rej) => {
            rej(err);
        });
    }

    return new Promise((res, rej) => {
      worker.onmessage = async ev => {
        if (ev.data === 'started') res();
        else {
            const importFrom = (typeof __webpack_require__ === 'function') ? import('../../..') : import(mainJS);
            const {
                worker_schedule_task,
            } = await importFrom;

            let [module, memory, state] = event.data;
            worker_schedule_task(module, memory, state);
        }
      };
      worker.onerror = rej;
    });
}
export function scheduleTask(task, module, memory) {
    postMessage([task, module, memory]);
}

export function isWorker() {
    return 'WorkerGlobalScope' in self && self instanceof WorkerGlobalScope;
}

// Second: Entry script for the actual web worker.
if (isWorker()) {
    //console.log("pool::worker(entry) started");
    Error.stackTraceLimit = 50;

    // Initialize wasm module, and memory. `state` is the shared state,
    // to be used with `worker_entry_point`.
    self.onmessage = async event => {
        // This crate only works with bundling via webpack or not
        // using a bundler at all:
        // When bundling with webpack, this file is relative to the wasm
        // module file (or package.json) located in `../../..` generated by
        // wasm-pack.
        // When using it without any bundlers, the module that
        // provided the `helper` object below is loaded; in other words
        // the main wasm module.
        if (event.data.length == 4) {
            let [module, memory, state, mainJS] = event.data;
            const importFrom = (typeof __webpack_require__ === 'function') ? import('../../..') : import(mainJS);
            try {
                const {
                    default: init,
                    worker_entry_point,
                    worker_entry_point_with_val
                } = await importFrom;
                await init(module, memory);

                worker_entry_point(state);
                postMessage('started');
                // There shouldn't be any additional messages after the first.
                self.onmessage = event => {
                    console.error("Unexpected message", event);
                }
            } catch (err) {
                // Propagate to main `onerror`:
                setTimeout(() => {
                    throw err;
                    //Terminate the worker
                    close();
                });
                throw err;
            }
        } else {
            let [module, memory, ctx, mainJS, wasm_module, wasm_memory] = event.data;
            const importFrom = (typeof __webpack_require__ === 'function') ? import('../../..') : import(mainJS);
            try {
                const {
                    default: init,
                    wasm_entry_point,
                } = await importFrom;
                await init(module, memory);

                wasm_entry_point(ctx, wasm_module, wasm_memory);
                postMessage('started');
                // There shouldn't be any additional messages after the first.
                self.onmessage = event => {
                    console.error("Unexpected message", event);
                }
            } catch (err) {
                // Propagate to main `onerror`:
                setTimeout(() => {
                    throw err;
                    //Terminate the worker
                    close();
                });
                throw err;
            }
        }
    }
}