README.md

Snapshot test sketch

see especially the // snapshot worker? comments in main.js.

tested on linux with moddable version 54d8e94710ed6f8c310f046c4fbc83c967ccd346

Run as usual

mkdir -p build
mcconfig -o build -d -m

Expected Results

bundleSource reading...
setBundle...
from vatHost: ok
deliver...
from vatHost: 0
from vatHost: 1
from vatHost: 2
from vatHost: 1
demo concludes.
vatHost handling: ["setBundle","(function buildRootObject(vatPowers) {\n  const { freeze } = Object;\n  const { testLog } = vatPowers;\n\n  let count = 0;\n\n  return freeze({\n    incr() {\n      return count++;\n    },\n    decr() {\n      return count--;\n    },\n  });\n});\n"]
vatHost handling: ["deliver","message","slot1",{"method":"incr","args":[]}]
vatHost handling: ["deliver","message","slot1",{"method":"incr","args":[]}]
vatHost handling: ["deliver","message","slot1",{"method":"decr","args":[]}]
vatHost handling: ["deliver","message","slot1",{"method":"incr","args":[]}]

alice-vat.js

(function buildRootObject(vatPowers) {
  const { freeze } = Object;
  const { testLog } = vatPowers;

  let count = 0;

  return freeze({
    incr() {
      return count++;
    },
    decr() {
      return count--;
    },
  });
});

main.js

/*
 * based on Moddable worker example
 */

import Worker from "worker";
import { File } from "file";

function traceln(txt) {
  trace(txt);
  trace("\n");
}

function bundleSource(vatSrc) {
  traceln("bundleSource reading...", vatSrc);
  return new File(vatSrc).read(String);
}

function makePromiseKit() {
  let resolve, reject;
  const promise = new Promise((win, lose) => {
    resolve = win;
    reject = lose;
  });
  return { promise, resolve, reject };
}

export async function main() {
  let vatWorker = new Worker("vatHost", {
    allocation: 6 * 1024,
    stackCount: 64,
    slotCount: 32,
  });

  let sync = makePromiseKit();
  vatWorker.onmessage = function (message) {
    trace("from vatHost: ");
    traceln(message);
    sync.resolve();
    sync = makePromiseKit();
  };
  const post = (msg) => vatWorker.postMessage(msg);

  const aliceVatSrc = bundleSource("./alice-vat.js");

  traceln("setBundle...");
  post(["setBundle", aliceVatSrc]);
  await sync.promise;
  // snapshot the vatWorker?

  traceln("deliver...");
  post(["deliver", "message", "slot1", { method: "incr", args: [] }]);
  await sync.promise;
  post(["deliver", "message", "slot1", { method: "incr", args: [] }]);
  await sync.promise;
  // snapshot the vatWorker?
  post(["deliver", "message", "slot1", { method: "decr", args: [] }]);
  await sync.promise;
  post(["deliver", "message", "slot1", { method: "incr", args: [] }]);
  await sync.promise;

  traceln("demo concludes.");
}

main().catch((err) => traceln(err));

manifest.json

{
  "include": [
    "$(MODDABLE)/examples/manifest_base.json",
    "$(MODDABLE)/modules/files/file/manifest.json",
    "$(MODULES)/base/worker/manifest.json"
  ],
  "creation": {
    "static": 12288,
    "chunk": {
      "initial": 1536,
      "incremental": 512
    },
    "heap": {
      "initial": 64,
      "incremental": 32
    },
    "stack": 128,
    "keys": {
      "available": 32,
      "name": 53,
      "symbol": 3
    },
    "main": "main"
  },
  "modules": {
    "*": ["./main", "./vatHost"]
  }
}

run.sh

# tested on linux
# moddable version 54d8e94710ed6f8c310f046c4fbc83c967ccd346
mkdir -p build
mcconfig -o build -d -m

vatHost.js

const { freeze } = Object; // cf. harden

function testLog(...args) {
  trace(`TEST: ${JSON.stringify(args)}\n`);
}

function main(port) {
  const clist = {};
  let nextSlot = 1;

  const vatCmp = new Compartment();
  const handle = freeze(async ([type, ...margs]) => {
    trace(`vatHost handling: ${JSON.stringify([type, ...margs])}\n`);

    switch (type) {
      case "setBundle":
        {
          const [bundle] = margs;
          const buildRoot = vatCmp.evaluate(bundle);
          clist[`slot${nextSlot++}`] = buildRoot({ testLog });
          port.postMessage("ok");
        }
        break;
      case "deliver":
        {
          const [dtype, targetRef, { method, args }] = margs;
          const target = clist[targetRef];
          const result = target[method](...args);
          port.postMessage(result);
        }
        break;
      default:
        throw new Error(type);
    }
  });

  port.onmessage = handle;
}

main(self);