Sharing values between contexts in the same runtime

[mshick]

I see this functionality mentioned in the readme, and in a couple of issues, notably #152 , but I can't seem to make it work.

My situation, simplified, is as below. I happen to be using the async variant, in case that has something to do with my inability to share across contexts.

async main() {
  const runtime = module.newRuntime();
  const context1 = runtime.newContext();

  await context1.evalCodeAsync(`
  function add(x) {
    return x + 50;
  };
  `);

    const test1Res = context.unwrapResult(await context1.evalCodeAsync(`add(50)`));
    console.log('add result1 (should be 100):', context1.getNumber(test1Res));
    test1Res.dispose();

    const contextPointer = context1.ctx.value;

   const context2 = runtime.newContext({contextPointer});
  
    // Throws with 'add' is not defined.
    const test2Res = context2.unwrapResult(await context2.evalCodeAsync(`add(10)`));
    console.log('add result2 (should be 60):', context2.getNumber(test2Res));
    test2Res.dispose();
}

Any help would be greatly appreciated.

[justjake]

Here context2 should actually a reference to context1 since they have the same underlying memory pointer address. The issue is there’s a bug in the asyncified runtime’s newContext method where it ignores the passed pointer, so you are actually getting two contexts in the same runtime.

I think you are misusing the API. There’s no point to having context JS objects pointing to the same context C pointer. To make a painful analogy, let’s say the pointer is a door, and the QuickJSContext object is a doorknob. What your code is trying to do is attach two doorknobs to the same door.

Contexts in a runtime do not share any globals. What I mean by “sharing values” is that you can take a handle returned from one context, and pass it as a parameter into another context, if the contexts share the same runtime.