Investigate parallel listener calls

[marcelomorgado]

On the development environment, are being called simultaneously and resulting in unexpected behaviors. Actually, blocks are being mined so shortly that a listener for a block is being called before of the call from the last block. For now, a call will be ignored if has another call running. Comment extracted from: tasit-action > Action.js > #addConfirmationListener:

// Note:
// On the development env (using ganache-cli)
// Blocks are being mined simultaneously and generating a sort of unexpected behaviors like:
// - once listeners called many times
// - sequential blocks giving same confirmation to a transaction
// - false-positive reorg event emission
// - collaborating for tests non-determinism
//
// Tech debt:
// See if there is another way to avoid these problems, if not
// this solution should be improved with a state structure identifying state per event
//
// Question:
// Is it possible that that behavior (listener concurrent calls for the same event) is desirable?

Extracted from: https://github.com/tasitlabs/TasitSDK/pull/369#discussion_r280218408

[pcowgill]

For now, a call will be ignored if has another call running.

Is this explicitly enforced in our code, or is this the default behavior?

[marcelomorgado]

@pcowgill commented:

Is the non-determinism mostly for tests where the listener is added before or after sending the tx? Or is it a little of both?

We're sure it's not just getting called again with another confirmation for each instantaneous block, right? If so, we could probably disable that in our code and check number of confirmations on each listener call. Or something like that.

[marcelomorgado]

For now, a call will be ignored if has another call running.

Is this explicitly enforced in our code, or is this the default behavior?

Is this explicitly enforced in our code:

From Subscription class:

const listener = async (...args) => {
  const eventListener = this.#eventListeners.get(eventName);
  const { isRunning } = eventListener;

  if (isRunning) {
    console.info(`Listener is already running`);
    return;
  }

  this.#decorateEventListener(eventName, { isRunning: true });
  await baseListener(...args);
  this.#decorateEventListener(eventName, { isRunning: false });
};

[pcowgill]

Got it - thanks