WIF Sweeping/Watchtower Race-Condition

[jimtendo]

Hi Paytaca Team,

There appears to be a race-condition of sorts with the Sweep function of Paytaca.

The way this works currently is that, upon sweeping:

1. A subscribe call is made to Watchtower
2. A follow-up getBalance call is then made

https://github.com/paytaca/paytaca-app/blob/master/src/wallet/sweep.js#L17

The subscription call will not trigger an immediate refresh of the balance in Watchtower in many cases. This means if funding of a WIF takes place outside of a Paytaca Wallet and a user attempts to sweep it from within Paytaca, the balance will often show as zero.

In personal testing, I have noticed that sometimes, after trying an initial sweep that shows balance as zero, I can come back a few minutes later and it'll show (but this does not seem to happen in all cases - one suspicion I had is that it might be refreshing, after subscription, on block confirmations, but am not certain on that).

For the CashStamps use-case, I've hacked in a temporary work-around here that attempts to subscribe the addresses to Watchtower before funding takes place:

https://github.com/harvmaster/CashStamps/blob/main/src/components/FundingDialog.vue#L195