PaychGet has poor usability

[raulk]

Description

PaychGet has poor usability. It either gets or creates the channel. The last parameter is called ensureFunds, which makes me think it’ll do an “upsert” ensuring that at least that much funds are available.

What it in fact does is:

• if the channel doesn’t exist, it creates it and funds it with ensureFunds.
• if the channel exists, it adds ensureFunds to it.

This is poor UX because it creates a catch-22 situation.

Say I know I want a channel between A and B with N funds. I know my balance, but I don’t know if the payment channel exists beforehand, and the very method that lets me query that will actually create the channel for me. The only deterministic way to use this is by setting ensureFunds=0, which defeats the purpose of this field altogether.

Possible solution

The ideal solution is to make this method behave like advertised (ensuring that N funds exists in the channel), but there may be timing conditions with messages appearing on chain, yada-yada-yada.

[dirkmc]

The UX is definitely a little confusing here.

We're actually changing this so that the last parameter is called Amt.
The reason that we always want to increase the total amount in the payment channel is to satisfy the following use case:

• In one process Alice wants to create deal 1 with Bob worth 5 FIL
• In another process Alice wants to create deal 2 with Bob worth 7 FIL

We want the total amount reserved in the channel to be 12 FIL (enough for both deals).

I think it may make most sense to

1. Change the name of the API call to make it clear what it's doing
2. Add another API call that allows a client to check if there's a channel between from -> to, and how much is in the channel

Do we currently have a use case for point 2 above?

[hoffmabc]

I'm not sure what you'd change the name to. PaychNew or PaychCreate would make sense if it didn't also provide the ability to top up a channel. Maybe that's an ok name, something like PaychTopoff or PaychDeposit.

I definitely think there's a demand for use case #2.

[ghost]

I found this confusing at first too. Maybe PaychGetOrCreate could make this clearer to users?

+1 on Amt

[dirkmc]

#3448 provides the ability to find out how much available funds there are for a given from / to combination

[TippyFlitsUK]

Hi @raulk

This issue has not been updated in some time. Should we close it or keep it open?

[raulk]

I don't have the bandwidth to verify if the concerns are resolved. @TippyFlitsUK is this something you can test yourself and see if the UX is more coherent now?

[TippyFlitsUK]

Leave it to me @raulk . Many thanks for your confirmation!!