Xud: No reason given for "no matches" of small market orders

[raladev]

Steps:

1. place sell 0.92168142 ETH/BTC 0.03471718 order as a maker
2. try to fill it as a taker - buy 0.00002 ETH/BTC mkt

Actual result:
'No matches' message

Expected result:
also cli output/placeorder response should contain message with reason of unmatching (0.92168142*0.00002 < 100 sat)

[kilrau]

This is because of the dust order change. Agree that there should be a message saying the order not meeting the minimum quantity.

[sangaman]

I wouldn't describe this as a bug, this functionality just doesn't exist currently. We discussed a similar topic in another issue or PR (informing the user why a dust order was discarded) but we don't currently have any sort of field on the grpc response to explain why there was no match or why an order was discarded. So we could add something like this, an informational message/field that gives the user details about the matching perhaps, but it would be a new feature.

[kilrau]

Agree that it's no a bug per se. Sounds like what should be done!

[rsercano]

May I have a look at this?

[kilrau]

Sure, just to clarify: this is about adding a field in the grpc response to specify why the order was discarded ("quantity below threshold") and to display this reason on the cli.

[rsercano]

As I checked this in deep, I don't think this's about adding a new field to grpc, for limit orders as @raladev showed we're already throwing an error and showing the error message, but for market orders, there's only one check for dust orders and it checks only order quantity and there's no order.quantity*order.price calculation naturally because price is not clear unless we read it from orderbook.

Therefore, let me know how to proceed with this please? @sangaman @raladev @kilrau

[kilrau]

Thanks for looking into it. I still believe this is about adding a new field to the grpc response. Maybe @sangaman can weigh in with a concrete implementation proposal. Until then lets hold off on this issue.