Xud: LND: switch to https://api.lightning.community/#sendpaymentv2

[kilrau]

EDIT: lndbtc & lndltc are upgraded to 0.11 and from that perspective we are ready to enable MPP. Question now is if to move to the streaming call sendpaymentv2 since MPP is currently not available in the sync version sendpaymentsync. TBD if it ever will be (see https://github.com/ExchangeUnion/xud/issues/1590#issuecomment-680199496).

[sangaman]

As I understand it for this issue we are waiting for 0.10.1 to be used for lnd in the xud-docker repo.

[kilrau]

And before that lndltc to be upgraded to that version too, yes.

cc @losh11

[losh11]

lndltc 0.10.1 release is planned. currently have an alpha running on my computer, just trying to fix a few issues, then will release ASAP

[kilrau]

If you need help with testing -> push the branch and ping us :muscle:

[rsercano]

This API uses streaming instead of unary calls we already use, this's the unary call we use; https://api.lightning.community/#sendpaymentsync and there's no unary call for sendpaymentv2

Just to ensure, will we switch to stream calls? Note that since this's async, I'm not sure how to handle this.

[kilrau]

True, didn't see that. We ideally would want to stick with https://api.lightning.community/#sendpaymentsync. Can you check if it supports max_parts? https://api.lightning.community/#sendpaymentsync indicates it doesn't, but maybe the documentation is wrong.

[rsercano]

Unfortunately it doesn't as of today https://github.com/lightningnetwork/lnd/blob/fc12656a1a62e5d69430bba6e4feb8cfbaf21542/lnrpc/rpc.proto#L590

[losh11]

sendpaymentv2 has no sync call, which is the only version which supports MPP.

[kilrau]

sendpaymentv2 has no sync call, which is the only version which supports MPP.

Is it realistic that MPP will be available in sendpaymentsync at some point or should we switch to sendpaymentv2? @roasbeef

[Roasbeef]

sendpaymentsync was only a workaround as we didn't yet support streaming
responses over the REST interface. SendPaymentv2 will be the only endpoint
that'll be maintained and extended from now on.

On Tue, Aug 25, 2020 at 11:35 AM Kilian Rausch | ⚡ OpenDEX ⚡ <
[email protected]> wrote:

sendpaymentv2 has no sync call, which is the only version which supports
MPP.

Is it realistic that MPP will be available in sendpaymentsync at some
point or should we switch to sendpaymentv2? @Roasbeef
https://github.com/Roasbeef

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[erkarl]

sendpaymentsync was only a workaround as we didn't yet support streaming responses over the REST interface. SendPaymentv2 will be the only endpoint that'll be maintained and extended from now on.
…
On Tue, Aug 25, 2020 at 11:35 AM Kilian Rausch | zap OpenDEX zap < @.*> wrote: sendpaymentv2 has no sync call, which is the only version which supports MPP. Is it realistic that MPP will be available in sendpaymentsync at some point or should we switch to sendpaymentv2? @Roasbeef https://github.com/Roasbeef — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1590 (comment)>, or unsubscribe https://github.com/notifications/unsubscribe-auth/AAHTWLWBQ7M66ER4JWXJM3DSCP75TANCNFSM4NPU4UOA .

@sangaman maybe it's time we decouple SwapClient.sendPayment from returning the preimage? I believe this will also simplify the logic for swaps and align it with how we're sending payments for Connext.

[sangaman]

maybe it's time we decouple SwapClient.sendPayment from returning the preimage? I believe this will also simplify the logic for swaps and align it with how we're sending payments for Connext.

We could certainly do that but it seems like it may still be easiest to keep it as is and handle the async nature of SendPaymentv2 within LndClient. From our perspective there aren't any intermediary steps we'd need to take between the payment being started and the payment succeeding/failing, unless perhaps we want to log information such as when the HTLC is ready, but even then we could do that within LndClient.