Splice: Better balance checking #6748
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@rustyrussell One question I was unsure of here -> if there is an HTLC in the channel struct should that be counted as a pending HTLC or should it only be considered if it is in certain specific states? |
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| if (!amount_msat_add(&funding_amount, | ||
| funding_amount, | ||
| pending_htlcs[TX_INITIATOR])) | ||
| peer_failed_warn(peer->pps, &peer->channel_id, | ||
| "Unable to calculate starting channel amount"); | ||
| if (!amount_msat_add(&funding_amount, | ||
| funding_amount, | ||
| pending_htlcs[TX_ACCEPTER])) | ||
| peer_failed_warn(peer->pps, &peer->channel_id, | ||
| "Unable to calculate starting channel amount"); |
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I cried in the last couple of days to understand this logic here, and I am still not sure 100% for what this code does
Can you clarify this operation? and why do we need to look at the pending htlc? we can not just look at the peer->channel->view? to get the balance of the channel. it should contains the on-flight htlc too, right?
Please add a couple of comments in the code to make the review easy to look at, thanks
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It seems pending HTLC amounts are not included in the channel->view amount as my initial splicing code assumed. I've asked rusty for some clarification here: #6748 (comment)
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I am still confused by this change here.
From the following comment https://github.com/ElementsProject/lightning/blob/master/common/initial_channel.h#L19 the peer->channel->view contains all the pending change, this mean that it contains also the pending_htlcs?
Is the comment outdated?
Can you clarify these operations for readers, please?
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as far as I understand, peer->channel->view only contains the main outputs.
I think there's a semantic confusion here, because the doc on the view field talks about "pending" in the sense of whether protocol changes (such as add_htlc) are committed with a signature, but the new code here is using "pending" in the sense of "live" or "in-flight" HTLCs. should probably drop the use of the world pending.
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Yes, pending means "uncommitted" in that comment. Should be fixed!
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Fixed up Python whitespace which was annoying flake8, and rebased onto #6802 for test flake fixes. |
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* Regression test added for Issue ElementsProject#6572 (issuecomment-1730808863) w/stuck HTLC * `check_balance` adjusted to calculate pending HTLCs explicitly * Test confirmed to fail prior to PR ElementsProject#6713 ChangeLog-Fixed: Issue splicing with pending / stuck HTLCs fixed.
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Rebased on master. |
| if (!amount_msat_add(&funding_amount, | ||
| funding_amount, | ||
| pending_htlcs[TX_INITIATOR])) | ||
| peer_failed_warn(peer->pps, &peer->channel_id, | ||
| "Unable to calculate starting channel amount"); | ||
| if (!amount_msat_add(&funding_amount, | ||
| funding_amount, | ||
| pending_htlcs[TX_ACCEPTER])) | ||
| peer_failed_warn(peer->pps, &peer->channel_id, | ||
| "Unable to calculate starting channel amount"); |
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I am still confused by this change here.
From the following comment https://github.com/ElementsProject/lightning/blob/master/common/initial_channel.h#L19 the peer->channel->view contains all the pending change, this mean that it contains also the pending_htlcs?
Is the comment outdated?
Can you clarify these operations for readers, please?
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Yes, note that htlcs need to be in a committed state for splicing, so this code (which omits the committed check for htlcs) is actually correct here (though not general). I don't think you need to recalc funding_amount though. channel->funding_sats is this? |
check_balanceadjusted to calculate pending HTLCs explicitlyChangeLog-Fixed: Issue splicing with pending / stuck HTLCs fixed.