pay: Annotate both local alias and real scid with channel hints #6428
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Debugging a number of payments showed that we sometimes waste a number of attempts routing through a channel via its alias, rather than its scid. This is because while we annotate the scid when it has been set, we do not do so for the alias. The alias then is picked for routing despite not having enough capacity, failing the attempt locally. It can also happen that we alternate between scid and alias, doubling the number of failed attempts before we can make progress. This patch sets the hint for the alias to a capacity of 0 and disables it as if the peer were offline. This means when available we'll always use the scid, which is also far easier to read in the logs. Changelog-Fixed: pay: We now track spendable amounts when routing on both the local alias as well as the short channel ID
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The channel selection did not consider the amounts that we are trying to transfer, which in a multiplexed channel world could end up always selecting a channel that is too small for the payment. We also log which channel was selected based on the selector that is passed in, allowing us to better follow the decisions. Changelog-Fixed: pay: `sendonion` and `sendpay` will now consider amounts involved when using picking one channel for a peer
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The alias may not be set for non-alias channels after they confirm. The other branch is safe because we only consider active channels. Changelog-None Fixes ElementsProject#6450
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The alias may not be set for non-alias channels after they confirm. The other branch is safe because we only consider active channels. Changelog-None Fixes #6450
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Debugging a number of payments showed that we sometimes waste a number of attempts routing through a channel via its alias, rather than its scid. This is because while we annotate the scid when it has been set, we do not do so for the alias. The alias then is picked for routing despite not having enough capacity, failing the attempt locally.
It can also happen that we alternate between scid and alias, doubling the number of failed attempts before we can make progress.
This patch sets the hint for the alias to a capacity of 0 and disables it as if the peer were offline. This means when available we'll always use the scid, which is also far easier to read in the logs.
Changelog-Fixed: pay: We now track spendable amounts when routing on both the local alias as well as the short channel ID