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chanbackup: update on-disk backup file with unconfirmed channels #3993

Merged
merged 5 commits into from
Mar 10, 2020
Merged

chanbackup: update on-disk backup file with unconfirmed channels #3993

merged 5 commits into from
Mar 10, 2020

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guggero
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@guggero guggero commented Feb 10, 2020

Fixes #3816.

Currently there is a discrepancy between the backups obtained through the gRPC call and the content of the automatically created channel.backup file. The RPC backups do contain pending channels while the backup file does not.
This PR aims to fix that discrepancy.

@guggero guggero added safety General label for issues/PRs related to the safety of using the software recovery Related to the backup/restoration of LND data (e.g. wallet seeds) backups SCB Related to static channel backup labels Feb 10, 2020
@guggero guggero added this to the 0.10.0 milestone Feb 10, 2020
@guggero guggero requested review from cfromknecht and removed request for Roasbeef February 10, 2020 16:15
cfromknecht
cfromknecht reviewed Feb 12, 2020
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solid pr, no issues with the existing code. my only other question is are these pending channels ever cleaned up if the channels never confirm? it seems like they could continue to inflate the size of our channel.backup indefinitely unless they are later pruned, no?

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@guggero
fundingmgr+channelnotifier: add channel config to pending chan ntfn
182835d 
To be able to write a new channel backup file for pending channels,
we need to include the channel configuration in the pending channel
notification event.
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guggero commented Feb 14, 2020

are these pending channels ever cleaned up if the channels never confirm?

Good question. What happens with them in the channel DB? Are they detected and removed after a certain time? Or would you need to call abandonchannel on them? If the latter is true then we can just add the close notification to AbandonChannel.
But still, you might want to keep the backup in case it ever confirms for whatever reason. It's a few hundred bytes per channel and their number should be very limited so I'm not too worried about the size of the backup file.

halseth
halseth suggested changes Mar 4, 2020
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halseth commented Mar 4, 2020

are these pending channels ever cleaned up if the channels never confirm?

Good question. What happens with them in the channel DB? Are they detected and removed after a certain time? Or would you need to call abandonchannel on them? If the latter is true then we can just add the close notification to AbandonChannel.
But still, you might want to keep the backup in case it ever confirms for whatever reason. It's a few hundred bytes per channel and their number should be very limited so I'm not too worried about the size of the backup file.

Yes, currently they will stay around (only if you're the initiator) until abandonchannel is called. There is an existing issue/PR to address this: #1755, for now I think it is okay the backup stays around until abandon channel is called.

@guggero
channel_notifier: update backup on pending chan
d8c62c3 
To fix the discrepancy between getting the channel backups via
RPC where all pending channels are included, we also update the
channel.backup file on disk whenever we get a pending channel
event notification.
@guggero
itest: test unconfirmed channel backup file
8a2c02f
@guggero
rpcserver: don't skip pending channels in backup subscription
4e0c276 
The synchronous call to get all channel backups also include
channels that are pending at the moment of the call. A previous
commit added pending channels to the file based backup as well. So
this is the last backup method that needs to be adjusted to also
contain unconfirmed channels.
@guggero
rpcserver+itest: remove channel from backup when abandoning it
ab024b9
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guggero commented Mar 4, 2020

I added a commit to remove the channel from the backup file if abaondonchannel is called.

@guggero guggero requested a review from halseth March 4, 2020 10:00
halseth
halseth approved these changes Mar 4, 2020
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LGTM 💯

Roasbeef
Roasbeef approved these changes Mar 10, 2020
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LGTM 🌊

@Roasbeef Roasbeef merged commit cbef26b into lightningnetwork:master Mar 10, 2020
@guggero guggero deleted the unconfirmed-chanbackup branch March 10, 2020 09:00
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@halseth halseth halseth approved these changes

@Roasbeef Roasbeef Roasbeef approved these changes

@cfromknecht cfromknecht Awaiting requested review from cfromknecht

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unconfirmed channels are not included in channel backup when using gRPC
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@guggero @halseth @Roasbeef @cfromknecht