Personally I've always found the overload of a prelude enum to be
confusing, and never bothered to handle it properly in bindings as
a result. To avoid needing to do so now, we simply move the
newly-introduced `io::Result` usages over to
`Result<_, io::Error>`.
MonitorUpdatingPersister is an implementation of Persister that stores
ChannelMonitorUpdates separately from ChannelMonitors. Its RFC is
in #2545, at https://github.com/orgs/lightningdevkit/discussions/2545.
Co-Authored-By: Elias Rohrer <dev@tnull.de>
While there is no great way to handle a true failure to persist a
`ChannelMonitorUpdate`, it is confusing for users for there to be
no error variant at all on an I/O operation.
Thus, here we re-add the error variant removed over the past
handful of commits, but rather than handle it in a truly unsafe
way, we simply panic, optimizing for maximum mutex poisoning to
ensure any future operations fail and return immediately.
In the future, we may consider changing the handling of this to
instead set some "disconnect all peers and fail all operations"
bool to give the user a better chance to shutdown in a semi-orderly
fashion, but there's only so much that can be done in lightning if
we truly cannot persist new updates.
When a `ChannelMonitorUpdate` fails to apply, it generally means
we cannot reach our storage backend. This, in general, is a
critical issue, but is often only a transient issue.
Sadly, users see the failure variant and return it on any I/O
error, resulting in channel force-closures due to transient issues.
Users don't generally expect force-closes in most cases, and
luckily with async `ChannelMonitorUpdate`s supported we don't take
any risk by "delaying" the `ChannelMonitorUpdate` indefinitely.
Thus, here we drop the `PermanentFailure` variant entirely, making
all failures instead be "the update is in progress, but won't ever
complete", which is equivalent if we do not close the channel
automatically.
Firstly, we switch our BP over to use `FilesystemStore`, which also gives us test
coverage and ensures the compatibility.
Then, we remove the superseded `KVStorePersister` trait and
the `FilesystemPersister` code.
We upstream the `KVStore` interface trait from LDK Node, which will
replace `KVStorePersister` in the coming commits.
Besides persistence, `KVStore` implementations will also offer to `list`
keys present in a given `namespace` and `read` the stored values.
In the next commit(s) we'll start holding `ChannelMonitorUpdate`s
that are being persisted in `Channel`s until they're done
persisting. In order to do that, switch to applying the updates by
reference instead of value.
When a `chain::Watch` `ChannelMonitor` update method is called, the
user has three options:
(a) persist the monitor update immediately and return success,
(b) fail to persist the monitor update immediately and return
failure,
(c) return a flag indicating the monitor update is in progress and
will complete in the future.
(c) is rather harmless, and in some deployments should be expected
to be the return value for all monitor update calls, but currently
requires returning `Err(ChannelMonitorUpdateErr::TemporaryFailure)`
which isn't very descriptive and sounds scarier than it is.
Instead, here, we change the return type used to be a single enum
(rather than a Result) and rename `TemporaryFailure`
`UpdateInProgress`.
The bindings generator is pretty naive in its generic resolution
and doesn't like `where` clauses for bounds that are simple traits.
This should eventually change, but for now its simplest to just
inline the relevant generic bounds.
P2PGossipSync logs before delegating to NetworkGraph in its
EventHandler. In order to share this handling with RapidGossipSync,
NetworkGraph needs to take a logger so that it can implement
EventHandler instead.
