Introduce a wtclient `Manager` which handles tower clients. It indexes
clients by the policy used. The policy field is thus removed from the
`Config` struct which configures the Manager and is instead added to a
new `towerClientCfg` which configures a specific client managed by the
manager. For now, only the `NewClient` method is added to the Manager.
It can be used to construct a new `TowerClient`. The Manager currently
does notthing with the clients added to it.
This commit also adds tests for the DB changes made in the previous
commit since we can now read the new field with the FetchChanInfos
method.
The commit following this one does the backfill migration.
In this commit, a new key, cChanMaxCommitmentHeight, is added to the
channel details bucket. This key will hold the highest commitment number
that the tower has been handed for this channel. In this commit, we
start writing to it in the two places where a backup is first persisted
in the tower client db: 1) CommitUpdate and 2) in the Queue's `addItem`
method. The logic for both 1 & 2 is tested in the next commit which adds
a DB helper that allows us to read the new field.
A follow up commit will do a migration to back-fill the new field.
This is to avoid a potential race on WriteMessage and Flush internals.
Because there is no locking on WriteMessage and Flush, if we allow
writeMessage calls in Start after the writeHandler has started,
the writeMessage calls may call WriteMessage/Flush at the same time
that writeMessage calls from the writeHandler does. Since there is
no locking, internals like b.nextHeaderSend can race and cause
panics.
Running test cases in parallel with shared state means that they
can intermingle if they're run at the same time and set up incorrect
values when we assert on the number of channels we have. Moving the
peer setup into the parallel test run fixes this because no single
test case can interfere with the other.
In processZombieUpdate, the SCID passed to MarkEdgeLive should _not_ be
derived from the ChannelEdgeInfo ChannelID field since this field will
not be populated when GetChannelByID returns a ChannelEdgeInfo along
with an ErrZombieEdge error. So this commit ensures that a usable
SCID is provided to processZombieUpdate.
Let MarkEdgLive return a new ErrNotZombieEdge error if an entry with the
given channel ID cannot be found. In processZombieUpdate, we then
check for this error and log accordingly.
