This commit introduces a new `IsRunning()` method to the `StateMachine`.
This method allows callers to safely query whether the state machine
is currently active after it has been started and before it has been
stopped.
To ensure thread-safety, the internal `running` status flag is
implemented using `atomic.Bool` (from `sync/atomic`). Without atomic
operations, concurrent accesses to a simple boolean flag from different
goroutines (e.g., one goroutine calling `IsRunning()` while another
executes `Start()` or `Stop()`) could lead to stale reads or data races.
Since we have not removed all call-sites that make use of this
parameter, we can remove it. This helps hide DB-specific details from
the interface we will introduce for the graph store.
In preparation for creating a clean interface for the graph store, we
want to hide anything that is DB specific from the exposed methods on
the interface. Currently the `ForEachNodeChannel` and the
`FetchOtherNode` methods of the `KVStore` expose a `kvdb.RTx` parameter
which is bbolt specific. There is only one call-site of
`ForEachNodeChannel` actually makes use of the passed `kvdb.RTx`
parameter, and that is in the `establishPersistentConnections` method of
the `server` which then passes the tx parameter to `FetchOtherNode`.
So to clean-up the interface such that the `kvdb.RTx` is no longer
exposed: we instead create one new method called
`ForEachSourceNodeChannel` which can be used to replace the above
mentioned call-site. So as of this commit, all the remaining call-site
of `ForEachNodeChannel` pass in a nil param for `kvdb.RTx` - meaning we
can remove the parameter in a future commit.
Later on we will create an interface for the persisted graph data. We
want this interface to be as small and as neat as possible. In
preparation for this, we remove this unused `Wipe` method.
The `GraphSource` interface in the `autopilot` package is directly
implemented by the `graphdb.KVStore` and so we will eventually thread
contexts through to this interface. So in this commit, we start updating
the autopilot system to thread contexts through in preparation for
passing the context through to any calls made to the GraphSource.
Two context.TODOs are added here which will be addressed in follow up
commits.
Replace all tests calls to the private `forEachNode` method on the
`KVStore` with the exported ForEachNode method. This is in preparation
for having the tests run against an abstract DB backend.
Remove the kvdb.Backend parameter from the `createChannelEdge` helper.
This is all in preparation for having the unit tests run against any DB
backend.
This commit cleans up the graph test code by removing unused kvdb type
parameters from the `createTextVertex` and `createLightningNode` helper
methods. We also pass in the testing parameter now so that we dont need
to check the error each time we call `createTestVertex`.
For any method that takes a context that has a select that listens on
the systems quit channel, we should also listen on the ctx since we
should not need to worry about if this context is derived internally or
externally.
With this, we move a context.TODO() out of the gossiper and into the
brontide package - this will be removed in a future PR which focuses on
threading contexts through that code.
The `GossiperSyncer` makes various calls to the `ChannelGraphTimeSeries`
interface which threads through to the graph DB. So in preparation for
threading context through to all the methods on that interface, we
update the GossipSyncer accordingly by passing contexts through.
Two `context.TODO()`s are added in this commit. They will be removed in
the upcoming commits.
Pass the parent LND context to the gossiper, let it derive a child
context that gets cancelled on Stop. Pass the context through to any
methods that will eventually thread it through to any graph DB calls.
One `context.TODO()` is added here - this will be removed in the next
commit.
NOTE: for any internal methods that the context gets passed to, if those
methods already listen on the gossiper's `quit` channel, then then don't
need to also listen on the passed context's Done() channel because the
quit channel is closed at the same time that the context is cancelled.
In preparation for starting to thread a single parent context through
LND, we update the main `server.Start` method to take a context so that
it can later pass it to any subsytem's Start method it calls. We also
pass the context to `newServer` since it makes some calls that will
eventually reach the DB (for example the graph db).
We want `context.TODO()` to be high signal in the code-base. It should
signal clearly that work is required to thread parent context through to
the call-site. So to keep the signal-to-noise ratio high, we remove any
context.TODO() calls from tests since these will never need to be
replace by a parent context.
After this commit, there is only a single context.TODO() left in the
code-base.
We want `context.TODO()` to be high signal in the code-base. It should
signal clearly that work is required to thread parent context through to
the call-site. So to keep the signal-to-noise ratio high, we remove any
context.TODO() calls from tests since these will never need to be
replace by a parent context.
