Initial draft for bsp support.
This shows two communication pattern around BSP.
First, if the request can be handled with the build knowledge is readily available in `NetworkChannel` we can reply immediately. `BuildServerImpl#onBspBuildTargets` is an example for that.
Second, if the request requires `State`, then we can forward the parameter into a custom command, and reply back from a command. `BuildServerProtocol.bspBuildTargetSources` is an example of that since it needs to invoke tasks to generate sources.
java.util.ServiceLoader uses findResources(), which was not
overriden in ReverseLookupClassLoader, causing resources available
in the descendant classloader not to be discovered when a service
loader instance was using the top classloader.
Having the progress reports directly generated in beforeWork delays the
task from being submitted to the executor. This commit moves all of the
reporting onto the background thread to avoid these delays since
progress is less important than task evaluation.
The old implementation of checkBuildSources can easily take 20ms to run
when called in MainLoop.processCommand. It is rarely faster than 4-5ms.
To reduce this overhead, I stopped using the checkBuildSources task in
processCommand. Instead, I manually cache the build source hashes in a
global state variable and add a file monitor that invalidate the entire
set of source hashes if any changes are detected. This could probably be
more efficient, but I figure that build sources change infrequently
enough that it's fine to just invalidate the entire list of source
hashes.
Because the CheckBuildSources instance is already watching the meta
build, I reworked Continuous to use that FileTreeRepository for the
build sources if it is available.
Bonus: fixes https://github.com/sbt/sbt/issues/5482
I was surprised to find this method in a flamegraph* so I optimized it.
TaskProgress was actually on the hotpath of task evaluation so every
single task was slower to be enqueued with the CompletionService. After
this change, containsSkipTasks dropped out of the flamegraph.
*The flamegraph was for a compile loop where sbt constantly modified a
single source file and re-compiled it. The containsSkipTasks method
appeared in over 2% of the method calls.