Internal reactor queue blocks further type-checking of currently type-checked file

[TIHan]

Whenever we save a file, incremental builder picks up on the file change and invalidates all files that depend on it, and potentially it will invalidate other incremental builds(projects). An IDE may request analysis on the files that depended on the one that was changed; this blocks the reactor queue from processing anything until all the requests for analyses have been finished. The result is that the tooling stops being functional in the file that you currently saved and are editing, even though the information exists.

• Make incremental builder cache be accessed on any thread Removing reactor-queue dependencies #10292
• Make data structures, such as Dictionary, be ConcurrentDictionary in parts of the compiler. Making several uses of Dictionary types be ConcurrentDictionary #10308
• Lock type provider calls to be single-threaded (no parallel TP calls). Sequentialise type provider calls by using a lock rather than requiring the Reactor single threading #10310
• Start removing requirements of reactor-queue for data that exists. Removing reactor-queue dependencies #10292

As part of 10292 we will do all of these:

• All of the FSharpCheckFileResults operations will no longer use the Reactor and hence no longer by async.
• The four operations Get*UsesOfAllSymbolsIn* were only async to support cancellation. For clarity these will no no longer by async and instead accept an optional cancellation token
• userOpName is removed from all the operations which are no longer async (it is there for async causality tracing)
• StructuredDescriptionTextAsync and DescriptionTextAsync no longer used the Reactor thread. They are marked as obsolete, and instead synchronous StructuredDescriptionText and DescriptionText should be used
• The caches scriptClosureCache and incrementalBuildersCache are now usable from any thread
• The optional argument hasTextChangedSinceLastTypecheck is removed from FSharpChecker API as it no longer needed by Visual F# Tools since 2017 rewrite
• The optional argument textSnapshotInfo is removed from FSharpChecker API as it only existed to pass back to hasTextChangedSinceLastTypecheck

[auduchinok]

Seems to be related to #4537.

[dsyme]

@auduchinok @saul I've added notes about the further work to remove the reliance on the reactor in #10292 , will also copy them over there. This leads to API changes in FCS, see the notes.

[auduchinok]

@dsyme This is fantastic news, I'm looking forward to seeing how it works!