chore(lsp): avoid redundant type checking

[asterite]

Description

Problem

No issue, just something I noticed.

Summary

The LSP communication has notifications (synchronous) and requests (asynchronous). Some of the notifications we are handling are:

• a file was opened
• a file contents changed
• a file was saved
• a file was closed

In each of these notifications we would run type-checking on the package the file is in. Because this is synchronous, all subsequent requests will have to wait for this notifications to be handled, meaning having to wait the type-checker.

The first thing this PR does is to not immediately type-check on notifications. Instead, we remember that the package changed and then, when needed, we type-check it. This already slightly improves things as we could sometimes get multiple "file contents changed" notifications in a row, if the user is typing relatively fast.

The next thing is that when the user opens a file in the editor we'd only need to type-check the package if it's the first time that package is opened. If the user opens another file in the same package there's no need to type-check things again. There was a noticeable slowdown when you'd navigate by clicking on items because if that item's file wasn't open you'd have to wait for type-checking to finish (and same if you'd click on another item next, etc.).

When a file is saved there's no need to type-check as "file saved" is only that (if you change a file and save it quickly we still get two separate notifications). What we do need to do is to output the errors to the "Problems" view. Then, there's a special handling here for when the user saves after no change happened. This is for when the user goes to the console and does git checkout some-other-branch where VSCode wouldn't realize files changed. In that case we do full type-checking (Rust Analyzer seems to do the same).

Then, when a file is closed there's no need to do type-checking.

Finally, we kept a counter of open files. When it reached zero we'd clean all cached data. That meant that if you closed all files and opened one, you'd have to wait for type-checking. I'm thinking keeping the cache is better here as, at least I, sometimes close all files when I have too many open and I don't want to lose all the type-checking information in that case.

Additional Context

This doesn't solve the issue of sometimes having to wait a couple of seconds before getting inlay hints, etc., but it should make things a bit more smooth/responsive.

Documentation

Check one:

• No documentation needed.
• Documentation included in this PR.
• [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Test Suite Duration'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.20.

Benchmark suite	Current: a1df3f9	Previous: e7fb7f3	Ratio
test_report_AztecProtocol_aztec-packages_noir-projects_noir-protocol-circuits_crates_blob	3 s	2 s	1.50
test_report_AztecProtocol_aztec-packages_noir-projects_noir-protocol-circuits_crates_private-kernel-lib	2 s	1 s	2
test_report_AztecProtocol_aztec-packages_noir-projects_noir-protocol-circuits_crates_reset-kernel-lib	2 s	1 s	2
test_report_zkpassport_noir-ecdsa_	2 s	1 s	2

This comment was automatically generated by workflow using github-action-benchmark.

CC: @TomAFrench