Postpone wait for build job

[snjeza]

A related issue - #2519

[CsCherrYY]

Just tried this patch, the capabilities are registered indeed before building and after the project is imported, however, the language features (e.g., definition, completion) are still unusable when building (we can call these requests, but no response). After the building process is finished, the features are usable.

Or is there anything I'm missing?

[snjeza]

@CsCherrYY You may want to take a look at #2519 (comment)

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I think it is possible. However, which language feature do you expect will be available without proper project configuration? Completion for example requires at least that the dependencies are available to be helpful.
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[rgrunber]

I'm fine with merging, it's just difficult to find cases where the benefit is very clear.

I think any delegate command should benefit by being able to respond sooner since it no longer relies on the autobuild completing. However, there are delegate commands that basically rely on the index, or maybe they rely on certain parts of JDT that ultimately depend on the autobuild. Testing this change, I can definitely see the paste event being properly handled immediately after ServiceReady whereas before it would need to wait for the autobuild to also complete. Unfortunately I also see cases where the autobuild blocks the paste event from continuing to execute.

From my understanding of the protocol, if ServiceReady is sent out sooner, then the client will begin sending other requests (eg. delegate commands), and if they're handled sooner that should be an improvement.

[testforstephen]

Another root cause about features not responding during autobuild is lock conflicts. According to our analysis, we see that when a feature is not responding, it actually never enters the LSP dispatcher class JDTLanguageServer.java yet. This means that lsp4j's jsonrpc processor is blocked by some handler during autobuild, and subsequent lsp requests are queued at lsp4j jsonrpc layer. This is another key performance issue #2518 we need to improve.