When swift-format crashes before we send all data to its stdin, we get a SIGPIPE when trying to write more data to its studio on Linux. This, in turn, takes SourceKit-LSP down.
Do the same trick that we do when launching `JSONRPCConnection` of disabling SIGPIPE globally if we can’t disable it for individual pipes.
rdar://147665695
There is only one real class that implements the `SourceKitD` protocol, so there really isn’t any need for the protocol + class split at all. Unify them to make code simpler to reason about.
We would hit quadratic behavior in `AsyncQueue` when the build system floods us with `build/logMessage` or `build/task(Start|Progress|Finish)` notifications because we record a dependency on all of the pending log message handling tasks.
We can extend the improvement made in https://github.com/swiftlang/sourcekit-lsp/pull/1840 to fix this quadratic problem: If the current task depends on a task with metadata that depends on itself (ie. all tasks of metadata that needs to be executed in-order), we only need to depend on the last task with that metadata.
This covers many message types and we can now only get into quadratic behavior if we get flooded with two different kinds of messages: One that does not have a self-dependency and one that depends on the message without a self-dependency. In terms of LSP messages, this could be a document read followed by a document update, but I think this is a lot more unlikely than getting spammed with one type of message.
We were blocking the initialization response on `self.buildSystemManager.testFiles`, which requires the list of test files to be determined. Make that operation asynchronous so that a slow build server can’t take down all of SourceKit-LSP.
Otherwise, we return the failed diagnostic report even after sourcekitd has been restored.
Also, make sure that we don't show the `semantic editor is disabled` error to users.
Otherwise, the close does not get handled by the SourceKit plugin. In practice, it doesn’t matter too much because the SourceKit plugin will implicitly close the last completion session when a new one is opened but we should fix this.
SourceKit-LSP prepares the currently active file for editor functionality and currently infers the currently active document from whichever received the last `TextDocumentRequest`.
If an editor is capable of doing so, it should be able to report the document that the user currently has focused so that SourceKit-LSP does not have to infer this information from other requests.
Also clean up some handling code for experimental capabilities.
If the build system is sending us with `buildTarget/didChange`, we would always create processor count * 4 new entries in the `indexingQueue` to rescan those files, if they are up-to-date. This can be quite wasteful if the underlying files didn’t actually change. Do a quick scan up-front to check if the files actually need to be re-scanned up-front.
