internal/lsp/protocol: send responses for cancelled requests

LSP https://microsoft.github.io/language-server-protocol/specifications/specification-current/#cancelRequest
expects the server to send back the response even when the request is cancelled.

Gopls LSP protocol implements the cancellation using the context cancellation.
That is, upon a cancellation request from the client, the server calls the
corresponding canceller that cancels the context passed to the handler.
Reusing this cancelled context for the replyer is not safe because code in any layer
can decide to shortcircuit and skip sending the data back to the client.
E.g. https://cs.opensource.google/go/tools/+/master:internal/jsonrpc2/stream.go;l=63

This CL make sure to pass the detached context to the replier.

Alternative, or a better approach to avoid any unexpected side-effect of
using a detached context is to send out the response at the point of cancellation
with a separate context. But that requires more significant code change.

Testing is currently hard, but maybe doable once the current refactoring is
done. Test is left as a TODO.

Change-Id: I4611af00ad913e96b62c6b7180c6673b0465daf9
Reviewed-on: https://go-review.googlesource.com/c/tools/+/232300
Reviewed-by: Ian Cottrell <iancottrell@google.com>
1 file changed
tree: 5c59bd0aca2987bae12f2a065a73ed9db5e8f4fd
  1. benchmark/
  2. blog/
  3. cmd/
  4. container/
  5. cover/
  6. go/
  7. godoc/
  8. gopls/
  9. imports/
  10. internal/
  11. playground/
  12. present/
  13. refactor/
  14. txtar/
  15. .gitattributes
  16. .gitignore
  17. AUTHORS
  18. codereview.cfg
  19. CONTRIBUTING.md
  20. CONTRIBUTORS
  21. go.mod
  22. go.sum
  23. LICENSE
  24. PATENTS
  25. README.md
README.md

Go Tools

This subrepository holds the source for various packages and tools that support the Go programming language.

Some of the tools, godoc and vet for example, are included in binary Go distributions.

Others, including the Go guru and the test coverage tool, can be fetched with go get.

Packages include a type-checker for Go and an implementation of the Static Single Assignment form (SSA) representation for Go programs.

Download/Install

The easiest way to install is to run go get -u golang.org/x/tools/.... You can also manually git clone the repository to $GOPATH/src/golang.org/x/tools.

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://golang.org/doc/contribute.html.

The main issue tracker for the tools repository is located at https://github.com/golang/go/issues. Prefix your issue with “x/tools/(your subdir):” in the subject line, so it is easy to find.