internal/lsp/cache: clarify buildPackageHandle

Before, buildPackageHandle and buildKey were mutually recursive.
Together they performed a sequential recursion over Metadata.Deps,
calling GetFile and parseGoHandle for every file, and then
finally (in postorder) binding a Handle for the type checking step.

This change inlines buildKey to make the recursion more obvious,
performs the recursion over dependencies first, followed by
the reading of Go source files for this package, in parallel.
(The IWL benchmark reports improvement but its variance is so
high I'm not sure I trust it.) Other opportunities for parallelism
are pointed out in new comments.

The Bind operation for typechecking calls dep.check for each
dependency in a separate goroutine. It no longer waits for
each one since it is only prefetching the information
that will be required during import processing, which will
block until the information becomes available.

Before, both reading and parsing appear to occur twice:
once in buildPackageHandle and once in doTypeCheck.
(Perhaps the second was a cache hits, but there's no need
to rely on a cache.)
Now, only file reading (GetFile) occurs in buildPackageHandle,
since that's all that's needed for the packageKey.
And parsing only occurs in doTypeCheck. The source.FileHandles
are plumbed through as parameters.

Also:
- move parseGoHandles to a local function, since it exists only
  for buildPackageKey. It no longer parses, it only reads.
- lots of TODO comments for possible optimizations,
  and typical measured times of various operations.
- remove obsolete comment re: Bind and finalizers.

Change-Id: Iad049884607b73eaa6701bdf7771f96b042142d5
Reviewed-on: https://go-review.googlesource.com/c/tools/+/411913
Run-TryBot: Alan Donovan <adonovan@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
4 files changed
tree: 3d550adc67a7afa96bdcde570553a2bc30a775eb
  1. benchmark/
  2. blog/
  3. cmd/
  4. container/
  5. copyright/
  6. cover/
  7. go/
  8. godoc/
  9. gopls/
  10. imports/
  11. internal/
  12. playground/
  13. present/
  14. refactor/
  15. txtar/
  16. .gitattributes
  17. .gitignore
  18. .prettierrc
  19. AUTHORS
  20. codereview.cfg
  21. CONTRIBUTING.md
  22. CONTRIBUTORS
  23. go.mod
  24. go.sum
  25. LICENSE
  26. PATENTS
  27. README.md
README.md

Go Tools

PkgGoDev

This repository provides the golang.org/x/tools module, comprising various tools and packages mostly for static analysis of Go programs, some of which are listed below. Use the “Go reference” link above for more information about any package.

It also contains the golang.org/x/tools/gopls module, whose root package is a language-server protocol (LSP) server for Go. An LSP server analyses the source code of a project and responds to requests from a wide range of editors such as VSCode and Vim, allowing them to support IDE-like functionality.

Selected commands:

  • cmd/goimports formats a Go program like go fmt and additionally inserts import statements for any packages required by the file after it is edited.
  • cmd/callgraph prints the call graph of a Go program.
  • cmd/digraph is a utility for manipulating directed graphs in textual notation.
  • cmd/stringer generates declarations (including a String method) for “enum” types.
  • cmd/toolstash is a utility to simplify working with multiple versions of the Go toolchain.

These commands may be fetched with a command such as go install golang.org/x/tools/cmd/goimports@latest.

Selected packages:

  • go/ssa provides a static single-assignment form (SSA) intermediate representation (IR) for Go programs, similar to a typical compiler, for use by analysis tools.

  • go/packages provides a simple interface for loading, parsing, and type checking a complete Go program from source code.

  • go/analysis provides a framework for modular static analysis of Go programs.

  • go/callgraph provides call graphs of Go programs using a variety of algorithms with different trade-offs.

  • go/ast/inspector provides an optimized means of traversing a Go parse tree for use in analysis tools.

  • go/cfg provides a simple control-flow graph (CFG) for a Go function.

  • go/expect reads Go source files used as test inputs and interprets special comments within them as queries or assertions for testing.

  • go/gcexportdata and go/gccgoexportdata read and write the binary files containing type information used by the standard and gccgo compilers.

  • go/types/objectpath provides a stable naming scheme for named entities (“objects”) in the go/types API.

Numerous other packages provide more esoteric functionality.

Contributing

This repository uses Gerrit for code changes. To learn how to submit changes, 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.

JavaScript and CSS Formatting

This repository uses prettier to format JS and CSS files.

The version of prettier used is 1.18.2.

It is encouraged that all JS and CSS code be run through this before submitting a change. However, it is not a strict requirement enforced by CI.