internal/lsp/cache: simplify modtidy

Previously, the modtidy operation used a persistent map
of handles in the central store that cached the result
of a parsing the go.mod file after running 'go mod tidy'.
The key was complex, including the session, view, imports
of all dependencies, and the names of all unsaved overlays.
The fine-grained key prevented spurious cache hits for
invalid inputs by (we suspect) preventing nearly all cache hits.

The existing snapshot invalidation mechanism should be
sufficient to solve this problem, as the map entry is evicted
whenever the metadata or overlays change. So, this change
avoids keeping handles in the central store, so they are
never shared across views.

Also, modtidy exploited the fact that a packageHandle
used to include a copy of all the Go source files
of each package, to avoid having to read the files
itself. As a result it would entail lots of unnecessary
work building package handles and reading dependencies
when it has no business even thinking about type checking.

This change:
- extracts the logic to read Metadata.{GoFiles,CompiledGo}Files
  so that it can be shared by modtidy and buildPackageHandle.
- packageHandle.imports has moved into mod_tidy.
  One call (to compute the hash key) has gone away,
  as have various other hashing operations.
- removes the packagesMap typed persistent.Map wrapper.
- analysis: check cache before calling buildPackageHandle.
- decouple Handle from Store so that unstored handles may
  be used.
- adds various TODO comments for further simplification.

Change-Id: Ibdc086ca76d6483b094ef48aac5b1dd0cdd04973
Reviewed-on: https://go-review.googlesource.com/c/tools/+/417116
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Run-TryBot: Alan Donovan <adonovan@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
9 files changed
tree: 60a971067b869f2599473da0f7e19e4d272d512f
  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.