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diff --git a/content/working-with-go.md b/content/working-with-go.md deleted file mode 100644 index 2a5d7a6..0000000 --- a/content/working-with-go.md +++ /dev/null @@ -1,285 +0,0 @@ -+++ -title = "Working with Go" -date = 2021-08-05 -[taxonomies] -tags = ["go"] -+++ - -_This document assumes go version \>= 1.16_. - -## Go Modules - -[Go modules](https://blog.golang.org/using-go-modules) have been added -in 2019 with Go 1.11. A number of changes were introduced with [Go -1.16](https://blog.golang.org/go116-module-changes). This document is a -reference for me so that I can find answers to things I keep forgetting. - -### Creating a new module - -To create a new module, run `go mod init golang.fcuny.net/m`. This will -create two files: `go.mod` and `go.sum`. - -In the `go.mod` file you'll find: - -- the module import path (prefixed with `module`) -- the list of dependencies (within `require`) -- the version of go to use for the module - -### Versioning - -To bump the version of a module: - -```bash -$ git tag v1.2.3 -$ git push --tags -``` - -Then as a user: - -```bash -$ go get -d golang.fcuny.net/m@v1.2.3 -``` - -### Updating dependencies - -To update the dependencies, run `go mod tidy` - -### Editing a module - -If you need to modify a module, you can check out the module in your -workspace (`git clone <module URL>`). - -Edit the `go.mod` file to add - -```go -replace <module URL> => <path of the local checkout> -``` - -Then modify the code of the module and the next time you compile the -project, the cloned module will be used. - -This is particularly useful when trying to debug an issue with an -external module. - -### Vendor-ing modules - -It's still possible to vendor modules by running `go mod vendor`. This -can be useful in the case of a CI setup that does not have access to -internet. - -### Proxy - -As of version 1.13, the variable `GOPROXY` defaults to -`https://proxy.golang.org,direct` (see -[here](https://github.com/golang/go/blob/c95464f0ea3f87232b1f3937d1b37da6f335f336/src/cmd/go/internal/cfg/cfg.go#L269)). -As a result, when running something like -`go get golang.org/x/tools/gopls@latest`, the request goes through the -proxy. - -There's a number of ways to control the behavior, they are documented -[here](https://golang.org/ref/mod#private-modules). - -There's a few interesting things that can be done when using the proxy. -There's a few special URLs (better documentation -[here](https://golang.org/ref/mod#goproxy-protocol)): - -| path | description | -| --------------------- | ---------------------------------------------------------------------------------------- | -| $mod/@v/list | Returns the list of known versions - there's one version per line and it's in plain text | -| $mod/@v/$version.info | Returns metadata about a version in JSON format | -| $mod/@v/$version.mod | Returns the `go.mod` file for that version | - -For example, looking at the most recent versions for `gopls`: - -```bash -; curl -s -L https://proxy.golang.org/golang.org/x/tools/gopls/@v/list|sort -r|head -v0.7.1-pre.2 -v0.7.1-pre.1 -v0.7.1 -v0.7.0-pre.3 -v0.7.0-pre.2 -v0.7.0-pre.1 -v0.7.0 -v0.6.9-pre.1 -v0.6.9 -v0.6.8-pre.1 -``` - -Let's check the details for the most recent version - -```bash -; curl -s -L https://proxy.golang.org/golang.org/x/tools/gopls/@v/list|sort -r|head -v0.7.1-pre.2 -v0.7.1-pre.1 -v0.7.1 -v0.7.0-pre.3 -v0.7.0-pre.2 -v0.7.0-pre.1 -v0.7.0 -v0.6.9-pre.1 -v0.6.9 -v0.6.8-pre.1 -``` - -And let's look at the content of the `go.mod` for that version too: - -```bash -; curl -s -L https://proxy.golang.org/golang.org/x/tools/gopls/@v/v0.7.1-pre.2.mod -module golang.org/x/tools/gopls - -go 1.17 - -require ( - github.com/BurntSushi/toml v0.3.1 // indirect - github.com/google/go-cmp v0.5.5 - github.com/google/safehtml v0.0.2 // indirect - github.com/jba/templatecheck v0.6.0 - github.com/sanity-io/litter v1.5.0 - github.com/sergi/go-diff v1.1.0 - golang.org/x/mod v0.4.2 - golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect - golang.org/x/sys v0.0.0-20210510120138-977fb7262007 - golang.org/x/text v0.3.6 // indirect - golang.org/x/tools v0.1.6-0.20210802203754-9b21a8868e16 - golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect - honnef.co/go/tools v0.2.0 - mvdan.cc/gofumpt v0.1.1 - mvdan.cc/xurls/v2 v2.2.0 -) -``` - -# Tooling - -### LSP - -`gopls` is the default implementation of the language server protocol -maintained by the Go team. To install the latest version, run -`go install golang.org/x/tools/gopls@latest` - -### `staticcheck` - -[`staticcheck`](https://staticcheck.io/) is a great tool to run against -your code to find issues. To install the latest version, run -`go install honnef.co/go/tools/cmd/staticcheck@latest`. - -## Emacs integration - -### `go-mode` - -[This is the mode](https://github.com/dominikh/go-mode.el) to install to -get syntax highlighting (mostly). - -### Integration with LSP - -Emacs has a pretty good integration with LSP, and ["Eglot for better -programming experience in -Emacs"](https://whatacold.io/blog/2022-01-22-emacs-eglot-lsp/) is a good -starting point. - -#### eglot - -[This is the main mode to install](https://github.com/joaotavora/eglot). - -The configuration is straightforward, this is what I use: - -```lisp -;; for go's LSP I want to use staticcheck and placeholders for completion -(customize-set-variable 'eglot-workspace-configuration - '((:gopls . - ((staticcheck . t) - (matcher . "CaseSensitive") - (usePlaceholders . t))))) - -;; ensure we load eglot for some specific modes -(dolist (hook '(go-mode-hook nix-mode-hook)) - (add-hook hook 'eglot-ensure)) -``` - -`eglot` integrates well with existing modes for Emacs, mainly xref, -flymake, eldoc. - -## Profiling - -### pprof - -[pprof](https://github.com/google/pprof) is a tool to visualize -performance data. Let's start with the following test: - -```go -package main - -import ( - "strings" - "testing" -) - -func BenchmarkStringJoin(b *testing.B) { - input := []string{"a", "b"} - for i := 0; i <= b.N; i++ { - r := strings.Join(input, " ") - if r != "a b" { - b.Errorf("want a b got %s", r) - } - } -} -``` - -Let's run a benchmark with -`go test . -bench=. -cpuprofile cpu_profile.out`: - -```go -goos: linux -goarch: amd64 -pkg: golang.fcuny.net/m -cpu: Intel(R) Core(TM) i3-1005G1 CPU @ 1.20GHz -BenchmarkStringJoin-4 41833486 26.85 ns/op 3 B/op 1 allocs/op -PASS -ok golang.fcuny.net/m 1.327s -``` - -And let's take a look at the profile with -`go tool pprof cpu_profile.out` - -```bash -File: m.test -Type: cpu -Time: Aug 15, 2021 at 3:01pm (PDT) -Duration: 1.31s, Total samples = 1.17s (89.61%) -Entering interactive mode (type "help" for commands, "o" for options) -(pprof) top -Showing nodes accounting for 1100ms, 94.02% of 1170ms total -Showing top 10 nodes out of 41 - flat flat% sum% cum cum% - 240ms 20.51% 20.51% 240ms 20.51% runtime.memmove - 220ms 18.80% 39.32% 320ms 27.35% runtime.mallocgc - 130ms 11.11% 50.43% 450ms 38.46% runtime.makeslice - 110ms 9.40% 59.83% 1150ms 98.29% golang.fcuny.net/m.BenchmarkStringJoin - 110ms 9.40% 69.23% 580ms 49.57% strings.(*Builder).grow (inline) - 110ms 9.40% 78.63% 1040ms 88.89% strings.Join - 70ms 5.98% 84.62% 300ms 25.64% strings.(*Builder).WriteString - 50ms 4.27% 88.89% 630ms 53.85% strings.(*Builder).Grow (inline) - 40ms 3.42% 92.31% 40ms 3.42% runtime.nextFreeFast (inline) - 20ms 1.71% 94.02% 20ms 1.71% runtime.getMCache (inline) -``` - -We can get a breakdown of the data for our module: - -```bash -(pprof) list golang.fcuny.net -Total: 1.17s -ROUTINE ======================== golang.fcuny.net/m.BenchmarkStringJoin in /home/fcuny/workspace/gobench/app_test.go - 110ms 1.15s (flat, cum) 98.29% of Total - . . 5: "testing" - . . 6:) - . . 7: - . . 8:func BenchmarkStringJoin(b *testing.B) { - . . 9: b.ReportAllocs() - 10ms 10ms 10: input := []string{"a", "b"} - . . 11: for i := 0; i <= b.N; i++ { - 20ms 1.06s 12: r := strings.Join(input, " ") - 80ms 80ms 13: if r != "a b" { - . . 14: b.Errorf("want a b got %s", r) - . . 15: } - . . 16: } - . . 17:} -``` |