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diff --git a/content/notes/working-with-go.org b/content/notes/working-with-go.org deleted file mode 100644 index e00f635..0000000 --- a/content/notes/working-with-go.org +++ /dev/null @@ -1,264 +0,0 @@ -#+TITLE: Working with Go -#+DATE: <2021-08-05 Thu> -#+TAGS[]: go emacs -#+toc: t - -/This document assumes go version >= 1.16/. - -* Go Modules -[[https://blog.golang.org/using-go-modules][Go modules]] have been added in 2019 with Go 1.11. A number of changes were introduced with [[https://blog.golang.org/go116-module-changes][Go 1.16]]. 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: -#+begin_src sh -$ git tag v1.2.3 -$ git push --tags -#+end_src - -Then as a user: -#+begin_src sh -$ go get -d golang.fcuny.net/m@v1.2.3 -#+end_src -** 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 -#+begin_src go -replace <module URL> => <path of the local checkout> -#+end_src - -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 [[https://github.com/golang/go/blob/c95464f0ea3f87232b1f3937d1b37da6f335f336/src/cmd/go/internal/cfg/cfg.go#L269][here]]). 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 [[https://golang.org/ref/mod#private-modules][here]]. - -There's a few interesting things that can be done when using the proxy. There's a few special URLs (better documentation [[https://golang.org/ref/mod#goproxy-protocol][here]]): -| 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=: -#+begin_src sh -; 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 -#+end_src - -Let's check the details for the most recent version -#+begin_src sh -; 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 -#+end_src - -And let's look at the content of the =go.mod= for that version too: -#+begin_src sh -; 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 -) -#+end_src -* 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= -[[https://staticcheck.io/][=staticcheck=]] 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= -[[https://github.com/dominikh/go-mode.el][This is the mode]] to install to get syntax highlighting (mostly). -** Integration with LSP -Emacs has a pretty good integration with LSP. -https://geeksocket.in/posts/emacs-lsp-go/ -*** =lsp-mode= -[[src:https://github.com/emacs-lsp/lsp-mode][This is the main mode to install]]. It provides the integration with LSP. - -I've configured the mode like this: -#+begin_src elisp -(use-package lsp-mode - :ensure t - :commands (lsp lsp-deferred) - :diminish lsp-mode - :hook ((go-mode . lsp-deferred) - (lsp-mode . (lambda() (let ((lsp-keymap-prefix "C-c l")) - (lsp-enable-which-key-integration))))) - :config - (define-key lsp-mode-map (kbd "C-c l") lsp-command-map) - (lsp-register-custom-settings - '(("gopls.completeUnimported" t t) - ("gopls.staticcheck" t t))) - :bind - (("C-c l i" . lsp-ui-imenu)) - :custom - (lsp-session-file (expand-file-name "lsp-session-v1" fcuny/path-emacs-var)) - (lsp-enable-snippet nil) - (lsp-signature-doc-lines 5) - (lsp-modeline-diagnostic-scope :workspace) - (lsp-completion-provider :capf) - (lsp-completion-enable t) - (lsp-enable-indentation t) - (lsp-eldoc-render-all t) - (lsp-prefer-flymake nil)) -#+end_src - -+ =C-c l= brings a menu via [[https://github.com/abo-abo/hydra][hydra]] -+ By default it seems that =staticcheck= is not used, so I force it with the =lsp-register-custom-settings= -+ I prefer [[https://www.flycheck.org/en/latest/][flycheck]] -*** =lsp-ui= -This is mostly for UI tweaks. I use the following configuration -#+begin_src elisp -(use-package lsp-ui - :ensure t - :hook (lsp-mode . lsp-ui-mode) - :commands lsp-ui-mode - :custom - (lsp-ui-doc-delay 0.4) - (lsp-ui-doc-enable t) - (lsp-ui-doc-position 'top) - (lsp-ui-doc-include-signature t) - (lsp-ui-peek-enable t) - (lsp-ui-sideline-enable t) - (lsp-ui-imenu-enable t) - (lsp-ui-flycheck-enable t)) - -#+end_src -*** =lsp-ivy= -I use ivy for completion, [[https://github.com/emacs-lsp/lsp-ivy][it provides]] completion based on the current workspace. This is my configuration: -#+begin_src elisp -(use-package lsp-ivy - :ensure t - :commands lsp-ivy-workspace-symbol) -#+end_src -*** =lsp-treemacs= -[[https://github.com/emacs-lsp/lsp-treemacs][It provides]] some nice improvement regarding the UI. This is my configuration: -#+begin_src elisp -(use-package lsp-treemacs - :ensure t - :config - (lsp-treemacs-sync-mode 1)) - -#+end_src -* Profiling -** pprof -[[https://github.com/google/pprof][pprof]] is a tool to visualize performance data. Let's start with the following test: -#+begin_src 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) - } - } -} -#+end_src - -Let's run a benchmark with ~go test . -bench=. -cpuprofile cpu_profile.out~: -#+begin_src 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 -#+end_src - -And let's take a look at the profile with =go tool pprof cpu_profile.out= -#+begin_src sh -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) -#+end_src - -We can get a breakdown of the data for our module: -#+begin_src sh -(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:} -#+end_src |