Note #62 GopherCon Russia 2020

Мои старые друзья 28 марта проводят GopherCon Russia 2020! В этому году у меня не получается поехать :(

Но! У меня есть 1 билет, который я подарю тому, кто первый напишет в чате канала(кнопка discuss), как придумали название известной консольной утилиты “grep”?

Удачи :)

P.S. подробности и регистрация на сайте: https://www.gophercon-russia.ru/

Note #63 A new Go API for Protocol Buffers

В официальном #golang блоге появилась статья про новый Go API для Protocol Buffers.

Рекомендую почитать! ->

https://blog.golang.org/a-new-go-api-for-protocol-buffers

Note #64 New net/url.URL.Redacted method in go 1.15

В Go1.15 появится удобный метод net/url.URL.Redacted [1], по сути, похож на url.URL.String(), только заменяет пароли на xxxxxxx, будет удобно для логирования:

package main

import (
  "fmt"
  "net/url"
)

func main() {
  u := &url.URL{
    Scheme: "https",
    User:   url.UserPassword("user", "password"),
    Host:   "example.com",
    Path:   "foo/bar",
  }
  fmt.Println(u.Redacted())
  u.User = url.UserPassword("me", "newerPassword")
  fmt.Println(u.Redacted())
}
// gotip run main.go
// https://user:[email protected]/foo/bar
// https://me:[email protected]/foo/bar

Links:
[1] https://go-review.googlesource.com/c/go/+/207082/

Note #65: новые темплейты в Go плайграунде!

* тесты
* поддержка нескольких файлов включая go.mod!
* можно напечатать картинку

https://play.golang.org

Note #66: Go плайграунд теперь исполняет код в multi-threaded linux контейнере

Если у вас есть необходимость в демонстрации многопоточного кода на Go, который использует несколько горутин и которые, в свою очередь, используют один поток (thread) операционной системы или несколько потоков (threads), которые используют разные ядра. В общем теперь можно изучать go параллелизм в плайграунде 🙌

package main

import (
  "fmt"
  "runtime"
)

func main() {
  fmt.Printf("GOOS[%s] GOARCH[%s] GOMAXPROCS[%d] NumCPU[%d]", runtime.GOOS, runtime.GOARCH, runtime.GOMAXPROCS(0), runtime.NumCPU())
}
// OOS[linux] GOARCH[amd64] GOMAXPROCS[8] NumCPU[8]

P.S. объяснение от Брэда Фицпатрика:
Это стало возможным после того, как удалили поддержку Native Client (GOOS=nacl) в Go 1.14, и теперь go плайграунд запускается с помощью gVisor.
https://github.com/golang/go/issues/25224
https://github.com/golang/playground/commit/4d362417fd14b0b8349150cb28c3e8f2e756932e

Note #67 What's coming in Go 1.15

Daniel Martí aka @mvdan_ недавно выступал на онлайн конференции "Go Remote Fest" с докладом: "What's coming in Go 1.15"!

Слайды его доклада можно найти по ссылке [1] или

Top 5 изменений:
- slightly smaller binaries (0.2% но все же =)
- new linker (еще WIP но можно ужно читать/смотреть [2]
- embed tzdata with time/tzdata https://github.com/golang/go/issues/38017
- add testing.TB.TempDir https://github.com/golang/go/issues/35998
- add testing.T.Deadline https://github.com/golang/go/issues/28135

Links:
- [1] https://docs.google.com/presentation/d/1veyF0y6Ynr6AFzd9gXi4foaURlgbMxM-tmB4StDrdAM/edit#slide=id.g840eaeb4b4_0_99
- [2] https://docs.google.com/document/d/1D13QhciikbdLtaI67U6Ble5d_1nsI4befEd6_k1z91U/view

Note #68: The Rules of Optimization Club

1. You do not optimize.
2. You do not optimize, without measuring first.
3. When the performance is not bound by the code, but by external factors, the optimization is over.
4. Only optimize code that already has full unit test coverage.
5. One factor at a time.
6. No unresolved bugs, no schedule pressure.
7. Testing will go on as long as it has to.
8. If this is your first night at Optimization Club, you have to write a test case.

from https://wiki.c2.com/?RulesOfOptimizationClub

Note #69: Debugging concurrency programs in Go

Slides of my talk: "Debugging concurrency programs in Go" from @GoWayFest

https://bit.ly/2C0vJOG

Note #70: eBPF and golang

Extended BPF has a new homepage: https://ebpf.io #bpf #ebpf 🎉

Extra links:
- go binding for bcc tools https://github.com/iovisor/gobpf
- interesting article from Brendan Greg about golang bcc/BPF function tracing http://www.brendangregg.com/blog/2017-01-31/golang-bcc-bpf-function-tracing.html

Cloud native BPF Workshop:

GH Repo: https://github.com/kinvolk/cloud-native-bpf-workshop
Slides: -> https://github.com/kinvolk/cloud-native-bpf-workshop/blob/master/slides.pdf

TIL: go get -x

If you need to run go get with debug info, it can surprise you because there is no -v or —verbose flag.
But we can run -x to show debug info TBH print the commands get eXecutes:

go get -x -u github.com/gliderlabs/ssh

P.S. -x also works with go mod.

Note #71 The seven rules of a great Git commit message

1. Separate subject from body with a blank line
2. Limit the subject line to 50 characters
3. Capitalize the subject line
4. Do not end the subject line with a period
5. Use the imperative mood in the subject line
6. Wrap the body at 72 characters
7. Use the body to explain what and why vs. how

https://chris.beams.io/posts/git-commit/

Note #72 TestMain in Go 1.15 testing package no longer calls os.Exit

tl;dr
- Go1.15 has been released
- Changed the implementation of the testing package so that TestMain no longer calls os.Exit
- It is realized by changing the implementation of testing.M and modifying the template of the main function generated by go test.

Found interesting article with great examples of changes between 1.14 and 1.15 -> https://qiita.com/hgsgtk/items/40e63150affed01f6573

TIP: right click translate into English.

Визуализация нового пропозала про дженерики с отличными примерами от Владимир Вивьен

https://twitter.com/vladimirvivien/status/1297595414590427142?s=21

TIL: that "fallthrough" ignors the next "case" condition.
This code will print "one" and "two".

package main

import (
  "fmt"
)

func main() {
  a := 10
  switch {
  case a < 20:
    fmt.Println("one")
    fallthrough
  case a < 10:
    fmt.Println("two")
  }
}

source https://twitter.com/yoavgo/status/1315622694554140673

P.S. я уже когда-то писал об этом тут https://yangx.top/golang_for_two/53

Init time tracing coming to Go 1.16

GODEBUG=inittrace=1 prints a summary of execution time and memory allocation
information for completed package initialization work.

https://github.com/golang/go/commit/7c58ef732efd9bf0d0882bb95371ce1909924a75

Experimental refactoring tool for Go from Russ Cox

no docs, but few interesting examples https://github.com/rsc/rf/tree/main/testdata

https://github.com/rsc/rf

Go Slice Tricks Cheat Sheet

https://ueokande.github.io/go-slice-tricks/

Подъехали видео с последнего GopherCon 2020

https://www.youtube.com/playlist?list=PL2ntRZ1ySWBfUint2hCE1JRxRWChloasB

Пишите в комментариях какой больше всего доклад понравился?

My engineering axioms by Martin Rue:

1. Change is constant.
2. Your product is an asset, but code is a liability.
3. Duplication is less costly than premature abstraction.
4. Code should be easy to delete.
5. Existing code exerts a powerful influence.
6. Accidental complexity is one of the biggest risks.
7. Technical excellence can be shadowed by bad personal skills.
8. You are not your code. Be kind to the coder, not to the code.
9. Treat people who know less than you with respect and patience.
10. The only true authority stems from knowledge, not from position.
11. Teaching is a form of learning in disguise.
12. Lift the skills of people around you, not just yourself.
13. The longer you wait the more you'll know.
14. A good type system is worth its weight plus some.
15. The right team of people trumps everything else.
16. Stick to boring technology, unless there's a good reason not to.
17. Have the smallest team possible, but no smaller. Grow it carefully.
18. Rest.
19. Don't pick a solution until you've thought of at least one more.
20. Have opinions, but avoid expressing them in ways that cause other people to believe you won't change them.
21. It's OK to say "I don't know" or "I need to research that before I have an answer".
22. Writing throwaway code to explore a problem space is underrated.
23. Manage state carefully.
24. It's all about trade-offs.
25. A good design is one in which you can change your mind without changing too much code.

https://martinrue.com/my-engineering-axioms/

Happy New Year’; DROP TABLE 2020;--