GoSXBGo! - Introduction to the language

Introduction to the go programming language, a bit of background, several example.

Built for meetup event: http://www.meetup.com/fr/Go-SXB-Go/events/224878195/?eventId=224878195

Transcript

1. Go SXB Go! First release 16 September 2015 Leo Unbekandt CTO, Scalingo
2. The meetup: Go SXB Go!
3. Why this meetup Thousands of loc running in production to run our product. Working with Go for ± 30 months Lot of things to share about the language Create/Stimulate the local community Spread the language
4. How this meetup will take place Introduction to the language Please make remarks, tro.. arguments about anything
5. Why speaking about go?
6. Using a language with a nice mascot? The gopher
7. Language background
8. History 2007: Rob Pike (UTF­8, Plan 9), Ken Thompson (B, C) at Google 2009: First public release, BSD License The gopher ... again 2012: 1.0 Released August 2015: 1.5 Released
9. Why this new language? Efficient large scale D o n ' t t h i n k l a r g e a p p s , b u t l a r g e t e a m s Distributed systems A n y a p p i s d i s t r i b u t e d t o d a y , m a k i n g r e q u e s t t o r e m o t e A P I ? Y O U R a p p i s d i s t r i b u t e d ! Multicore hardware M o o r ' s l a w i s n o t w o r k i n g a n y m o r e , p r o c e s s o r s a r e n o t b e t t e r , t h e y a r e p a r a l l e l Speed of compilation P r o b l e m a t G o o g l e , s o m e b i n a r i e s t a k e s e v e r a l h o u r s t o b u i l d
10. Why using go? Concurrency Types Scalability Simplicity Fast development cycle Very readable Garbage collected Awesome tooling Much more...
11. Respect the tradition UTF­8 Inside p a c k a g e m a i n i m p o r t " f m t " f u n c m a i n ( ) { f m t . P r i n t l n ( " H e l l o w o r l d ! ☺ " ) } Run
12. Example web server p a c k a g e m a i n i m p o r t ( " f m t " " l o g " " n e t / h t t p " ) f u n c m a i n ( ) { h t t p . H a n d l e F u n c ( " / " , f u n c ( w h t t p . R e s p o n s e W r i t e r , r * h t t p . R e q u e s t ) { l o g . P r i n t l n ( " C o n n e c t i o n c o m i n g f r o m " , r . R e m o t e A d d r ) f m t . F p r i n t f ( w , " H e l l o W o r l d " ) } ) l o g . P r i n t l n ( " L i s t e n i n g o n p o r t 5 0 0 0 " ) h t t p . L i s t e n A n d S e r v e ( " : 5 0 0 0 " , n i l ) } Run
13. Concurrency
14. What is concurrency? Not parallelism! (Rob Pike 2012) (https://talks.golang.org/2012/waza.slide)
15. Concurrency Model Communicating Sequential Processes 1978 Communicate by sharing memory → Not recommanded but possible Share memory by communicating → Go model
16. Example (broken example) v a r ( i = 0 ) f u n c n e x t I D ( ) i n t { i + = 1 r e t u r n i } f u n c m a i n ( ) { g o f u n c ( ) { f m t . P r i n t l n ( n e x t I D ( ) ) } ( ) f m t . P r i n t l n ( n e x t I D ( ) ) t i m e . S l e e p ( t i m e . S e c o n d ) } Question? What does it display?
17. Example (broken example) v a r ( i = 0 ) f u n c n e x t I D ( ) i n t { i + = 1 r e t u r n i } f u n c m a i n ( ) { g o f u n c ( ) { f m t . P r i n t l n ( n e x t I D ( ) ) } ( ) f m t . P r i n t l n ( n e x t I D ( ) ) t i m e . S l e e p ( t i m e . S e c o n d ) } Answer: unknown
18. Examples (mutex, non idiomatic method) " f m t " v a r ( i = 0 m I D = s y n c . M u t e x { } ) f u n c n e x t I D ( ) i n t { m I D . L o c k ( ) i + = 1 m I D . U n l o c k ( ) r e t u r n i } f u n c m a i n ( ) { g o f u n c ( ) { f m t . P r i n t l n ( n e x t I D ( ) ) } ( ) f m t . P r i n t l n ( n e x t I D ( ) ) t i m e . S l e e p ( t i m e . S e c o n d ) }
19. Examples (go method) v a r ( g e n = m a k e ( c h a n i n t ) ) f u n c i n i t ( ) { f o r i : = 0 ; ; i + + { g e n < - i } } f u n c m a i n ( ) { g o f u n c ( ) { f m t . P r i n t l n ( < - g e n ) } ( ) f m t . P r i n t l n ( < - g e n ) t i m e . S l e e p ( t i m e . S e c o n d ) }
20. Examples (go method) v a r ( g e n = m a k e ( c h a n i n t ) ) f u n c i n i t ( ) { f o r i : = 0 ; ; i + + { g e n < - i } } f u n c m a i n ( ) { g o f u n c ( ) { f m t . P r i n t l n ( < - g e n ) } ( ) f m t . P r i n t l n ( < - g e n ) t i m e . S l e e p ( t i m e . S e c o n d ) }
21. Type System Immutable UTF­8 string Immutable pointers, forget C pointer arithmetic Implicit interfaces Bits of reflectivity Garbage collected (not really part of the type system)
22. Structures t y p e P o i n t s t r u c t { X , Y i n t s t a t e s t r i n g }
23. Methods t y p e A n i m a l s t r u c t { / / . . . } f u n c ( a A n i m a l ) W a l k ( ) { / / D o s o m e t h i n g } f u n c m a i n ( ) { a : = A n i m a l { } a . W a l k ( ) }
24. Interfaces t y p e W r i t e r i n t e r f a c e { W r i t e ( [ ] b y t e ) ( i n t , e r r o r ) }
25. Interfaces example p a c k a g e m a i n i m p o r t ( " f m t " " i o " " o s " ) f u n c w r i t e T o F i l e ( c o n t e n t s t r i n g ) e r r o r { f d , e r r : = o s . O p e n ( " / t m p / t o t o " ) i f e r r ! = n i l { r e t u r n e r r } n , e r r : = f d . W r i t e ( [ ] b y t e ( c o n t e n t ) ) } f u n c m a i n ( ) { w r i t e T o F i l e ( " t o t o " ) } Run
26. Great tooling
27. At one condition Defined directory structure $ G O P A T H / b i n / p r o g r a m 1 p k g / l i n u x _ a m d 6 4 / g i t h u b . c o m / S o u l o u p a c k a g e 1 . a s r c / g i t h u b . c o m / S o u l o u / p a c k a g e 1 / l i b . g o p r o g r a m 1 / m a i n . g o s p o t d . g o
28. The go tool g o g e t Get a remote package and install it locally g o r u n Build and run a go program (script­like) g o b u i l d Build the package/program g o i n s t a l l Build the program and put it in $GOPATH/bin g o t e s t Run the tests of your project
29. One format to rule them all g o f m t Format your code to respect go conventions p a c k a g e m a i n i m p o r t ( " f m t " ) f u n c m a i n ( ) { f m t . P r i n t l n ( " H e l l o " ) } Becomes p a c k a g e m a i n i m p o r t ( " f m t " ) f u n c m a i n ( ) { f m t . P r i n t l n ( " H e l l o " ) }
30. Import paths All import paths are relative to your GOPATH $ G O P A T H s r c / g i t h u b . c o m / S o u l o u / p a c k a g e 1 In the gocode requiring this package: i m p o r t ( " g i t h u b . c o m / S o u l o u / p a c k a g e 1 " ) f u n c m a i n ( ) { p a c k a g e 1 . M y F u n c t i o n ( ) }
31. Remote dependencies If a program requires the following package i m p o r t " g o l a n g . o r g / x / n e t / w e b s o c k e t " Fetching, building and installing a package is one command away $ g o g e t g o l a n g . o r g / x / n e t / w e b s o c k e t That's it your system is read
32. Dependency managements The Go team has willingly not embedded any system L e t m e r e m i n d y o u t h i s b e f o r e a n y t r o l l i n g : * R u b y g e m s i s e x t e r n a l t o t h e c o r e R u b y p r o j e c t * N P M i s e x t e r n a l t o t h e c o r e N o d e J S p r o j e c t * M a v e n i s e x t e r n a l t o t h e c o r e J a v a p r o j e c t Let the community build tools, and we'll see. Stop repeating “They have learnt nothing”
33. Small parenthesis about Go 1.5 and vendoring If you have the following packages: $ G O P A T H / s r c / g i t h u b . c o m / S o u l o u / p r o g r a m 1 / v e n d o r / g o l a n g . o r g / x / n e t / w e b s o c k e t g o l a n g . o r g / x / n e t / w e b s o c k e t And you require r e q u i r e " g o l a n g . o r g / x / n e t / w e b s o c k e t " The one in the directory vendor of your project will be used.
34. My personal combo Godeps + Gopkg.in Godeps Build by Keith Rarick (ex­Heroku) Handles the vendored dependencies of your project. Gopkg.in Built by Gustavo Niemeyer (Canonical) Simplify semver usage with Go
35. Godeps g o d e p s a v e Vendor all the dependencies in Godeps/_workspace Don't update any, remove unused, add new g o d e p u p d a t e < p a c k a g e n a m e > Update a precise package by upding project version by global g o d e p g o b u i l d / t e s t / r u n / i n s t a l l Wrapper around the Go tools which adds Godeps/_workspace in $GOPATH (will be deprecated when Go official vendoring will be considered stable)
36. Gopkg.in Wrapper over github to use tags github.com/nsqio/go­nsq (https://github.com/nsqio/go­nsq) i m p o r t " g o k p g . i o / n s q i o / n s q . v 0 " Different from i m p o r t " g o k p g . i o / n s q i o / n s q . v 1 " Want to update on your branch g o g e t - u g o p k g . i o / n s q i o / n s q . v 0 g o d e p u p d a t e g o p k g . i n / n s q i o / n s q . v 0
37. Compatible architectures
38. Environment variable magic G O O S = l i n u x G O A R C H = a r m G O A R M = 7 g o b u i l d p r o g r a m 1 $ f i l e p r o g r a m 1 p r o g r a m 1 : E L F 3 2 - b i t L S B e x e c u t a b l e , A R M , E A B I 5 v e r s i o n 1 ( S Y S V ) , s t a t i c a l l y l i n k e d , n o t s t r i p p e d GOOS l i n u x d a r w i n w i n d o w s f r e e b s d s o l a r i s a n d r o i d i o s . . . GOARCH 3 8 6 a m d 6 4 a r m a r m 6 4 p p c 6 4 golang.org/doc/install/source (https://golang.org/doc/install/source)
39. C Compatibility You want to use a C library? p a c k a g e m a i n / / # i n c l u d e < s t d i o . h > i m p o r t " C " f u n c m a i n ( ) { s : = C . C S t r i n g ( " H e l l o w o r l d " ) C . p u t s ( s ) } golang.org/cmd/cgo/ (https://golang.org/cmd/cgo/)
40. Who's using it? Google, obviously Cloudflare, awesome blog: blog.cloudflare.com (https://blog.cloudflare.com) Canonical, flag product: juju github.com/juju/juju (https://github.com/juju/juju)
41. Who's using it? (more) Apple, they are hiring go devs jobs.apple.com/us/search (https://jobs.apple.com/us/search) And many, many, many more. Every big vendor is using Go today. Twitter, Docker, Facebook, Amazon, IBM, Uber, Tumblr, Mozilla, MongoDB, Dropbox, etc. github.com/golang/go/wiki/GoUsers (https://github.com/golang/go/wiki/GoUsers) Look at their Github account
42. Future of this meetup 1/month More technical topics CFP is already open Guests
43. A few resources A guide to learn the language [interactive website] (http://tour.golang.org) Concurrency is not Parallelism [slides] (https://talks.golang.org/2012/waza.slide) Go Concurrency Patterns [slides] (https://talks.golang.org/2012/concurrency.slide) Advanced Go Concurrency Patterns [slides] (https://talks.golang.org/2013/advconc.slide) The official go blog [website] (https://blog.golang.org) Godoc: documentation of all the public packages [website] (https://godoc.org)
44. Credits Gopher images by Renee French under Creative Commons Attributions 3.0 More gopher images here (https://blog.golang.org/gopher)
45. Thank you Leo Unbekandt CTO, Scalingo leo@scalingo.com (mailto:leo@scalingo.com) https://scalingo.com (https://scalingo.com) @Soulou (http://twitter.com/Soulou)