Since Go1

... it’s been 4 years

Alexander “surma” Surma
nuboLAB, GDG Berlin Golang
2013-12-12

Dates

  1. Go 1.0: 2012-03-28
  2. Go 1.1: 2013-05-13
  3. Go 1.2: 2013-12-04
They are now striving for a 6 month release cycle. 3 months iteration, 3 monts testing. Therefore, code freeze for Go 1.3 is on 2014-03-01, release on 2014-06-01.

Race detector

  • Compilation: go run -race program.go
  • Specially crafted, CPU-hungry binary
  • Algorithm has been implemented/used by the Chrome Development Team
  • Detects concurrent access to shared variables
var sharedVariable = 1

func worker() {
    for {
        sharedVariable += 1
        time.Sleep(100 * time.Millisecond)
    }
}

func main() {
    go worker()
    for {
        fmt.Printf("> %d\n", sharedVariable)
        time.Sleep(1 * time.Second)
    }
}

Preemptive Scheduling

  • Schedular was cooperative (I/O, channel sends, time.Sleep(),…)
  • for {} could starve all other goroutines
  • The scheduler is invoked occasionally upon entry to a function
  • for {} can still starve all other goroutines. But not in realistic use-cases.

First-class C++ bindings

  • With cgo you can call C code from Go
  • For C++ you had to write a C-Wrapper as a library
  • cgo now understands C++
  • v8-Bindings anyone?
package main

// int fortytwo()
// {
//      return 42;
// }
import "C"
import "fmt"

func main() {
    fmt.Println(int(C.fortytwo()))
    // Output: 42
}

Test coverage

Fast way: 
$ go test -cover *.go
ok      command-line-arguments  0.038s  coverage: 43.2% of statements
Details: 
$ go test -coverprofile=c.out *.go
$ go tool cover -func=c.out
github.com/voxelbrain/auth/authenticationservice.go:    init                            100.0%
github.com/voxelbrain/auth/authenticationservice.go:    Verify                          100.0%
github.com/voxelbrain/auth/authenticationservice.go:    verifyDataEndpoints             83.3%
github.com/voxelbrain/auth/authenticationservice.go:    verifyAuthenticationEndpoints   82.4%
github.com/voxelbrain/auth/authenticationservice.go:    AuthenticationServiceHandler    0.0%
// ...
total:                                                  (statements)                    43.2%

Test coverage

Web goodness: 
$ go tool cover -html=c.out -o coverage.html

Method values

Prelude: 
    type BinaryFunc(a, b int) int
    var f BinaryFunc
The old way: 
    f = func(a, b int) int {
        return someStruct.BinaryMethod(a, b)
    }
Now: 
    f = someStruct.BinaryMethod

Small things

  • text/template now has eq, ne, lt, gt, …
  • Easy cross-compilation
  • freebsd/arm, netbsd/386, netbsd/amd64, netbsd/arm, openbsd/386 and openbsd/amd64
  • Performance
fmt.Sprintf("%[3]c %[1]c %c\n", 'a', 'b', 'c')

Go 1.3?

Incoming changes

  • os/fsnotify
  • cgo: Objective-C support
  • Complete linker overhaul
  • runtime: 100% precise garbage collection
  • nacl/amd64p32, nacl/386, darwin/arm? android/arm?
  • runtime: shared library support?

<Thank You!>

Questions?

emaila.surma@nubolab.org
g++AlexanderSurma
twittersurmair
githubsurma