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@axiaoxin
Last active December 13, 2018 12:07
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Go Patterns
package faninout
import (
"fmt"
)
func main() {
randomNumbers := []int{13, 44, 56, 99, 9, 45, 67, 90, 78, 23}
// generate the common channel with inputs
inputChan := generatePipeline(randomNumbers)
// Fan-out to 2 Go-routine
c1 :=squareNumber(inputChan)
c2 :=squareNumber(inputChan)
// Fan-in the resulting squared numbers
c := fanIn(c1, c2)
sum := 0
// Do the summation
for i := 0; i < len(randomNumbers); i++ {
sum += <-c
}
fmt.Printf("Total Sum of Squares: %d", sum)
}
func generatePipeline(numbers []int) <-chan int {
out := make(chan int)
go func() {
for _, n := range numbers {
out <- n
}
close(out)
}()
return out
}
func squareNumber(in <-chan int) <-chan int {
out := make(chan int)
go func() {
for n := range in {
out <- n * n
}
close(out)
}()
return out
}
func fanIn(input1, input2 <-chan int) <-chan int {
c := make(chan int)
go func() {
for {
select {
case s := <-input1: c <- s
case s := <-input2: c <- s
}
}
}()
return c
}
package future
import (
"fmt"
"io/ioutil"
"net/http"
)
type data struct {
Body []byte
Error error
}
func futureData(url string) <-chan data {
c := make(chan data, 1)
go func() {
var body []byte
var err error
resp, err := http.Get(url)
defer resp.Body.Close()
body, err = ioutil.ReadAll(resp.Body)
c <- data{Body: body, Error: err}
}()
return c
}
func main() {
future := futureData("http://test.future.com")
// do many other things
body := <-future
fmt.Printf("response: %#v", string(body.Body))
fmt.Printf("error: %#v", body.Error)
}
package main
import "fmt"
// Generator func which produces data which might be computationally expensive.
func fib(n int) chan int {
c := make(chan int)
go func() {
for i, j:= 0, 1; i < n ; i, j = i+j,i {
c <- i
}
close(c)
}()
return c
}
func main() {
// fib returns the fibonacci numbers lesser than 1000
for i := range fib(1000) {
// Consumer which consumes the data produced by the generator, which further does some extra computations
v := i*i
fmt.Println(v)
}
}
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