Go pipeline concurrency pattern using channels.

Pipeline.go

package main

import (
	"fmt"
	"math/rand"
	"strings"
)

const (
	Alphabet string = "abcdefghijkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ"
)

/*
	Pipeline pattern, useful when transforming data all the way from database all the way to the client
	1. Generate/retrieve data
	2. Transform data
	3. Return data
*/
func Pipeline() {
	recordsChannel := GenerateRecords()
	transformedRecords := TransformRecords(recordsChannel)
	for record := range transformedRecords {
		fmt.Println(record)
	}
}

func GenerateRecords() <-chan string {
	out := make(chan string)
	go func() {
		for k := 0; k < 20; k++ {
			data := strings.Builder{}
			for i := 0; i < 10; i++ {
				data.WriteString(string(Alphabet[rand.Intn(len(Alphabet))]))
			}

			out <- data.String()
		}

		close(out)
	}()

	return out
}

func TransformRecords(recordChannel <-chan string) <-chan string {
	out := make(chan string)
	go func() {
		// receive and transform value
		for rec := range recordChannel {
			out <- strings.ToUpper(rec)
		}

		// close out channel
		close(out)
	}()

	return out
}

func main() {
	Pipeline()
}