and my high-performance version

mocking-bob/more-paralellism.go

@@ -0,0 +1,84 @@
+package main
+
+import (
+	// we want *real* random
+	"crypto/rand"
+	"fmt"
+	"os"
+	"unicode"
+)
+
+func main() {
+	jobList := make(chan [2]chan rune, 4096)
+
+	// spin up an appropriate amount of workers for this task
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+	go worker(jobList)
+
+	outchans := make(chan chan rune, 4096)
+	done := make(chan struct{}, 1)
+
+	go func(o chan chan rune) {
+		for r := range o {
+			fmt.Printf("%c", <-r)
+		}
+		done <- struct{}{}
+	}(outchans)
+
+	for _, str := range os.Args[1:] {
+		for _, c := range str {
+			in := make(chan rune, 1)
+			out := make(chan rune, 1)
+			outchans <- out
+			jobList <- [2]chan rune{in, out}
+			in <- c
+			close(in)
+		}
+		out := make(chan rune, 1)
+		outchans <- out
+		out <- ' '
+		close(out)
+	}
+	close(outchans)
+
+	<-done
+}
+
+func worker(jobList chan [2]chan rune) {
+	b := make([]byte, 1)
+	for job := range jobList {
+		c := <-job[0]
+		_, err := rand.Read(b)
+		if err != nil {
+			job[1] <- c
+			close(job[1])
+			continue
+		}
+		if b[0]%2 == 0 {
+			// switch case
+			if unicode.ToUpper(c) == c {
+				job[1] <- unicode.ToLower(c)
+			} else {
+				job[1] <- unicode.ToUpper(c)
+			}
+			close(job[1])
+			continue
+		}
+		job[1] <- c
+		close(job[1])
+	}
+}