fix waitgroup

example-go-channel/Makefile

@@ -8,6 +8,10 @@ simple:
 	GO111MODULE="off" go build -v -x -o ~/go/bin/simple-worker simple-worker.go
 	simple-worker
 
+main1:
+	GO111MODULE="off" go build -v -x -o ~/go/bin/main1 main.go
+	main1
+
 return-vals:
 	GO111MODULE="off" go build -v -x -o ~/go/bin/return-vals return-vals.go
 	return-vals

example-go-channel/main.go

@@ -12,21 +12,23 @@ func generateNumbers(total int, ch chan<- int, wg *sync.WaitGroup) {
 	defer wg.Done()
 
 	for idx := 1; idx <= total; idx++ {
-		fmt.Printf("START sending %d to channel\n", idx)
+		fmt.Printf("START generateNumbers() sending %d to channel\n", idx)
 		ch <- idx
 		// res, err := (<-r)()
-		fmt.Printf("END sending %d to channel\n", idx)
+		fmt.Printf("END generateNumbers() sending %d to channel\n", idx)
 	}
 	wg.Wait()
-	fmt.Printf("END wg sending to channel\n")
+	fmt.Printf("END generateNumbers() wg sending to channel\n")
 }
 
 func printInt(idx int, ch <-chan int, wg *sync.WaitGroup) {
 	defer wg.Done()
 
+	fmt.Printf("START printInt() for chan range\n")
 	for num := range ch {
 		fmt.Printf("%d: read %d from channel\n", idx, num)
 	}
+	fmt.Printf("START printInt() for chan range\n")
 }
 
 func main() {

example-go-channel/sendFunction.go

@@ -4,55 +4,65 @@
 package main
 
 import (
-	"fmt"
+	"log"
 	"sync"
 )
 
-var wg sync.WaitGroup
-var functionChan chan func (*sync.WaitGroup)
-
 type funcWait struct {
 	f func()
 	wgF sync.WaitGroup
+	val int
 	err error
 	res int
 }
 
+var functionChan chan *funcWait
+var afunc funcWait
+var wg sync.WaitGroup
 
-func generateNumbers(total int, ch chan<- func (), wg *sync.WaitGroup) {
-	defer wg.Done()
+func generateNumbers(total int, ch chan<- *funcWait, af *funcWait) {
 
-	fmt.Printf("sending %d to channel\n", total)
-	ch <- func() {
-		fmt.Printf("inside f() sending %d to channel\n", total)
-	}
+	log.Println("generateNumbers() START total =", total)
+	ch <- af
+	log.Println("generateNumbers() END total =", total)
 }
 
-func andlabsGoroutine(ch <-chan func(), wg *sync.WaitGroup) {
+func andlabsGoroutine(ch <-chan *funcWait, wg *sync.WaitGroup) {
 	defer wg.Done()
 
+	log.Println("andlabsGoroutine() START")
 	for f := range ch {
-		fmt.Printf("read f() from channel\n")
-		f()
+		log.Println("andlabsGoroutine() read f() from channel")
+		f.f()
 	}
+	log.Printf("andlabsGoroutine() END")
 }
 
 func main() {
-	functionChan = make(chan func(*sync.WaitGroup))
+	functionChan = make(chan *funcWait)
 
-	r := make(chan func() (int, error))
-	res, err = (<-r)()
+	// syntax to get the return values from a channel
+//	r := make(chan func() (int, error))
+//	afunc.res, afunc.err = (<-r)()
 
 	wg.Add(1)
 	go andlabsGoroutine(functionChan, &wg)
 
-	for idx := 1; idx <= total; idx++ {
-		generateNumbers(idx, functionChan, &wg)
+	// afunc.wgF = wg
+	afunc.f = func() {
+		log.Println("\tGOT INSIDE: running f() from inside the structure & inside the wait group goroutine", afunc.val)
 	}
 
+	for idx := 1; idx <= 10; idx++ {
+		afunc.val = idx * 20
+		generateNumbers(idx, functionChan, &afunc)
+	}
+	wg.Done()
+
 	close(functionChan)
+	// close(wg)
 
-	fmt.Println("Waiting for goroutines to finish...")
+	log.Println("Waiting for goroutines to finish...")
 	wg.Wait()
-	fmt.Println("Done!")
+	log.Println("Done!")
 }