small examples + readme adjustments

Author: steevehook

atomics/README.md

@@ -281,6 +281,7 @@ go tool objdump -s main.main exec
 
 - [Race Example](https://github.com/golang-basics/concurrency/blob/master/atomics/race/main.go)
 - [Basic Counter](https://github.com/golang-basics/concurrency/blob/master/atomics/basic-counter/main.go)
+- [Race Fixed Example](https://github.com/golang-basics/concurrency/blob/master/atomics/race-fixed/main.go)
 - [atomic.Value - Reader/Writer Example](https://github.com/golang-basics/concurrency/blob/master/atomics/value/reader-writer/main.go)
 - [atomic.Value - Calculator Example](https://github.com/golang-basics/concurrency/blob/master/atomics/value/calculator/main.go)
 - [atomic.Value - panic](https://github.com/golang-basics/concurrency/blob/master/atomics/value/panic/main.go)

atomics/basic-counter/main.go

@@ -15,19 +15,19 @@ func main() {
 
 	wg.Add(1)
 	go func() {
+		defer wg.Done()
 		time.Sleep(10 * time.Millisecond)
-		fmt.Println(atomic.LoadInt64(&count))
-		wg.Done()
+		fmt.Println("count in go routine", atomic.LoadInt64(&count))
 	}()
 
+	wg.Add(50)
 	for i := 0; i < 50; i++ {
-		wg.Add(1)
 		go func() {
+			defer wg.Done()
 			time.Sleep(10 * time.Millisecond)
 			atomic.AddInt64(&count, 1)
-			wg.Done()
 		}()
 	}
 	wg.Wait()
-	fmt.Println(count)
+	fmt.Println("count in main", count)
 }

atomics/race-fixed/main.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+)
+
+func main() {
+	var count int32
+	var wg sync.WaitGroup
+	wg.Add(5)
+	go func() {
+		defer wg.Done()
+		atomic.StoreInt32(&count, 10)
+	}()
+	go func() {
+		defer wg.Done()
+		atomic.StoreInt32(&count, -15)
+	}()
+	go func() {
+		defer wg.Done()
+		atomic.StoreInt32(&count, 1)
+	}()
+	go func() {
+		defer wg.Done()
+		atomic.StoreInt32(&count, 0)
+	}()
+	go func() {
+		defer wg.Done()
+		atomic.StoreInt32(&count, 100)
+	}()
+	wg.Wait()
+
+	fmt.Println("count", count)
+}

atomics/value/reader-writer/main.go

@@ -35,14 +35,14 @@ func main() {
 	wg.Add(5)
 	for i := 0; i < 5; i++ {
 		go func() {
+			defer wg.Done()
 			// we're gonna get a panic this way
 			// cfg := v.Load().(Config)
 			cfg, ok := v.Load().(Config)
 			if !ok {
 				log.Fatalf("received different type: %T", cfg)
 			}
 			fmt.Println("cfg", cfg)
-			wg.Done()
 		}()
 	}
 	wg.Wait()