interesting

src/043-state-goroutine/state-goroutine-compare.go

@@ -0,0 +1,66 @@
+// ## State Goroutine (Comparison)
+
+package main
+
+import "fmt"
+import "time"
+import "math/rand"
+import "sync"
+import "sync/atomic"
+import "runtime"
+
+func randKey() int {
+	return rand.Intn(10)
+}
+
+func randVal() int {
+	return rand.Intn(100)
+}
+
+// Globally-accessible state.
+var data = make(map[int]int)
+
+var dataMutex = &sync.Mutex{}
+
+// Keep track of how many ops we do.
+var opCount int64 = 0
+
+// Generate random reads.
+func generateReads() {
+	total := 0
+	for {
+		key := randKey()
+		dataMutex.Lock()
+		total += data[key]
+		dataMutex.Unlock()
+		atomic.AddInt64(&opCount, 1)
+		runtime.Gosched()
+	}
+}
+
+// Generate random writes.
+func generateWrites() {
+	for {
+		key := randKey()
+		val := randVal()
+		dataMutex.Lock()
+		data[key] = val
+		dataMutex.Unlock()
+		atomic.AddInt64(&opCount, 1)
+		runtime.Gosched()
+	}
+}
+
+func main() {
+	for r := 0; r < 100; r++ {
+		go generateReads()
+	}
+	for w := 0; w < 10; w++ {
+		go generateWrites()
+	}
+
+	time.Sleep(10 * time.Second)
+
+	finalOpCount := atomic.LoadInt64(&opCount)
+	fmt.Println(finalOpCount)
+}