diff --git a/30-coordination/coordination/main.go b/30-coordination/coordination/main.go
index 006813d..ea37ecc 100644
--- a/30-coordination/coordination/main.go
+++ b/30-coordination/coordination/main.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"math"
 	"math/rand"
 	"sync"
@@ -11,6 +12,10 @@ func main() {
 	main1()
 	main2()
 	main3()
+	main4()
+	main5()
+	main6()
+	main7()
 }
 
 func doSum(count int, val *int, waitGroup *sync.WaitGroup, mutex *sync.Mutex) {
@@ -78,7 +83,7 @@ func main2() {
 	Printfln("Cached Value: %v", len(squares))
 }
 
-func generateSquares(max int, waitGroup *sync.WaitGroup, rwMutex *sync.RWMutex, readyCond *sync.Cond, squares map[int]int) {
+func generateSquares3(max int, waitGroup *sync.WaitGroup, rwMutex *sync.RWMutex, readyCond *sync.Cond, squares map[int]int) {
 	// 开启写锁
 	rwMutex.Lock()
 	// 重新读取值，防止缓存被其他goroutine修改
@@ -95,7 +100,7 @@ func generateSquares(max int, waitGroup *sync.WaitGroup, rwMutex *sync.RWMutex,
 	waitGroup.Done()
 }
 
-func readSquares(id, max, iterations int, r *rand.Rand, waitGroup *sync.WaitGroup, readyCond *sync.Cond, squares map[int]int) {
+func readSquares3(id, max, iterations int, r *rand.Rand, waitGroup *sync.WaitGroup, readyCond *sync.Cond, squares map[int]int) {
 	readyCond.L.Lock()
 	for len(squares) == 0 {
 		readyCond.Wait()
@@ -121,12 +126,140 @@ func main3() {
 	numRoutines := 2
 	for i := 0; i < numRoutines; i++ {
 		waitGroup.Add(1)
-		go readSquares(i, 10, 5, r, &waitGroup, readyCond, squares)
+		go readSquares3(i, 10, 5, r, &waitGroup, readyCond, squares)
 	}
 
 	waitGroup.Add(1)
-	go generateSquares(10, &waitGroup, &rwMutex, readyCond, squares)
+	go generateSquares3(10, &waitGroup, &rwMutex, readyCond, squares)
 
 	waitGroup.Wait()
 	Printfln("Cached Value: %v", len(squares))
 }
+
+func generateSquares4(max int, squares map[int]int) {
+	// 重新读取值，防止缓存被其他goroutine修改
+	Printfln("Generating data...")
+	for i := 0; i < max; i++ {
+		squares[i] = int(math.Pow(float64(i), 2))
+	}
+}
+
+func readSquares4(id, max, iterations int, r *rand.Rand, waitGroup *sync.WaitGroup, once *sync.Once, squares map[int]int) {
+	once.Do(func() {
+		generateSquares4(max, squares)
+	})
+	for i := 0; i < iterations; i++ {
+		key := r.Intn(max)
+		Printfln("#%v,%v Read Index: %v = %v ", id, i, key, squares[key])
+		time.Sleep(time.Millisecond * 100)
+	}
+	waitGroup.Done()
+}
+
+func main4() {
+	Printfln("\nmain4:")
+
+	var waitGroup = sync.WaitGroup{}
+	var once = sync.Once{}
+	var squares = map[int]int{}
+
+	var r = rand.New(rand.NewSource(time.Now().UnixNano()))
+	numRoutines := 2
+	for i := 0; i < numRoutines; i++ {
+		waitGroup.Add(1)
+		go readSquares4(i, 10, 5, r, &waitGroup, &once, squares)
+	}
+
+	waitGroup.Wait()
+	Printfln("Cached Value: %v", len(squares))
+}
+
+func processRequest(ctx context.Context, wg *sync.WaitGroup, count int) {
+	total := 0
+	for i := 0; i < count; i++ {
+		select {
+		case <-ctx.Done():
+			if context.Canceled == ctx.Err() {
+				Printfln("Request cancelled")
+			} else {
+				Printfln("Stopping processing - deadline reached")
+			}
+			goto end
+		default:
+			Printfln("Processing request: %v ", total)
+			total++
+			time.Sleep(time.Millisecond * 250)
+		}
+	}
+	Printfln("Request processed... %v ", total)
+end:
+	wg.Done()
+}
+
+func main5() {
+	Printfln("\nmain5:")
+	waitGroup := sync.WaitGroup{}
+	waitGroup.Add(1)
+	Printfln("Request dispatched...")
+	ctx, cancel := context.WithCancel(context.Background())
+	go processRequest(ctx, &waitGroup, 10)
+
+	time.Sleep(time.Second)
+	Printfln("Cancelling request...")
+	cancel()
+
+	waitGroup.Wait()
+}
+
+func main6() {
+	Printfln("\nmain6:")
+	waitGroup := sync.WaitGroup{}
+	waitGroup.Add(1)
+	Printfln("Request dispatched...")
+	ctx, _ := context.WithTimeout(context.Background(), time.Second*2)
+	go processRequest(ctx, &waitGroup, 10)
+
+	waitGroup.Wait()
+}
+
+const (
+	countKey = iota
+	sleepPeriodKey
+)
+
+func processRequestContextValue(ctx context.Context, wg *sync.WaitGroup) {
+	total := 0
+	count := ctx.Value(countKey).(int)
+	sleepPeriod := ctx.Value(sleepPeriodKey).(time.Duration)
+	for i := 0; i < count; i++ {
+		select {
+		case <-ctx.Done():
+			if context.Canceled == ctx.Err() {
+				Printfln("Request cancelled")
+			} else {
+				Printfln("Stopping processing - deadline reached")
+			}
+			goto end
+		default:
+			Printfln("Processing request: %v ", total)
+			total++
+			time.Sleep(sleepPeriod)
+		}
+	}
+	Printfln("Request processed... %v ", total)
+end:
+	wg.Done()
+}
+
+func main7() {
+	Printfln("\nmain7:")
+	waitGroup := sync.WaitGroup{}
+	waitGroup.Add(1)
+	Printfln("Request dispatched...")
+	ctx, _ := context.WithTimeout(context.Background(), time.Second*2)
+	ctx = context.WithValue(ctx, countKey, 4)
+	ctx = context.WithValue(ctx, sleepPeriodKey, time.Millisecond*250)
+	go processRequestContextValue(ctx, &waitGroup)
+
+	waitGroup.Wait()
+}