doc&test: add example and update doc for retry package

retry/retry.go

@@ -34,21 +34,24 @@ type RetryFunc func() error
 // Option is for adding retry config
 type Option func(*RetryConfig)
 
-// RetryTimes set times of retry
+// RetryTimes set times of retry.
+// Play: https://go.dev/play/p/ssfVeU2SwLO
 func RetryTimes(n uint) Option {
 	return func(rc *RetryConfig) {
 		rc.retryTimes = n
 	}
 }
 
-// RetryDuration set duration of retries
+// RetryDuration set duration of retries.
+// Play: https://go.dev/play/p/nk2XRmagfVF
 func RetryDuration(d time.Duration) Option {
 	return func(rc *RetryConfig) {
 		rc.retryDuration = d
 	}
 }
 
-// Context set retry context config
+// Context set retry context config.
+// Play: https://go.dev/play/p/xnAOOXv9GkS
 func Context(ctx context.Context) Option {
 	return func(rc *RetryConfig) {
 		rc.context = ctx
@@ -56,7 +59,8 @@ func Context(ctx context.Context) Option {
 }
 
 // Retry executes the retryFunc repeatedly until it was successful or canceled by the context
-// The default times of retries is 5 and the default duration between retries is 3 seconds
+// The default times of retries is 5 and the default duration between retries is 3 seconds.
+// Play: https://go.dev/play/p/nk2XRmagfVF
 func Retry(retryFunc RetryFunc, opts ...Option) error {
 	config := &RetryConfig{
 		retryTimes:    DefaultRetryTimes,

retry/retry_example_test.go

@@ -0,0 +1,93 @@
+package retry
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+)
+
+func ExampleContext() {
+	ctx, cancel := context.WithCancel(context.TODO())
+
+	number := 0
+	increaseNumber := func() error {
+		number++
+		if number > 3 {
+			cancel()
+		}
+		return errors.New("error occurs")
+	}
+
+	Retry(increaseNumber,
+		RetryDuration(time.Microsecond*50),
+		Context(ctx),
+	)
+
+	fmt.Println(number)
+
+	// Output:
+	// 4
+}
+
+func ExampleRetryDuration() {
+	number := 0
+	increaseNumber := func() error {
+		number++
+		if number == 3 {
+			return nil
+		}
+		return errors.New("error occurs")
+	}
+
+	err := Retry(increaseNumber, RetryDuration(time.Microsecond*50))
+	if err != nil {
+		return
+	}
+
+	fmt.Println(number)
+
+	// Output:
+	// 3
+}
+
+func ExampleRetryTimes() {
+	number := 0
+
+	increaseNumber := func() error {
+		number++
+		if number == 3 {
+			return nil
+		}
+		return errors.New("error occurs")
+	}
+
+	err := Retry(increaseNumber, RetryTimes(2))
+	if err != nil {
+		fmt.Println(err)
+	}
+
+	// Output:
+	// function retry.ExampleRetryTimes.func1 run failed after 2 times retry
+}
+
+func ExampleRetry() {
+	number := 0
+	increaseNumber := func() error {
+		number++
+		if number == 3 {
+			return nil
+		}
+		return errors.New("error occurs")
+	}
+
+	err := Retry(increaseNumber, RetryDuration(time.Microsecond*50))
+	if err != nil {
+		return
+	}
+
+	fmt.Println(number)
+
+	// Output:
+	// 3
+}