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

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
+}