README
¶
retry
Simple utils for exponential back off.
SYNOPSIS
https://golang.ir/play/p/epPT1bJoU2e
package main
import (
"context"
"errors"
"fmt"
"time"
"github.com/shogo82148/go-retry"
)
type Result int
func DoSomething(ctx context.Context) (Result, error) {
// do something here that should to do exponential backoff https://en.wikipedia.org/wiki/Exponential_backoff
return 0, errors.New("fails")
}
var policy = retry.Policy{
MinDelay: 100 * time.Millisecond,
MaxDelay: time.Second,
MaxCount: 10,
}
func DoSomethingWithRetry(ctx context.Context) (Result, error) {
retrier := policy.Start(ctx)
for retrier.Continue() {
if res, err := DoSomething(ctx); err == nil {
return res, nil
}
}
return 0, errors.New("tried very hard, but no luck")
}
func main() {
fmt.Println(DoSomethingWithRetry(context.Background()))
}
https://golang.ir/play/p/aEYgJuXsatd
package main
import (
"context"
"errors"
"fmt"
"time"
"github.com/shogo82148/go-retry"
)
func DoSomething(ctx context.Context) error {
// do something here that should to do exponential backoff https://en.wikipedia.org/wiki/Exponential_backoff
return errors.New("fails")
}
var policy = retry.Policy{
MinDelay: 100 * time.Millisecond,
MaxDelay: time.Second,
MaxCount: 10,
}
func DoSomethingWithRetry(ctx context.Context) error {
return policy.Do(ctx, func() error {
return DoSomething(ctx)
})
}
func main() {
fmt.Println(DoSomethingWithRetry(context.Background()))
}
package main
import (
"context"
"errors"
"fmt"
"time"
"github.com/shogo82148/go-retry"
)
type Result int
func DoSomething(ctx context.Context) (Result, error) {
// do something here that should to do exponential backoff https://en.wikipedia.org/wiki/Exponential_backoff
return 0, errors.New("fails")
}
var policy = retry.Policy{
MinDelay: 100 * time.Millisecond,
MaxDelay: time.Second,
MaxCount: 10,
}
func DoSomethingWithRetry(ctx context.Context) (Result, error) {
return retry.DoValue(ctx, policy, DoSomething)
}
func main() {
fmt.Println(DoSomethingWithRetry(context.Background()))
}
PRIOR ARTS
This package is based on lestrrat-go/backoff and Yak Shaving With Backoff Libraries in Go. lestrrat-go/backoff's interface is so cool, but I want more simple one.
Songmu/retry is very simple, but it is too simple for me.
Documentation
¶
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func DoValue ¶ added in v1.2.0
DoValue executes f with retrying policy. It is a shorthand of Policy.Start and Retrier.Continue. If f returns an error, retry to execute f until f returns nil error. If the error implements interface{ Temporary() bool } and Temporary() returns false, DoValue doesn't retry and returns the error.
Example ¶
policy := &retry.Policy{
MaxCount: 3,
}
count := 0
_, err := retry.DoValue(context.Background(), policy, func() (int, error) {
count++
fmt.Printf("#%d: unstable func is called!\n", count)
return 0, errors.New("some error!")
})
if err != nil {
fmt.Println(err)
}
Output: #1: unstable func is called! #2: unstable func is called! #3: unstable func is called! some error!
func MarkPermanent ¶
MarkPermanent marks err as a permanent error. It returns the error that implements interface{ Temporary() bool } and Temporary() returns false.
Example ¶
policy := &retry.Policy{}
err := policy.Do(context.Background(), func() error {
fmt.Println("unstable func is called!")
return retry.MarkPermanent(errors.New("some error!"))
})
fmt.Println(err)
Output: unstable func is called! some error!
Types ¶
type Policy ¶
type Policy struct {
// MinDelay is a first delay for retrying.
// Zero or negative value means no delay.
MinDelay time.Duration
// MaxDelay is the maximum delay for retrying.
// If MaxDelay is less than MinDelay, MinDelay is used as the maximum delay.
MaxDelay time.Duration
// MaxCount is max retry count.
// Zero or negative value means retry forever.
MaxCount int
// Jitter adds random delay.
// Zero means no jitter.
// Negative value shorten the delay.
Jitter time.Duration
}
Policy is a retry policy.
func (*Policy) Do ¶
Do executes f with retrying policy. It is a shorthand of Policy.Start and Retrier.Continue. If f returns an error, retry to execute f until f returns nil error. If the error implements interface{ Temporary() bool } and Temporary() returns false, Do doesn't retry and returns the error.
Example ¶
policy := &retry.Policy{
MaxCount: 3,
}
count := 0
err := policy.Do(context.Background(), func() error {
count++
fmt.Printf("#%d: unstable func is called!\n", count)
return errors.New("some error!")
})
if err != nil {
fmt.Println(err)
}
Output: #1: unstable func is called! #2: unstable func is called! #3: unstable func is called! some error!
func (*Policy) Start ¶
Start starts retrying
Example ¶
count := 0
unstableFunc := func() error {
count++
fmt.Printf("#%d: unstableFunc is called!\n", count)
if count < 3 {
return errors.New("some error!")
}
return nil
}
policy := &retry.Policy{}
retrier := policy.Start(context.Background())
for retrier.Continue() {
err := unstableFunc()
if err == nil {
fmt.Println("Success")
break
}
}
if err := retrier.Err(); err != nil {
log.Fatal(err)
}
Output: #1: unstableFunc is called! #2: unstableFunc is called! #3: unstableFunc is called! Success
Source Files