├── README.md ├── backoff_test.go ├── backoff.go └── LICENSE /README.md: -------------------------------------------------------------------------------- 1 | ## Backoff library with maximum number of calls 2 | 3 | Usage: 4 | 5 | Please do copy & paste the code, don't create more dependencies :) 6 | 7 | ``` 8 | // Retries the function f backing off the double of 9 | // time each retry until a successfully call is made. 10 | retry := backoff.NewDoubleTimeBackoff(100*time.Millisecond, 1*time.Second, 10) 11 | 12 | // it would retry after 100 Millis, 200 Millis, 400 Millis, ..., up to 1 Second, 10 times in total 13 | retry.Do(func() error { 14 | return MyLogic() 15 | }) 16 | ``` 17 | -------------------------------------------------------------------------------- /backoff_test.go: -------------------------------------------------------------------------------- 1 | package backoff 2 | 3 | import ( 4 | "errors" 5 | "testing" 6 | "time" 7 | ) 8 | 9 | func TestBackoff(t *testing.T) { 10 | okAfter := 5 11 | calls := 0 12 | 13 | b := NewDoubleTimeBackoff(100*time.Millisecond, 1*time.Second, 10) 14 | err := b.Do(func() error { 15 | calls++ 16 | if calls > okAfter { 17 | return nil 18 | } 19 | return errors.New("not ok") 20 | }) 21 | if err != nil { 22 | t.Fatalf("Error should be nil but is: %v", err) 23 | } 24 | if calls > 10 { 25 | t.Fatalf("Calls should be < 10 but is: %v", calls) 26 | } 27 | } 28 | 29 | func TestBackoffMaxCalls(t *testing.T) { 30 | okAfter := 5 31 | calls := 0 32 | 33 | b := NewDoubleTimeBackoff(100*time.Millisecond, 1*time.Second, 2) 34 | err := b.Do(func() error { 35 | calls++ 36 | if calls > okAfter { 37 | return nil 38 | } 39 | return errors.New("not ok") 40 | }) 41 | if err == nil { 42 | t.Fatalf("Error should be not nil but is: %v", err) 43 | } 44 | if calls != 2 { 45 | t.Fatalf("Calls should be 2 but is: %v", calls) 46 | } 47 | } 48 | -------------------------------------------------------------------------------- /backoff.go: -------------------------------------------------------------------------------- 1 | package backoff 2 | 3 | import ( 4 | "log" 5 | "time" 6 | ) 7 | 8 | type Retrier interface { 9 | // Do executes the function doing retries in case it returns an error 10 | Do(f func() error) error 11 | } 12 | 13 | type DoubleTimeBackoff struct { 14 | initialBackoff time.Duration 15 | maxBackoff time.Duration 16 | maxCalls int 17 | } 18 | 19 | // NewDoubleTimeBackoff retries the function f backing off the double of 20 | // time each retry until a successfully call is made. 21 | // initialBackoff is minimal time to wait for the next call 22 | // maxBackoff is the maximum time between calls, if is 0 there is no maximum 23 | // maxCalls is the maximum number of calls to the function, if is 0 there is no maximum 24 | func NewDoubleTimeBackoff(initialBackoff, maxBackoff time.Duration, maxCalls int) Retrier { 25 | if initialBackoff == 0 { 26 | initialBackoff = 100 * time.Millisecond 27 | } 28 | return &DoubleTimeBackoff{ 29 | initialBackoff: initialBackoff, 30 | maxBackoff: maxBackoff, 31 | maxCalls: maxCalls, 32 | } 33 | } 34 | 35 | func (b *DoubleTimeBackoff) Do(f func() error) error { 36 | backoff := time.Duration(0) 37 | calls := 0 38 | for { 39 | err := f() 40 | if err == nil { 41 | return nil 42 | } 43 | calls++ 44 | if (calls >= b.maxCalls) && (b.maxCalls != 0) { 45 | return err 46 | } 47 | switch { 48 | case backoff == 0: 49 | backoff = b.initialBackoff 50 | case (backoff >= b.maxBackoff) && (b.maxBackoff != 0): 51 | backoff = b.maxBackoff 52 | default: 53 | backoff *= 2 54 | } 55 | log.Printf("[backoff %v] Retry after %v due to the Error: %v\n", calls, backoff, err) 56 | time.Sleep(backoff) 57 | } 58 | } 59 | 60 | type NilBackoff struct{} 61 | 62 | // NewNilBackoff it just calls the function, it usefull for testing 63 | func NewNilBackoff() Retrier { 64 | return NilBackoff{} 65 | } 66 | func (NilBackoff) Do(f func() error) error { 67 | return f() 68 | } 69 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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