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-rw-r--r--pkg/backoff/backoff.go43
1 files changed, 43 insertions, 0 deletions
diff --git a/pkg/backoff/backoff.go b/pkg/backoff/backoff.go
new file mode 100644
index 0000000..6ce7bee
--- /dev/null
+++ b/pkg/backoff/backoff.go
@@ -0,0 +1,43 @@
+package backoff
+
+import (
+ "math/rand"
+ "time"
+)
+
+// Backoff returns the backoff duration for a specific retry attempt.
+type Backoff func(uint64) time.Duration
+
+// NewExponentialWithJitter returns a backoff implementation that
+// exponentially increases the backoff duration for each retry from min,
+// never exceeding max. Some randomization is added to the backoff duration.
+// It panics if min >= max.
+func NewExponentialWithJitter(min, max time.Duration) Backoff {
+ if min <= 0 {
+ min = time.Millisecond * 100
+ }
+ if max <= 0 {
+ max = time.Second * 10
+ }
+ if min >= max {
+ panic("max must be larger than min")
+ }
+
+ return func(attempt uint64) time.Duration {
+ e := min << attempt
+ if e <= 0 || e > max {
+ e = max
+ }
+
+ return time.Duration(jitter(int64(e)))
+ }
+}
+
+// jitter returns a random integer distributed in the range [n/2..n).
+func jitter(n int64) int64 {
+ if n == 0 {
+ return 0
+ }
+
+ return n/2 + rand.Int63n(n/2)
+}