Adding upstream version 1.1.0.upstream/1.1.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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)
+}