lock: Retry locking with an increasing random interval (#17200)

internal/dsync/utils.go

@@ -0,0 +1,39 @@
+// Copyright (c) 2015-2021 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package dsync
+
+import (
+	"math/rand"
+	"time"
+)
+
+func backoffWait(min, unit, cap time.Duration) func(*rand.Rand, uint) time.Duration {
+	if unit > time.Hour {
+		// Protect against integer overflow
+		panic("unit cannot exceed one hour")
+	}
+	return func(r *rand.Rand, attempt uint) time.Duration {
+		sleep := min
+		sleep += unit * time.Duration(attempt)
+		if sleep > cap {
+			sleep = cap
+		}
+		sleep -= time.Duration(r.Float64() * float64(sleep))
+		return sleep
+	}
+}