1 files changed, 44 insertions, 0 deletions
diff --git a/refstore/files/update_lock_packed.go b/refstore/files/update_lock_packed.go
new file mode 100644
index 00000000..f74a4f5e
--- /dev/null
+++ b/refstore/files/update_lock_packed.go
@@ -0,0 +1,44 @@
+package files
+
+import (
+	"errors"
+	"os"
+	"time"
+)
+
+func (executor *refUpdateExecutor) createPackedRefsLock(timeout time.Duration) error {
+	const (
+		initialBackoffMs     = 1
+		backoffMaxMultiplier = 1000
+	)
+
+	deadline := time.Now().Add(timeout)
+	multiplier := 1
+	n := 1
+
+	for {
+		file, err := executor.store.commonRoot.OpenFile("packed-refs.lock", os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o644)
+		if err == nil {
+			return file.Close()
+		}
+
+		if !errors.Is(err, os.ErrExist) {
+			return err
+		}
+
+		if timeout == 0 || (timeout > 0 && time.Now().After(deadline)) {
+			return err
+		}
+
+		backoffMs := multiplier * initialBackoffMs
+		waitMs := (750 + executor.store.lockRand.Intn(500)) * backoffMs / 1000
+		time.Sleep(time.Duration(waitMs) * time.Millisecond)
+
+		multiplier += 2*n + 1
+		if multiplier > backoffMaxMultiplier {
+			multiplier = backoffMaxMultiplier
+		} else {
+			n++
+		}
+	}
+}