batch tun reads

overlay/device.go

@@ -16,3 +16,38 @@ type Device interface {
 	SupportsMultiqueue() bool
 	NewMultiQueueReader() (io.ReadWriteCloser, error)
 }
+
+// BatchReader is an optional interface that devices can implement
+// to support reading multiple packets in a single batch operation.
+// This can significantly reduce syscall overhead under high load.
+type BatchReader interface {
+	// ReadBatch reads up to len(packets) packets into the provided buffers.
+	// Each packet is read into packets[i] and its length is stored in sizes[i].
+	// Returns the number of packets read, or an error.
+	// A return of (0, nil) indicates no packets were available (non-blocking).
+	ReadBatch(packets [][]byte, sizes []int) (int, error)
+}
+
+// AsBatchReader returns a BatchReader if the reader supports batch operations,
+// otherwise returns nil.
+func AsBatchReader(r io.ReadWriteCloser) BatchReader {
+	if br, ok := r.(BatchReader); ok {
+		return br
+	}
+	return nil
+}
+
+// BatchEnabler is an optional interface for devices that need explicit
+// enabling of batch read support (e.g., setting non-blocking mode).
+type BatchEnabler interface {
+	EnableBatchReading() error
+}
+
+// EnableBatchReading enables batch reading on the device if supported.
+// Returns nil if the device doesn't support or need explicit enabling.
+func EnableBatchReading(d interface{}) error {
+	if be, ok := d.(BatchEnabler); ok {
+		return be.EnableBatchReading()
+	}
+	return nil
+}