Method Swap

utils/log/logger.go:512–524

Swap atomically swaps the underlying file the sink writes to. The caller opens newFile; the previous file is returned so the caller can close it after Swap returns. Buffered writes are flushed to the previous file before the swap, and the cap-tripped state is reset. Concurrent log Writes are safe —

(newFile *os.File)

// cappedWriteSyncer's mutex, so no record can land half-written
// across the swap boundary.
func (s *DebugFileSink) Swap(newFile *os.File) error {
	if s == nil || s.capped == nil || s.buffered == nil || newFile == nil {
		return fmt.Errorf("debug file sink: swap called on uninitialized sink or nil file")
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	if err := s.buffered.Sync(); err != nil {
		return fmt.Errorf("debug file sink: flush before swap: %w", err)
	}
	s.capped.swap(zapcore.AddSync(newFile))
	s.originPath = newFile.Name()
	return nil
}

// RotateForScope swaps the sink to a per-scope file derived from the
// sink's origin path. Scope semantics are caller-defined; for the