Method swap

utils/log/logger.go:406–412

swap atomically replaces the inner WriteSyncer and resets the cap counters. Called by DebugFileSink.Swap after the upstream buffer has been flushed; bytes written before swap are guaranteed to land in the OLD inner because this method holds the write mutex.

(inner zapcore.WriteSyncer)

// been flushed; bytes written before swap are guaranteed to land in
// the OLD inner because this method holds the write mutex.
func (s *cappedWriteSyncer) swap(inner zapcore.WriteSyncer) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.inner = inner
	s.written.Store(0)
	s.capped.Store(false)
}

// DebugFileSink is the caller-side handle for the debug-level file sink
// attached by AddDebugFileSink. It owns the buffered + capped writer