memory.go
func (b *ChannelMemoryBackend) Flush() {
	b.flushWg.Add(1)
	b.events <- eventFlush
	b.flushWg.Wait()
}
func (b *ChannelMemoryBackend) Flush() {
	b.flushWg.Add(1)
	b.events <- eventFlush
	b.flushWg.Wait()
}
// Flush waits until all records in the buffered channel have been processed.