sequencer
availableBuffer
MultiProducerSequencer
BatchEventProcessor
Sequence
Sequencer
EventProcessor
AbstractSequencer
RingBuffer
add()..
getHighestPublishedSequence()
ProcessingSequenceBarrier
SequenceBarrier
long value
entries
publish()序列号，有效性
gatingSequenceCache
dependentSequence
Disruptor
cursor
get()..
