go saram 消費者調用邏輯

業務層：

NewConsumer(client.mBrokers, group, topic, config)

cluster-comsuer.go

構造Consumer：

consumer, err := sarama.NewConsumerFromClient(client.Client)

c.client.RefreshCoordinator(groupID)//獲取組協調者

起循環

for {

c.nextTick

}

nextTick:

重平衡->訂閱主題->fetchOffsets->針對該主題分區下的offset起一個分區消費者->然後調用分區消費者的ConsumePartition

comsumer.go

ConsumePartition(topic string, partition int32, offset int64)->

c.refBrokerConsumer(leader)->

c.newBrokerConsumer(broker)->

go withRecover(bc.subscriptionConsumer)->

bc.fetchNewMessages()->

bc.broker.Fetch(request)

broker.go

 b.sendAndReceive(request, response)->

versionedDecode(buf, res, req.version())  and res is 

respons, response is FetchResponse type

encode_decoder.go

in.decode(&helper, version)  FetchResponse type decode is:

fetch_repsonse.go

decode(pd packetDecoder, version int16)->

records.decode(recordsDecoder);

records.go

decode(pd packetDecoder)->

record_batch.go

decode(pd packetDecoder) include 解壓縮