environment:
fabric v2.2.0
出块规则
- 容量大于PreferredMaxBytes时出块
- 交易数量大于MaxMessageCount时出块
- 不满足上面条件，但有交易待出的话，超时BatchTimeout出块
(参数都在configtx.yaml上设置)
BlockCutter流程
block_cutter流程图
BlockCutter代码分析
代码位于：orderer/common/blockcutter/blockcutter.go，该模块用于将Envelope消息进行打包切分区块
// Ordered should be invoked sequentially as messages are ordered
//
// messageBatches length: 0, pending: false
// - impossible, as we have just received a message
// messageBatches length: 0, pending: true
// - no batch is cut and there are messages pending
// messageBatches length: 1, pending: false
// - the message count reaches BatchSize.MaxMessageCount
// messageBatches length: 1, pending: true
// - the current message will cause the pending batch size in bytes to exceed BatchSize.PreferredMaxBytes.
// messageBatches length: 2, pending: false
// - the current message size in bytes exceeds BatchSize.PreferredMaxBytes, therefore isolated in its own batch.
// messageBatches length: 2, pending: true
// - impossible
//
// Note that messageBatches can not be greater than 2.
// messageBatches的长度<=2
func (r *receiver) Ordered(msg *cb.Envelope) (messageBatches [][]*cb.Envelope, pending bool) {
if len(r.pendingBatch) == 0 { // 判断当前批次是否为空，如果为空标记区块形成时间
// We are beginning a new batch, mark the time
r.PendingBatchStartTime = time.Now()
}
// 获取order配置，主要是获取BatchTimeout，MaxMessageCount， AbsoluteMaxBytes等上述三个参数用于判定形成区块的规则
ordererConfig, ok := r.sharedConfigFetcher.OrdererConfig()
if !ok {
logger.Panicf("Could not retrieve orderer config to query batch parameters, block cutting is not possible")
}
batchSize := ordererConfig.BatchSize()
// 获取当前消息大小
messageSizeBytes := messageSizeBytes(msg)
if messageSizeBytes > batchSize.PreferredMaxBytes { //当当前消息大于PreferredMaxBytes时，直接Cut形成区块Batch
logger.Debugf("The current message, with %v bytes, is larger than the preferred batch size of %v bytes and will be isolated.", messageSizeBytes, batchSize.PreferredMaxBytes)
// cut pending batch, if it has any messages
// 该条件就是最多形成2个区块Batch的代码
if len(r.pendingBatch) > 0 {
messageBatch := r.Cut()
messageBatches = append(messageBatches, messageBatch)
}
// create new batch with single message
// 创建一个新的Batch只有该消息（大于PreferredMaxBytes值）
messageBatches = append(messageBatches, []*cb.Envelope{msg})
// Record that this batch took no time to fill
r.Metrics.BlockFillDuration.With("channel", r.ChannelID).Observe(0)
return
}
// 当消息不大于PreferredMaxBytes时，判断消息该消息与之前的消息大小是否大于PreferredMaxBytes
messageWillOverflowBatchSizeBytes := r.pendingBatchSizeBytes+messageSizeBytes > batchSize.PreferredMaxBytes
// 如果大于2MB(默认)则形成区块
if messageWillOverflowBatchSizeBytes {
logger.Debugf("The current message, with %v bytes, will overflow the pending batch of %v bytes.", messageSizeBytes, r.pendingBatchSizeBytes)
logger.Debugf("Pending batch would overflow if current message is added, cutting batch now.")
messageBatch := r.Cut()
r.PendingBatchStartTime = time.Now()
messageBatches = append(messageBatches, messageBatch)
}
logger.Debugf("Enqueuing message into batch")
r.pendingBatch = append(r.pendingBatch, msg)
r.pendingBatchSizeBytes += messageSizeBytes
pending = true
// 判断Batch消息是否大于MaxMessageCount，如果是则形成区块Batch
if uint32(len(r.pendingBatch)) >= batchSize.MaxMessageCount {
logger.Debugf("Batch size met, cutting batch")
messageBatch := r.Cut()
messageBatches = append(messageBatches, messageBatch)
pending = false
}
return
}
// Cut returns the current batch and starts a new one
func (r *receiver) Cut() []*cb.Envelope {
if r.pendingBatch != nil {
r.Metrics.BlockFillDuration.With("channel", r.ChannelID).Observe(time.Since(r.PendingBatchStartTime).Seconds())
}
r.PendingBatchStartTime = time.Time{}
batch := r.pendingBatch
r.pendingBatch = nil
r.pendingBatchSizeBytes = 0
return batch
}
- Ordered为添加新的交易到缓冲区，返回messageBatches(即可以打包的block数组)和缓冲区状态pending
- messageBatches的长度不会超过2
- pending是留个超时是否打包来判断用的
- Cut函数为取出缓冲区打成一个block返回
超时打包代码
代码位于：orderer/consensus/solo/consensus.go
func (ch *chain) main() {
// 创建打包超时定时器
var timer <-chan time.Time
var err error
// 循环接收消息
for {
// 获取当前的配置序号
seq := ch.support.Sequence()
err = nil
select {
case msg := <-ch.sendChan:
if msg.configMsg == nil {
// NormalMsg
if msg.configSeq < seq {
_, err = ch.support.ProcessNormalMsg(msg.normalMsg)
if err != nil {
logger.Warningf("Discarding bad normal message: %s", err)
continue
}
}
// 把交易分组，每组为一个batch
batches, pending := ch.support.BlockCutter().Ordered(msg.normalMsg)
for _, batch := range batches {
block := ch.support.CreateNextBlock(batch)
ch.support.WriteBlock(block, nil)
}
switch {
case timer != nil && !pending: // 如果计时开始但缓冲区没数据，把计时关掉
// Timer is already running but there are no messages pending, stop the timer
timer = nil
case timer == nil && pending: // 如果计时没开始但缓冲区有数据，开始计时
// Timer is not already running and there are messages pending, so start it
timer = time.After(ch.support.SharedConfig().BatchTimeout())
logger.Debugf("Just began %s batch timer", ch.support.SharedConfig().BatchTimeout().String())
default:
// Do nothing when:
// 1. Timer is already running and there are messages pending
// 2. Timer is not set and there are no messages pending
}
}
... ...
// 打包BatchTimeout超时定时器触发
case <-timer:
//clear the timer
timer = nil
// 直接对缓存的message进行Cut打包
batch := ch.support.BlockCutter().Cut()
// 如果batch为空，说明无消息可打包，继续等待消息
if len(batch) == 0 {
logger.Warningf("Batch timer expired with no pending requests, this might indicate a bug")
continue
}
// 创建区块，写入账本
logger.Debugf("Batch timer expired, creating block")
block := ch.support.CreateNextBlock(batch)
ch.support.WriteBlock(block, nil)
// 接收到exit chan时退出主逻辑
case <-ch.exitChan:
logger.Debugf("Exiting")
return
}
}
}
从上面代码可以看出如果缓冲区有数据就打开计时器，到超时如果还有数据在缓冲区的话就打包缓冲区里面的数据
文章github地址
参考:
Fabric 1.4源码详解（一）Order BlockCutter