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Fabric solo源码之单元测试部分(1)
Fabric solo共识很简单,其本身就是为Fabric的开发人员做实验用的。通过这个简单的本地可运行的共识,能够让开发人员在本地开发共识外的代码。也正是这样,我们可以本地运行solo共识,分析Fabric其他部分的代码。
这里先通过solo共识的单元测试及外围的辅助代码,分析Fabric的共识流程和系统逻辑。
fabric solo单元测试过程涉及到的文件:
- hyperledger/fabric/orderer/consensus/solo/ 共识部分及其单元测试
- hyperledger/fabric/orderer/mocks/common/blockcutter/ 切分块部分
- hyperledger/fabric/orderer/mocks/common/multichannel/ 写入账本的部分
基础
在通道关闭后,即close(chan),仍可尝试读取,再关闭后,直接返回空,但关闭后,不可写入。 参考Solo的测试函数TestStart。
package main
import "fmt"
func main() {ch := make(chan struct{})close(ch)defer func() {//为什么这样会异常?ch已经被close.//ch <- struct{}{}//如下,却可以?关闭后,可以尝试读取,在关闭后,直接返回nila := <-chfmt.Println("a", a)}()}
func TestStart(t *testing.T)
fabric/orderer/consensus/solo/consensus_test.go(源码):
//这个函数在测试什么功能?cutNext?跟TestHaltBeforeTimeout差不多呀?
func TestStart(t *testing.T) {batchTimeout, _ := time.ParseDuration("1ms")support := &mockmultichannel.ConsenterSupport{Blocks: make(chan *cb.Block),BlockCutterVal: mockblockcutter.NewReceiver(),SharedConfigVal: &mockconfig.Orderer{BatchTimeoutVal: batchTimeout},}//通过close关闭了mock的<-Receiver.Block//但是close不会阻塞吗?close之后还能用吗?close通道后,可尝试读取,关闭后,会返回空close(support.BlockCutterVal.Block)//在此,创建chainbs, _ := New().HandleChain(support, nil)//启动solo,在Start中启动协程bs.Start()defer bs.Halt()//CutNext干啥的还没搞清楚-->用于切块的,通过该标志,可以实现灵活的划分块,//CutNext=true接来下每次同步消息,都要成块//CutNext=false表示接下来的每次同步,都不成块support.BlockCutterVal.CutNext = true//这里,先调用bs.Order,将返回只传入到assert.Nil判断error是否为空//没有Recever.Block<-struct{}{},那mock ordered <-Receriver.Block不会阻塞吗?//因为之前close(chan)所以mock <-Block不会阻塞assert.Nil(t, bs.Order(testMessage, 0))select {case <-support.Blocks://应该读取空块吧?但是用来做什么的,表明块处理完了?收到的是写入的块//即solo中,ch.support.WriteBlock(block, nil)中进行的,实际上,//在fabric/orderer/mocks/common/multichannel/multichannel.go的WriteBlock中log.Println("support blocks")case <-bs.Errored():t.Fatalf("Expected not to exit")}
}
TestHaltBeforeTimeout
- 分析方法:
采用return+日志的较笨的方式进行分析,使用了两个tips:
- go test不会输出标准日志,即fmt.Println不在再test时输出日志;但可以log.Println()
- 使用-run参数指定要测试的函数,可以指定分析test函数,有助于分析代码
localhost:solo liu$ go test -v -run TestHaltBeforeTimeout
=== RUN TestHaltBeforeTimeout
2019/04/17 22:13:22 here
2019/04/17 22:13:22 chan order sendchan
2019/04/17 22:13:22 mock ordered
2019/04/17 22:13:22 sync will blocking
2019-04-17 22:13:22.875 CST [orderer/consensus/solo] main -> DEBU 001 Exiting
2019/04/17 22:13:22 solo finished
--- PASS: TestHaltBeforeTimeout (0.00s)
PASS
ok github.com/hyperledger/fabric/orderer/consensus/solo 0.044s
localhost:solo liu$
- 源码中可借鉴的部分:
- 通过chan struct{}的方式强调同步关系,以后再看到下代码,要立刻明白这是在进行同步操作,接着就要找到同步双方
bc.Block <- struct{}{}
- 使用interface管理具体实例,自己这样用的较少,需要学习下这种编程方式,体会其优势所在
//interface:
// Receiver defines a sink for the ordered broadcast messages
type Receiver interface {// Ordered should be invoked sequentially as messages are ordered// Each batch in `messageBatches` will be wrapped into a block.// `pending` indicates if there are still messages pending in the receiver. It// is useful for Kafka orderer to determine the `LastOffsetPersisted` of block.Ordered(msg *cb.Envelope) (messageBatches [][]*cb.Envelope, pending bool)// Cut returns the current batch and starts a new oneCut() []*cb.Envelope
}
//...
//solo:batches, _ := ch.support.BlockCutter().Ordered(msg.normalMsg)func NewReceiver() *Receiver {return &Receiver{IsolatedTx: false,CutAncestors: false,CutNext: false,Block: make(chan struct{}),}
}//...
//mock: 实际操作的对象
// Ordered will add or cut the batch according to the state of Receiver, it blocks reading from Block on return
func (mbc *Receiver) Ordered(env *cb.Envelope) ([][]*cb.Envelope, bool) {log.Println("mock ordered")defer func() {<-mbc.Block}()...
}
- 源码逻辑
这里分析TestHaltBeforeTimeout(t *testing.T)的数据流,主要包括三个部分:
- 启动solo算法,Test调用goWithWait启动solo算法
- 调用syncQueueMessage小消息加入到处理队列中,其角色类似客户端
- 模拟执行,solo算法中,调用 chain.support.BlockCutter().Ordered(msg.normalMsg)模拟执行,执行完会通过写入Receiver.Block同步chan,告知syncQueueMessage处理完成;注意这里的chain.support.BlockCutter().Ordered(msg.normalMsg)是接口的抽象关系,真正调用的是fabric/orderer/mocks/common/blockcutter/blockcutter.go中的Ordered。
具体分析,见如下代码中的注释
fabric/orderer/consensus/solo/consensus_test.go :
func syncQueueMessage(msg *cb.Envelope, chain *chain, bc *mockblockcutter.Receiver) {chain.Order(msg, 0)bc.Block <- struct{}{}//这是在做什么?同步用吗,不会阻塞吗?//bc.Block单独用来同步的,会用struct{}{}来强调表示,夜即无缓冲chan//但他是跟谁同步呢?//从名字看,是同步消息队列-->通过"断路测试"(我自己起的名字嘿,就是通过return,continue,截断程序,加上日志以分析数据流)//该阻塞用于和模拟执行的同步,在fabric/orderer/mocks/common/blockcutter/blockcutter.go的Ordered函数中,该函数结束后//会向Receiver.Block写入同步信号,告知syncQue...模拟处理处已经完成
}type waitableGo struct {done chan struct{}
}func goWithWait(target func()) *waitableGo {wg := &waitableGo{done: make(chan struct{}),}go func() {target()//该协程会阻塞在这;处理从sync加入的消息close(wg.done)//用来对外通知}()//外边结束,里边还不结束吗?return wg
}
// This test checks that if consenter is halted before a timer fires, nothing is actually written.
func TestHaltBeforeTimeout(t *testing.T) {batchTimeout, _ := time.ParseDuration("1ms")//support的构造还不清楚support := &mockmultichannel.ConsenterSupport{Blocks: make(chan *cb.Block),//消息发送BlockCutterVal: mockblockcutter.NewReceiver(),SharedConfigVal: &mockconfig.Orderer{BatchTimeoutVal: batchTimeout},}defer close(support.BlockCutterVal.Block)bs := newChain(support)//bs.main是solo算法的启动函数,是个死循环,处理函数wg := goWithWait(bs.main)//启动solo算法,在goWithWait中启动协程,并通过通道通信defer bs.Halt()//中止log.Println("here")syncQueueMessage(testMessage, bs, support.BlockCutterVal)//将消息送入solo排序,//sync阻塞,根本不会接着执行啊-->sync是和mock处理同步的log.Println("sync will blocking")bs.Halt()//中止solo共识select {case <-support.Blocks: //应该读取空块吧?但是用来做什么的,表明块处理完了?收到的是写入的块//即solo中,ch.support.WriteBlock(block, nil)中进行的,实际上,//在fabric/orderer/mocks/common/multichannel/multichannel.go的WriteBlock中t.Fatalf("Expected no invocations of Append")log.Println("block exit")//不从这退出case <-wg.done://共识算法退出标志log.Println("solo finished")}
}
fabric/orderer/consensus/solo/consensus.go:
// Order accepts normal messages for ordering
func (ch *chain) Order(env *cb.Envelope, configSeq uint64) error {//外部通过调用order加入消息//这里,这样处理的目的是什么?//注意这里是两个case,正常是同步sendchan,但是如果要结束系统,由exitchan告知退出//而不用一直阻塞在这里,等待接收处理消息,让外部服务顺滑退出select {case ch.sendChan <- &message{configSeq: configSeq,normalMsg: env,}:log.Println("chan order sendchan")return nilcase <-ch.exitChan: //退出信号return fmt.Errorf("Exiting")}
}
//solo共识算法的主题部分,这里只关心一条数据链路,其他分支省略
func (ch *chain) main() {var timer <-chan time.Timevar err errorfor {seq := ch.support.Sequence()err = nilselect {case msg := <-ch.sendChan://读取发来的消息log.Println("chan receive msg")//continue ;我的代码review的笨办法,日志+断路//事实证明,这里接收sync发来的同步消息if msg.configMsg == nil {// NormalMsgif msg.configSeq < seq {_, err = ch.support.ProcessNormalMsg(msg.normalMsg)if err != nil {logger.Warningf("Discarding bad normal message: %s", err)continue}}//多个断路返回,确定接收同步信号在此,ordered进行了模拟处理batches, _ := ch.support.BlockCutter().Ordered(msg.normalMsg)if len(batches) == 0 && timer == nil {//正常情况下,消息从这结束timer = time.After(ch.support.SharedConfig().BatchTimeout())continue}...} else {...}case <-timer:...case <-ch.exitChan:logger.Debugf("Exiting")return}}
}
fabric/orderer/mocks/common/blockcutter/blockcutter.go:
// Ordered will add or cut the batch according to the state of Receiver, it blocks reading from Block on return
func (mbc *Receiver) Ordered(env *cb.Envelope) ([][]*cb.Envelope, bool) {defer func() { //模拟执行完,会告知syncque...处理完<-mbc.Block}()...
}// Cut terminates the current batch, returning it
func (mbc *Receiver) Cut() []*cb.Envelope {...
}
fabric/orderer/mocks/common/multichannel/multichannel.go
// WriteBlock writes data to the Blocks channel
func (mcs *ConsenterSupport) WriteBlock(block *cb.Block, encodedMetadataValue []byte) {if encodedMetadataValue != nil {block.Metadata.Metadata[cb.BlockMetadataIndex_ORDERER] = utils.MarshalOrPanic(&cb.Metadata{Value: encodedMetadataValue})}mcs.HeightVal++mcs.Blocks <- block //here
}
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