Page 194 - 《软件学报》2021年第6期
P. 194
1768 Journal of Software 软件学报 Vol.32, No.6, June 2021
date6date,
value6chosen.value,
committed6chosen.committed]
BecomeLeaderCandidate(i)==
/\currentState[i]=Candidate
/\\E P\in Quorums:
LET voteGranted=={m\in messages:/\m.mtype=RequestVoteResponse
/\m.mdest=i
/\m.msource\in P
/\m.mterm=currentTerm[i]
/\m.mvoteGranted=TRUE}
allLog==UNION {m.mlog:m\in voteGranted}
endLine==LET allPoint=={m.mend:m\in voteResponded}
IN e==CHOOSE e1\in allPoint:
(\A e2\in allPoint:e1[1]\geq e2[1])
toRecover=={n\in 0..endLine:log[i][n].committed=FALSE}
toSync=={〈〈n,Merge({l[2]:l\in {t\in allLog:t[1]=n}},sync[i],currentTerm[i])〉〉
:n\in toRecover}
IN
/\\A p\in P:\E m\in voteGranted:m.msource=p
/\log′=[log EXCEPT ![i]=[n\in Index6IF n\in toRecover THEN
(CHOOSE e\in toSync:e[1]=n)[2]
ELSE log[i][n]]]
/\end′=[end EXCEPT ![i][sync[i]]=〈〈currentTerm[i],end〉〉]
/\currentState′=[currentState EXCEPT ![i]=LeaderCandidate]
/\syncTrack′=[syncTrack EXCEPT ![i]=[j\in Server6sync[i]]]
/\UNCHANGED 〈〈messages,currentTerm,votedFor,sync,elections〉〉
-------------------------------------------------------------------------------------------------------------------
• RequestSync(i):当 i 为主节点或主节点候选者时,对其他每个节点 p,i 向 p 发送任期为 syncTrack[i][p]的
日志项.这些日志项可以乱序地发送和接受;
• HandleRequestSyncRequest(i):节点 i 收到同步请求 m.当 m.msync<sync[i]或 m.msync>sync[i]时,i 拒绝请
求并回复 RequestSyncResponse 消息,将 sync[i]告知发送者.当 m.msync=sync[i]时,i 同意请求,回复确认,
并根据 m.mend(可以接受的任期为 m.msync 的日志项的最大编号)和 m.mentries(任期为 m.msync 的日
志项)修改 end[i]和 log[i].对日志的修改为:删除日志中所有编号大于 m.mend 的日志项,并将编号不超
过 m.mend 的日志项替换为 m.mentries 中相应的项.
-----------------------------------------------------------------------------
RequestSync(i)==
/\currentState[i]\in {LeaderCandidate,Leader}
/\\E s\in 0..sync[i]:
LET start==Min({n\in Index:log[i][n].term=s})
end==Max({n\in Index:log[i][n].term=s})
