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homework-jianmu/source/libs/sync/src/syncAppendEntries.c

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/*
* Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
*
* This program is free software: you can use, redistribute, and/or modify
* it under the terms of the GNU Affero General Public License, version 3
* or later ("AGPL"), as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#define _DEFAULT_SOURCE
#include "syncAppendEntries.h"
#include "syncMessage.h"
#include "syncRaftLog.h"
#include "syncRaftStore.h"
#include "syncUtil.h"
// TLA+ Spec
// HandleAppendEntriesRequest(i, j, m) ==
// LET logOk == \/ m.mprevLogIndex = 0
// \/ /\ m.mprevLogIndex > 0
// /\ m.mprevLogIndex <= Len(log[i])
// /\ m.mprevLogTerm = log[i][m.mprevLogIndex].term
// IN /\ m.mterm <= currentTerm[i]
// /\ \/ /\ \* reject request
// \/ m.mterm < currentTerm[i]
// \/ /\ m.mterm = currentTerm[i]
// /\ state[i] = Follower
// /\ \lnot logOk
// /\ Reply([mtype |-> AppendEntriesResponse,
// mterm |-> currentTerm[i],
// msuccess |-> FALSE,
// mmatchIndex |-> 0,
// msource |-> i,
// mdest |-> j],
// m)
// /\ UNCHANGED <<serverVars, logVars>>
// \/ \* return to follower state
// /\ m.mterm = currentTerm[i]
// /\ state[i] = Candidate
// /\ state' = [state EXCEPT ![i] = Follower]
// /\ UNCHANGED <<currentTerm, votedFor, logVars, messages>>
// \/ \* accept request
// /\ m.mterm = currentTerm[i]
// /\ state[i] = Follower
// /\ logOk
// /\ LET index == m.mprevLogIndex + 1
// IN \/ \* already done with request
// /\ \/ m.mentries = << >>
// \/ /\ m.mentries /= << >>
// /\ Len(log[i]) >= index
// /\ log[i][index].term = m.mentries[1].term
// \* This could make our commitIndex decrease (for
// \* example if we process an old, duplicated request),
// \* but that doesn't really affect anything.
// /\ commitIndex' = [commitIndex EXCEPT ![i] =
// m.mcommitIndex]
// /\ Reply([mtype |-> AppendEntriesResponse,
// mterm |-> currentTerm[i],
// msuccess |-> TRUE,
// mmatchIndex |-> m.mprevLogIndex +
// Len(m.mentries),
// msource |-> i,
// mdest |-> j],
// m)
// /\ UNCHANGED <<serverVars, log>>
// \/ \* conflict: remove 1 entry
// /\ m.mentries /= << >>
// /\ Len(log[i]) >= index
// /\ log[i][index].term /= m.mentries[1].term
// /\ LET new == [index2 \in 1..(Len(log[i]) - 1) |->
// log[i][index2]]
// IN log' = [log EXCEPT ![i] = new]
// /\ UNCHANGED <<serverVars, commitIndex, messages>>
// \/ \* no conflict: append entry
// /\ m.mentries /= << >>
// /\ Len(log[i]) = m.mprevLogIndex
// /\ log' = [log EXCEPT ![i] =
// Append(log[i], m.mentries[1])]
// /\ UNCHANGED <<serverVars, commitIndex, messages>>
// /\ UNCHANGED <<candidateVars, leaderVars>>
//
int32_t syncNodeFollowerCommit(SSyncNode* ths, SyncIndex newCommitIndex) {
if (ths->state != TAOS_SYNC_STATE_FOLLOWER) {
sNTrace(ths, "can not do follower commit");
return -1;
}
// maybe update commit index, leader notice me
if (newCommitIndex > ths->commitIndex) {
// has commit entry in local
if (newCommitIndex <= ths->pLogStore->syncLogLastIndex(ths->pLogStore)) {
// advance commit index to sanpshot first
SSnapshot snapshot;
ths->pFsm->FpGetSnapshotInfo(ths->pFsm, &snapshot);
if (snapshot.lastApplyIndex >= 0 && snapshot.lastApplyIndex > ths->commitIndex) {
SyncIndex commitBegin = ths->commitIndex;
SyncIndex commitEnd = snapshot.lastApplyIndex;
ths->commitIndex = snapshot.lastApplyIndex;
sNTrace(ths, "commit by snapshot from index:%" PRId64 " to index:%" PRId64, commitBegin, commitEnd);
}
SyncIndex beginIndex = ths->commitIndex + 1;
SyncIndex endIndex = newCommitIndex;
// update commit index
ths->commitIndex = newCommitIndex;
// call back Wal
int32_t code = ths->pLogStore->syncLogUpdateCommitIndex(ths->pLogStore, ths->commitIndex);
ASSERT(code == 0);
code = syncNodeDoCommit(ths, beginIndex, endIndex, ths->state);
ASSERT(code == 0);
}
}
return 0;
}
int32_t syncNodeOnAppendEntries(SSyncNode* ths, const SRpcMsg* pRpcMsg) {
SyncAppendEntries* pMsg = pRpcMsg->pCont;
SRpcMsg rpcRsp = {0};
// if already drop replica, do not process
if (!syncNodeInRaftGroup(ths, &(pMsg->srcId))) {
syncLogRecvAppendEntries(ths, pMsg, "not in my config");
goto _IGNORE;
}
// prepare response msg
int32_t code = syncBuildAppendEntriesReply(&rpcRsp, ths->vgId);
if (code != 0) {
syncLogRecvAppendEntries(ths, pMsg, "build rsp error");
goto _IGNORE;
}
SyncAppendEntriesReply* pReply = rpcRsp.pCont;
pReply->srcId = ths->myRaftId;
pReply->destId = pMsg->srcId;
pReply->term = ths->pRaftStore->currentTerm;
pReply->success = false;
// pReply->matchIndex = ths->pLogStore->syncLogLastIndex(ths->pLogStore);
pReply->matchIndex = SYNC_INDEX_INVALID;
pReply->lastSendIndex = pMsg->prevLogIndex + 1;
pReply->startTime = ths->startTime;
if (pMsg->term < ths->pRaftStore->currentTerm) {
syncLogRecvAppendEntries(ths, pMsg, "reject, small term");
goto _SEND_RESPONSE;
}
if (pMsg->term > ths->pRaftStore->currentTerm) {
pReply->term = pMsg->term;
}
syncNodeStepDown(ths, pMsg->term);
syncNodeResetElectTimer(ths);
SyncIndex startIndex = ths->pLogStore->syncLogBeginIndex(ths->pLogStore);
SyncIndex lastIndex = ths->pLogStore->syncLogLastIndex(ths->pLogStore);
if (pMsg->prevLogIndex > lastIndex) {
syncLogRecvAppendEntries(ths, pMsg, "reject, index not match");
goto _SEND_RESPONSE;
}
if (pMsg->prevLogIndex >= startIndex) {
SyncTerm myPreLogTerm = syncNodeGetPreTerm(ths, pMsg->prevLogIndex + 1);
// ASSERT(myPreLogTerm != SYNC_TERM_INVALID);
if (myPreLogTerm == SYNC_TERM_INVALID) {
syncLogRecvAppendEntries(ths, pMsg, "reject, pre-term invalid");
goto _SEND_RESPONSE;
}
if (myPreLogTerm != pMsg->prevLogTerm) {
syncLogRecvAppendEntries(ths, pMsg, "reject, pre-term not match");
goto _SEND_RESPONSE;
}
}
// accept
pReply->success = true;
bool hasAppendEntries = pMsg->dataLen > 0;
if (hasAppendEntries) {
SSyncRaftEntry* pAppendEntry = syncEntryBuildFromAppendEntries(pMsg);
ASSERT(pAppendEntry != NULL);
SyncIndex appendIndex = pMsg->prevLogIndex + 1;
SSyncRaftEntry* pLocalEntry = NULL;
int32_t code = ths->pLogStore->syncLogGetEntry(ths->pLogStore, appendIndex, &pLocalEntry);
if (code == 0) {
if (pLocalEntry->term == pAppendEntry->term) {
// do nothing
sNTrace(ths, "log match, do nothing, index:%" PRId64, appendIndex);
} else {
// truncate
code = ths->pLogStore->syncLogTruncate(ths->pLogStore, appendIndex);
if (code != 0) {
char logBuf[128];
snprintf(logBuf, sizeof(logBuf), "ignore, truncate error, append-index:%" PRId64, appendIndex);
syncLogRecvAppendEntries(ths, pMsg, logBuf);
syncEntryDestory(pLocalEntry);
syncEntryDestory(pAppendEntry);
goto _IGNORE;
}
// append
code = ths->pLogStore->syncLogAppendEntry(ths->pLogStore, pAppendEntry);
if (code != 0) {
char logBuf[128];
snprintf(logBuf, sizeof(logBuf), "ignore, append error, append-index:%" PRId64, appendIndex);
syncLogRecvAppendEntries(ths, pMsg, logBuf);
syncEntryDestory(pLocalEntry);
syncEntryDestory(pAppendEntry);
goto _IGNORE;
}
}
} else {
if (terrno == TSDB_CODE_WAL_LOG_NOT_EXIST) {
// log not exist
// truncate
code = ths->pLogStore->syncLogTruncate(ths->pLogStore, appendIndex);
if (code != 0) {
char logBuf[128];
snprintf(logBuf, sizeof(logBuf), "ignore, log not exist, truncate error, append-index:%" PRId64, appendIndex);
syncLogRecvAppendEntries(ths, pMsg, logBuf);
syncEntryDestory(pLocalEntry);
syncEntryDestory(pAppendEntry);
goto _IGNORE;
}
// append
code = ths->pLogStore->syncLogAppendEntry(ths->pLogStore, pAppendEntry);
if (code != 0) {
char logBuf[128];
snprintf(logBuf, sizeof(logBuf), "ignore, log not exist, append error, append-index:%" PRId64, appendIndex);
syncLogRecvAppendEntries(ths, pMsg, logBuf);
syncEntryDestory(pLocalEntry);
syncEntryDestory(pAppendEntry);
goto _IGNORE;
}
} else {
// error
char logBuf[128];
snprintf(logBuf, sizeof(logBuf), "ignore, get local entry error, append-index:%" PRId64 " err:%d", appendIndex,
terrno);
syncLogRecvAppendEntries(ths, pMsg, logBuf);
syncEntryDestory(pLocalEntry);
syncEntryDestory(pAppendEntry);
goto _IGNORE;
}
}
// update match index
pReply->matchIndex = pAppendEntry->index;
syncEntryDestory(pLocalEntry);
syncEntryDestory(pAppendEntry);
} else {
// no append entries, do nothing
// maybe has extra entries, no harm
// update match index
pReply->matchIndex = pMsg->prevLogIndex;
}
// maybe update commit index, leader notice me
syncNodeFollowerCommit(ths, pMsg->commitIndex);
syncLogRecvAppendEntries(ths, pMsg, "accept");
goto _SEND_RESPONSE;
_IGNORE:
rpcFreeCont(rpcRsp.pCont);
return 0;
_SEND_RESPONSE:
// msg event log
syncLogSendAppendEntriesReply(ths, pReply, "");
// send response
syncNodeSendMsgById(&pReply->destId, ths, &rpcRsp);
return 0;
}
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