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Commit4bf43fa

Browse files
knizhnikkelvich
authored andcommitted
Start rewriting multimaster to 2PC
1 parente7c5d11 commit4bf43fa

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3 files changed

+49
-150
lines changed

3 files changed

+49
-150
lines changed

‎arbiter.c

Lines changed: 14 additions & 112 deletions
Original file line numberDiff line numberDiff line change
@@ -458,7 +458,7 @@ static void MtmAppendBuffer(MtmBuffer* txBuffer, TransactionId xid, int node, Mt
458458
MTM_TRACE("Send message %s CSN=%ld to node %d from node %d for global transaction %d/local transaction %d\n",
459459
messageText[ts->cmd],ts->csn,node+1,MtmNodeId,ts->gtid.xid,ts->xid);
460460
Assert(ts->cmd!=MSG_INVALID);
461-
buf->data[buf->used].code=ts->cmd;
461+
buf->data[buf->used].code=ts->status==TRANSACTION_STATUS_ABORTED ?MSG_ABORTED :MSG_PREPARED;
462462
buf->data[buf->used].dxid=xid;
463463
buf->data[buf->used].sxid=ts->xid;
464464
buf->data[buf->used].csn=ts->csn;
@@ -467,21 +467,6 @@ static void MtmAppendBuffer(MtmBuffer* txBuffer, TransactionId xid, int node, Mt
467467
buf->used+=1;
468468
}
469469

470-
staticvoidMtmBroadcastMessage(MtmBuffer*txBuffer,MtmTransState*ts)
471-
{
472-
inti;
473-
intn=1;
474-
for (i=0;i<MtmNodes;i++)
475-
{
476-
if (TransactionIdIsValid(ts->xids[i])) {
477-
Assert(i+1!=MtmNodeId);
478-
MtmAppendBuffer(txBuffer,ts->xids[i],i,ts);
479-
n+=1;
480-
}
481-
}
482-
Assert(n==ds->nNodes);
483-
}
484-
485470
staticvoidMtmTransSender(Datumarg)
486471
{
487472
intnNodes=MtmNodes;
@@ -508,12 +493,7 @@ static void MtmTransSender(Datum arg)
508493
MtmLock(LW_SHARED);
509494

510495
for (ts=ds->votingTransactions;ts!=NULL;ts=ts->nextVoting) {
511-
if (MtmIsCoordinator(ts)) {
512-
MtmBroadcastMessage(txBuffer,ts);
513-
}else {
514-
MtmAppendBuffer(txBuffer,ts->gtid.xid,ts->gtid.node-1,ts);
515-
}
516-
ts->cmd=MSG_INVALID;
496+
MtmAppendBuffer(txBuffer,ts->gtid.xid,ts->gtid.node-1,ts);
517497
}
518498
ds->votingTransactions=NULL;
519499
MtmUnlock();
@@ -634,109 +614,31 @@ static void MtmTransReceiver(Datum arg)
634614
MtmArbiterMessage*msg=&rxBuffer[i].data[j];
635615
MtmTransState*ts= (MtmTransState*)hash_search(xid2state,&msg->dxid,HASH_FIND,NULL);
636616
Assert(ts!=NULL);
637-
Assert(ts->cmd==MSG_INVALID);
638617
Assert(msg->node>0&&msg->node <=nNodes&&msg->node!=MtmNodeId);
639-
ts->xids[msg->node-1]=msg->sxid;
640-
641-
if (MtmIsCoordinator(ts)) {
642-
switch (msg->code) {
643-
caseMSG_READY:
644-
Assert(ts->status==TRANSACTION_STATUS_ABORTED||ts->status==TRANSACTION_STATUS_IN_PROGRESS);
645-
Assert(ts->nVotes<ds->nNodes);
646-
ds->nodeTransDelay[msg->node-1]+=MtmGetCurrentTime()-ts->csn;
647-
if (++ts->nVotes==ds->nNodes) {
648-
/* All nodes are finished their transactions */
649-
if (ts->status==TRANSACTION_STATUS_IN_PROGRESS) {
650-
ts->nVotes=1;/* I voted myself */
651-
ts->cmd=MSG_PREPARE;
652-
}else {
653-
ts->status=TRANSACTION_STATUS_ABORTED;
654-
ts->cmd=MSG_ABORT;
655-
MtmAdjustSubtransactions(ts);
656-
MtmWakeUpBackend(ts);
657-
}
658-
MtmSendNotificationMessage(ts);
659-
}
660-
break;
618+
Assert (MtmIsCoordinator(ts));
619+
switch (msg->code) {
661620
caseMSG_PREPARED:
662-
Assert(ts->status==TRANSACTION_STATUS_IN_PROGRESS);
663-
Assert(ts->nVotes<ds->nNodes);
664-
if (msg->csn>ts->csn) {
665-
ts->csn=msg->csn;
666-
MtmSyncClock(ts->csn);
667-
}
668-
if (++ts->nVotes==ds->nNodes) {
669-
/* ts->csn is maximum of CSNs at all nodes */
670-
ts->nVotes=1;/* I voted myself */
671-
ts->cmd=MSG_COMMIT;
672-
ts->csn=MtmAssignCSN();
673-
ts->status=TRANSACTION_STATUS_UNKNOWN;
674-
MtmAdjustSubtransactions(ts);
675-
MtmSendNotificationMessage(ts);
676-
}
677-
break;
678-
caseMSG_COMMITTED:
679-
Assert(ts->status==TRANSACTION_STATUS_UNKNOWN);
680-
Assert(ts->nVotes<ds->nNodes);
681-
if (++ts->nVotes==ds->nNodes) {
682-
/* All nodes have the same CSN */
683-
MtmWakeUpBackend(ts);
621+
if (ts->status==TRANSACTION_STATUS_IN_PROGRESS) {
622+
if (msg->csn>ts->csn) {
623+
ts->csn=msg->csn;
624+
MtmSyncClock(ts->csn);
625+
}
626+
if (++ts->nVotes==ds->nNodes) {
627+
MtmWakeUpBackend(ts);
628+
}
684629
}
685630
break;
686631
caseMSG_ABORTED:
687-
Assert(ts->status==TRANSACTION_STATUS_ABORTED||ts->status==TRANSACTION_STATUS_IN_PROGRESS);
688-
Assert(ts->nVotes<ds->nNodes);
689-
ts->status=TRANSACTION_STATUS_ABORTED;
690-
if (++ts->nVotes==ds->nNodes) {
691-
ts->cmd=MSG_ABORT;
692-
MtmAdjustSubtransactions(ts);
693-
MtmSendNotificationMessage(ts);
694-
MtmWakeUpBackend(ts);
695-
}
696-
break;
697-
default:
698-
Assert(false);
699-
}
700-
}else {/* replica */
701-
switch (msg->code) {
702-
caseMSG_PREPARE:
703-
Assert(ts->status==TRANSACTION_STATUS_IN_PROGRESS);
704-
if ((msg->disabledNodeMask& ~ds->disabledNodeMask)!=0) {
705-
/* Coordinator's disabled mask is wider than my: so reject such transaction to avoid
706-
commit on smaller subset of nodes */
632+
if (ts->status==TRANSACTION_STATUS_IN_PROGRESS) {
707633
ts->status=TRANSACTION_STATUS_ABORTED;
708-
ts->cmd=MSG_ABORT;
709-
MtmAdjustSubtransactions(ts);
710-
MtmWakeUpBackend(ts);
711-
}else {
712-
ts->status=TRANSACTION_STATUS_UNKNOWN;
713-
ts->csn=MtmAssignCSN();
714-
ts->cmd=MSG_PREPARED;
715-
}
716-
MtmSendNotificationMessage(ts);
717-
break;
718-
caseMSG_COMMIT:
719-
Assert(ts->status==TRANSACTION_STATUS_UNKNOWN);
720-
Assert(ts->csn<msg->csn);
721-
ts->csn=msg->csn;
722-
MtmSyncClock(ts->csn);
723-
ts->cmd=MSG_COMMITTED;
724-
MtmAdjustSubtransactions(ts);
725-
MtmSendNotificationMessage(ts);
726-
MtmWakeUpBackend(ts);
727-
break;
728-
caseMSG_ABORT:
729-
if (ts->status!=TRANSACTION_STATUS_ABORTED) {
730-
Assert(ts->status==TRANSACTION_STATUS_UNKNOWN||ts->status==TRANSACTION_STATUS_IN_PROGRESS);
731-
ts->status=TRANSACTION_STATUS_ABORTED;
732634
MtmAdjustSubtransactions(ts);
733635
MtmWakeUpBackend(ts);
734636
}
735637
break;
736638
default:
737639
Assert(false);
738640
}
739-
}
641+
}
740642
}
741643
MtmUnlock();
742644

‎multimaster.c

Lines changed: 33 additions & 31 deletions
Original file line numberDiff line numberDiff line change
@@ -64,7 +64,6 @@ typedef struct {
6464
boolisReplicated;/* transaction on replica */
6565
boolisDistributed;/* transaction performed INSERT/UPDATE/DELETE and has to be replicated to other nodes */
6666
boolcontainsDML;/* transaction contains DML statements */
67-
boolisPrepared;/* transaction is prepared as part of 2PC */
6867
csn_tsnapshot;/* transaction snaphsot */
6968
}MtmCurrentTrans;
7069

@@ -100,8 +99,8 @@ static void MtmSetTransactionStatus(TransactionId xid, int nsubxids, Transaction
10099
staticvoidMtmInitialize(void);
101100
staticvoidMtmXactCallback(XactEventevent,void*arg);
102101
staticvoidMtmBeginTransaction(MtmCurrentTrans*x);
103-
staticvoidMtmPrecommitTransaction(MtmCurrentTrans*x);
104102
staticboolMtmCommitTransaction(TransactionIdxid,intnsubxids,TransactionId*subxids);
103+
staticvoidMtmPrePrepareTransaction(MtmCurrentTrans*x);
105104
staticvoidMtmPrepareTransaction(MtmCurrentTrans*x);
106105
staticvoidMtmCommitPreparedTransaction(MtmCurrentTrans*x);
107106
staticvoidMtmEndTransaction(MtmCurrentTrans*x,boolcommit);
@@ -347,15 +346,6 @@ bool MtmXidInMVCCSnapshot(TransactionId xid, Snapshot snapshot)
347346
returnPgXidInMVCCSnapshot(xid,snapshot);
348347
}
349348

350-
staticuint32MtmXidHashFunc(constvoid*key,Sizekeysize)
351-
{
352-
return (uint32)*(TransactionId*)key;
353-
}
354-
355-
staticintMtmXidMatchFunc(constvoid*key1,constvoid*key2,Sizekeysize)
356-
{
357-
return*(TransactionId*)key1-*(TransactionId*)key2;
358-
}
359349

360350
staticvoidMtmTransactionListAppend(MtmTransState*ts)
361351
{
@@ -489,8 +479,8 @@ MtmXactCallback(XactEvent event, void *arg)
489479
caseXACT_EVENT_START:
490480
MtmBeginTransaction(&dtmTx);
491481
break;
492-
caseXACT_EVENT_PRE_COMMIT:
493-
MtmPrecommitTransaction(&dtmTx);
482+
caseXACT_EVENT_PRE_PREPARE:
483+
MtmPrePrepareTransaction(&dtmTx);
494484
break;
495485
caseXACT_EVENT_PREPARE:
496486
MtmPrepareTransaction(&dtmTx);
@@ -598,16 +588,14 @@ MtmCheckClusterLock()
598588
}
599589

600590
/*
601-
* This functions is called as pre-commit callback.
602-
* We need to pass snapshot to WAL-sender, so create record in transaction status hash table
603-
* before commit
591+
* Prepare transaction for two-phase commit
604592
*/
605-
staticvoidMtmPrecommitTransaction(MtmCurrentTrans*x)
593+
MtmPrePrepareTransaction(MtmCurrentTrans*x)
606594
{
607595
MtmTransState*ts;
608596
inti;
609597

610-
if (!x->isDistributed||x->isPrepared) {
598+
if (!x->isDistributed) {
611599
return;
612600
}
613601

@@ -632,7 +620,6 @@ static void MtmPrecommitTransaction(MtmCurrentTrans* x)
632620
ts->snapshot=x->isReplicated|| !x->containsDML ?INVALID_CSN :x->snapshot;
633621
ts->csn=MtmAssignCSN();
634622
ts->gtid=x->gtid;
635-
ts->cmd=MSG_INVALID;
636623
ts->procno=MyProc->pgprocno;
637624
ts->nVotes=0;
638625
ts->voteCompleted= false;
@@ -644,24 +631,41 @@ static void MtmPrecommitTransaction(MtmCurrentTrans* x)
644631
ts->gtid.xid=x->xid;
645632
ts->gtid.node=MtmNodeId;
646633
}
647-
for (i=0;i<MtmNodes;i++) {
648-
ts->xids[i]=InvalidTransactionId;
649-
}
650634
MtmTransactionListAppend(ts);
651635

652636
MtmUnlock();
653637

654638
MTM_TRACE("%d: MtmPrepareTransaction prepare commit of %d CSN=%ld\n",MyProcPid,x->xid,ts->csn);
655639
}
656640

657-
staticvoid
658641
MtmPrepareTransaction(MtmCurrentTrans*x)
659-
{
660-
MtmPrecommitTransaction(x);
661-
MTM_TRACE("Prepare transaction %d",x->xid);
662-
x->isPrepared= true;
642+
{
643+
MtmLock(LW_EXCLUSIVE);
644+
if (ts->status=TRANSACTION_STATUS_IN_PROGRESS) {
645+
ts->status=TRANSACTION_STATUS_UNKNOWN;
646+
MtmAdjustSubtransactions(ts);
647+
}
648+
649+
if (!MtmIsCoordinator(ts)) {
650+
MtmSendNotificationMessage(ts);/* send notification to coordinator */
651+
MtmUnlock();
652+
}else {
653+
/* wait N commits or just one ABORT */
654+
ts->nVotes+=1;
655+
while (ts->nVotes!=dtm->nNodes&&ts->status==TRANSACTION_STATUS_PROGRESS) {
656+
MtmUnlock();
657+
WaitLatch(&MyProc->procLatch,WL_LATCH_SET,-1);
658+
ResetLatch(&MyProc->procLatch);
659+
MtmLock(LW_SHARED);
660+
}
661+
MtmUnlock();
662+
if (ts->status==TRANSACTION_STATUS_ABORTED) {
663+
elog(ERROR,"Distributed transaction %d is rejected by DTM",x->xid);
664+
}
665+
}
663666
}
664667

668+
665669
staticvoid
666670
MtmCommitPreparedTransaction(MtmCurrentTrans*x)
667671
{
@@ -1679,14 +1683,12 @@ HTAB* MtmCreateHash(void)
16791683
Assert(MtmNodes>0);
16801684
memset(&info,0,sizeof(info));
16811685
info.keysize=sizeof(TransactionId);
1682-
info.entrysize=sizeof(MtmTransState)+ (MtmNodes-1)*sizeof(TransactionId);
1683-
info.hash=MtmXidHashFunc;
1684-
info.match=MtmXidMatchFunc;
1686+
info.entrysize=sizeof(MtmTransState);
16851687
htab=ShmemInitHash(
16861688
"xid2state",
16871689
MTM_HASH_SIZE,MTM_HASH_SIZE,
16881690
&info,
1689-
HASH_ELEM |HASH_FUNCTION |HASH_COMPARE
1691+
HASH_ELEM
16901692
);
16911693
returnhtab;
16921694
}

‎multimaster.h

Lines changed: 2 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -19,6 +19,7 @@
1919
#defineMULTIMASTER_SLOT_PATTERN "mtm_slot_%d"
2020
#defineMULTIMASTER_MIN_PROTO_VERSION 1
2121
#defineMULTIMASTER_MAX_PROTO_VERSION 1
22+
#defineMULTIMASTER_MAX_GID 32
2223

2324
#defineUSEC 1000000
2425

@@ -51,12 +52,7 @@ typedef enum
5152
{
5253
MSG_INVALID,
5354
MSG_HANDSHAKE,
54-
MSG_READY,
55-
MSG_PREPARE,
56-
MSG_COMMIT,
57-
MSG_ABORT,
5855
MSG_PREPARED,
59-
MSG_COMMITTED,
6056
MSG_ABORTED,
6157
MSG_STATUS
6258
}MtmMessageCode;
@@ -88,11 +84,10 @@ typedef struct MtmTransState
8884
finally should be nNodes-1 */
8985
intprocno;/* pgprocno of transaction coordinator waiting for responses from replicas,
9086
used to notify coordinator by arbiter */
91-
MtmMessageCodecmd;/*Notification message codetobe sent */
87+
boolvoteCompleted;/*Responses necessarytomake a decision are received by coordinator of transaction */
9288
intnSubxids;/* Number of subtransanctions */
9389
structMtmTransState*nextVoting;/* Next element in L1-list of voting transactions. */
9490
structMtmTransState*next;/* Next element in L1 list of all finished transaction present in xid2state hash */
95-
boolvoteCompleted;/* Responses necessary to make a decision are received by coordinator of transaction */
9691
TransactionIdxids[1];/* transaction ID at replicas: varying size MtmNodes */
9792
}MtmTransState;
9893

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