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knizhnikknizhnik
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reduce in-doubt stage in MMTS
1 parent 23dc2ff commit e22f28e

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5 files changed

+68
-40
lines changed

5 files changed

+68
-40
lines changed

‎contrib/mmts/arbiter.c

Lines changed: 63 additions & 31 deletions
Original file line numberDiff line numberDiff line change
@@ -76,11 +76,20 @@
7676
#define MAX_ROUTES 16
7777
#define BUFFER_SIZE 1024
7878

79+
typedef enum
80+
{
81+
MSG_PREPARE,
82+
MSG_COMMIT,
83+
MSG_ABORT
84+
} MessageCode;
85+
86+
7987
typedef struct
8088
{
89+
MessageCode code; /* Message code: MSG_PREPARE, MSG_COMMIT, MSG_ABORT
90+
int node; /* Sender node ID */
8191
TransactionId dxid; /* Transaction ID at destination node */
8292
TransactionId sxid; /* Transaction IO at sender node */
83-
int node; /* Sender node ID */
8493
csn_t csn; /* local CSN in case of sending data from replica to master, global CSN master->replica */
8594
} DtmCommitMessage;
8695

@@ -100,15 +109,15 @@ static BackgroundWorker DtmSender = {
100109
"mm-sender",
101110
BGWORKER_SHMEM_ACCESS | BGWORKER_BACKEND_DATABASE_CONNECTION, /* do not need connection to the database */
102111
BgWorkerStart_ConsistentState,
103-
1, /* restrart in one second (is it possible to restort immediately?) */
112+
1, /* restart in one second (is it possible to restart immediately?) */
104113
DtmTransSender
105114
};
106115

107116
static BackgroundWorker DtmRecevier = {
108117
"mm-receiver",
109118
BGWORKER_SHMEM_ACCESS | BGWORKER_BACKEND_DATABASE_CONNECTION, /* do not need connection to the database */
110119
BgWorkerStart_ConsistentState,
111-
1, /* restrart in one second (is it possible to restort immediately?) */
120+
1, /* restart in one second (is it possible to restart immediately?) */
112121
DtmTransReceiver
113122
};
114123

@@ -300,6 +309,25 @@ static int readSocket(int sd, void* buf, int buf_size)
300309
return rc;
301310
}
302311

312+
static bool IsCoordinator(DtmTransState* ts)
313+
{
314+
return ts->dsid.node == MMNodeId;
315+
}
316+
317+
static void DtmAppendBuffer(MessageCode code, DtmBuffer* txBuffer, TransactionId xid, int node, DtmTransState* ts)
318+
{
319+
DtmBuffer* buf = &txBuffer[node];
320+
if (buf->used == BUFFER_SIZE) {
321+
writeSocket(sockets[node], buf->data, buf->used*sizeof(DtmCommitMessage));
322+
buf->used = 0;
323+
}
324+
buf->data[buf->used].code = code;
325+
buf->data[buf->used].dxid = xid;
326+
buf->data[buf->used].sxid = ts->xid;
327+
buf->data[buf->used].csn = ts->status == TRANSACTION_STATUS_ABORTED ? INVALID_CSN : ts->csn;
328+
buf->data[buf->used].node = MMNodeId;
329+
buf->used += 1;
330+
}
303331

304332
static void DtmTransSender(Datum arg)
305333
{
@@ -327,38 +355,18 @@ static void DtmTransSender(Datum arg)
327355
SpinLockRelease(&ds->votingSpinlock);
328356

329357
for (; ts != NULL; ts = ts->nextVoting) {
330-
if (ts->gtid.node == MMNodeId) {
331-
/* Coordinator is broadcasting confirmations to replicas */
358+
if (IsCoordinator(ts)) {
359+
/* Coordinator is broadcasting PREPARE message to replicas */
332360
for (i = 0; i < nNodes; i++) {
333361
if (TransactionIdIsValid(ts->xids[i])) {
334-
if (txBuffer[i].used == BUFFER_SIZE) {
335-
writeSocket(sockets[i], txBuffer[i].data, txBuffer[i].used*sizeof(DtmCommitMessage));
336-
txBuffer[i].used = 0;
337-
}
338-
DTM_TRACE("Send notification %ld to replica %d from coordinator %d for transaction %d (local transaction %d)\n",
339-
ts->csn, i+1, MMNodeId, ts->xid, ts->xids[i]);
340-
341-
txBuffer[i].data[txBuffer[i].used].dxid = ts->xids[i];
342-
txBuffer[i].data[txBuffer[i].used].sxid = ts->xid;
343-
txBuffer[i].data[txBuffer[i].used].csn = ts->csn;
344-
txBuffer[i].data[txBuffer[i].used].node = MMNodeId;
345-
txBuffer[i].used += 1;
362+
DtmAppendBuffer(CMD_PREPARE, txBuffer, ts->xids[i], i, ts);
346363
}
347364
}
348365
} else {
349-
/* Replica is notifying master */
350-
i = ts->gtid.node-1;
351-
if (txBuffer[i].used == BUFFER_SIZE) {
352-
writeSocket(sockets[i], txBuffer[i].data, txBuffer[i].used*sizeof(DtmCommitMessage));
353-
txBuffer[i].used = 0;
354-
}
366+
/* Replica is notifying master that it is ready to PREPARE */
355367
DTM_TRACE("Send notification %ld to coordinator %d from node %d for transaction %d (local transaction %d)\n",
356368
ts->csn, ts->gtid.node, MMNodeId, ts->gtid.xid, ts->xid);
357-
txBuffer[i].data[txBuffer[i].used].dxid = ts->gtid.xid;
358-
txBuffer[i].data[txBuffer[i].used].sxid = ts->xid;
359-
txBuffer[i].data[txBuffer[i].used].node = MMNodeId;
360-
txBuffer[i].data[txBuffer[i].used].csn = ts->csn;
361-
txBuffer[i].used += 1;
369+
DtmAppendBuffer(CMD_PREPARE, txBuffer, ts->gtid.xid, ts->gtid.node-1, ts);
362370
}
363371
}
364372
for (i = 0; i < nNodes; i++) {
@@ -431,9 +439,33 @@ static void DtmTransReceiver(Datum arg)
431439
DtmCommitMessage* msg = &rxBuffer[i].data[j];
432440
DtmTransState* ts = (DtmTransState*)hash_search(xid2state, &msg->dxid, HASH_FIND, NULL);
433441
Assert(ts != NULL);
434-
if (msg->csn > ts->csn) {
435-
ts->csn = msg->csn;
436-
}
442+
switch (msg->code) {
443+
case CMD_PREPARE:
444+
if (IsCoordinator(ts)) {
445+
switch (msg->command) {
446+
case CMD_PREPARE:
447+
448+
if (ts->state == TRANSACTION_STATUS_IN_PROGRESS:
449+
/* transaction is in-prepared stage (in-doubt): calculate max CSN */
450+
if (msg->csn > ts->csn) {
451+
ts->csn = msg->csn;
452+
}
453+
Assert(ts->nVotes < dtm->nNodes);
454+
if (++ts->nVotes == dtm->nNodes) { /* receive responses from all nodes */
455+
ts->status = TRANSACTION_STATUS_COMMIT;
456+
457+
if (ts->state == TRANSACTION_STATUS_UNKNOWN) {
458+
/* All nodes are ready to prepare: switch transaction to in-doubt state */
459+
ts->csn = dtm_get_csn();
460+
ts->status = TRANSACTION_STATUS_IN_PROGRESS;
461+
/* and broadcast PREPARE message */
462+
MMSendNotificationMessage(ts);
463+
} else if (ts->state == CMD_ABORT) {
464+
ts->status = TRANSACTION_STATUS_ABORTED;
465+
466+
} else {
467+
Assert(ts->state == TRANSACTION_STATUS_IN_PROGRESS);
468+
437469
Assert((unsigned)(msg->node-1) <= (unsigned)nNodes);
438470
ts->xids[msg->node-1] = msg->sxid;
439471
DTM_TRACE("Receive response %ld for transaction %d votes %d from node %d (transaction %d)\n",

‎contrib/mmts/multimaster.c

Lines changed: 4 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -342,15 +342,13 @@ DtmAdjustOldestXid(TransactionId xid)
342342
ts = (DtmTransState*)hash_search(xid2state, &xid, HASH_FIND, NULL);
343343
if (ts != NULL) {
344344
timestamp_t cutoff_time = ts->csn - DtmVacuumDelay*USEC;
345-
#if 0
346345
for (ts = dtm->transListHead; ts != NULL && ts->csn < cutoff_time; prev = ts, ts = ts->next) {
347346
Assert(ts->status == TRANSACTION_STATUS_COMMITTED || ts->status == TRANSACTION_STATUS_ABORTED);
348347
if (prev != NULL) {
349348
/* Remove information about too old transactions */
350349
hash_search(xid2state, &prev->xid, HASH_REMOVE, NULL);
351350
}
352351
}
353-
#endif
354352
}
355353
if (prev != NULL) {
356354
dtm->transListHead = prev;
@@ -477,8 +475,7 @@ DtmEndTransaction(DtmCurrentTrans* x)
477475
x->gtid.xid = InvalidTransactionId;
478476
}
479477

480-
static void
481-
SendNotificationMessage(DtmTransState* ts)
478+
void MMSendNotificationMessage(DtmTransState* ts)
482479
{
483480
DtmTransState* votingList;
484481

@@ -551,7 +548,7 @@ DtmFinishTransaction(TransactionId xid, int nsubxids, TransactionId *subxids, Xi
551548
ts->status = status;
552549
}
553550
if (dtmTx.isReplicated) {
554-
SendNotificationMessage(ts);
551+
MMSendNotificationMessage(ts);
555552
}
556553
}
557554
LWLockRelease(dtm->hashLock);
@@ -1026,11 +1023,11 @@ MMVoteForTransaction(DtmTransState* ts)
10261023
Assert(ts->nVotes == dtm->nNodes);
10271024

10281025
/* ... and then send notifications to replicas */
1029-
SendNotificationMessage(ts);
1026+
MMSendNotificationMessage(ts);
10301027
} else {
10311028
/* I am replica: first notify coordinator... */
10321029
ts->nVotes = dtm->nNodes-1; /* I just need one confirmation from coordinator */
1033-
SendNotificationMessage(ts);
1030+
MMSendNotificationMessage(ts);
10341031
/* ... and wait response from it */
10351032
DTM_TRACE("Node %d waiting latch...\n", MMNodeId);
10361033
WaitLatch(&MyProc->procLatch, WL_LATCH_SET, -1);

‎contrib/mmts/multimaster.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -73,6 +73,7 @@ extern void MMReceiverStarted(void);
7373
extern void MMExecute(void* work, int size);
7474
extern void MMExecutor(int id, void* work, size_t size);
7575
extern HTAB* MMCreateHash(void);
76+
extern void MMSendNotificationMessage(DtmTransState* ts);
7677
extern DtmState* MMGetState(void);
7778

7879
#endif

‎contrib/mmts/tests/dtmbench

26.3 KB
Binary file not shown.

‎contrib/mmts/tests/dtmbench.cpp

Lines changed: 0 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -179,7 +179,6 @@ void* writer(void* arg)
179179
void initializeDatabase()
180180
{
181181
connection conn(cfg.connections[0]);
182-
#if 0
183182
printf("creating extension\n");
184183
{
185184
nontransaction txn(conn);
@@ -197,7 +196,6 @@ void initializeDatabase()
197196
txn.commit();
198197
}
199198
printf("table t created\n");
200-
#endif
201199
printf("inserting stuff into t\n");
202200
{
203201
work txn(conn);

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