Obtain xmin from GTM

knizhnik · knizhnik · commit 58f9465f2250 · 2015-09-23T18:18:28.000+03:00
diff --git a/contrib/pg_xtm/pg_dtm.c b/contrib/pg_xtm/pg_dtm.c
@@ -68,6 +68,7 @@ static void DtmInitialize(void);
 static void DtmXactCallback(XactEvent event, void *arg);
 static TransactionId DtmGetNextXid(void);
 static TransactionId DtmGetNewTransactionId(bool isSubXact);
+static TransactionId DtmGetOldestXmin(Relation rel, bool ignoreVacuum);
 
 static bool TransactionIdIsInDtmSnapshot(TransactionId xid);
 static bool TransactionIdIsInDoubt(TransactionId xid);
@@ -81,10 +82,11 @@ static Snapshot CurrentTransactionSnapshot;
 
 static TransactionId DtmNextXid;
 static SnapshotData DtmSnapshot = { HeapTupleSatisfiesMVCC };
+static TransactionId DtmMinXid;
 static bool DtmHasGlobalSnapshot;
 static bool DtmIsGlobalTransaction;
 static int DtmLocalXidReserve;
-static TransactionManager DtmTM = { DtmGetTransactionStatus, DtmSetTransactionStatus, DtmGetSnapshot, DtmGetNewTransactionId };
+static TransactionManager DtmTM = { DtmGetTransactionStatus, DtmSetTransactionStatus, DtmGetSnapshot, DtmGetNewTransactionId, DtmGetOldestXmin };
 
 
 #define XTM_TRACE(fmt, ...)
@@ -163,9 +165,14 @@ static void DtmMergeSnapshots(Snapshot dst, Snapshot src)
 	DumpSnapshot(src, "DTM");
 
 	/* Merge two snapshots: produce most restrictive snapshots whihc includes running transactions from both of them */
-    if (src->xmin < dst->xmin) dst->xmin = src->xmin;
+    if (src->xmin < dst->xmin) {
+        dst->xmin = src->xmin;
+        ProcArrayInstallImportedXmin(src->xmin, DtmNextXid);
+        //MyPgXact->xmin = TransactionXmin = src->xmin;
+    }
     if (src->xmax < dst->xmax) dst->xmax = src->xmax;
 
+    
 	n = dst->xcnt;
 	for (xid = dst->xmax; xid <= src->xmin; xid++) {
 		dst->xip[n++] = xid;
@@ -186,9 +193,20 @@ static void DtmMergeSnapshots(Snapshot dst, Snapshot src)
 	DumpSnapshot(dst, "merged");
 }
 
+static TransactionId DtmGetOldestXmin(Relation rel, bool ignoreVacuum)
+{
+    TransactionId xmin = GetOldestLocalXmin(rel, ignoreVacuum);
+#if 0
+    if (TransactionIdIsValid(DtmSnapshot.xmin) && TransactionIdPrecedes(DtmSnapshot.xmin, xmin)) { 
+        xmin = DtmSnapshot.xmin;
+    }
+#endif
+    return xmin;
+}
+
 static void DtmUpdateRecentXmin(void)
 {
-	TransactionId xmin = DtmSnapshot.xmin;
+	TransactionId xmin = DtmMinXid;//DtmSnapshot.xmin;
 
 	XTM_TRACE("XTM: DtmUpdateRecentXmin \n");
 
@@ -462,7 +480,7 @@ static Snapshot DtmGetSnapshot(Snapshot snapshot)
     
 	if (TransactionIdIsValid(DtmNextXid)) {
 		if (!DtmHasGlobalSnapshot) {
-			DtmGlobalGetSnapshot(DtmNextXid, &DtmSnapshot);
+			DtmGlobalGetSnapshot(DtmNextXid, &DtmSnapshot, &DtmMinXid);
 		}
 		DtmMergeSnapshots(snapshot, &DtmSnapshot);
         if (!IsolationUsesXactSnapshot()) {
@@ -675,7 +693,7 @@ dtm_begin_transaction(PG_FUNCTION_ARGS)
 	int nParticipants = PG_GETARG_INT32(0);
 	Assert(!TransactionIdIsValid(DtmNextXid));
 
-	DtmNextXid = DtmGlobalStartTransaction(nParticipants, &DtmSnapshot);
+	DtmNextXid = DtmGlobalStartTransaction(nParticipants, &DtmSnapshot, &DtmMinXid);
 	Assert(TransactionIdIsValid(DtmNextXid));
     XTM_INFO("%d: Start global transaction %d\n", getpid(), DtmNextXid);
 
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
@@ -44,7 +44,7 @@
 #include "miscadmin.h"
 #include "pg_trace.h"
 
-TransactionManager DefaultTM = { CLOGTransactionIdGetStatus, CLOGTransactionIdSetTreeStatus, GetLocalSnapshotData, GetNewLocalTransactionId };
+TransactionManager DefaultTM = { CLOGTransactionIdGetStatus, CLOGTransactionIdSetTreeStatus, GetLocalSnapshotData, GetNewLocalTransactionId, GetOldestLocalXmin };
 TransactionManager* TM = &DefaultTM;
 
 /*
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
@@ -1262,6 +1262,12 @@ TransactionIdIsActive(TransactionId xid)
 }
 
 
+TransactionId
+GetOldestXmin(Relation rel, bool ignoreVacuum)
+{
+    return TM->GetOldestXmin(rel, ignoreVacuum);
+}
+
 /*
  * GetOldestXmin -- returns oldest transaction that was running
  *					when any current transaction was started.
@@ -1311,7 +1317,7 @@ TransactionIdIsActive(TransactionId xid)
  * GetOldestXmin() move backwards, with no consequences for data integrity.
  */
 TransactionId
-GetOldestXmin(Relation rel, bool ignoreVacuum)
+GetOldestLocalXmin(Relation rel, bool ignoreVacuum)
 {
 	ProcArrayStruct *arrayP = procArray;
 	TransactionId result;
diff --git a/src/include/access/xtm.h b/src/include/access/xtm.h
@@ -13,13 +13,15 @@
 
 #include "access/clog.h"
 #include "utils/snapmgr.h"
+#include "utils/relcache.h"
 
 typedef struct
 {
     XidStatus (*GetTransactionStatus)(TransactionId xid, XLogRecPtr *lsn);
     void (*SetTransactionStatus)(TransactionId xid, int nsubxids, TransactionId *subxids, XidStatus status, XLogRecPtr lsn);
     Snapshot (*GetSnapshot)(Snapshot snapshot);
     TransactionId (*GetNewTransactionId)(bool isSubXact);
+    TransactionId (*GetOldestXmin)(Relation rel, bool ignoreVacuum);
 } TransactionManager;
 
 extern TransactionManager* TM;
diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h
@@ -56,6 +56,7 @@ extern bool TransactionIdIsRunning(TransactionId xid);
 extern bool TransactionIdIsInProgress(TransactionId xid);
 extern bool TransactionIdIsActive(TransactionId xid);
 extern TransactionId GetOldestXmin(Relation rel, bool ignoreVacuum);
+extern TransactionId GetOldestLocalXmin(Relation rel, bool ignoreVacuum);
 extern TransactionId GetOldestActiveTransactionId(void);
 extern TransactionId GetOldestSafeDecodingTransactionId(void);
 
