Rename ShmemVariableCache to TransamVariables

The old name was misleading: It's not a cache, the values kept in the
struct are the authoritative source.

Reviewed-by: Tristan Partin, Richard Guo
Discussion: https://www.postgresql.org/message-id/6537d63d-4bb5-46f8-9b5d-73a8ba4720ab@iki.fi

contrib/amcheck/verify_heapam.c

@@ -81,12 +81,12 @@ typedef struct ToastedAttribute
 typedef struct HeapCheckContext
 {
 	/*
-	 * Cached copies of values from ShmemVariableCache and computed values
-	 * from them.
+	 * Cached copies of values from TransamVariables and computed values from
+	 * them.
 	 */
-	FullTransactionId next_fxid;	/* ShmemVariableCache->nextXid */
+	FullTransactionId next_fxid;	/* TransamVariables->nextXid */
 	TransactionId next_xid;		/* 32-bit version of next_fxid */
-	TransactionId oldest_xid;	/* ShmemVariableCache->oldestXid */
+	TransactionId oldest_xid;	/* TransamVariables->oldestXid */
 	FullTransactionId oldest_fxid;	/* 64-bit version of oldest_xid, computed
 									 * relative to next_fxid */
 	TransactionId safe_xmin;	/* this XID and newer ones can't become
@@ -1924,8 +1924,8 @@ update_cached_xid_range(HeapCheckContext *ctx)
 {
 	/* Make cached copies */
 	LWLockAcquire(XidGenLock, LW_SHARED);
-	ctx->next_fxid = ShmemVariableCache->nextXid;
-	ctx->oldest_xid = ShmemVariableCache->oldestXid;
+	ctx->next_fxid = TransamVariables->nextXid;
+	ctx->oldest_xid = TransamVariables->oldestXid;
 	LWLockRelease(XidGenLock);
 
 	/* And compute alternate versions of the same */
@@ -2062,7 +2062,7 @@ get_xid_status(TransactionId xid, HeapCheckContext *ctx,
 	*status = XID_COMMITTED;
 	LWLockAcquire(XactTruncationLock, LW_SHARED);
 	clog_horizon =
-		FullTransactionIdFromXidAndCtx(ShmemVariableCache->oldestClogXid,
+		FullTransactionIdFromXidAndCtx(TransamVariables->oldestClogXid,
 									   ctx);
 	if (FullTransactionIdPrecedesOrEquals(clog_horizon, fxid))
 	{

src/backend/access/transam/clog.c

@@ -758,12 +758,12 @@ ZeroCLOGPage(int64 pageno, bool writeXlog)
 
 /*
  * This must be called ONCE during postmaster or standalone-backend startup,
- * after StartupXLOG has initialized ShmemVariableCache->nextXid.
+ * after StartupXLOG has initialized TransamVariables->nextXid.
  */
 void
 StartupCLOG(void)
 {
-	TransactionId xid = XidFromFullTransactionId(ShmemVariableCache->nextXid);
+	TransactionId xid = XidFromFullTransactionId(TransamVariables->nextXid);
 	int64		pageno = TransactionIdToPage(xid);
 
 	LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);
@@ -782,7 +782,7 @@ StartupCLOG(void)
 void
 TrimCLOG(void)
 {
-	TransactionId xid = XidFromFullTransactionId(ShmemVariableCache->nextXid);
+	TransactionId xid = XidFromFullTransactionId(TransamVariables->nextXid);
 	int64		pageno = TransactionIdToPage(xid);
 
 	LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);

src/backend/access/transam/commit_ts.c

@@ -211,8 +211,8 @@ TransactionTreeSetCommitTsData(TransactionId xid, int nsubxids,
 	commitTsShared->dataLastCommit.nodeid = nodeid;
 
 	/* and move forwards our endpoint, if needed */
-	if (TransactionIdPrecedes(ShmemVariableCache->newestCommitTsXid, newestXact))
-		ShmemVariableCache->newestCommitTsXid = newestXact;
+	if (TransactionIdPrecedes(TransamVariables->newestCommitTsXid, newestXact))
+		TransamVariables->newestCommitTsXid = newestXact;
 	LWLockRelease(CommitTsLock);
 }
 
@@ -315,8 +315,8 @@ TransactionIdGetCommitTsData(TransactionId xid, TimestampTz *ts,
 		return *ts != 0;
 	}
 
-	oldestCommitTsXid = ShmemVariableCache->oldestCommitTsXid;
-	newestCommitTsXid = ShmemVariableCache->newestCommitTsXid;
+	oldestCommitTsXid = TransamVariables->oldestCommitTsXid;
+	newestCommitTsXid = TransamVariables->newestCommitTsXid;
 	/* neither is invalid, or both are */
 	Assert(TransactionIdIsValid(oldestCommitTsXid) == TransactionIdIsValid(newestCommitTsXid));
 	LWLockRelease(CommitTsLock);
@@ -593,7 +593,7 @@ ZeroCommitTsPage(int64 pageno, bool writeXlog)
 
 /*
  * This must be called ONCE during postmaster or standalone-backend startup,
- * after StartupXLOG has initialized ShmemVariableCache->nextXid.
+ * after StartupXLOG has initialized TransamVariables->nextXid.
  */
 void
 StartupCommitTs(void)
@@ -683,7 +683,7 @@ ActivateCommitTs(void)
 	}
 	LWLockRelease(CommitTsLock);
 
-	xid = XidFromFullTransactionId(ShmemVariableCache->nextXid);
+	xid = XidFromFullTransactionId(TransamVariables->nextXid);
 	pageno = TransactionIdToCTsPage(xid);
 
 	/*
@@ -707,10 +707,10 @@ ActivateCommitTs(void)
 	 * Invalid temporarily.
 	 */
 	LWLockAcquire(CommitTsLock, LW_EXCLUSIVE);
-	if (ShmemVariableCache->oldestCommitTsXid == InvalidTransactionId)
+	if (TransamVariables->oldestCommitTsXid == InvalidTransactionId)
 	{
-		ShmemVariableCache->oldestCommitTsXid =
-			ShmemVariableCache->newestCommitTsXid = ReadNextTransactionId();
+		TransamVariables->oldestCommitTsXid =
+			TransamVariables->newestCommitTsXid = ReadNextTransactionId();
 	}
 	LWLockRelease(CommitTsLock);
 
@@ -759,8 +759,8 @@ DeactivateCommitTs(void)
 	TIMESTAMP_NOBEGIN(commitTsShared->dataLastCommit.time);
 	commitTsShared->dataLastCommit.nodeid = InvalidRepOriginId;
 
-	ShmemVariableCache->oldestCommitTsXid = InvalidTransactionId;
-	ShmemVariableCache->newestCommitTsXid = InvalidTransactionId;
+	TransamVariables->oldestCommitTsXid = InvalidTransactionId;
+	TransamVariables->newestCommitTsXid = InvalidTransactionId;
 
 	LWLockRelease(CommitTsLock);
 
@@ -874,18 +874,18 @@ SetCommitTsLimit(TransactionId oldestXact, TransactionId newestXact)
 	 * "future" or signal a disabled committs.
 	 */
 	LWLockAcquire(CommitTsLock, LW_EXCLUSIVE);
-	if (ShmemVariableCache->oldestCommitTsXid != InvalidTransactionId)
+	if (TransamVariables->oldestCommitTsXid != InvalidTransactionId)
 	{
-		if (TransactionIdPrecedes(ShmemVariableCache->oldestCommitTsXid, oldestXact))
-			ShmemVariableCache->oldestCommitTsXid = oldestXact;
-		if (TransactionIdPrecedes(newestXact, ShmemVariableCache->newestCommitTsXid))
-			ShmemVariableCache->newestCommitTsXid = newestXact;
+		if (TransactionIdPrecedes(TransamVariables->oldestCommitTsXid, oldestXact))
+			TransamVariables->oldestCommitTsXid = oldestXact;
+		if (TransactionIdPrecedes(newestXact, TransamVariables->newestCommitTsXid))
+			TransamVariables->newestCommitTsXid = newestXact;
 	}
 	else
 	{
-		Assert(ShmemVariableCache->newestCommitTsXid == InvalidTransactionId);
-		ShmemVariableCache->oldestCommitTsXid = oldestXact;
-		ShmemVariableCache->newestCommitTsXid = newestXact;
+		Assert(TransamVariables->newestCommitTsXid == InvalidTransactionId);
+		TransamVariables->oldestCommitTsXid = oldestXact;
+		TransamVariables->newestCommitTsXid = newestXact;
 	}
 	LWLockRelease(CommitTsLock);
 }
@@ -897,9 +897,9 @@ void
 AdvanceOldestCommitTsXid(TransactionId oldestXact)
 {
 	LWLockAcquire(CommitTsLock, LW_EXCLUSIVE);
-	if (ShmemVariableCache->oldestCommitTsXid != InvalidTransactionId &&
-		TransactionIdPrecedes(ShmemVariableCache->oldestCommitTsXid, oldestXact))
-		ShmemVariableCache->oldestCommitTsXid = oldestXact;
+	if (TransamVariables->oldestCommitTsXid != InvalidTransactionId &&
+		TransactionIdPrecedes(TransamVariables->oldestCommitTsXid, oldestXact))
+		TransamVariables->oldestCommitTsXid = oldestXact;
 	LWLockRelease(CommitTsLock);
 }
 

src/backend/access/transam/subtrans.c

@@ -250,7 +250,7 @@ ZeroSUBTRANSPage(int64 pageno)
 
 /*
  * This must be called ONCE during postmaster or standalone-backend startup,
- * after StartupXLOG has initialized ShmemVariableCache->nextXid.
+ * after StartupXLOG has initialized TransamVariables->nextXid.
  *
  * oldestActiveXID is the oldest XID of any prepared transaction, or nextXid
  * if there are none.
@@ -271,7 +271,7 @@ StartupSUBTRANS(TransactionId oldestActiveXID)
 	LWLockAcquire(SubtransSLRULock, LW_EXCLUSIVE);
 
 	startPage = TransactionIdToPage(oldestActiveXID);
-	nextXid = ShmemVariableCache->nextXid;
+	nextXid = TransamVariables->nextXid;
 	endPage = TransactionIdToPage(XidFromFullTransactionId(nextXid));
 
 	while (startPage != endPage)

src/backend/access/transam/twophase.c

@@ -958,7 +958,7 @@ AdjustToFullTransactionId(TransactionId xid)
 	Assert(TransactionIdIsValid(xid));
 
 	LWLockAcquire(XidGenLock, LW_SHARED);
-	nextFullXid = ShmemVariableCache->nextXid;
+	nextFullXid = TransamVariables->nextXid;
 	LWLockRelease(XidGenLock);
 
 	nextXid = XidFromFullTransactionId(nextFullXid);
@@ -1948,7 +1948,7 @@ restoreTwoPhaseData(void)
  *
  * Scan the shared memory entries of TwoPhaseState and determine the range
  * of valid XIDs present.  This is run during database startup, after we
- * have completed reading WAL.  ShmemVariableCache->nextXid has been set to
+ * have completed reading WAL.  TransamVariables->nextXid has been set to
  * one more than the highest XID for which evidence exists in WAL.
  *
  * We throw away any prepared xacts with main XID beyond nextXid --- if any
@@ -1967,7 +1967,7 @@ restoreTwoPhaseData(void)
  * backup should be rolled in.
  *
  * Our other responsibility is to determine and return the oldest valid XID
- * among the prepared xacts (if none, return ShmemVariableCache->nextXid).
+ * among the prepared xacts (if none, return TransamVariables->nextXid).
  * This is needed to synchronize pg_subtrans startup properly.
  *
  * If xids_p and nxids_p are not NULL, pointer to a palloc'd array of all
@@ -1977,7 +1977,7 @@ restoreTwoPhaseData(void)
 TransactionId
 PrescanPreparedTransactions(TransactionId **xids_p, int *nxids_p)
 {
-	FullTransactionId nextXid = ShmemVariableCache->nextXid;
+	FullTransactionId nextXid = TransamVariables->nextXid;
 	TransactionId origNextXid = XidFromFullTransactionId(nextXid);
 	TransactionId result = origNextXid;
 	TransactionId *xids = NULL;
@@ -2196,7 +2196,7 @@ RecoverPreparedTransactions(void)
  *
  * If setParent is true, set up subtransaction parent linkages.
  *
- * If setNextXid is true, set ShmemVariableCache->nextXid to the newest
+ * If setNextXid is true, set TransamVariables->nextXid to the newest
  * value scanned.
  */
 static char *
@@ -2205,7 +2205,7 @@ ProcessTwoPhaseBuffer(TransactionId xid,
 					  bool fromdisk,
 					  bool setParent, bool setNextXid)
 {
-	FullTransactionId nextXid = ShmemVariableCache->nextXid;
+	FullTransactionId nextXid = TransamVariables->nextXid;
 	TransactionId origNextXid = XidFromFullTransactionId(nextXid);
 	TransactionId *subxids;
 	char	   *buf;