Volatile-qualify the ProcArray PGPROC pointer in a bunch of routines

that examine fields that could change under them.  This is just to make
really sure that when we are fetching a value 'only once', that's what
actually happens.  Possibly this is a bug that should be back-patched,
but in the absence of solid evidence that it's needed, I won't bother.

diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 577f73a31f199ec70b7c924d8b013c1eae87d784..a467df990e1e6bde2e6eea9daf3aac5183f5aae6 100644 (file)
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -23,7 +23,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.29 2007/09/05 18:10:47 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.30 2007/09/05 21:11:19 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -233,7 +233,7 @@ TransactionIdIsInProgress(TransactionId xid)
 
        for (i = 0; i < arrayP->numProcs; i++)
        {
-               PGPROC     *proc = arrayP->procs[i];
+               volatile PGPROC    *proc = arrayP->procs[i];
 
                /* Fetch xid just once - see GetNewTransactionId */
                TransactionId pxid = proc->xid;
@@ -361,7 +361,7 @@ TransactionIdIsActive(TransactionId xid)
 
        for (i = 0; i < arrayP->numProcs; i++)
        {
-               PGPROC     *proc = arrayP->procs[i];
+               volatile PGPROC    *proc = arrayP->procs[i];
 
                /* Fetch xid just once - see GetNewTransactionId */
                TransactionId pxid = proc->xid;
@@ -434,7 +434,7 @@ GetOldestXmin(bool allDbs, bool ignoreVacuum)
 
        for (index = 0; index < arrayP->numProcs; index++)
        {
-               PGPROC     *proc = arrayP->procs[index];
+               volatile PGPROC    *proc = arrayP->procs[index];
 
                if (ignoreVacuum && proc->inVacuum)
                        continue;
@@ -613,7 +613,7 @@ GetSnapshotData(Snapshot snapshot, bool serializable)
         */
        for (index = 0; index < arrayP->numProcs; index++)
        {
-               PGPROC     *proc = arrayP->procs[index];
+               volatile PGPROC    *proc = arrayP->procs[index];
                TransactionId xid;
 
                /* Ignore procs running LAZY VACUUM */
@@ -672,7 +672,7 @@ GetSnapshotData(Snapshot snapshot, bool serializable)
                                if (nxids > 0)
                                {
                                        memcpy(snapshot->subxip + subcount,
-                                                  proc->subxids.xids,
+                                                  (void *) proc->subxids.xids,
                                                   nxids * sizeof(TransactionId));
                                        subcount += nxids;
                                }
@@ -739,7 +739,7 @@ GetTransactionsInCommit(TransactionId **xids_p)
 
        for (index = 0; index < arrayP->numProcs; index++)
        {
-               PGPROC     *proc = arrayP->procs[index];
+               volatile PGPROC    *proc = arrayP->procs[index];
                /* Fetch xid just once - see GetNewTransactionId */
                TransactionId pxid = proc->xid;
 
@@ -773,7 +773,7 @@ HaveTransactionsInCommit(TransactionId *xids, int nxids)
 
        for (index = 0; index < arrayP->numProcs; index++)
        {
-               PGPROC     *proc = arrayP->procs[index];
+               volatile PGPROC    *proc = arrayP->procs[index];
                /* Fetch xid just once - see GetNewTransactionId */
                TransactionId pxid = proc->xid;
 
@@ -861,7 +861,7 @@ BackendXidGetPid(TransactionId xid)
 
        for (index = 0; index < arrayP->numProcs; index++)
        {
-               PGPROC     *proc = arrayP->procs[index];
+               volatile PGPROC    *proc = arrayP->procs[index];
 
                if (proc->xid == xid)
                {
@@ -909,7 +909,7 @@ GetCurrentVirtualXIDs(TransactionId limitXmin)
 
        for (index = 0; index < arrayP->numProcs; index++)
        {
-               PGPROC     *proc = arrayP->procs[index];
+               volatile PGPROC    *proc = arrayP->procs[index];
                /* Fetch xmin just once - might change on us? */
                TransactionId pxmin = proc->xmin;
 
@@ -963,7 +963,7 @@ CountActiveBackends(void)
         */
        for (index = 0; index < arrayP->numProcs; index++)
        {
-               PGPROC     *proc = arrayP->procs[index];
+               volatile PGPROC    *proc = arrayP->procs[index];
 
                if (proc == MyProc)
                        continue;                       /* do not count myself */
@@ -993,7 +993,7 @@ CountDBBackends(Oid databaseid)
 
        for (index = 0; index < arrayP->numProcs; index++)
        {
-               PGPROC     *proc = arrayP->procs[index];
+               volatile PGPROC    *proc = arrayP->procs[index];
 
                if (proc->pid == 0)
                        continue;                       /* do not count prepared xacts */
@@ -1020,7 +1020,7 @@ CountUserBackends(Oid roleid)
 
        for (index = 0; index < arrayP->numProcs; index++)
        {
-               PGPROC     *proc = arrayP->procs[index];
+               volatile PGPROC    *proc = arrayP->procs[index];
 
                if (proc->pid == 0)
                        continue;                       /* do not count prepared xacts */
@@ -1072,7 +1072,7 @@ CheckOtherDBBackends(Oid databaseId)
 
                for (index = 0; index < arrayP->numProcs; index++)
                {
-                       PGPROC     *proc = arrayP->procs[index];
+                       volatile PGPROC    *proc = arrayP->procs[index];
 
                        if (proc->databaseId != databaseId)
                                continue;