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Remove volatile qualifiers from proc.c and procarray.c 

Prior to commit 0709b7ee72, access to
variables within a spinlock-protected critical section had to be done
through a volatile pointer, but that should no longer be necessary.

Michael Paquier
This commit is contained in:
Robert Haas 2015-10-16 14:20:36 -04:00
parent 430008b5a7
commit d53e3d5fe0
2 changed files with 19 additions and 36 deletions
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20
src/backend/storage/ipc/procarray.c
View File

@ -3718,8 +3718,6 @@ static int
KnownAssignedXidsGetAndSetXmin(TransactionId *xarray, TransactionId *xmin,
TransactionId xmax)
{
/* use volatile pointer to prevent code rearrangement */
volatile ProcArrayStruct *pArray = procArray;
int count = 0;
int head,
tail;
@ -3734,10 +3732,10 @@ KnownAssignedXidsGetAndSetXmin(TransactionId *xarray, TransactionId *xmin,
*
* Must take spinlock to ensure we see up-to-date array contents.
*/
SpinLockAcquire(&pArray->known_assigned_xids_lck);
tail = pArray->tailKnownAssignedXids;
head = pArray->headKnownAssignedXids;
SpinLockRelease(&pArray->known_assigned_xids_lck);
SpinLockAcquire(&procArray->known_assigned_xids_lck);
tail = procArray->tailKnownAssignedXids;
head = procArray->headKnownAssignedXids;
SpinLockRelease(&procArray->known_assigned_xids_lck);
for (i = tail; i < head; i++)
{
@ -3777,8 +3775,6 @@ KnownAssignedXidsGetAndSetXmin(TransactionId *xarray, TransactionId *xmin,
static TransactionId
KnownAssignedXidsGetOldestXmin(void)
{
/* use volatile pointer to prevent code rearrangement */
volatile ProcArrayStruct *pArray = procArray;
int head,
tail;
int i;
@ -3786,10 +3782,10 @@ KnownAssignedXidsGetOldestXmin(void)
/*
* Fetch head just once, since it may change while we loop.
*/
SpinLockAcquire(&pArray->known_assigned_xids_lck);
tail = pArray->tailKnownAssignedXids;
head = pArray->headKnownAssignedXids;
SpinLockRelease(&pArray->known_assigned_xids_lck);
SpinLockAcquire(&procArray->known_assigned_xids_lck);
tail = procArray->tailKnownAssignedXids;
head = procArray->headKnownAssignedXids;
SpinLockRelease(&procArray->known_assigned_xids_lck);
for (i = tail; i < head; i++)
{

35
src/backend/storage/lmgr/proc.c
View File

@ -283,15 +283,13 @@ InitProcGlobal(void)
void
InitProcess(void)
{
/* use volatile pointer to prevent code rearrangement */
volatile PROC_HDR *procglobal = ProcGlobal;
PGPROC * volatile * procgloballist;
/*
* ProcGlobal should be set up already (if we are a backend, we inherit
* this by fork() or EXEC_BACKEND mechanism from the postmaster).
*/
if (procglobal == NULL)
if (ProcGlobal == NULL)
elog(PANIC, "proc header uninitialized");
if (MyProc != NULL)
@ -299,11 +297,11 @@ InitProcess(void)
/* Decide which list should supply our PGPROC. */
if (IsAnyAutoVacuumProcess())
procgloballist = &procglobal->autovacFreeProcs;
procgloballist = &ProcGlobal->autovacFreeProcs;
else if (IsBackgroundWorker)
procgloballist = &procglobal->bgworkerFreeProcs;
procgloballist = &ProcGlobal->bgworkerFreeProcs;
else
procgloballist = &procglobal->freeProcs;
procgloballist = &ProcGlobal->freeProcs;
/*
* Try to get a proc struct from the appropriate free list. If this
@ -314,7 +312,7 @@ InitProcess(void)
*/
SpinLockAcquire(ProcStructLock);
set_spins_per_delay(procglobal->spins_per_delay);
set_spins_per_delay(ProcGlobal->spins_per_delay);
MyProc = *procgloballist;
@ -578,13 +576,10 @@ InitAuxiliaryProcess(void)
void
PublishStartupProcessInformation(void)
{
/* use volatile pointer to prevent code rearrangement */
volatile PROC_HDR *procglobal = ProcGlobal;
SpinLockAcquire(ProcStructLock);
procglobal->startupProc = MyProc;
procglobal->startupProcPid = MyProcPid;
ProcGlobal->startupProc = MyProc;
ProcGlobal->startupProcPid = MyProcPid;
SpinLockRelease(ProcStructLock);
}
@ -627,12 +622,9 @@ HaveNFreeProcs(int n)
{
PGPROC *proc;
/* use volatile pointer to prevent code rearrangement */
volatile PROC_HDR *procglobal = ProcGlobal;
SpinLockAcquire(ProcStructLock);
proc = procglobal->freeProcs;
proc = ProcGlobal->freeProcs;
while (n > 0 && proc != NULL)
{
@ -772,8 +764,6 @@ RemoveProcFromArray(int code, Datum arg)
static void
ProcKill(int code, Datum arg)
{
/* use volatile pointer to prevent code rearrangement */
volatile PROC_HDR *procglobal = ProcGlobal;
PGPROC *proc;
PGPROC * volatile * procgloballist;
@ -822,7 +812,7 @@ ProcKill(int code, Datum arg)
*procgloballist = proc;
/* Update shared estimate of spins_per_delay */
procglobal->spins_per_delay = update_spins_per_delay(procglobal->spins_per_delay);
ProcGlobal->spins_per_delay = update_spins_per_delay(ProcGlobal->spins_per_delay);
SpinLockRelease(ProcStructLock);
@ -1644,9 +1634,6 @@ ProcSendSignal(int pid)
if (RecoveryInProgress())
{
/* use volatile pointer to prevent code rearrangement */
volatile PROC_HDR *procglobal = ProcGlobal;
SpinLockAcquire(ProcStructLock);
/*
@ -1657,8 +1644,8 @@ ProcSendSignal(int pid)
* backend, so BackendPidGetProc() will not return any pid at all. So
* we remember the information for this special case.
*/
if (pid == procglobal->startupProcPid)
proc = procglobal->startupProc;
if (pid == ProcGlobal->startupProcPid)
proc = ProcGlobal->startupProc;
SpinLockRelease(ProcStructLock);
}