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Use dlists instead of SHM_QUEUE for syncrep queue

Browse Source 
Part of a series to remove SHM_QUEUE. ilist.h style lists are more widely used
and have an easier to use interface.

Reviewed-by: Thomas Munro <thomas.munro@gmail.com> (in an older version)
Discussion: https://postgr.es/m/20221120055930.t6kl3tyivzhlrzu2@awork3.anarazel.de
Discussion: https://postgr.es/m/20200211042229.msv23badgqljrdg2@alap3.anarazel.de
This commit is contained in:
Andres Freund
2023-01-18 12:15:05 -08:00
parent 5764f611e1
commit 12605414a7
5 changed files with 41 additions and 57 deletions
Download Patch File Download Diff File Expand all files Collapse all files

89
src/backend/replication/syncrep.c
View File

@@ -182,7 +182,7 @@ SyncRepWaitForLSN(XLogRecPtr lsn, bool commit)
else
mode = Min(SyncRepWaitMode, SYNC_REP_WAIT_FLUSH);
Assert(SHMQueueIsDetached(&(MyProc->syncRepLinks)));
Assert(dlist_node_is_detached(&MyProc->syncRepLinks));
Assert(WalSndCtl != NULL);
LWLockAcquire(SyncRepLock, LW_EXCLUSIVE);
@@ -318,7 +318,7 @@ SyncRepWaitForLSN(XLogRecPtr lsn, bool commit)
* assertions, but better safe than sorry).
*/
pg_read_barrier();
Assert(SHMQueueIsDetached(&(MyProc->syncRepLinks)));
Assert(dlist_node_is_detached(&MyProc->syncRepLinks));
MyProc->syncRepState = SYNC_REP_NOT_WAITING;
MyProc->waitLSN = 0;
@@ -339,31 +339,32 @@ SyncRepWaitForLSN(XLogRecPtr lsn, bool commit)
static void
SyncRepQueueInsert(int mode)
{
PGPROC *proc;
dlist_head *queue;
dlist_iter iter;
Assert(mode >= 0 && mode < NUM_SYNC_REP_WAIT_MODE);
proc = (PGPROC *) SHMQueuePrev(&(WalSndCtl->SyncRepQueue[mode]),
&(WalSndCtl->SyncRepQueue[mode]),
offsetof(PGPROC, syncRepLinks));
queue = &WalSndCtl->SyncRepQueue[mode];
while (proc)
dlist_reverse_foreach(iter, queue)
{
PGPROC *proc = dlist_container(PGPROC, syncRepLinks, iter.cur);
/*
* Stop at the queue element that we should after to ensure the queue
* is ordered by LSN.
* Stop at the queue element that we should insert after to ensure the
* queue is ordered by LSN.
*/
if (proc->waitLSN < MyProc->waitLSN)
break;
proc = (PGPROC *) SHMQueuePrev(&(WalSndCtl->SyncRepQueue[mode]),
&(proc->syncRepLinks),
offsetof(PGPROC, syncRepLinks));
{
dlist_insert_after(&proc->syncRepLinks, &MyProc->syncRepLinks);
return;
}
}
if (proc)
SHMQueueInsertAfter(&(proc->syncRepLinks), &(MyProc->syncRepLinks));
else
SHMQueueInsertAfter(&(WalSndCtl->SyncRepQueue[mode]), &(MyProc->syncRepLinks));
/*
* If we get here, the list was either empty, or this process needs to be
* at the head.
*/
dlist_push_head(queue, &MyProc->syncRepLinks);
}
/*
@@ -373,8 +374,8 @@ static void
SyncRepCancelWait(void)
{
LWLockAcquire(SyncRepLock, LW_EXCLUSIVE);
if (!SHMQueueIsDetached(&(MyProc->syncRepLinks)))
SHMQueueDelete(&(MyProc->syncRepLinks));
if (!dlist_node_is_detached(&MyProc->syncRepLinks))
dlist_delete_thoroughly(&MyProc->syncRepLinks);
MyProc->syncRepState = SYNC_REP_NOT_WAITING;
LWLockRelease(SyncRepLock);
}
@@ -386,13 +387,13 @@ SyncRepCleanupAtProcExit(void)
* First check if we are removed from the queue without the lock to not
* slow down backend exit.
*/
if (!SHMQueueIsDetached(&(MyProc->syncRepLinks)))
if (!dlist_node_is_detached(&MyProc->syncRepLinks))
{
LWLockAcquire(SyncRepLock, LW_EXCLUSIVE);
/* maybe we have just been removed, so recheck */
if (!SHMQueueIsDetached(&(MyProc->syncRepLinks)))
SHMQueueDelete(&(MyProc->syncRepLinks));
if (!dlist_node_is_detached(&MyProc->syncRepLinks))
dlist_delete_thoroughly(&MyProc->syncRepLinks);
LWLockRelease(SyncRepLock);
}
@@ -879,20 +880,17 @@ static int
SyncRepWakeQueue(bool all, int mode)
{
volatile WalSndCtlData *walsndctl = WalSndCtl;
PGPROC *proc = NULL;
PGPROC *thisproc = NULL;
int numprocs = 0;
dlist_mutable_iter iter;
Assert(mode >= 0 && mode < NUM_SYNC_REP_WAIT_MODE);
Assert(LWLockHeldByMeInMode(SyncRepLock, LW_EXCLUSIVE));
Assert(SyncRepQueueIsOrderedByLSN(mode));
proc = (PGPROC *) SHMQueueNext(&(WalSndCtl->SyncRepQueue[mode]),
&(WalSndCtl->SyncRepQueue[mode]),
offsetof(PGPROC, syncRepLinks));
while (proc)
dlist_foreach_modify(iter, &WalSndCtl->SyncRepQueue[mode])
{
PGPROC *proc = dlist_container(PGPROC, syncRepLinks, iter.cur);
/*
* Assume the queue is ordered by LSN
*/
@@ -900,18 +898,9 @@ SyncRepWakeQueue(bool all, int mode)
return numprocs;
/*
* Move to next proc, so we can delete thisproc from the queue.
* thisproc is valid, proc may be NULL after this.
* Remove from queue.
*/
thisproc = proc;
proc = (PGPROC *) SHMQueueNext(&(WalSndCtl->SyncRepQueue[mode]),
&(proc->syncRepLinks),
offsetof(PGPROC, syncRepLinks));
/*
* Remove thisproc from queue.
*/
SHMQueueDelete(&(thisproc->syncRepLinks));
dlist_delete_thoroughly(&proc->syncRepLinks);
/*
* SyncRepWaitForLSN() reads syncRepState without holding the lock, so
@@ -924,12 +913,12 @@ SyncRepWakeQueue(bool all, int mode)
* Set state to complete; see SyncRepWaitForLSN() for discussion of
* the various states.
*/
thisproc->syncRepState = SYNC_REP_WAIT_COMPLETE;
proc->syncRepState = SYNC_REP_WAIT_COMPLETE;
/*
* Wake only when we have set state and removed from queue.
*/
SetLatch(&(thisproc->procLatch));
SetLatch(&(proc->procLatch));
numprocs++;
}
@@ -983,19 +972,17 @@ SyncRepUpdateSyncStandbysDefined(void)
static bool
SyncRepQueueIsOrderedByLSN(int mode)
{
PGPROC *proc = NULL;
XLogRecPtr lastLSN;
dlist_iter iter;
Assert(mode >= 0 && mode < NUM_SYNC_REP_WAIT_MODE);
lastLSN = 0;
proc = (PGPROC *) SHMQueueNext(&(WalSndCtl->SyncRepQueue[mode]),
&(WalSndCtl->SyncRepQueue[mode]),
offsetof(PGPROC, syncRepLinks));
while (proc)
dlist_foreach(iter, &WalSndCtl->SyncRepQueue[mode])
{
PGPROC *proc = dlist_container(PGPROC, syncRepLinks, iter.cur);
/*
* Check the queue is ordered by LSN and that multiple procs don't
* have matching LSNs
@@ -1004,10 +991,6 @@ SyncRepQueueIsOrderedByLSN(int mode)
return false;
lastLSN = proc->waitLSN;
proc = (PGPROC *) SHMQueueNext(&(WalSndCtl->SyncRepQueue[mode]),
&(proc->syncRepLinks),
offsetof(PGPROC, syncRepLinks));
}
return true;

2
src/backend/replication/walsender.c
View File

@@ -3275,7 +3275,7 @@ WalSndShmemInit(void)
MemSet(WalSndCtl, 0, WalSndShmemSize());
for (i = 0; i < NUM_SYNC_REP_WAIT_MODE; i++)
SHMQueueInit(&(WalSndCtl->SyncRepQueue[i]));
dlist_init(&(WalSndCtl->SyncRepQueue[i]));
for (i = 0; i < max_wal_senders; i++)
{

2
src/backend/storage/lmgr/proc.c
View File

@@ -410,7 +410,7 @@ InitProcess(void)
/* Initialize fields for sync rep */
MyProc->waitLSN = 0;
MyProc->syncRepState = SYNC_REP_NOT_WAITING;
SHMQueueElemInit(&(MyProc->syncRepLinks));
dlist_node_init(&MyProc->syncRepLinks);
/* Initialize fields for group XID clearing. */
MyProc->procArrayGroupMember = false;