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Replace BackendIds with 0-based ProcNumbers

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Now that BackendId was just another index into the proc array, it was
redundant with the 0-based proc numbers used in other places. Replace
all usage of backend IDs with proc numbers.

The only place where the term "backend id" remains is in a few pgstat
functions that expose backend IDs at the SQL level. Those IDs are now
in fact 0-based ProcNumbers too, but the documentation still calls
them "backend ids". That term still seems appropriate to describe what
the numbers are, so I let it be.

One user-visible effect is that pg_temp_0 is now a valid temp schema
name, for backend with ProcNumber 0.

Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/8171f1aa-496f-46a6-afc3-c46fe7a9b407@iki.fi
This commit is contained in:
Heikki Linnakangas
2024-03-03 19:38:22 +02:00
parent ab355e3a88
commit 024c521117
71 changed files with 571 additions and 579 deletions
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18
src/backend/access/transam/clog.c
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@@ -501,7 +501,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
* still work, just less efficiently -- we handle this case by
* switching to a different bank lock in the loop below.
*/
if (nextidx != INVALID_PGPROCNO &&
if (nextidx != INVALID_PROC_NUMBER &&
GetPGProcByNumber(nextidx)->clogGroupMemberPage != proc->clogGroupMemberPage)
{
/*
@@ -509,7 +509,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
* needs an XID status update.
*/
proc->clogGroupMember = false;
pg_atomic_write_u32(&proc->clogGroupNext, INVALID_PGPROCNO);
pg_atomic_write_u32(&proc->clogGroupNext, INVALID_PROC_NUMBER);
return false;
}
@@ -525,9 +525,9 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
* If the list was not empty, the leader will update the status of our
* XID. It is impossible to have followers without a leader because the
* first process that has added itself to the list will always have
* nextidx as INVALID_PGPROCNO.
* nextidx as INVALID_PROC_NUMBER.
*/
if (nextidx != INVALID_PGPROCNO)
if (nextidx != INVALID_PROC_NUMBER)
{
int extraWaits = 0;
@@ -543,7 +543,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
}
pgstat_report_wait_end();
Assert(pg_atomic_read_u32(&proc->clogGroupNext) == INVALID_PGPROCNO);
Assert(pg_atomic_read_u32(&proc->clogGroupNext) == INVALID_PROC_NUMBER);
/* Fix semaphore count for any absorbed wakeups */
while (extraWaits-- > 0)
@@ -568,13 +568,13 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
* group.
*/
nextidx = pg_atomic_exchange_u32(&procglobal->clogGroupFirst,
INVALID_PGPROCNO);
INVALID_PROC_NUMBER);
/* Remember head of list so we can perform wakeups after dropping lock. */
wakeidx = nextidx;
/* Walk the list and update the status of all XIDs. */
while (nextidx != INVALID_PGPROCNO)
while (nextidx != INVALID_PROC_NUMBER)
{
PGPROC *nextproc = &ProcGlobal->allProcs[nextidx];
int thispageno = nextproc->clogGroupMemberPage;
@@ -633,12 +633,12 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
* clogGroupNext to invalid while saving the semaphores to an array, then
* a single write barrier, then another pass unlocking the semaphores.)
*/
while (wakeidx != INVALID_PGPROCNO)
while (wakeidx != INVALID_PROC_NUMBER)
{
PGPROC *wakeproc = &ProcGlobal->allProcs[wakeidx];
wakeidx = pg_atomic_read_u32(&wakeproc->clogGroupNext);
pg_atomic_write_u32(&wakeproc->clogGroupNext, INVALID_PGPROCNO);
pg_atomic_write_u32(&wakeproc->clogGroupNext, INVALID_PROC_NUMBER);
/* ensure all previous writes are visible before follower continues. */
pg_write_barrier();