database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-19 13:42:17 +03:00
Code Activity

Replace BackendIds with 0-based ProcNumbers

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

36
src/backend/storage/ipc/procsignal.c
View File

@@ -43,10 +43,10 @@
* observe it only once.)
*
* Each process that wants to receive signals registers its process ID
* in the ProcSignalSlots array. The array is indexed by backend ID to make
* in the ProcSignalSlots array. The array is indexed by ProcNumber to make
* slot allocation simple, and to avoid having to search the array when you
* know the backend ID of the process you're signaling. (We do support
* signaling without backend ID, but it's a bit less efficient.)
* know the ProcNumber of the process you're signaling. (We do support
* signaling without ProcNumber, but it's a bit less efficient.)
*
* The flags are actually declared as "volatile sig_atomic_t" for maximum
* portability. This should ensure that loads and stores of the flag
@@ -83,7 +83,7 @@ typedef struct
} ProcSignalHeader;
/*
* We reserve a slot for each possible BackendId, plus one for each
* We reserve a slot for each possible ProcNumber, plus one for each
* possible auxiliary process type. (This scheme assumes there is not
* more than one of any auxiliary process type at a time.)
*/
@@ -161,16 +161,16 @@ ProcSignalInit(void)
ProcSignalSlot *slot;
uint64 barrier_generation;
if (MyBackendId <= 0)
elog(ERROR, "MyBackendId not set");
if (MyBackendId > NumProcSignalSlots)
elog(ERROR, "unexpected MyBackendId %d in ProcSignalInit (max %d)", MyBackendId, NumProcSignalSlots);
slot = &ProcSignal->psh_slot[MyBackendId - 1];
if (MyProcNumber < 0)
elog(ERROR, "MyProcNumber not set");
if (MyProcNumber >= NumProcSignalSlots)
elog(ERROR, "unexpected MyProcNumber %d in ProcSignalInit (max %d)", MyProcNumber, NumProcSignalSlots);
slot = &ProcSignal->psh_slot[MyProcNumber];
/* sanity check */
if (slot->pss_pid != 0)
elog(LOG, "process %d taking over ProcSignal slot %d, but it's not empty",
MyProcPid, MyBackendId - 1);
MyProcPid, MyProcNumber);
/* Clear out any leftover signal reasons */
MemSet(slot->pss_signalFlags, 0, NUM_PROCSIGNALS * sizeof(sig_atomic_t));
@@ -218,6 +218,7 @@ CleanupProcSignalState(int status, Datum arg)
* won't try to access it after it's no longer ours (and perhaps even
* after we've unmapped the shared memory segment).
*/
Assert(MyProcSignalSlot != NULL);
MyProcSignalSlot = NULL;
/* sanity check */
@@ -246,7 +247,7 @@ CleanupProcSignalState(int status, Datum arg)
* SendProcSignal
* Send a signal to a Postgres process
*
* Providing backendId is optional, but it will speed up the operation.
* Providing procNumber is optional, but it will speed up the operation.
*
* On success (a signal was sent), zero is returned.
* On error, -1 is returned, and errno is set (typically to ESRCH or EPERM).
@@ -254,13 +255,13 @@ CleanupProcSignalState(int status, Datum arg)
* Not to be confused with ProcSendSignal
*/
int
SendProcSignal(pid_t pid, ProcSignalReason reason, BackendId backendId)
SendProcSignal(pid_t pid, ProcSignalReason reason, ProcNumber procNumber)
{
volatile ProcSignalSlot *slot;
if (backendId != InvalidBackendId)
if (procNumber != INVALID_PROC_NUMBER)
{
slot = &ProcSignal->psh_slot[backendId - 1];
slot = &ProcSignal->psh_slot[procNumber];
/*
* Note: Since there's no locking, it's possible that the target
@@ -281,10 +282,11 @@ SendProcSignal(pid_t pid, ProcSignalReason reason, BackendId backendId)
else
{
/*
* BackendId not provided, so search the array using pid. We search
* Pronumber not provided, so search the array using pid. We search
* the array back to front so as to reduce search overhead. Passing
* InvalidBackendId means that the target is most likely an auxiliary
* process, which will have a slot near the end of the array.
* INVALID_PROC_NUMBER means that the target is most likely an
* auxiliary process, which will have a slot near the end of the
* array.
*/
int i;