database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-10-27 00:12:01 +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

18
src/include/storage/lock.h
View File

@@ -19,9 +19,9 @@
#endif
#include "lib/ilist.h"
#include "storage/backendid.h"
#include "storage/lockdefs.h"
#include "storage/lwlock.h"
#include "storage/procnumber.h"
#include "storage/shmem.h"
#include "utils/timestamp.h"
@@ -42,7 +42,7 @@ extern PGDLLIMPORT bool Debug_deadlocks;
/*
* Top-level transactions are identified by VirtualTransactionIDs comprising
* PGPROC fields backendId and lxid. For recovered prepared transactions, the
* PGPROC fields procNumber and lxid. For recovered prepared transactions, the
* LocalTransactionId is an ordinary XID; LOCKTAG_VIRTUALTRANSACTION never
* refers to that kind. These are guaranteed unique over the short term, but
* will be reused after a database restart or XID wraparound; hence they
@@ -50,7 +50,7 @@ extern PGDLLIMPORT bool Debug_deadlocks;
*
* Note that struct VirtualTransactionId can not be assumed to be atomically
* assignable as a whole. However, type LocalTransactionId is assumed to
* be atomically assignable, and the backend ID doesn't change often enough
* be atomically assignable, and the proc number doesn't change often enough
* to be a problem, so we can fetch or assign the two fields separately.
* We deliberately refrain from using the struct within PGPROC, to prevent
* coding errors from trying to use struct assignment with it; instead use
@@ -58,7 +58,7 @@ extern PGDLLIMPORT bool Debug_deadlocks;
*/
typedef struct
{
BackendId backendId; /* backendId from PGPROC */
ProcNumber procNumber; /* proc number of the PGPROC */
LocalTransactionId localTransactionId; /* lxid from PGPROC */
} VirtualTransactionId;
@@ -67,15 +67,15 @@ typedef struct
#define VirtualTransactionIdIsValid(vxid) \
(LocalTransactionIdIsValid((vxid).localTransactionId))
#define VirtualTransactionIdIsRecoveredPreparedXact(vxid) \
((vxid).backendId == InvalidBackendId)
((vxid).procNumber == INVALID_PROC_NUMBER)
#define VirtualTransactionIdEquals(vxid1, vxid2) \
((vxid1).backendId == (vxid2).backendId && \
((vxid1).procNumber == (vxid2).procNumber && \
(vxid1).localTransactionId == (vxid2).localTransactionId)
#define SetInvalidVirtualTransactionId(vxid) \
((vxid).backendId = InvalidBackendId, \
((vxid).procNumber = INVALID_PROC_NUMBER, \
(vxid).localTransactionId = InvalidLocalTransactionId)
#define GET_VXID_FROM_PGPROC(vxid_dst, proc) \
((vxid_dst).backendId = (proc).vxid.backendId, \
((vxid_dst).procNumber = (proc).vxid.procNumber, \
(vxid_dst).localTransactionId = (proc).vxid.lxid)
/* MAX_LOCKMODES cannot be larger than the # of bits in LOCKMASK */
@@ -233,7 +233,7 @@ typedef struct LOCKTAG
/* ID info for a virtual transaction is its VirtualTransactionId */
#define SET_LOCKTAG_VIRTUALTRANSACTION(locktag,vxid) \
((locktag).locktag_field1 = (vxid).backendId, \
((locktag).locktag_field1 = (vxid).procNumber, \
(locktag).locktag_field2 = (vxid).localTransactionId, \
(locktag).locktag_field3 = 0, \
(locktag).locktag_field4 = 0, \