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pgstat: move transactional code into pgstat_xact.c.
The transactional integration code is largely independent from the rest of pgstat.c. Subsequent commits will add more related code. Author: Andres Freund <andres@anarazel.de> Reviewed-By: Thomas Munro <thomas.munro@gmail.com> Discussion: https://postgr.es/m/20220404041516.cctrvpadhuriawlq@alap3.anarazel.de
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-163
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5 files changed

+189
-163
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‎src/backend/postmaster/pgstat.c‎

Lines changed: 30 additions & 154 deletions
Original file line numberDiff line numberDiff line change
@@ -198,8 +198,6 @@ static time_t last_pgstat_start_time;
198198

199199
static bool pgStatRunningInCollector = false;
200200

201-
static PgStat_SubXactStatus *pgStatXactStack = NULL;
202-
203201
/*
204202
* Info about current "snapshot" of stats file
205203
*/
@@ -740,158 +738,6 @@ pgstat_initialize(void)
740738
}
741739

742740

743-
/* ------------------------------------------------------------
744-
* Transaction integration
745-
* ------------------------------------------------------------
746-
*/
747-
748-
/*
749-
* Called from access/transam/xact.c at top-level transaction commit/abort.
750-
*/
751-
void
752-
AtEOXact_PgStat(bool isCommit, bool parallel)
753-
{
754-
PgStat_SubXactStatus *xact_state;
755-
756-
AtEOXact_PgStat_Database(isCommit, parallel);
757-
758-
/* handle transactional stats information */
759-
xact_state = pgStatXactStack;
760-
if (xact_state != NULL)
761-
{
762-
Assert(xact_state->nest_level == 1);
763-
Assert(xact_state->prev == NULL);
764-
765-
AtEOXact_PgStat_Relations(xact_state, isCommit);
766-
}
767-
pgStatXactStack = NULL;
768-
769-
/* Make sure any stats snapshot is thrown away */
770-
pgstat_clear_snapshot();
771-
}
772-
773-
/*
774-
* Called from access/transam/xact.c at subtransaction commit/abort.
775-
*/
776-
void
777-
AtEOSubXact_PgStat(bool isCommit, int nestDepth)
778-
{
779-
PgStat_SubXactStatus *xact_state;
780-
781-
/* merge the sub-transaction's transactional stats into the parent */
782-
xact_state = pgStatXactStack;
783-
if (xact_state != NULL &&
784-
xact_state->nest_level >= nestDepth)
785-
{
786-
/* delink xact_state from stack immediately to simplify reuse case */
787-
pgStatXactStack = xact_state->prev;
788-
789-
AtEOSubXact_PgStat_Relations(xact_state, isCommit, nestDepth);
790-
791-
pfree(xact_state);
792-
}
793-
}
794-
795-
/*
796-
* Save the transactional stats state at 2PC transaction prepare.
797-
*/
798-
void
799-
AtPrepare_PgStat(void)
800-
{
801-
PgStat_SubXactStatus *xact_state;
802-
803-
xact_state = pgStatXactStack;
804-
if (xact_state != NULL)
805-
{
806-
Assert(xact_state->nest_level == 1);
807-
Assert(xact_state->prev == NULL);
808-
809-
AtPrepare_PgStat_Relations(xact_state);
810-
}
811-
}
812-
813-
/*
814-
* Clean up after successful PREPARE.
815-
*
816-
* Note: AtEOXact_PgStat is not called during PREPARE.
817-
*/
818-
void
819-
PostPrepare_PgStat(void)
820-
{
821-
PgStat_SubXactStatus *xact_state;
822-
823-
/*
824-
* We don't bother to free any of the transactional state, since it's all
825-
* in TopTransactionContext and will go away anyway.
826-
*/
827-
xact_state = pgStatXactStack;
828-
if (xact_state != NULL)
829-
{
830-
Assert(xact_state->nest_level == 1);
831-
Assert(xact_state->prev == NULL);
832-
833-
PostPrepare_PgStat_Relations(xact_state);
834-
}
835-
pgStatXactStack = NULL;
836-
837-
/* Make sure any stats snapshot is thrown away */
838-
pgstat_clear_snapshot();
839-
}
840-
841-
/*
842-
* Discard any data collected in the current transaction. Any subsequent
843-
* request will cause new snapshots to be read.
844-
*
845-
* This is also invoked during transaction commit or abort to discard
846-
* the no-longer-wanted snapshot.
847-
*/
848-
void
849-
pgstat_clear_snapshot(void)
850-
{
851-
pgstat_assert_is_up();
852-
853-
/* Release memory, if any was allocated */
854-
if (pgStatLocalContext)
855-
MemoryContextDelete(pgStatLocalContext);
856-
857-
/* Reset variables */
858-
pgStatLocalContext = NULL;
859-
pgStatDBHash = NULL;
860-
replSlotStatHash = NULL;
861-
subscriptionStatHash = NULL;
862-
863-
/*
864-
* Historically the backend_status.c facilities lived in this file, and
865-
* were reset with the same function. For now keep it that way, and
866-
* forward the reset request.
867-
*/
868-
pgstat_clear_backend_activity_snapshot();
869-
}
870-
871-
/*
872-
* Ensure (sub)transaction stack entry for the given nest_level exists, adding
873-
* it if needed.
874-
*/
875-
PgStat_SubXactStatus *
876-
pgstat_xact_stack_level_get(int nest_level)
877-
{
878-
PgStat_SubXactStatus *xact_state;
879-
880-
xact_state = pgStatXactStack;
881-
if (xact_state == NULL || xact_state->nest_level != nest_level)
882-
{
883-
xact_state = (PgStat_SubXactStatus *)
884-
MemoryContextAlloc(TopTransactionContext,
885-
sizeof(PgStat_SubXactStatus));
886-
xact_state->nest_level = nest_level;
887-
xact_state->prev = pgStatXactStack;
888-
xact_state->first = NULL;
889-
pgStatXactStack = xact_state;
890-
}
891-
return xact_state;
892-
}
893-
894-
895741
/* ------------------------------------------------------------
896742
* Public functions used by backends follow
897743
* ------------------------------------------------------------
@@ -1319,6 +1165,36 @@ pgstat_send_inquiry(TimestampTz clock_time, TimestampTz cutoff_time, Oid databas
13191165
pgstat_send(&msg, sizeof(msg));
13201166
}
13211167

1168+
/*
1169+
* Discard any data collected in the current transaction. Any subsequent
1170+
* request will cause new snapshots to be read.
1171+
*
1172+
* This is also invoked during transaction commit or abort to discard
1173+
* the no-longer-wanted snapshot.
1174+
*/
1175+
void
1176+
pgstat_clear_snapshot(void)
1177+
{
1178+
pgstat_assert_is_up();
1179+
1180+
/* Release memory, if any was allocated */
1181+
if (pgStatLocalContext)
1182+
MemoryContextDelete(pgStatLocalContext);
1183+
1184+
/* Reset variables */
1185+
pgStatLocalContext = NULL;
1186+
pgStatDBHash = NULL;
1187+
replSlotStatHash = NULL;
1188+
subscriptionStatHash = NULL;
1189+
1190+
/*
1191+
* Historically the backend_status.c facilities lived in this file, and
1192+
* were reset with the same function. For now keep it that way, and
1193+
* forward the reset request.
1194+
*/
1195+
pgstat_clear_backend_activity_snapshot();
1196+
}
1197+
13221198
/*
13231199
* Support function for the SQL-callable pgstat* functions. Returns
13241200
* the collected statistics for one database or NULL. NULL doesn't mean

‎src/backend/utils/activity/Makefile‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -23,9 +23,10 @@ OBJS = \
2323
pgstat_function.o \
2424
pgstat_relation.o \
2525
pgstat_replslot.o \
26+
pgstat_slru.o \
2627
pgstat_subscription.o \
2728
pgstat_wal.o \
28-
pgstat_slru.o \
29+
pgstat_xact.o \
2930
wait_event.o
3031

3132
include $(top_srcdir)/src/backend/common.mk

‎src/backend/utils/activity/pgstat_xact.c‎

Lines changed: 139 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,139 @@
1+
/* -------------------------------------------------------------------------
2+
*
3+
* pgstat_xact.c
4+
* Transactional integration for the cumulative statistics system.
5+
*
6+
* Copyright (c) 2001-2022, PostgreSQL Global Development Group
7+
*
8+
* IDENTIFICATION
9+
* src/backend/utils/activity/pgstat_xact.c
10+
* -------------------------------------------------------------------------
11+
*/
12+
13+
#include "postgres.h"
14+
15+
#include "access/transam.h"
16+
#include "access/xact.h"
17+
#include "pgstat.h"
18+
#include "utils/memutils.h"
19+
#include "utils/pgstat_internal.h"
20+
21+
22+
static PgStat_SubXactStatus *pgStatXactStack = NULL;
23+
24+
25+
/*
26+
* Called from access/transam/xact.c at top-level transaction commit/abort.
27+
*/
28+
void
29+
AtEOXact_PgStat(bool isCommit, bool parallel)
30+
{
31+
PgStat_SubXactStatus *xact_state;
32+
33+
AtEOXact_PgStat_Database(isCommit, parallel);
34+
35+
/* handle transactional stats information */
36+
xact_state = pgStatXactStack;
37+
if (xact_state != NULL)
38+
{
39+
Assert(xact_state->nest_level == 1);
40+
Assert(xact_state->prev == NULL);
41+
42+
AtEOXact_PgStat_Relations(xact_state, isCommit);
43+
}
44+
pgStatXactStack = NULL;
45+
46+
/* Make sure any stats snapshot is thrown away */
47+
pgstat_clear_snapshot();
48+
}
49+
50+
/*
51+
* Called from access/transam/xact.c at subtransaction commit/abort.
52+
*/
53+
void
54+
AtEOSubXact_PgStat(bool isCommit, int nestDepth)
55+
{
56+
PgStat_SubXactStatus *xact_state;
57+
58+
/* merge the sub-transaction's transactional stats into the parent */
59+
xact_state = pgStatXactStack;
60+
if (xact_state != NULL &&
61+
xact_state->nest_level >= nestDepth)
62+
{
63+
/* delink xact_state from stack immediately to simplify reuse case */
64+
pgStatXactStack = xact_state->prev;
65+
66+
AtEOSubXact_PgStat_Relations(xact_state, isCommit, nestDepth);
67+
68+
pfree(xact_state);
69+
}
70+
}
71+
72+
/*
73+
* Save the transactional stats state at 2PC transaction prepare.
74+
*/
75+
void
76+
AtPrepare_PgStat(void)
77+
{
78+
PgStat_SubXactStatus *xact_state;
79+
80+
xact_state = pgStatXactStack;
81+
if (xact_state != NULL)
82+
{
83+
Assert(xact_state->nest_level == 1);
84+
Assert(xact_state->prev == NULL);
85+
86+
AtPrepare_PgStat_Relations(xact_state);
87+
}
88+
}
89+
90+
/*
91+
* Clean up after successful PREPARE.
92+
*
93+
* Note: AtEOXact_PgStat is not called during PREPARE.
94+
*/
95+
void
96+
PostPrepare_PgStat(void)
97+
{
98+
PgStat_SubXactStatus *xact_state;
99+
100+
/*
101+
* We don't bother to free any of the transactional state, since it's all
102+
* in TopTransactionContext and will go away anyway.
103+
*/
104+
xact_state = pgStatXactStack;
105+
if (xact_state != NULL)
106+
{
107+
Assert(xact_state->nest_level == 1);
108+
Assert(xact_state->prev == NULL);
109+
110+
PostPrepare_PgStat_Relations(xact_state);
111+
}
112+
pgStatXactStack = NULL;
113+
114+
/* Make sure any stats snapshot is thrown away */
115+
pgstat_clear_snapshot();
116+
}
117+
118+
/*
119+
* Ensure (sub)transaction stack entry for the given nest_level exists, adding
120+
* it if needed.
121+
*/
122+
PgStat_SubXactStatus *
123+
pgstat_xact_stack_level_get(int nest_level)
124+
{
125+
PgStat_SubXactStatus *xact_state;
126+
127+
xact_state = pgStatXactStack;
128+
if (xact_state == NULL || xact_state->nest_level != nest_level)
129+
{
130+
xact_state = (PgStat_SubXactStatus *)
131+
MemoryContextAlloc(TopTransactionContext,
132+
sizeof(PgStat_SubXactStatus));
133+
xact_state->nest_level = nest_level;
134+
xact_state->prev = pgStatXactStack;
135+
xact_state->first = NULL;
136+
pgStatXactStack = xact_state;
137+
}
138+
return xact_state;
139+
}

‎src/include/pgstat.h‎

Lines changed: 11 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -969,13 +969,6 @@ extern void PgstatCollectorMain(int argc, char *argv[]) pg_attribute_noreturn();
969969
/* Functions for backend initialization */
970970
extern void pgstat_initialize(void);
971971

972-
/* transactional integration */
973-
extern void AtEOXact_PgStat(bool isCommit, bool parallel);
974-
extern void AtEOSubXact_PgStat(bool isCommit, int nestDepth);
975-
extern void AtPrepare_PgStat(void);
976-
extern void PostPrepare_PgStat(void);
977-
extern void pgstat_clear_snapshot(void);
978-
979972
/* Functions called from backends */
980973
extern void pgstat_report_stat(bool force);
981974
extern void pgstat_vacuum_stat(void);
@@ -986,6 +979,7 @@ extern void pgstat_reset_single_counter(Oid objectid, PgStat_Single_Reset_Type t
986979
extern void pgstat_reset_shared_counters(const char *);
987980

988981
/* stats accessors */
982+
extern void pgstat_clear_snapshot(void);
989983
extern PgStat_ArchiverStats *pgstat_fetch_stat_archiver(void);
990984
extern PgStat_BgWriterStats *pgstat_fetch_stat_bgwriter(void);
991985
extern PgStat_CheckpointerStats *pgstat_fetch_stat_checkpointer(void);
@@ -1157,6 +1151,16 @@ extern void pgstat_report_subscription_error(Oid subid, bool is_apply_error);
11571151
extern void pgstat_report_subscription_drop(Oid subid);
11581152

11591153

1154+
/*
1155+
* Functions in pgstat_xact.c
1156+
*/
1157+
1158+
extern void AtEOXact_PgStat(bool isCommit, bool parallel);
1159+
extern void AtEOSubXact_PgStat(bool isCommit, int nestDepth);
1160+
extern void AtPrepare_PgStat(void);
1161+
extern void PostPrepare_PgStat(void);
1162+
1163+
11601164
/*
11611165
* Functions in pgstat_wal.c
11621166
*/

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