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pgstat_bgwriter.c
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1 /* -------------------------------------------------------------------------
2  *
3  * pgstat_bgwriter.c
4  * Implementation of bgwriter statistics.
5  *
6  * This file contains the implementation of bgwriter statistics. It is kept
7  * separate from pgstat.c to enforce the line between the statistics access /
8  * storage implementation and the details about individual types of
9  * statistics.
10  *
11  * Copyright (c) 2001-2022, PostgreSQL Global Development Group
12  *
13  * IDENTIFICATION
14  * src/backend/utils/activity/pgstat_bgwriter.c
15  * -------------------------------------------------------------------------
16  */
17 
18 #include "postgres.h"
19 
20 #include "utils/pgstat_internal.h"
21 
22 
24 
25 
26 /*
27  * Report bgwriter statistics
28  */
29 void
31 {
33  static const PgStat_BgWriterStats all_zeroes;
34 
37 
38  /*
39  * This function can be called even if nothing at all has happened. In
40  * this case, avoid unnecessarily modifying the stats entry.
41  */
42  if (memcmp(&PendingBgWriterStats, &all_zeroes, sizeof(all_zeroes)) == 0)
43  return;
44 
46 
47 #define BGWRITER_ACC(fld) stats_shmem->stats.fld += PendingBgWriterStats.fld
48  BGWRITER_ACC(buf_written_clean);
49  BGWRITER_ACC(maxwritten_clean);
50  BGWRITER_ACC(buf_alloc);
51 #undef BGWRITER_ACC
52 
54 
55  /*
56  * Clear out the statistics buffer, so it can be re-used.
57  */
59 }
60 
61 /*
62  * Support function for the SQL-callable pgstat* functions. Returns
63  * a pointer to the bgwriter statistics struct.
64  */
67 {
69 
71 }
72 
73 void
75 {
77 
78  /* see explanation above PgStatShared_BgWriter for the reset protocol */
79  LWLockAcquire(&stats_shmem->lock, LW_EXCLUSIVE);
81  &stats_shmem->stats,
82  sizeof(stats_shmem->stats),
83  &stats_shmem->changecount);
84  stats_shmem->stats.stat_reset_timestamp = ts;
85  LWLockRelease(&stats_shmem->lock);
86 }
87 
88 void
90 {
92  PgStat_BgWriterStats *reset_offset = &stats_shmem->reset_offset;
94 
96  &stats_shmem->stats,
97  sizeof(stats_shmem->stats),
98  &stats_shmem->changecount);
99 
100  LWLockAcquire(&stats_shmem->lock, LW_SHARED);
101  memcpy(&reset, reset_offset, sizeof(stats_shmem->stats));
102  LWLockRelease(&stats_shmem->lock);
103 
104  /* compensate by reset offsets */
105 #define BGWRITER_COMP(fld) pgStatLocal.snapshot.bgwriter.fld -= reset.fld;
106  BGWRITER_COMP(buf_written_clean);
107  BGWRITER_COMP(maxwritten_clean);
108  BGWRITER_COMP(buf_alloc);
109 #undef BGWRITER_COMP
110 }
#define MemSet(start, val, len)
Definition: c.h:1008
int64 TimestampTz
Definition: timestamp.h:39
Assert(fmt[strlen(fmt) - 1] !='\n')
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1196
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1800
@ LW_SHARED
Definition: lwlock.h:105
@ LW_EXCLUSIVE
Definition: lwlock.h:104
void pgstat_snapshot_fixed(PgStat_Kind kind)
Definition: pgstat.c:899
PgStat_LocalState pgStatLocal
Definition: pgstat.c:195
@ PGSTAT_KIND_BGWRITER
Definition: pgstat.h:49
PgStat_BgWriterStats * pgstat_fetch_stat_bgwriter(void)
#define BGWRITER_ACC(fld)
PgStat_BgWriterStats PendingBgWriterStats
void pgstat_bgwriter_reset_all_cb(TimestampTz ts)
#define BGWRITER_COMP(fld)
void pgstat_bgwriter_snapshot_cb(void)
void pgstat_report_bgwriter(void)
static void pgstat_end_changecount_write(uint32 *cc)
#define pgstat_assert_is_up()
static void pgstat_begin_changecount_write(uint32 *cc)
static void pgstat_copy_changecounted_stats(void *dst, void *src, size_t len, uint32 *cc)
void reset(void)
Definition: sql-declare.c:600
PgStat_BgWriterStats reset_offset
PgStat_BgWriterStats stats
TimestampTz stat_reset_timestamp
Definition: pgstat.h:265
PgStat_Snapshot snapshot
PgStat_ShmemControl * shmem
PgStatShared_BgWriter bgwriter
PgStat_BgWriterStats bgwriter