Line data    Source code

       1              : /*-------------------------------------------------------------------------
       2              :  *
       3              :  * xlogstats.c
       4              :  *      Functions for WAL Statistics
       5              :  *
       6              :  * Copyright (c) 2022-2026, PostgreSQL Global Development Group
       7              :  *
       8              :  * IDENTIFICATION
       9              :  *      src/backend/access/transam/xlogstats.c
      10              :  *
      11              :  *-------------------------------------------------------------------------
      12              :  */
      13              : #include "postgres.h"
      14              : 
      15              : #include "access/xlogreader.h"
      16              : #include "access/xlogstats.h"
      17              : 
      18              : /*
      19              :  * Calculate the size of a record, split into !FPI and FPI parts.
      20              :  */
      21              : void
      22           14 : XLogRecGetLen(XLogReaderState *record, uint32 *rec_len,
      23              :               uint32 *fpi_len)
      24              : {
      25              :     int         block_id;
      26              : 
      27              :     /*
      28              :      * Calculate the amount of FPI data in the record.
      29              :      *
      30              :      * XXX: We peek into xlogreader's private decoded backup blocks for the
      31              :      * bimg_len indicating the length of FPI data.
      32              :      */
      33           14 :     *fpi_len = 0;
      34           24 :     for (block_id = 0; block_id <= XLogRecMaxBlockId(record); block_id++)
      35              :     {
      36           10 :         if (!XLogRecHasBlockRef(record, block_id))
      37            0 :             continue;
      38              : 
      39           10 :         if (XLogRecHasBlockImage(record, block_id))
      40            0 :             *fpi_len += XLogRecGetBlock(record, block_id)->bimg_len;
      41              :     }
      42              : 
      43              :     /*
      44              :      * Calculate the length of the record as the total length - the length of
      45              :      * all the block images.
      46              :      */
      47           14 :     *rec_len = XLogRecGetTotalLen(record) - *fpi_len;
      48           14 : }
      49              : 
      50              : /*
      51              :  * Store per-rmgr and per-record statistics for a given record.
      52              :  */
      53              : void
      54           14 : XLogRecStoreStats(XLogStats *stats, XLogReaderState *record)
      55              : {
      56              :     RmgrId      rmid;
      57              :     uint8       recid;
      58              :     uint32      rec_len;
      59              :     uint32      fpi_len;
      60              : 
      61              :     Assert(stats != NULL && record != NULL);
      62              : 
      63           14 :     stats->count++;
      64              : 
      65           14 :     rmid = XLogRecGetRmid(record);
      66              : 
      67           14 :     XLogRecGetLen(record, &rec_len, &fpi_len);
      68              : 
      69              :     /* Update per-rmgr statistics */
      70              : 
      71           14 :     stats->rmgr_stats[rmid].count++;
      72           14 :     stats->rmgr_stats[rmid].rec_len += rec_len;
      73           14 :     stats->rmgr_stats[rmid].fpi_len += fpi_len;
      74              : 
      75              :     /*
      76              :      * Update per-record statistics, where the record is identified by a
      77              :      * combination of the RmgrId and the four bits of the xl_info field that
      78              :      * are the rmgr's domain (resulting in sixteen possible entries per
      79              :      * RmgrId).
      80              :      */
      81              : 
      82           14 :     recid = XLogRecGetInfo(record) >> 4;
      83              : 
      84              :     /*
      85              :      * XACT records need to be handled differently. Those records use the
      86              :      * first bit of those four bits for an optional flag variable and the
      87              :      * following three bits for the opcode. We filter opcode out of xl_info
      88              :      * and use it as the identifier of the record.
      89              :      */
      90           14 :     if (rmid == RM_XACT_ID)
      91            4 :         recid &= 0x07;
      92              : 
      93           14 :     stats->record_stats[rmid][recid].count++;
      94           14 :     stats->record_stats[rmid][recid].rec_len += rec_len;
      95           14 :     stats->record_stats[rmid][recid].fpi_len += fpi_len;
      96           14 : }