pg_walsummary.c

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/*-------------------------------------------------------------------------
 *
 * pg_walsummary.c
 *      Prints the contents of WAL summary files.
 *
 * Copyright (c) 2017-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/bin/pg_walsummary/pg_walsummary.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"
 
#include <fcntl.h>
#include <limits.h>
 
#include "common/blkreftable.h"
#include "common/int.h"
#include "common/logging.h"
#include "fe_utils/option_utils.h"
#include "getopt_long.h"
 
typedef struct ws_options
{
    bool        individual;
    bool        quiet;
} ws_options;
 
typedef struct ws_file_info
{
    int         fd;
    char       *filename;
} ws_file_info;
 
static BlockNumber *block_buffer = NULL;
static unsigned block_buffer_size = 512;    /* Initial size. */
 
static void dump_one_relation(ws_options *opt, RelFileLocator *rlocator,
                              ForkNumber forknum, BlockNumber limit_block,
                              BlockRefTableReader *reader);
static void help(const char *progname);
static int  compare_block_numbers(const void *a, const void *b);
static int  walsummary_read_callback(void *callback_arg, void *data,
                                     int length);
static void walsummary_error_callback(void *callback_arg, char *fmt,...) pg_attribute_printf(2, 3);
 
/*
 * Main program.
 */
int
main(int argc, char *argv[])
{
    static struct option long_options[] = {
        {"individual", no_argument, NULL, 'i'},
        {"quiet", no_argument, NULL, 'q'},
        {NULL, 0, NULL, 0}
    };
 
    const char *progname;
    int         optindex;
    int         c;
    ws_options  opt;
 
    memset(&opt, 0, sizeof(ws_options));
 
    pg_logging_init(argv[0]);
    progname = get_progname(argv[0]);
    set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_walsummary"));
    handle_help_version_opts(argc, argv, progname, help);
 
    /* process command-line options */
    while ((c = getopt_long(argc, argv, "iq",
                            long_options, &optindex)) != -1)
    {
        switch (c)
        {
            case 'i':
                opt.individual = true;
                break;
            case 'q':
                opt.quiet = true;
                break;
            default:
                /* getopt_long already emitted a complaint */
                pg_log_error_hint("Try \"%s --help\" for more information.", progname);
                exit(1);
        }
    }
 
    if (optind >= argc)
    {
        pg_log_error("no input files specified");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    while (optind < argc)
    {
        ws_file_info ws;
        BlockRefTableReader *reader;
        RelFileLocator rlocator;
        ForkNumber  forknum;
        BlockNumber limit_block;
 
        ws.filename = argv[optind++];
        if ((ws.fd = open(ws.filename, O_RDONLY | PG_BINARY, 0)) < 0)
            pg_fatal("could not open file \"%s\": %m", ws.filename);
 
        reader = CreateBlockRefTableReader(walsummary_read_callback, &ws,
                                           ws.filename,
                                           walsummary_error_callback, NULL);
        while (BlockRefTableReaderNextRelation(reader, &rlocator, &forknum,
                                               &limit_block))
            dump_one_relation(&opt, &rlocator, forknum, limit_block, reader);
 
        DestroyBlockRefTableReader(reader);
        close(ws.fd);
    }
 
    exit(0);
}
 
/*
 * Dump details for one relation.
 */
static void
dump_one_relation(ws_options *opt, RelFileLocator *rlocator,
                  ForkNumber forknum, BlockNumber limit_block,
                  BlockRefTableReader *reader)
{
    unsigned    i = 0;
    unsigned    nblocks;
    BlockNumber startblock = InvalidBlockNumber;
    BlockNumber endblock = InvalidBlockNumber;
 
    /* Dump limit block, if any. */
    if (limit_block != InvalidBlockNumber)
        printf("TS %u, DB %u, REL %u, FORK %s: limit %u\n",
               rlocator->spcOid, rlocator->dbOid, rlocator->relNumber,
               forkNames[forknum], limit_block);
 
    /* If we haven't allocated a block buffer yet, do that now. */
    if (block_buffer == NULL)
        block_buffer = palloc_array(BlockNumber, block_buffer_size);
 
    /* Try to fill the block buffer. */
    nblocks = BlockRefTableReaderGetBlocks(reader,
                                           block_buffer,
                                           block_buffer_size);
 
    /* If we filled the block buffer completely, we must enlarge it. */
    while (nblocks >= block_buffer_size)
    {
        unsigned    new_size;
 
        /* Double the size, being careful about overflow. */
        new_size = block_buffer_size * 2;
        if (new_size < block_buffer_size)
            new_size = PG_UINT32_MAX;
        block_buffer = repalloc_array(block_buffer, BlockNumber, new_size);
 
        /* Try to fill the newly-allocated space. */
        nblocks +=
            BlockRefTableReaderGetBlocks(reader,
                                         block_buffer + block_buffer_size,
                                         new_size - block_buffer_size);
 
        /* Save the new size for later calls. */
        block_buffer_size = new_size;
    }
 
    /* If we don't need to produce any output, skip the rest of this. */
    if (opt->quiet)
        return;
 
    /*
     * Sort the returned block numbers. If the block reference table was using
     * the bitmap representation for a given chunk, the block numbers in that
     * chunk will already be sorted, but when the array-of-offsets
     * representation is used, we can receive block numbers here out of order.
     */
    qsort(block_buffer, nblocks, sizeof(BlockNumber), compare_block_numbers);
 
    /* Dump block references. */
    while (i < nblocks)
    {
        /*
         * Find the next range of blocks to print, but if --individual was
         * specified, then consider each block a separate range.
         */
        startblock = endblock = block_buffer[i++];
        if (!opt->individual)
        {
            while (i < nblocks && block_buffer[i] == endblock + 1)
            {
                endblock++;
                i++;
            }
        }
 
        /* Format this range of block numbers as a string. */
        if (startblock == endblock)
            printf("TS %u, DB %u, REL %u, FORK %s: block %u\n",
                   rlocator->spcOid, rlocator->dbOid, rlocator->relNumber,
                   forkNames[forknum], startblock);
        else
            printf("TS %u, DB %u, REL %u, FORK %s: blocks %u..%u\n",
                   rlocator->spcOid, rlocator->dbOid, rlocator->relNumber,
                   forkNames[forknum], startblock, endblock);
    }
}
 
/*
 * Quicksort comparator for block numbers.
 */
static int
compare_block_numbers(const void *a, const void *b)
{
    BlockNumber aa = *(BlockNumber *) a;
    BlockNumber bb = *(BlockNumber *) b;
 
    return pg_cmp_u32(aa, bb);
}
 
/*
 * Error callback.
 */
void
walsummary_error_callback(void *callback_arg, char *fmt,...)
{
    va_list     ap;
 
    va_start(ap, fmt);
    pg_log_generic_v(PG_LOG_ERROR, PG_LOG_PRIMARY, fmt, ap);
    va_end(ap);
 
    exit(1);
}
 
/*
 * Read callback.
 */
int
walsummary_read_callback(void *callback_arg, void *data, int length)
{
    ws_file_info *ws = callback_arg;
    int         rc;
 
    if ((rc = read(ws->fd, data, length)) < 0)
        pg_fatal("could not read file \"%s\": %m", ws->filename);
 
    return rc;
}
 
/*
 * help
 *
 * Prints help page for the program
 *
 * progname: the name of the executed program, such as "pg_walsummary"
 */
static void
help(const char *progname)
{
    printf(_("%s prints the contents of a WAL summary file.\n\n"), progname);
    printf(_("Usage:\n"));
    printf(_("  %s [OPTION]... FILE...\n"), progname);
    printf(_("\nOptions:\n"));
    printf(_("  -i, --individual          list block numbers individually, not as ranges\n"));
    printf(_("  -q, --quiet               don't print anything, just parse the files\n"));
    printf(_("  -V, --version             output version information, then exit\n"));
    printf(_("  -?, --help                show this help, then exit\n"));
 
    printf(_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
    printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
}