walsummary.h File Reference

#include <time.h>
#include "access/xlogdefs.h"
#include "nodes/pg_list.h"
#include "storage/fd.h"

Include dependency graph for walsummary.h:

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Data Structures
struct	WalSummaryIO
struct	WalSummaryFile

Typedefs
typedef struct WalSummaryIO	WalSummaryIO
typedef struct WalSummaryFile	WalSummaryFile

Functions
List *	GetWalSummaries (TimeLineID tli, XLogRecPtr start_lsn, XLogRecPtr end_lsn)
List *	FilterWalSummaries (List *wslist, TimeLineID tli, XLogRecPtr start_lsn, XLogRecPtr end_lsn)
bool	WalSummariesAreComplete (List *wslist, XLogRecPtr start_lsn, XLogRecPtr end_lsn, XLogRecPtr *missing_lsn)
File	OpenWalSummaryFile (WalSummaryFile *ws, bool missing_ok)
void	RemoveWalSummaryIfOlderThan (WalSummaryFile *ws, time_t cutoff_time)
int	ReadWalSummary (void *wal_summary_io, void *data, int length)
int	WriteWalSummary (void *wal_summary_io, void *data, int length)
void	ReportWalSummaryError (void *callback_arg, char *fmt,...) pg_attribute_printf(2

Typedef Documentation

WalSummaryFile

typedef struct WalSummaryFile WalSummaryFile

WalSummaryIO

typedef struct WalSummaryIO WalSummaryIO

Function Documentation

FilterWalSummaries()

List * FilterWalSummaries	(	List *	wslist,
		TimeLineID	tli,
		XLogRecPtr	start_lsn,
		XLogRecPtr	end_lsn
	)

Definition at line 100 of file walsummary.c.

{
    List       *result = NIL;
    ListCell   *lc;
 
    /* Loop over input. */
    foreach(lc, wslist)
    {
        WalSummaryFile *ws = lfirst(lc);
 
        /* Skip if it doesn't match the filter criteria. */
        if (tli != 0 && tli != ws->tli)
            continue;
        if (XLogRecPtrIsValid(start_lsn) && start_lsn > ws->end_lsn)
            continue;
        if (XLogRecPtrIsValid(end_lsn) && end_lsn < ws->start_lsn)
            continue;
 
        /* Add it to the result list. */
        result = lappend(result, ws);
    }
 
    return result;
}

References WalSummaryFile::end_lsn, lappend(), lfirst, NIL, WalSummaryFile::tli, and XLogRecPtrIsValid.

Referenced by PrepareForIncrementalBackup().

GetWalSummaries()

List * GetWalSummaries	(	TimeLineID	tli,
		XLogRecPtr	start_lsn,
		XLogRecPtr	end_lsn
	)

Definition at line 43 of file walsummary.c.

{
    DIR        *sdir;
    struct dirent *dent;
    List       *result = NIL;
 
    sdir = AllocateDir(XLOGDIR "/summaries");
    while ((dent = ReadDir(sdir, XLOGDIR "/summaries")) != NULL)
    {
        WalSummaryFile *ws;
        uint32      tmp[5];
        TimeLineID  file_tli;
        XLogRecPtr  file_start_lsn;
        XLogRecPtr  file_end_lsn;
 
        /* Decode filename, or skip if it's not in the expected format. */
        if (!IsWalSummaryFilename(dent->d_name))
            continue;
        sscanf(dent->d_name, "%08X%08X%08X%08X%08X",
               &tmp[0], &tmp[1], &tmp[2], &tmp[3], &tmp[4]);
        file_tli = tmp[0];
        file_start_lsn = ((uint64) tmp[1]) << 32 | tmp[2];
        file_end_lsn = ((uint64) tmp[3]) << 32 | tmp[4];
 
        /* Skip if it doesn't match the filter criteria. */
        if (tli != 0 && tli != file_tli)
            continue;
        if (XLogRecPtrIsValid(start_lsn) && start_lsn >= file_end_lsn)
            continue;
        if (XLogRecPtrIsValid(end_lsn) && end_lsn <= file_start_lsn)
            continue;
 
        /* Add it to the list. */
        ws = palloc(sizeof(WalSummaryFile));
        ws->tli = file_tli;
        ws->start_lsn = file_start_lsn;
        ws->end_lsn = file_end_lsn;
        result = lappend(result, ws);
    }
    FreeDir(sdir);
 
    return result;
}

References AllocateDir(), dirent::d_name, WalSummaryFile::end_lsn, FreeDir(), IsWalSummaryFilename(), lappend(), NIL, palloc(), ReadDir(), WalSummaryFile::start_lsn, WalSummaryFile::tli, XLOGDIR, and XLogRecPtrIsValid.

Referenced by GetOldestUnsummarizedLSN(), MaybeRemoveOldWalSummaries(), pg_available_wal_summaries(), and PrepareForIncrementalBackup().

OpenWalSummaryFile()

File OpenWalSummaryFile	(	WalSummaryFile *	ws,
		bool	missing_ok
	)

Definition at line 205 of file walsummary.c.

{
    char        path[MAXPGPATH];
    File        file;
 
    snprintf(path, MAXPGPATH,
             XLOGDIR "/summaries/%08X%08X%08X%08X%08X.summary",
             ws->tli,
             LSN_FORMAT_ARGS(ws->start_lsn),
             LSN_FORMAT_ARGS(ws->end_lsn));
 
    file = PathNameOpenFile(path, O_RDONLY);
    if (file < 0 && (errno != EEXIST || !missing_ok))
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not open file \"%s\": %m", path)));
 
    return file;
}

References WalSummaryFile::end_lsn, ereport, errcode_for_file_access(), errmsg(), ERROR, LSN_FORMAT_ARGS, MAXPGPATH, PathNameOpenFile(), snprintf, WalSummaryFile::start_lsn, WalSummaryFile::tli, and XLOGDIR.

Referenced by pg_wal_summary_contents(), and PrepareForIncrementalBackup().

ReadWalSummary()

int ReadWalSummary	(	void *	wal_summary_io,
		void *	data,
		int	length
	)

Definition at line 273 of file walsummary.c.

{
    WalSummaryIO *io = wal_summary_io;
    int         nbytes;
 
    nbytes = FileRead(io->file, data, length, io->filepos,
                      WAIT_EVENT_WAL_SUMMARY_READ);
    if (nbytes < 0)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not read file \"%s\": %m",
                        FilePathName(io->file))));
 
    io->filepos += nbytes;
    return nbytes;
}

References data, ereport, errcode_for_file_access(), errmsg(), ERROR, WalSummaryIO::file, FilePathName(), WalSummaryIO::filepos, and FileRead().

Referenced by pg_wal_summary_contents(), and PrepareForIncrementalBackup().

RemoveWalSummaryIfOlderThan()

void RemoveWalSummaryIfOlderThan	(	WalSummaryFile *	ws,
		time_t	cutoff_time
	)

Definition at line 230 of file walsummary.c.

{
    char        path[MAXPGPATH];
    struct stat statbuf;
 
    snprintf(path, MAXPGPATH,
             XLOGDIR "/summaries/%08X%08X%08X%08X%08X.summary",
             ws->tli,
             LSN_FORMAT_ARGS(ws->start_lsn),
             LSN_FORMAT_ARGS(ws->end_lsn));
 
    if (lstat(path, &statbuf) != 0)
    {
        if (errno == ENOENT)
            return;
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not stat file \"%s\": %m", path)));
    }
    if (statbuf.st_mtime >= cutoff_time)
        return;
    if (unlink(path) != 0)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not stat file \"%s\": %m", path)));
    ereport(DEBUG2,
            (errmsg_internal("removing file \"%s\"", path)));
}

References DEBUG2, WalSummaryFile::end_lsn, ereport, errcode_for_file_access(), errmsg(), errmsg_internal(), ERROR, LSN_FORMAT_ARGS, lstat, MAXPGPATH, snprintf, stat::st_mtime, WalSummaryFile::start_lsn, WalSummaryFile::tli, and XLOGDIR.

Referenced by MaybeRemoveOldWalSummaries().

ReportWalSummaryError()

void ReportWalSummaryError	(	void *	callback_arg,
		char *	fmt,
			...
	)

WalSummariesAreComplete()

bool WalSummariesAreComplete	(	List *	wslist,
		XLogRecPtr	start_lsn,
		XLogRecPtr	end_lsn,
		XLogRecPtr *	missing_lsn
	)

Definition at line 138 of file walsummary.c.

{
    XLogRecPtr  current_lsn = start_lsn;
    ListCell   *lc;
 
    /* Special case for empty list. */
    if (wslist == NIL)
    {
        *missing_lsn = InvalidXLogRecPtr;
        return false;
    }
 
    /* Make a private copy of the list and sort it by start LSN. */
    wslist = list_copy(wslist);
    list_sort(wslist, ListComparatorForWalSummaryFiles);
 
    /*
     * Consider summary files in order of increasing start_lsn, advancing the
     * known-summarized range from start_lsn toward end_lsn.
     *
     * Normally, the summary files should cover non-overlapping WAL ranges,
     * but this algorithm is intended to be correct even in case of overlap.
     */
    foreach(lc, wslist)
    {
        WalSummaryFile *ws = lfirst(lc);
 
        if (ws->start_lsn > current_lsn)
        {
            /* We found a gap. */
            break;
        }
        if (ws->end_lsn > current_lsn)
        {
            /*
             * Next summary extends beyond end of previous summary, so extend
             * the end of the range known to be summarized.
             */
            current_lsn = ws->end_lsn;
 
            /*
             * If the range we know to be summarized has reached the required
             * end LSN, we have proved completeness.
             */
            if (current_lsn >= end_lsn)
                return true;
        }
    }
 
    /*
     * We either ran out of summary files without reaching the end LSN, or we
     * hit a gap in the sequence that resulted in us bailing out of the loop
     * above.
     */
    *missing_lsn = current_lsn;
    return false;
}

References WalSummaryFile::end_lsn, InvalidXLogRecPtr, lfirst, list_copy(), list_sort(), ListComparatorForWalSummaryFiles(), NIL, and WalSummaryFile::start_lsn.

Referenced by PrepareForIncrementalBackup().

WriteWalSummary()

int WriteWalSummary	(	void *	wal_summary_io,
		void *	data,
		int	length
	)

Definition at line 294 of file walsummary.c.

{
    WalSummaryIO *io = wal_summary_io;
    int         nbytes;
 
    nbytes = FileWrite(io->file, data, length, io->filepos,
                       WAIT_EVENT_WAL_SUMMARY_WRITE);
    if (nbytes < 0)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not write file \"%s\": %m",
                        FilePathName(io->file))));
    if (nbytes != length)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not write file \"%s\": wrote only %d of %d bytes at offset %u",
                        FilePathName(io->file), nbytes,
                        length, (unsigned) io->filepos),
                 errhint("Check free disk space.")));
 
    io->filepos += nbytes;
    return nbytes;
}

References data, ereport, errcode_for_file_access(), errhint(), errmsg(), ERROR, WalSummaryIO::file, FilePathName(), WalSummaryIO::filepos, and FileWrite().

Referenced by SummarizeWAL().