walsummarizer.h File Reference

#include "access/xlogdefs.h"

Include dependency graph for walsummarizer.h:

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Functions
Size	WalSummarizerShmemSize (void)
void	WalSummarizerShmemInit (void)
pg_noreturn void	WalSummarizerMain (const void *startup_data, size_t startup_data_len)
void	GetWalSummarizerState (TimeLineID *summarized_tli, XLogRecPtr *summarized_lsn, XLogRecPtr *pending_lsn, int *summarizer_pid)
XLogRecPtr	GetOldestUnsummarizedLSN (TimeLineID *tli, bool *lsn_is_exact)
void	WakeupWalSummarizer (void)
void	WaitForWalSummarization (XLogRecPtr lsn)

Variables
PGDLLIMPORT bool	summarize_wal
PGDLLIMPORT int	wal_summary_keep_time

Function Documentation

GetOldestUnsummarizedLSN()

XLogRecPtr GetOldestUnsummarizedLSN ( TimeLineID *  tli, bool *  lsn_is_exact  )

extern

Definition at line 505 of file walsummarizer.c.

{
    TimeLineID  latest_tli;
    int         n;
    List       *tles;
    XLogRecPtr  unsummarized_lsn = InvalidXLogRecPtr;
    TimeLineID  unsummarized_tli = 0;
    bool        should_make_exact = false;
    List       *existing_summaries;
    ListCell   *lc;
    bool        am_wal_summarizer = AmWalSummarizerProcess();
 
    /* If not summarizing WAL, do nothing. */
    if (!summarize_wal)
        return InvalidXLogRecPtr;
 
    /*
     * If we are not the WAL summarizer process, then we normally just want to
     * read the values from shared memory. However, as an exception, if shared
     * memory hasn't been initialized yet, then we need to do that so that we
     * can read legal values and not remove any WAL too early.
     */
    if (!am_wal_summarizer)
    {
        LWLockAcquire(WALSummarizerLock, LW_SHARED);
 
        if (WalSummarizerCtl->initialized)
        {
            unsummarized_lsn = WalSummarizerCtl->summarized_lsn;
            if (tli != NULL)
                *tli = WalSummarizerCtl->summarized_tli;
            if (lsn_is_exact != NULL)
                *lsn_is_exact = WalSummarizerCtl->lsn_is_exact;
            LWLockRelease(WALSummarizerLock);
            return unsummarized_lsn;
        }
 
        LWLockRelease(WALSummarizerLock);
    }
 
    /*
     * Find the oldest timeline on which WAL still exists, and the earliest
     * segment for which it exists.
     *
     * Note that we do this every time the WAL summarizer process restarts or
     * recovers from an error, in case the contents of pg_wal have changed
     * under us e.g. if some files were removed, either manually - which
     * shouldn't really happen, but might - or by postgres itself, if
     * summarize_wal was turned off and then back on again.
     */
    (void) GetLatestLSN(&latest_tli);
    tles = readTimeLineHistory(latest_tli);
    for (n = list_length(tles) - 1; n >= 0; --n)
    {
        TimeLineHistoryEntry *tle = list_nth(tles, n);
        XLogSegNo   oldest_segno;
 
        oldest_segno = XLogGetOldestSegno(tle->tli);
        if (oldest_segno != 0)
        {
            /* Compute oldest LSN that still exists on disk. */
            XLogSegNoOffsetToRecPtr(oldest_segno, 0, wal_segment_size,
                                    unsummarized_lsn);
 
            unsummarized_tli = tle->tli;
            break;
        }
    }
 
    /*
     * Don't try to summarize anything older than the end LSN of the newest
     * summary file that exists for this timeline.
     */
    existing_summaries =
        GetWalSummaries(unsummarized_tli,
                        InvalidXLogRecPtr, InvalidXLogRecPtr);
    foreach(lc, existing_summaries)
    {
        WalSummaryFile *ws = lfirst(lc);
 
        if (ws->end_lsn > unsummarized_lsn)
        {
            unsummarized_lsn = ws->end_lsn;
            should_make_exact = true;
        }
    }
 
    /* It really should not be possible for us to find no WAL. */
    if (unsummarized_tli == 0)
        ereport(ERROR,
                errcode(ERRCODE_INTERNAL_ERROR),
                errmsg_internal("no WAL found on timeline %u", latest_tli));
 
    /*
     * If we're the WAL summarizer, we always want to store the values we just
     * computed into shared memory, because those are the values we're going
     * to use to drive our operation, and so they are the authoritative
     * values. Otherwise, we only store values into shared memory if shared
     * memory is uninitialized. Our values are not canonical in such a case,
     * but it's better to have something than nothing, to guide WAL retention.
     */
    LWLockAcquire(WALSummarizerLock, LW_EXCLUSIVE);
    if (am_wal_summarizer || !WalSummarizerCtl->initialized)
    {
        WalSummarizerCtl->initialized = true;
        WalSummarizerCtl->summarized_lsn = unsummarized_lsn;
        WalSummarizerCtl->summarized_tli = unsummarized_tli;
        WalSummarizerCtl->lsn_is_exact = should_make_exact;
        WalSummarizerCtl->pending_lsn = unsummarized_lsn;
    }
    else
        unsummarized_lsn = WalSummarizerCtl->summarized_lsn;
 
    /* Also return the to the caller as required. */
    if (tli != NULL)
        *tli = WalSummarizerCtl->summarized_tli;
    if (lsn_is_exact != NULL)
        *lsn_is_exact = WalSummarizerCtl->lsn_is_exact;
    LWLockRelease(WALSummarizerLock);
 
    return unsummarized_lsn;
}

References AmWalSummarizerProcess, ereport, errcode(), errmsg_internal(), ERROR, fb(), GetLatestLSN(), GetWalSummaries(), WalSummarizerData::initialized, InvalidXLogRecPtr, lfirst, list_length(), list_nth(), WalSummarizerData::lsn_is_exact, LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), WalSummarizerData::pending_lsn, readTimeLineHistory(), summarize_wal, WalSummarizerData::summarized_lsn, WalSummarizerData::summarized_tli, wal_segment_size, WalSummarizerCtl, XLogGetOldestSegno(), and XLogSegNoOffsetToRecPtr.

Referenced by KeepLogSeg(), and WalSummarizerMain().

GetWalSummarizerState()

void GetWalSummarizerState ( TimeLineID *  summarized_tli, XLogRecPtr *  summarized_lsn, XLogRecPtr *  pending_lsn, int *  summarizer_pid  )

extern

Definition at line 447 of file walsummarizer.c.

{
    LWLockAcquire(WALSummarizerLock, LW_SHARED);
    if (!WalSummarizerCtl->initialized)
    {
        /*
         * If initialized is false, the rest of the structure contents are
         * undefined.
         */
        *summarized_tli = 0;
        *summarized_lsn = InvalidXLogRecPtr;
        *pending_lsn = InvalidXLogRecPtr;
        *summarizer_pid = -1;
    }
    else
    {
        int         summarizer_pgprocno = WalSummarizerCtl->summarizer_pgprocno;
 
        *summarized_tli = WalSummarizerCtl->summarized_tli;
        *summarized_lsn = WalSummarizerCtl->summarized_lsn;
        if (summarizer_pgprocno == INVALID_PROC_NUMBER)
        {
            /*
             * If the summarizer has exited, the fact that it had processed
             * beyond summarized_lsn is irrelevant now.
             */
            *pending_lsn = WalSummarizerCtl->summarized_lsn;
            *summarizer_pid = -1;
        }
        else
        {
            *pending_lsn = WalSummarizerCtl->pending_lsn;
 
            /*
             * We're not fussed about inexact answers here, since they could
             * become stale instantly, so we don't bother taking the lock, but
             * make sure that invalid PID values are normalized to -1.
             */
            *summarizer_pid = GetPGProcByNumber(summarizer_pgprocno)->pid;
            if (*summarizer_pid <= 0)
                *summarizer_pid = -1;
        }
    }
    LWLockRelease(WALSummarizerLock);
}

References fb(), GetPGProcByNumber, WalSummarizerData::initialized, INVALID_PROC_NUMBER, InvalidXLogRecPtr, LW_SHARED, LWLockAcquire(), LWLockRelease(), WalSummarizerData::pending_lsn, WalSummarizerData::summarized_lsn, WalSummarizerData::summarized_tli, WalSummarizerData::summarizer_pgprocno, and WalSummarizerCtl.

Referenced by pg_get_wal_summarizer_state().

WaitForWalSummarization()

void WaitForWalSummarization ( XLogRecPtr  lsn )

extern

Definition at line 660 of file walsummarizer.c.

{
    TimestampTz initial_time,
                cycle_time,
                current_time;
    XLogRecPtr  prior_pending_lsn = InvalidXLogRecPtr;
    int         deadcycles = 0;
 
    initial_time = cycle_time = GetCurrentTimestamp();
 
    while (1)
    {
        long        timeout_in_ms = 10000;
        XLogRecPtr  summarized_lsn;
        XLogRecPtr  pending_lsn;
 
        CHECK_FOR_INTERRUPTS();
 
        /* If WAL summarization is disabled while we're waiting, give up. */
        if (!summarize_wal)
            return;
 
        /*
         * If the LSN summarized on disk has reached the target value, stop.
         */
        LWLockAcquire(WALSummarizerLock, LW_SHARED);
        summarized_lsn = WalSummarizerCtl->summarized_lsn;
        pending_lsn = WalSummarizerCtl->pending_lsn;
        LWLockRelease(WALSummarizerLock);
 
        /* If WAL summarization has progressed sufficiently, stop waiting. */
        if (summarized_lsn >= lsn)
            break;
 
        /* Recheck current time. */
        current_time = GetCurrentTimestamp();
 
        /* Have we finished the current cycle of waiting? */
        if (TimestampDifferenceMilliseconds(cycle_time,
                                            current_time) >= timeout_in_ms)
        {
            long        elapsed_seconds;
 
            /* Begin new wait cycle. */
            cycle_time = TimestampTzPlusMilliseconds(cycle_time,
                                                     timeout_in_ms);
 
            /*
             * Keep track of the number of cycles during which there has been
             * no progression of pending_lsn. If pending_lsn is not advancing,
             * that means that not only are no new files appearing on disk,
             * but we're not even incorporating new records into the in-memory
             * state.
             */
            if (pending_lsn > prior_pending_lsn)
            {
                prior_pending_lsn = pending_lsn;
                deadcycles = 0;
            }
            else
                ++deadcycles;
 
            /*
             * If we've managed to wait for an entire minute without the WAL
             * summarizer absorbing a single WAL record, error out; probably
             * something is wrong.
             *
             * We could consider also erroring out if the summarizer is taking
             * too long to catch up, but it's not clear what rate of progress
             * would be acceptable and what would be too slow. So instead, we
             * just try to error out in the case where there's no progress at
             * all. That seems likely to catch a reasonable number of the
             * things that can go wrong in practice (e.g. the summarizer
             * process is completely hung, say because somebody hooked up a
             * debugger to it or something) without giving up too quickly when
             * the system is just slow.
             */
            if (deadcycles >= 6)
                ereport(ERROR,
                        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                         errmsg("WAL summarization is not progressing"),
                         errdetail("Summarization is needed through %X/%08X, but is stuck at %X/%08X on disk and %X/%08X in memory.",
                                   LSN_FORMAT_ARGS(lsn),
                                   LSN_FORMAT_ARGS(summarized_lsn),
                                   LSN_FORMAT_ARGS(pending_lsn))));
 
 
            /*
             * Otherwise, just let the user know what's happening.
             */
            elapsed_seconds =
                TimestampDifferenceMilliseconds(initial_time,
                                                current_time) / 1000;
            ereport(WARNING,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg_plural("still waiting for WAL summarization through %X/%08X after %ld second",
                                   "still waiting for WAL summarization through %X/%08X after %ld seconds",
                                   elapsed_seconds,
                                   LSN_FORMAT_ARGS(lsn),
                                   elapsed_seconds),
                     errdetail("Summarization has reached %X/%08X on disk and %X/%08X in memory.",
                               LSN_FORMAT_ARGS(summarized_lsn),
                               LSN_FORMAT_ARGS(pending_lsn))));
        }
 
        /*
         * Align the wait time to prevent drift. This doesn't really matter,
         * but we'd like the warnings about how long we've been waiting to say
         * 10 seconds, 20 seconds, 30 seconds, 40 seconds ... without ever
         * drifting to something that is not a multiple of ten.
         */
        timeout_in_ms -=
            TimestampDifferenceMilliseconds(cycle_time, current_time);
 
        /* Wait and see. */
        ConditionVariableTimedSleep(&WalSummarizerCtl->summary_file_cv,
                                    timeout_in_ms,
                                    WAIT_EVENT_WAL_SUMMARY_READY);
    }
 
    ConditionVariableCancelSleep();
}

References CHECK_FOR_INTERRUPTS, ConditionVariableCancelSleep(), ConditionVariableTimedSleep(), ereport, errcode(), errdetail(), errmsg, errmsg_plural(), ERROR, fb(), GetCurrentTimestamp(), InvalidXLogRecPtr, LSN_FORMAT_ARGS, LW_SHARED, LWLockAcquire(), LWLockRelease(), WalSummarizerData::pending_lsn, summarize_wal, WalSummarizerData::summarized_lsn, WalSummarizerData::summary_file_cv, TimestampDifferenceMilliseconds(), TimestampTzPlusMilliseconds, WalSummarizerCtl, and WARNING.

Referenced by CleanupAfterArchiveRecovery(), and PrepareForIncrementalBackup().

WakeupWalSummarizer()

void WakeupWalSummarizer ( void  )

extern

Definition at line 637 of file walsummarizer.c.

{
    ProcNumber  pgprocno;
 
    if (WalSummarizerCtl == NULL)
        return;
 
    LWLockAcquire(WALSummarizerLock, LW_SHARED);
    pgprocno = WalSummarizerCtl->summarizer_pgprocno;
    LWLockRelease(WALSummarizerLock);
 
    if (pgprocno != INVALID_PROC_NUMBER)
        SetLatch(&GetPGProcByNumber(pgprocno)->procLatch);
}

References fb(), GetPGProcByNumber, INVALID_PROC_NUMBER, LW_SHARED, LWLockAcquire(), LWLockRelease(), SetLatch(), WalSummarizerData::summarizer_pgprocno, and WalSummarizerCtl.

Referenced by CreateCheckPoint().

WalSummarizerMain()

pg_noreturn void WalSummarizerMain ( const void *  startup_data, size_t  startup_data_len  )

extern

Definition at line 214 of file walsummarizer.c.

{
    sigjmp_buf  local_sigjmp_buf;
    MemoryContext context;
 
    /*
     * Within this function, 'current_lsn' and 'current_tli' refer to the
     * point from which the next WAL summary file should start. 'exact' is
     * true if 'current_lsn' is known to be the start of a WAL record or WAL
     * segment, and false if it might be in the middle of a record someplace.
     *
     * 'switch_lsn' and 'switch_tli', if set, are the LSN at which we need to
     * switch to a new timeline and the timeline to which we need to switch.
     * If not set, we either haven't figured out the answers yet or we're
     * already on the latest timeline.
     */
    XLogRecPtr  current_lsn;
    TimeLineID  current_tli;
    bool        exact;
    XLogRecPtr  switch_lsn = InvalidXLogRecPtr;
    TimeLineID  switch_tli = 0;
 
    Assert(startup_data_len == 0);
 
    AuxiliaryProcessMainCommon();
 
    ereport(DEBUG1,
            (errmsg_internal("WAL summarizer started")));
 
    /*
     * Properly accept or ignore signals the postmaster might send us
     */
    pqsignal(SIGHUP, SignalHandlerForConfigReload);
    pqsignal(SIGINT, SIG_IGN);  /* no query to cancel */
    pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
    /* SIGQUIT handler was already set up by InitPostmasterChild */
    pqsignal(SIGALRM, SIG_IGN);
    pqsignal(SIGPIPE, SIG_IGN);
    pqsignal(SIGUSR1, procsignal_sigusr1_handler);
    pqsignal(SIGUSR2, SIG_IGN); /* not used */
 
    /* Advertise ourselves. */
    on_shmem_exit(WalSummarizerShutdown, (Datum) 0);
    LWLockAcquire(WALSummarizerLock, LW_EXCLUSIVE);
    WalSummarizerCtl->summarizer_pgprocno = MyProcNumber;
    LWLockRelease(WALSummarizerLock);
 
    /* Create and switch to a memory context that we can reset on error. */
    context = AllocSetContextCreate(TopMemoryContext,
                                    "Wal Summarizer",
                                    ALLOCSET_DEFAULT_SIZES);
    MemoryContextSwitchTo(context);
 
    /*
     * Reset some signals that are accepted by postmaster but not here
     */
    pqsignal(SIGCHLD, SIG_DFL);
 
    /*
     * If an exception is encountered, processing resumes here.
     */
    if (sigsetjmp(local_sigjmp_buf, 1) != 0)
    {
        /* Since not using PG_TRY, must reset error stack by hand */
        error_context_stack = NULL;
 
        /* Prevent interrupts while cleaning up */
        HOLD_INTERRUPTS();
 
        /* Report the error to the server log */
        EmitErrorReport();
 
        /* Release resources we might have acquired. */
        LWLockReleaseAll();
        ConditionVariableCancelSleep();
        pgstat_report_wait_end();
        pgaio_error_cleanup();
        ReleaseAuxProcessResources(false);
        AtEOXact_Files(false);
        AtEOXact_HashTables(false);
 
        /*
         * Now return to normal top-level context and clear ErrorContext for
         * next time.
         */
        MemoryContextSwitchTo(context);
        FlushErrorState();
 
        /* Flush any leaked data in the top-level context */
        MemoryContextReset(context);
 
        /* Now we can allow interrupts again */
        RESUME_INTERRUPTS();
 
        /*
         * Sleep for 10 seconds before attempting to resume operations in
         * order to avoid excessive logging.
         *
         * Many of the likely error conditions are things that will repeat
         * every time. For example, if the WAL can't be read or the summary
         * can't be written, only administrator action will cure the problem.
         * So a really fast retry time doesn't seem to be especially
         * beneficial, and it will clutter the logs.
         */
        (void) WaitLatch(NULL,
                         WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
                         10000,
                         WAIT_EVENT_WAL_SUMMARIZER_ERROR);
    }
 
    /* We can now handle ereport(ERROR) */
    PG_exception_stack = &local_sigjmp_buf;
 
    /*
     * Unblock signals (they were blocked when the postmaster forked us)
     */
    sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
 
    /*
     * Fetch information about previous progress from shared memory, and ask
     * GetOldestUnsummarizedLSN to reset pending_lsn to summarized_lsn. We
     * might be recovering from an error, and if so, pending_lsn might have
     * advanced past summarized_lsn, but any WAL we read previously has been
     * lost and will need to be reread.
     *
     * If we discover that WAL summarization is not enabled, just exit.
     */
    current_lsn = GetOldestUnsummarizedLSN(&current_tli, &exact);
    if (!XLogRecPtrIsValid(current_lsn))
        proc_exit(0);
 
    /*
     * Loop forever
     */
    for (;;)
    {
        XLogRecPtr  latest_lsn;
        TimeLineID  latest_tli;
        XLogRecPtr  end_of_summary_lsn;
 
        /* Flush any leaked data in the top-level context */
        MemoryContextReset(context);
 
        /* Process any signals received recently. */
        ProcessWalSummarizerInterrupts();
 
        /* If it's time to remove any old WAL summaries, do that now. */
        MaybeRemoveOldWalSummaries();
 
        /* Find the LSN and TLI up to which we can safely summarize. */
        latest_lsn = GetLatestLSN(&latest_tli);
 
        /*
         * If we're summarizing a historic timeline and we haven't yet
         * computed the point at which to switch to the next timeline, do that
         * now.
         *
         * Note that if this is a standby, what was previously the current
         * timeline could become historic at any time.
         *
         * We could try to make this more efficient by caching the results of
         * readTimeLineHistory when latest_tli has not changed, but since we
         * only have to do this once per timeline switch, we probably wouldn't
         * save any significant amount of work in practice.
         */
        if (current_tli != latest_tli && !XLogRecPtrIsValid(switch_lsn))
        {
            List       *tles = readTimeLineHistory(latest_tli);
 
            switch_lsn = tliSwitchPoint(current_tli, tles, &switch_tli);
            ereport(DEBUG1,
                    errmsg_internal("switch point from TLI %u to TLI %u is at %X/%08X",
                                    current_tli, switch_tli, LSN_FORMAT_ARGS(switch_lsn)));
        }
 
        /*
         * If we've reached the switch LSN, we can't summarize anything else
         * on this timeline. Switch to the next timeline and go around again,
         * backing up to the exact switch point if we passed it.
         */
        if (XLogRecPtrIsValid(switch_lsn) && current_lsn >= switch_lsn)
        {
            /* Restart summarization from switch point. */
            current_tli = switch_tli;
            current_lsn = switch_lsn;
 
            /* Next timeline and switch point, if any, not yet known. */
            switch_lsn = InvalidXLogRecPtr;
            switch_tli = 0;
 
            /* Update (really, rewind, if needed) state in shared memory. */
            LWLockAcquire(WALSummarizerLock, LW_EXCLUSIVE);
            WalSummarizerCtl->summarized_lsn = current_lsn;
            WalSummarizerCtl->summarized_tli = current_tli;
            WalSummarizerCtl->lsn_is_exact = true;
            WalSummarizerCtl->pending_lsn = current_lsn;
            LWLockRelease(WALSummarizerLock);
 
            continue;
        }
 
        /* Summarize WAL. */
        end_of_summary_lsn = SummarizeWAL(current_tli,
                                          current_lsn, exact,
                                          switch_lsn, latest_lsn);
        Assert(XLogRecPtrIsValid(end_of_summary_lsn));
        Assert(end_of_summary_lsn >= current_lsn);
 
        /*
         * Update state for next loop iteration.
         *
         * Next summary file should start from exactly where this one ended.
         */
        current_lsn = end_of_summary_lsn;
        exact = true;
 
        /* Update state in shared memory. */
        LWLockAcquire(WALSummarizerLock, LW_EXCLUSIVE);
        WalSummarizerCtl->summarized_lsn = end_of_summary_lsn;
        WalSummarizerCtl->summarized_tli = current_tli;
        WalSummarizerCtl->lsn_is_exact = true;
        WalSummarizerCtl->pending_lsn = end_of_summary_lsn;
        LWLockRelease(WALSummarizerLock);
 
        /* Wake up anyone waiting for more summary files to be written. */
        ConditionVariableBroadcast(&WalSummarizerCtl->summary_file_cv);
    }
}

References ALLOCSET_DEFAULT_SIZES, AllocSetContextCreate, Assert, AtEOXact_Files(), AtEOXact_HashTables(), AuxiliaryProcessMainCommon(), ConditionVariableBroadcast(), ConditionVariableCancelSleep(), DEBUG1, EmitErrorReport(), ereport, errmsg_internal(), error_context_stack, fb(), FlushErrorState(), GetLatestLSN(), GetOldestUnsummarizedLSN(), HOLD_INTERRUPTS, InvalidXLogRecPtr, LSN_FORMAT_ARGS, WalSummarizerData::lsn_is_exact, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), LWLockReleaseAll(), MaybeRemoveOldWalSummaries(), MemoryContextReset(), MemoryContextSwitchTo(), MyProcNumber, on_shmem_exit(), WalSummarizerData::pending_lsn, PG_exception_stack, pgaio_error_cleanup(), pgstat_report_wait_end(), pqsignal, proc_exit(), ProcessWalSummarizerInterrupts(), procsignal_sigusr1_handler(), readTimeLineHistory(), ReleaseAuxProcessResources(), RESUME_INTERRUPTS, SIGALRM, SIGCHLD, SIGHUP, SignalHandlerForConfigReload(), SignalHandlerForShutdownRequest(), SIGPIPE, SIGUSR1, SIGUSR2, WalSummarizerData::summarized_lsn, WalSummarizerData::summarized_tli, WalSummarizerData::summarizer_pgprocno, SummarizeWAL(), WalSummarizerData::summary_file_cv, tliSwitchPoint(), TopMemoryContext, UnBlockSig, WaitLatch(), WalSummarizerCtl, WalSummarizerShutdown(), WL_EXIT_ON_PM_DEATH, WL_TIMEOUT, and XLogRecPtrIsValid.

WalSummarizerShmemInit()

void WalSummarizerShmemInit ( void  )

extern

Definition at line 183 of file walsummarizer.c.

{
    bool        found;
 
    WalSummarizerCtl = (WalSummarizerData *)
        ShmemInitStruct("Wal Summarizer Ctl", WalSummarizerShmemSize(),
                        &found);
 
    if (!found)
    {
        /*
         * First time through, so initialize.
         *
         * We're just filling in dummy values here -- the real initialization
         * will happen when GetOldestUnsummarizedLSN() is called for the first
         * time.
         */
        WalSummarizerCtl->initialized = false;
        WalSummarizerCtl->summarized_tli = 0;
        WalSummarizerCtl->summarized_lsn = InvalidXLogRecPtr;
        WalSummarizerCtl->lsn_is_exact = false;
        WalSummarizerCtl->summarizer_pgprocno = INVALID_PROC_NUMBER;
        WalSummarizerCtl->pending_lsn = InvalidXLogRecPtr;
        ConditionVariableInit(&WalSummarizerCtl->summary_file_cv);
    }
}

References ConditionVariableInit(), WalSummarizerData::initialized, INVALID_PROC_NUMBER, InvalidXLogRecPtr, WalSummarizerData::lsn_is_exact, WalSummarizerData::pending_lsn, ShmemInitStruct(), WalSummarizerData::summarized_lsn, WalSummarizerData::summarized_tli, WalSummarizerData::summarizer_pgprocno, WalSummarizerData::summary_file_cv, WalSummarizerCtl, and WalSummarizerShmemSize().

Referenced by CreateOrAttachShmemStructs().

WalSummarizerShmemSize()

Size WalSummarizerShmemSize ( void  )

extern

Definition at line 174 of file walsummarizer.c.

{
    return sizeof(WalSummarizerData);
}

Referenced by CalculateShmemSize(), and WalSummarizerShmemInit().

Variable Documentation

summarize_wal

PGDLLIMPORT bool summarize_wal

extern

Definition at line 145 of file walsummarizer.c.

Referenced by CleanupAfterArchiveRecovery(), GetOldestUnsummarizedLSN(), LaunchMissingBackgroundProcesses(), parse_basebackup_options(), PostmasterMain(), ProcessWalSummarizerInterrupts(), and WaitForWalSummarization().

wal_summary_keep_time

PGDLLIMPORT int wal_summary_keep_time

extern

Definition at line 146 of file walsummarizer.c.

Referenced by MaybeRemoveOldWalSummaries().