xlogwait.h File Reference

#include "access/xlogdefs.h"
#include "lib/pairingheap.h"
#include "port/atomics.h"
#include "storage/procnumber.h"
#include "storage/spin.h"
#include "tcop/dest.h"

Include dependency graph for xlogwait.h:

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Go to the source code of this file.

Data Structures
struct	WaitLSNProcInfo
struct	WaitLSNState

Typedefs
typedef enum WaitLSNType	WaitLSNType
typedef struct WaitLSNProcInfo	WaitLSNProcInfo
typedef struct WaitLSNState	WaitLSNState

Enumerations
enum	WaitLSNResult { WAIT_LSN_RESULT_SUCCESS , WAIT_LSN_RESULT_NOT_IN_RECOVERY , WAIT_LSN_RESULT_TIMEOUT }
enum	WaitLSNType { WAIT_LSN_TYPE_REPLAY = 0 , WAIT_LSN_TYPE_FLUSH = 1 , WAIT_LSN_TYPE_COUNT = 2 }

Functions
Size	WaitLSNShmemSize (void)
void	WaitLSNShmemInit (void)
void	WaitLSNWakeup (WaitLSNType lsnType, XLogRecPtr currentLSN)
void	WaitLSNCleanup (void)
WaitLSNResult	WaitForLSN (WaitLSNType lsnType, XLogRecPtr targetLSN, int64 timeout)

Variables
PGDLLIMPORT WaitLSNState *	waitLSNState

Typedef Documentation

WaitLSNProcInfo

typedef struct WaitLSNProcInfo WaitLSNProcInfo

WaitLSNState

typedef struct WaitLSNState WaitLSNState

WaitLSNType

typedef enum WaitLSNType WaitLSNType

Enumeration Type Documentation

WaitLSNResult

enum WaitLSNResult

Enumerator
WAIT_LSN_RESULT_SUCCESS
WAIT_LSN_RESULT_NOT_IN_RECOVERY
WAIT_LSN_RESULT_TIMEOUT

Definition at line 25 of file xlogwait.h.

{
    WAIT_LSN_RESULT_SUCCESS,    /* Target LSN is reached */
    WAIT_LSN_RESULT_NOT_IN_RECOVERY,    /* Recovery ended before or during our
                                         * wait */
    WAIT_LSN_RESULT_TIMEOUT     /* Timeout occurred */
} WaitLSNResult;

WaitLSNType

enum WaitLSNType

Enumerator
WAIT_LSN_TYPE_REPLAY
WAIT_LSN_TYPE_FLUSH
WAIT_LSN_TYPE_COUNT

Definition at line 36 of file xlogwait.h.

{
    WAIT_LSN_TYPE_REPLAY = 0,   /* Waiting for replay on standby */
    WAIT_LSN_TYPE_FLUSH = 1,    /* Waiting for flush on primary */
    WAIT_LSN_TYPE_COUNT = 2
} WaitLSNType;

Function Documentation

WaitForLSN()

WaitLSNResult WaitForLSN	(	WaitLSNType	lsnType,
		XLogRecPtr	targetLSN,
		int64	timeout
	)

Definition at line 314 of file xlogwait.c.

{
    XLogRecPtr  currentLSN;
    TimestampTz endtime = 0;
    int         wake_events = WL_LATCH_SET | WL_POSTMASTER_DEATH;
 
    /* Shouldn't be called when shmem isn't initialized */
    Assert(waitLSNState);
 
    /* Should have a valid proc number */
    Assert(MyProcNumber >= 0 && MyProcNumber < MaxBackends);
 
    if (timeout > 0)
    {
        endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(), timeout);
        wake_events |= WL_TIMEOUT;
    }
 
    /*
     * Add our process to the waiters heap.  It might happen that target LSN
     * gets reached before we do.  The check at the beginning of the loop
     * below prevents the race condition.
     */
    addLSNWaiter(targetLSN, lsnType);
 
    for (;;)
    {
        int         rc;
        long        delay_ms = -1;
 
        if (lsnType == WAIT_LSN_TYPE_REPLAY)
            currentLSN = GetXLogReplayRecPtr(NULL);
        else
            currentLSN = GetFlushRecPtr(NULL);
 
        /* Check that recovery is still in-progress */
        if (lsnType == WAIT_LSN_TYPE_REPLAY && !RecoveryInProgress())
        {
            /*
             * Recovery was ended, but check if target LSN was already
             * reached.
             */
            deleteLSNWaiter(lsnType);
 
            if (PromoteIsTriggered() && targetLSN <= currentLSN)
                return WAIT_LSN_RESULT_SUCCESS;
            return WAIT_LSN_RESULT_NOT_IN_RECOVERY;
        }
        else
        {
            /* Check if the waited LSN has been reached */
            if (targetLSN <= currentLSN)
                break;
        }
 
        if (timeout > 0)
        {
            delay_ms = TimestampDifferenceMilliseconds(GetCurrentTimestamp(), endtime);
            if (delay_ms <= 0)
                break;
        }
 
        CHECK_FOR_INTERRUPTS();
 
        rc = WaitLatch(MyLatch, wake_events, delay_ms,
                       (lsnType == WAIT_LSN_TYPE_REPLAY) ? WAIT_EVENT_WAIT_FOR_WAL_REPLAY : WAIT_EVENT_WAIT_FOR_WAL_FLUSH);
 
        /*
         * Emergency bailout if postmaster has died.  This is to avoid the
         * necessity for manual cleanup of all postmaster children.
         */
        if (rc & WL_POSTMASTER_DEATH)
            ereport(FATAL,
                    errcode(ERRCODE_ADMIN_SHUTDOWN),
                    errmsg("terminating connection due to unexpected postmaster exit"),
                    errcontext("while waiting for LSN"));
 
        if (rc & WL_LATCH_SET)
            ResetLatch(MyLatch);
    }
 
    /*
     * Delete our process from the shared memory heap.  We might already be
     * deleted by the startup process.  The 'inHeap' flags prevents us from
     * the double deletion.
     */
    deleteLSNWaiter(lsnType);
 
    /*
     * If we didn't reach the target LSN, we must be exited by timeout.
     */
    if (targetLSN > currentLSN)
        return WAIT_LSN_RESULT_TIMEOUT;
 
    return WAIT_LSN_RESULT_SUCCESS;
}

References addLSNWaiter(), Assert(), CHECK_FOR_INTERRUPTS, deleteLSNWaiter(), ereport, errcode(), errcontext, errmsg(), FATAL, GetCurrentTimestamp(), GetFlushRecPtr(), GetXLogReplayRecPtr(), MaxBackends, MyLatch, MyProcNumber, PromoteIsTriggered(), RecoveryInProgress(), ResetLatch(), TimestampDifferenceMilliseconds(), TimestampTzPlusMilliseconds, WAIT_LSN_RESULT_NOT_IN_RECOVERY, WAIT_LSN_RESULT_SUCCESS, WAIT_LSN_RESULT_TIMEOUT, WAIT_LSN_TYPE_REPLAY, WaitLatch(), waitLSNState, WL_LATCH_SET, WL_POSTMASTER_DEATH, and WL_TIMEOUT.

Referenced by ExecWaitStmt().

WaitLSNCleanup()

void WaitLSNCleanup

(

void

)

Definition at line 290 of file xlogwait.c.

{
    if (waitLSNState)
    {
        /*
         * We do a fast-path check of the inHeap flag without the lock.  This
         * flag is set to true only by the process itself.  So, it's only
         * possible to get a false positive.  But that will be eliminated by a
         * recheck inside deleteLSNWaiter().
         */
        if (waitLSNState->procInfos[MyProcNumber].inHeap)
            deleteLSNWaiter(waitLSNState->procInfos[MyProcNumber].lsnType);
    }
}

References deleteLSNWaiter(), WaitLSNProcInfo::inHeap, WaitLSNProcInfo::lsnType, MyProcNumber, WaitLSNState::procInfos, and waitLSNState.

Referenced by AbortTransaction(), and ProcKill().

WaitLSNShmemInit()

void WaitLSNShmemInit

(

void

)

Definition at line 78 of file xlogwait.c.

{
    bool        found;
 
    waitLSNState = (WaitLSNState *) ShmemInitStruct("WaitLSNState",
                                                    WaitLSNShmemSize(),
                                                    &found);
    if (!found)
    {
        int         i;
 
        /* Initialize heaps and tracking */
        for (i = 0; i < WAIT_LSN_TYPE_COUNT; i++)
        {
            pg_atomic_init_u64(&waitLSNState->minWaitedLSN[i], PG_UINT64_MAX);
            pairingheap_initialize(&waitLSNState->waitersHeap[i], waitlsn_cmp, NULL);
        }
 
        /* Initialize process info array */
        memset(&waitLSNState->procInfos, 0,
               (MaxBackends + NUM_AUXILIARY_PROCS) * sizeof(WaitLSNProcInfo));
    }
}

References i, MaxBackends, WaitLSNState::minWaitedLSN, NUM_AUXILIARY_PROCS, pairingheap_initialize(), pg_atomic_init_u64(), PG_UINT64_MAX, WaitLSNState::procInfos, ShmemInitStruct(), WAIT_LSN_TYPE_COUNT, WaitLSNState::waitersHeap, waitlsn_cmp(), WaitLSNShmemSize(), and waitLSNState.

Referenced by CreateOrAttachShmemStructs().

WaitLSNShmemSize()

Size WaitLSNShmemSize

(

void

)

Definition at line 67 of file xlogwait.c.

{
    Size        size;
 
    size = offsetof(WaitLSNState, procInfos);
    size = add_size(size, mul_size(MaxBackends + NUM_AUXILIARY_PROCS, sizeof(WaitLSNProcInfo)));
    return size;
}

References add_size(), MaxBackends, mul_size(), NUM_AUXILIARY_PROCS, and WaitLSNState::procInfos.

Referenced by CalculateShmemSize(), and WaitLSNShmemInit().

WaitLSNWakeup()

void WaitLSNWakeup	(	WaitLSNType	lsnType,
		XLogRecPtr	currentLSN
	)

Definition at line 269 of file xlogwait.c.

{
    int         i = (int) lsnType;
 
    Assert(i >= 0 && i < (int) WAIT_LSN_TYPE_COUNT);
 
    /*
     * Fast path check.  Skip if currentLSN is InvalidXLogRecPtr, which means
     * "wake all waiters" (e.g., during promotion when recovery ends).
     */
    if (XLogRecPtrIsValid(currentLSN) &&
        pg_atomic_read_u64(&waitLSNState->minWaitedLSN[i]) > currentLSN)
        return;
 
    wakeupWaiters(lsnType, currentLSN);
}

References Assert(), i, WaitLSNState::minWaitedLSN, pg_atomic_read_u64(), WAIT_LSN_TYPE_COUNT, waitLSNState, wakeupWaiters(), and XLogRecPtrIsValid.

Referenced by PerformWalRecovery(), and StartupXLOG().

Variable Documentation

waitLSNState

PGDLLIMPORT WaitLSNState* waitLSNState

extern

Definition at line 63 of file xlogwait.c.

Referenced by addLSNWaiter(), deleteLSNWaiter(), PerformWalRecovery(), updateMinWaitedLSN(), WaitForLSN(), WaitLSNCleanup(), WaitLSNShmemInit(), WaitLSNWakeup(), and wakeupWaiters().