#include "postgres.h"
#include "access/slru.h"
#include "access/subtrans.h"
#include "access/transam.h"
#include "pg_trace.h"
#include "utils/snapmgr.h"

Include dependency graph for subtrans.c:

Defines
#define	SUBTRANS_XACTS_PER_PAGE (BLCKSZ / sizeof(TransactionId))
#define	TransactionIdToPage(xid) ((xid) / (TransactionId) SUBTRANS_XACTS_PER_PAGE)
#define	TransactionIdToEntry(xid) ((xid) % (TransactionId) SUBTRANS_XACTS_PER_PAGE)
#define	SubTransCtl (&SubTransCtlData)
Functions
static int	ZeroSUBTRANSPage (int pageno)
static bool	SubTransPagePrecedes (int page1, int page2)
void	SubTransSetParent (TransactionId xid, TransactionId parent, bool overwriteOK)
TransactionId	SubTransGetParent (TransactionId xid)
TransactionId	SubTransGetTopmostTransaction (TransactionId xid)
Size	SUBTRANSShmemSize (void)
void	SUBTRANSShmemInit (void)
void	BootStrapSUBTRANS (void)
void	StartupSUBTRANS (TransactionId oldestActiveXID)
void	ShutdownSUBTRANS (void)
void	CheckPointSUBTRANS (void)
void	ExtendSUBTRANS (TransactionId newestXact)
void	TruncateSUBTRANS (TransactionId oldestXact)
Variables
static SlruCtlData	SubTransCtlData

Define Documentation

#define SUBTRANS_XACTS_PER_PAGE (BLCKSZ / sizeof(TransactionId))

Definition at line 51 of file subtrans.c.

#define SubTransCtl (&SubTransCtlData)

Definition at line 62 of file subtrans.c.

Referenced by BootStrapSUBTRANS(), CheckPointSUBTRANS(), ShutdownSUBTRANS(), SubTransGetParent(), SubTransSetParent(), SUBTRANSShmemInit(), TruncateSUBTRANS(), and ZeroSUBTRANSPage().

#define TransactionIdToEntry ( xid ) ((xid) % (TransactionId) SUBTRANS_XACTS_PER_PAGE)

Definition at line 54 of file subtrans.c.

Referenced by ExtendSUBTRANS(), SubTransGetParent(), and SubTransSetParent().

#define TransactionIdToPage ( xid ) ((xid) / (TransactionId) SUBTRANS_XACTS_PER_PAGE)

Definition at line 53 of file subtrans.c.

Referenced by ExtendSUBTRANS(), StartupSUBTRANS(), SubTransGetParent(), SubTransSetParent(), and TruncateSUBTRANS().

Function Documentation

void BootStrapSUBTRANS ( void )

Definition at line 198 of file subtrans.c.

References Assert, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), SimpleLruWritePage(), SubtransControlLock, SubTransCtl, and ZeroSUBTRANSPage().

Referenced by BootStrapXLOG().

{
    int         slotno;

    LWLockAcquire(SubtransControlLock, LW_EXCLUSIVE);

    /* Create and zero the first page of the subtrans log */
    slotno = ZeroSUBTRANSPage(0);

    /* Make sure it's written out */
    SimpleLruWritePage(SubTransCtl, slotno);
    Assert(!SubTransCtl->shared->page_dirty[slotno]);

    LWLockRelease(SubtransControlLock);
}

void CheckPointSUBTRANS ( void )

Definition at line 283 of file subtrans.c.

References SimpleLruFlush(), and SubTransCtl.

Referenced by CheckPointGuts().

{
    /*
     * Flush dirty SUBTRANS pages to disk
     *
     * This is not actually necessary from a correctness point of view. We do
     * it merely to improve the odds that writing of dirty pages is done by
     * the checkpoint process and not by backends.
     */
    TRACE_POSTGRESQL_SUBTRANS_CHECKPOINT_START(true);
    SimpleLruFlush(SubTransCtl, true);
    TRACE_POSTGRESQL_SUBTRANS_CHECKPOINT_DONE(true);
}

void ExtendSUBTRANS ( TransactionId newestXact )

Definition at line 307 of file subtrans.c.

References FirstNormalTransactionId, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), SubtransControlLock, TransactionIdEquals, TransactionIdToEntry, TransactionIdToPage, and ZeroSUBTRANSPage().

Referenced by GetNewTransactionId(), and RecordKnownAssignedTransactionIds().

{
    int         pageno;

    /*
     * No work except at first XID of a page.  But beware: just after
     * wraparound, the first XID of page zero is FirstNormalTransactionId.
     */
    if (TransactionIdToEntry(newestXact) != 0 &&
        !TransactionIdEquals(newestXact, FirstNormalTransactionId))
        return;

    pageno = TransactionIdToPage(newestXact);

    LWLockAcquire(SubtransControlLock, LW_EXCLUSIVE);

    /* Zero the page */
    ZeroSUBTRANSPage(pageno);

    LWLockRelease(SubtransControlLock);
}

void ShutdownSUBTRANS ( void )

Definition at line 266 of file subtrans.c.

References SimpleLruFlush(), and SubTransCtl.

Referenced by ShutdownXLOG().

{
    /*
     * Flush dirty SUBTRANS pages to disk
     *
     * This is not actually necessary from a correctness point of view. We do
     * it merely as a debugging aid.
     */
    TRACE_POSTGRESQL_SUBTRANS_CHECKPOINT_START(false);
    SimpleLruFlush(SubTransCtl, false);
    TRACE_POSTGRESQL_SUBTRANS_CHECKPOINT_DONE(false);
}

void StartupSUBTRANS ( TransactionId oldestActiveXID )

Definition at line 236 of file subtrans.c.

References LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), VariableCacheData::nextXid, ShmemVariableCache, SubtransControlLock, TransactionIdToPage, and ZeroSUBTRANSPage().

Referenced by StartupXLOG().

{
    int         startPage;
    int         endPage;

    /*
     * Since we don't expect pg_subtrans to be valid across crashes, we
     * initialize the currently-active page(s) to zeroes during startup.
     * Whenever we advance into a new page, ExtendSUBTRANS will likewise zero
     * the new page without regard to whatever was previously on disk.
     */
    LWLockAcquire(SubtransControlLock, LW_EXCLUSIVE);

    startPage = TransactionIdToPage(oldestActiveXID);
    endPage = TransactionIdToPage(ShmemVariableCache->nextXid);

    while (startPage != endPage)
    {
        (void) ZeroSUBTRANSPage(startPage);
        startPage++;
    }
    (void) ZeroSUBTRANSPage(startPage);

    LWLockRelease(SubtransControlLock);
}

TransactionId SubTransGetParent ( TransactionId xid )

Definition at line 105 of file subtrans.c.

References Assert, LWLockRelease(), SimpleLruReadPage_ReadOnly(), SubtransControlLock, SubTransCtl, TransactionIdFollowsOrEquals(), TransactionIdIsNormal, TransactionIdToEntry, TransactionIdToPage, and TransactionXmin.

Referenced by ConditionalXactLockTableWait(), SubTransGetTopmostTransaction(), TransactionIdDidAbort(), TransactionIdDidCommit(), and XactLockTableWait().

{
    int         pageno = TransactionIdToPage(xid);
    int         entryno = TransactionIdToEntry(xid);
    int         slotno;
    TransactionId *ptr;
    TransactionId parent;

    /* Can't ask about stuff that might not be around anymore */
    Assert(TransactionIdFollowsOrEquals(xid, TransactionXmin));

    /* Bootstrap and frozen XIDs have no parent */
    if (!TransactionIdIsNormal(xid))
        return InvalidTransactionId;

    /* lock is acquired by SimpleLruReadPage_ReadOnly */

    slotno = SimpleLruReadPage_ReadOnly(SubTransCtl, pageno, xid);
    ptr = (TransactionId *) SubTransCtl->shared->page_buffer[slotno];
    ptr += entryno;

    parent = *ptr;

    LWLockRelease(SubtransControlLock);

    return parent;
}

TransactionId SubTransGetTopmostTransaction ( TransactionId xid )

Definition at line 146 of file subtrans.c.

References Assert, SubTransGetParent(), TransactionIdFollowsOrEquals(), TransactionIdIsValid, TransactionIdPrecedes(), and TransactionXmin.

Referenced by CheckForSerializableConflictOut(), PredicateLockTuple(), TransactionIdIsInProgress(), and XidInMVCCSnapshot().

{
    TransactionId parentXid = xid,
                previousXid = xid;

    /* Can't ask about stuff that might not be around anymore */
    Assert(TransactionIdFollowsOrEquals(xid, TransactionXmin));

    while (TransactionIdIsValid(parentXid))
    {
        previousXid = parentXid;
        if (TransactionIdPrecedes(parentXid, TransactionXmin))
            break;
        parentXid = SubTransGetParent(parentXid);
    }

    Assert(TransactionIdIsValid(previousXid));

    return previousXid;
}

static bool SubTransPagePrecedes	(	int	page1,
		int	page2
	)			`[static]`

Definition at line 361 of file subtrans.c.

References TransactionIdPrecedes().

{
    TransactionId xid1;
    TransactionId xid2;

    xid1 = ((TransactionId) page1) * SUBTRANS_XACTS_PER_PAGE;
    xid1 += FirstNormalTransactionId;
    xid2 = ((TransactionId) page2) * SUBTRANS_XACTS_PER_PAGE;
    xid2 += FirstNormalTransactionId;

    return TransactionIdPrecedes(xid1, xid2);
}

void SubTransSetParent	(	TransactionId	xid,
		TransactionId	parent,
		bool	overwriteOK
	)

Definition at line 75 of file subtrans.c.

References Assert, InvalidTransactionId, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), SimpleLruReadPage(), SubtransControlLock, SubTransCtl, TransactionIdIsValid, TransactionIdToEntry, and TransactionIdToPage.

Referenced by AssignTransactionId(), ProcArrayApplyXidAssignment(), RecoverPreparedTransactions(), and StandbyRecoverPreparedTransactions().

{
    int         pageno = TransactionIdToPage(xid);
    int         entryno = TransactionIdToEntry(xid);
    int         slotno;
    TransactionId *ptr;

    Assert(TransactionIdIsValid(parent));

    LWLockAcquire(SubtransControlLock, LW_EXCLUSIVE);

    slotno = SimpleLruReadPage(SubTransCtl, pageno, true, xid);
    ptr = (TransactionId *) SubTransCtl->shared->page_buffer[slotno];
    ptr += entryno;

    /* Current state should be 0 */
    Assert(*ptr == InvalidTransactionId ||
           (*ptr == parent && overwriteOK));

    *ptr = parent;

    SubTransCtl->shared->page_dirty[slotno] = true;

    LWLockRelease(SubtransControlLock);
}

void SUBTRANSShmemInit ( void )

Definition at line 178 of file subtrans.c.

References NUM_SUBTRANS_BUFFERS, SimpleLruInit(), SubtransControlLock, and SubTransCtl.

Referenced by CreateSharedMemoryAndSemaphores().

{
    SubTransCtl->PagePrecedes = SubTransPagePrecedes;
    SimpleLruInit(SubTransCtl, "SUBTRANS Ctl", NUM_SUBTRANS_BUFFERS, 0,
                  SubtransControlLock, "pg_subtrans");
    /* Override default assumption that writes should be fsync'd */
    SubTransCtl->do_fsync = false;
}

Size SUBTRANSShmemSize ( void )

Definition at line 172 of file subtrans.c.

References NUM_SUBTRANS_BUFFERS, and SimpleLruShmemSize().

Referenced by CreateSharedMemoryAndSemaphores().

{
    return SimpleLruShmemSize(NUM_SUBTRANS_BUFFERS, 0);
}

void TruncateSUBTRANS ( TransactionId oldestXact )

Definition at line 337 of file subtrans.c.

References SimpleLruTruncate(), SubTransCtl, and TransactionIdToPage.

Referenced by CreateCheckPoint(), and CreateRestartPoint().

{
    int         cutoffPage;

    /*
     * The cutoff point is the start of the segment containing oldestXact. We
     * pass the *page* containing oldestXact to SimpleLruTruncate.
     */
    cutoffPage = TransactionIdToPage(oldestXact);

    SimpleLruTruncate(SubTransCtl, cutoffPage);
}

static int ZeroSUBTRANSPage ( int pageno ) [static]

Definition at line 223 of file subtrans.c.

References SimpleLruZeroPage(), and SubTransCtl.

Referenced by BootStrapSUBTRANS(), ExtendSUBTRANS(), and StartupSUBTRANS().

{
    return SimpleLruZeroPage(SubTransCtl, pageno);
}

Variable Documentation

SlruCtlData SubTransCtlData [static]

Definition at line 60 of file subtrans.c.

Header And Logo

subtrans.c File Reference

Defines

Functions

Variables

Define Documentation

Function Documentation

Variable Documentation