hio.c File Reference

#include "postgres.h"
#include "access/heapam.h"
#include "access/hio.h"
#include "access/htup_details.h"
#include "access/visibilitymap.h"
#include "storage/bufmgr.h"
#include "storage/freespace.h"
#include "storage/lmgr.h"

Include dependency graph for hio.c:

Go to the source code of this file.

Macros
#define	MAX_BUFFERS_TO_EXTEND_BY   64

Functions
void	RelationPutHeapTuple (Relation relation, Buffer buffer, HeapTuple tuple, bool token)
static Buffer	ReadBufferBI (Relation relation, BlockNumber targetBlock, ReadBufferMode mode, BulkInsertState bistate)
static bool	GetVisibilityMapPins (Relation relation, Buffer buffer1, Buffer buffer2, BlockNumber block1, BlockNumber block2, Buffer *vmbuffer1, Buffer *vmbuffer2)
static Buffer	RelationAddBlocks (Relation relation, BulkInsertState bistate, int num_pages, bool use_fsm, bool *did_unlock)
Buffer	RelationGetBufferForTuple (Relation relation, Size len, Buffer otherBuffer, int options, BulkInsertState bistate, Buffer *vmbuffer, Buffer *vmbuffer_other, int num_pages)

Macro Definition Documentation

MAX_BUFFERS_TO_EXTEND_BY

#define MAX_BUFFERS_TO_EXTEND_BY   64

Function Documentation

GetVisibilityMapPins()

static bool GetVisibilityMapPins ( Relation  relation, Buffer  buffer1, Buffer  buffer2, BlockNumber  block1, BlockNumber  block2, Buffer *  vmbuffer1, Buffer *  vmbuffer2  )

static

Definition at line 138 of file hio.c.

{
    bool        need_to_pin_buffer1;
    bool        need_to_pin_buffer2;
    bool        released_locks = false;
 
    /*
     * Swap buffers around to handle case of a single block/buffer, and to
     * handle if lock ordering rules require to lock block2 first.
     */
    if (!BufferIsValid(buffer1) ||
        (BufferIsValid(buffer2) && block1 > block2))
    {
        Buffer      tmpbuf = buffer1;
        Buffer     *tmpvmbuf = vmbuffer1;
        BlockNumber tmpblock = block1;
 
        buffer1 = buffer2;
        vmbuffer1 = vmbuffer2;
        block1 = block2;
 
        buffer2 = tmpbuf;
        vmbuffer2 = tmpvmbuf;
        block2 = tmpblock;
    }
 
    Assert(BufferIsValid(buffer1));
    Assert(buffer2 == InvalidBuffer || block1 <= block2);
 
    while (1)
    {
        /* Figure out which pins we need but don't have. */
        need_to_pin_buffer1 = PageIsAllVisible(BufferGetPage(buffer1))
            && !visibilitymap_pin_ok(block1, *vmbuffer1);
        need_to_pin_buffer2 = buffer2 != InvalidBuffer
            && PageIsAllVisible(BufferGetPage(buffer2))
            && !visibilitymap_pin_ok(block2, *vmbuffer2);
        if (!need_to_pin_buffer1 && !need_to_pin_buffer2)
            break;
 
        /* We must unlock both buffers before doing any I/O. */
        released_locks = true;
        LockBuffer(buffer1, BUFFER_LOCK_UNLOCK);
        if (buffer2 != InvalidBuffer && buffer2 != buffer1)
            LockBuffer(buffer2, BUFFER_LOCK_UNLOCK);
 
        /* Get pins. */
        if (need_to_pin_buffer1)
            visibilitymap_pin(relation, block1, vmbuffer1);
        if (need_to_pin_buffer2)
            visibilitymap_pin(relation, block2, vmbuffer2);
 
        /* Relock buffers. */
        LockBuffer(buffer1, BUFFER_LOCK_EXCLUSIVE);
        if (buffer2 != InvalidBuffer && buffer2 != buffer1)
            LockBuffer(buffer2, BUFFER_LOCK_EXCLUSIVE);
 
        /*
         * If there are two buffers involved and we pinned just one of them,
         * it's possible that the second one became all-visible while we were
         * busy pinning the first one.  If it looks like that's a possible
         * scenario, we'll need to make a second pass through this loop.
         */
        if (buffer2 == InvalidBuffer || buffer1 == buffer2
            || (need_to_pin_buffer1 && need_to_pin_buffer2))
            break;
    }
 
    return released_locks;
}

References Assert(), BUFFER_LOCK_EXCLUSIVE, BUFFER_LOCK_UNLOCK, BufferGetPage(), BufferIsValid(), InvalidBuffer, LockBuffer(), PageIsAllVisible(), tmpbuf, visibilitymap_pin(), and visibilitymap_pin_ok().

Referenced by RelationGetBufferForTuple().

ReadBufferBI()

static Buffer ReadBufferBI ( Relation  relation, BlockNumber  targetBlock, ReadBufferMode  mode, BulkInsertState  bistate  )

static

Definition at line 86 of file hio.c.

{
    Buffer      buffer;
 
    /* If not bulk-insert, exactly like ReadBuffer */
    if (!bistate)
        return ReadBufferExtended(relation, MAIN_FORKNUM, targetBlock,
                                  mode, NULL);
 
    /* If we have the desired block already pinned, re-pin and return it */
    if (bistate->current_buf != InvalidBuffer)
    {
        if (BufferGetBlockNumber(bistate->current_buf) == targetBlock)
        {
            /*
             * Currently the LOCK variants are only used for extending
             * relation, which should never reach this branch.
             */
            Assert(mode != RBM_ZERO_AND_LOCK &&
                   mode != RBM_ZERO_AND_CLEANUP_LOCK);
 
            IncrBufferRefCount(bistate->current_buf);
            return bistate->current_buf;
        }
        /* ... else drop the old buffer */
        ReleaseBuffer(bistate->current_buf);
        bistate->current_buf = InvalidBuffer;
    }
 
    /* Perform a read using the buffer strategy */
    buffer = ReadBufferExtended(relation, MAIN_FORKNUM, targetBlock,
                                mode, bistate->strategy);
 
    /* Save the selected block as target for future inserts */
    IncrBufferRefCount(buffer);
    bistate->current_buf = buffer;
 
    return buffer;
}

References Assert(), BufferGetBlockNumber(), BulkInsertStateData::current_buf, IncrBufferRefCount(), InvalidBuffer, MAIN_FORKNUM, mode, RBM_ZERO_AND_CLEANUP_LOCK, RBM_ZERO_AND_LOCK, ReadBufferExtended(), ReleaseBuffer(), and BulkInsertStateData::strategy.

Referenced by RelationGetBufferForTuple().

RelationAddBlocks()

static Buffer RelationAddBlocks ( Relation  relation, BulkInsertState  bistate, int  num_pages, bool  use_fsm, bool *  did_unlock  )

static

Definition at line 236 of file hio.c.

{
#define MAX_BUFFERS_TO_EXTEND_BY 64
    Buffer      victim_buffers[MAX_BUFFERS_TO_EXTEND_BY];
    BlockNumber first_block = InvalidBlockNumber;
    BlockNumber last_block = InvalidBlockNumber;
    uint32      extend_by_pages;
    uint32      not_in_fsm_pages;
    Buffer      buffer;
    Page        page;
 
    /*
     * Determine by how many pages to try to extend by.
     */
    if (bistate == NULL && !use_fsm)
    {
        /*
         * If we have neither bistate, nor can use the FSM, we can't bulk
         * extend - there'd be no way to find the additional pages.
         */
        extend_by_pages = 1;
    }
    else
    {
        uint32      waitcount;
 
        /*
         * Try to extend at least by the number of pages the caller needs. We
         * can remember the additional pages (either via FSM or bistate).
         */
        extend_by_pages = num_pages;
 
        if (!RELATION_IS_LOCAL(relation))
            waitcount = RelationExtensionLockWaiterCount(relation);
        else
            waitcount = 0;
 
        /*
         * Multiply the number of pages to extend by the number of waiters. Do
         * this even if we're not using the FSM, as it still relieves
         * contention, by deferring the next time this backend needs to
         * extend. In that case the extended pages will be found via
         * bistate->next_free.
         */
        extend_by_pages += extend_by_pages * waitcount;
 
        /* ---
         * If we previously extended using the same bistate, it's very likely
         * we'll extend some more. Try to extend by as many pages as
         * before. This can be important for performance for several reasons,
         * including:
         *
         * - It prevents mdzeroextend() switching between extending the
         *   relation in different ways, which is inefficient for some
         *   filesystems.
         *
         * - Contention is often intermittent. Even if we currently don't see
         *   other waiters (see above), extending by larger amounts can
         *   prevent future contention.
         * ---
         */
        if (bistate)
            extend_by_pages = Max(extend_by_pages, bistate->already_extended_by);
 
        /*
         * Can't extend by more than MAX_BUFFERS_TO_EXTEND_BY, we need to pin
         * them all concurrently.
         */
        extend_by_pages = Min(extend_by_pages, MAX_BUFFERS_TO_EXTEND_BY);
    }
 
    /*
     * How many of the extended pages should be entered into the FSM?
     *
     * If we have a bistate, only enter pages that we don't need ourselves
     * into the FSM.  Otherwise every other backend will immediately try to
     * use the pages this backend needs for itself, causing unnecessary
     * contention.  If we don't have a bistate, we can't avoid the FSM.
     *
     * Never enter the page returned into the FSM, we'll immediately use it.
     */
    if (num_pages > 1 && bistate == NULL)
        not_in_fsm_pages = 1;
    else
        not_in_fsm_pages = num_pages;
 
    /* prepare to put another buffer into the bistate */
    if (bistate && bistate->current_buf != InvalidBuffer)
    {
        ReleaseBuffer(bistate->current_buf);
        bistate->current_buf = InvalidBuffer;
    }
 
    /*
     * Extend the relation. We ask for the first returned page to be locked,
     * so that we are sure that nobody has inserted into the page
     * concurrently.
     *
     * With the current MAX_BUFFERS_TO_EXTEND_BY there's no danger of
     * [auto]vacuum trying to truncate later pages as REL_TRUNCATE_MINIMUM is
     * way larger.
     */
    first_block = ExtendBufferedRelBy(BMR_REL(relation), MAIN_FORKNUM,
                                      bistate ? bistate->strategy : NULL,
                                      EB_LOCK_FIRST,
                                      extend_by_pages,
                                      victim_buffers,
                                      &extend_by_pages);
    buffer = victim_buffers[0]; /* the buffer the function will return */
    last_block = first_block + (extend_by_pages - 1);
    Assert(first_block == BufferGetBlockNumber(buffer));
 
    /*
     * Relation is now extended. Initialize the page. We do this here, before
     * potentially releasing the lock on the page, because it allows us to
     * double check that the page contents are empty (this should never
     * happen, but if it does we don't want to risk wiping out valid data).
     */
    page = BufferGetPage(buffer);
    if (!PageIsNew(page))
        elog(ERROR, "page %u of relation \"%s\" should be empty but is not",
             first_block,
             RelationGetRelationName(relation));
 
    PageInit(page, BufferGetPageSize(buffer), 0);
    MarkBufferDirty(buffer);
 
    /*
     * If we decided to put pages into the FSM, release the buffer lock (but
     * not pin), we don't want to do IO while holding a buffer lock. This will
     * necessitate a bit more extensive checking in our caller.
     */
    if (use_fsm && not_in_fsm_pages < extend_by_pages)
    {
        LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
        *did_unlock = true;
    }
    else
        *did_unlock = false;
 
    /*
     * Relation is now extended. Release pins on all buffers, except for the
     * first (which we'll return).  If we decided to put pages into the FSM,
     * we can do that as part of the same loop.
     */
    for (uint32 i = 1; i < extend_by_pages; i++)
    {
        BlockNumber curBlock = first_block + i;
 
        Assert(curBlock == BufferGetBlockNumber(victim_buffers[i]));
        Assert(BlockNumberIsValid(curBlock));
 
        ReleaseBuffer(victim_buffers[i]);
 
        if (use_fsm && i >= not_in_fsm_pages)
        {
            Size        freespace = BufferGetPageSize(victim_buffers[i]) -
                SizeOfPageHeaderData;
 
            RecordPageWithFreeSpace(relation, curBlock, freespace);
        }
    }
 
    if (use_fsm && not_in_fsm_pages < extend_by_pages)
    {
        BlockNumber first_fsm_block = first_block + not_in_fsm_pages;
 
        FreeSpaceMapVacuumRange(relation, first_fsm_block, last_block);
    }
 
    if (bistate)
    {
        /*
         * Remember the additional pages we extended by, so we later can use
         * them without looking into the FSM.
         */
        if (extend_by_pages > 1)
        {
            bistate->next_free = first_block + 1;
            bistate->last_free = last_block;
        }
        else
        {
            bistate->next_free = InvalidBlockNumber;
            bistate->last_free = InvalidBlockNumber;
        }
 
        /* maintain bistate->current_buf */
        IncrBufferRefCount(buffer);
        bistate->current_buf = buffer;
        bistate->already_extended_by += extend_by_pages;
    }
 
    return buffer;
#undef MAX_BUFFERS_TO_EXTEND_BY
}

References BulkInsertStateData::already_extended_by, Assert(), BlockNumberIsValid(), BMR_REL, BUFFER_LOCK_UNLOCK, BufferGetBlockNumber(), BufferGetPage(), BufferGetPageSize(), BulkInsertStateData::current_buf, EB_LOCK_FIRST, elog, ERROR, ExtendBufferedRelBy(), FreeSpaceMapVacuumRange(), i, IncrBufferRefCount(), InvalidBlockNumber, InvalidBuffer, BulkInsertStateData::last_free, LockBuffer(), MAIN_FORKNUM, MarkBufferDirty(), Max, MAX_BUFFERS_TO_EXTEND_BY, Min, BulkInsertStateData::next_free, PageInit(), PageIsNew(), RecordPageWithFreeSpace(), RELATION_IS_LOCAL, RelationExtensionLockWaiterCount(), RelationGetRelationName, ReleaseBuffer(), SizeOfPageHeaderData, and BulkInsertStateData::strategy.

Referenced by RelationGetBufferForTuple().

RelationGetBufferForTuple()

Buffer RelationGetBufferForTuple	(	Relation	relation,
		Size	len,
		Buffer	otherBuffer,
		int	options,
		BulkInsertState	bistate,
		Buffer *	vmbuffer,
		Buffer *	vmbuffer_other,
		int	num_pages
	)

Definition at line 500 of file hio.c.

{
    bool        use_fsm = !(options & HEAP_INSERT_SKIP_FSM);
    Buffer      buffer = InvalidBuffer;
    Page        page;
    Size        nearlyEmptyFreeSpace,
                pageFreeSpace = 0,
                saveFreeSpace = 0,
                targetFreeSpace = 0;
    BlockNumber targetBlock,
                otherBlock;
    bool        unlockedTargetBuffer;
    bool        recheckVmPins;
 
    len = MAXALIGN(len);        /* be conservative */
 
    /* if the caller doesn't know by how many pages to extend, extend by 1 */
    if (num_pages <= 0)
        num_pages = 1;
 
    /* Bulk insert is not supported for updates, only inserts. */
    Assert(otherBuffer == InvalidBuffer || !bistate);
 
    /*
     * If we're gonna fail for oversize tuple, do it right away
     */
    if (len > MaxHeapTupleSize)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("row is too big: size %zu, maximum size %zu",
                        len, MaxHeapTupleSize)));
 
    /* Compute desired extra freespace due to fillfactor option */
    saveFreeSpace = RelationGetTargetPageFreeSpace(relation,
                                                   HEAP_DEFAULT_FILLFACTOR);
 
    /*
     * Since pages without tuples can still have line pointers, we consider
     * pages "empty" when the unavailable space is slight.  This threshold is
     * somewhat arbitrary, but it should prevent most unnecessary relation
     * extensions while inserting large tuples into low-fillfactor tables.
     */
    nearlyEmptyFreeSpace = MaxHeapTupleSize -
        (MaxHeapTuplesPerPage / 8 * sizeof(ItemIdData));
    if (len + saveFreeSpace > nearlyEmptyFreeSpace)
        targetFreeSpace = Max(len, nearlyEmptyFreeSpace);
    else
        targetFreeSpace = len + saveFreeSpace;
 
    if (otherBuffer != InvalidBuffer)
        otherBlock = BufferGetBlockNumber(otherBuffer);
    else
        otherBlock = InvalidBlockNumber;    /* just to keep compiler quiet */
 
    /*
     * We first try to put the tuple on the same page we last inserted a tuple
     * on, as cached in the BulkInsertState or relcache entry.  If that
     * doesn't work, we ask the Free Space Map to locate a suitable page.
     * Since the FSM's info might be out of date, we have to be prepared to
     * loop around and retry multiple times. (To ensure this isn't an infinite
     * loop, we must update the FSM with the correct amount of free space on
     * each page that proves not to be suitable.)  If the FSM has no record of
     * a page with enough free space, we give up and extend the relation.
     *
     * When use_fsm is false, we either put the tuple onto the existing target
     * page or extend the relation.
     */
    if (bistate && bistate->current_buf != InvalidBuffer)
        targetBlock = BufferGetBlockNumber(bistate->current_buf);
    else
        targetBlock = RelationGetTargetBlock(relation);
 
    if (targetBlock == InvalidBlockNumber && use_fsm)
    {
        /*
         * We have no cached target page, so ask the FSM for an initial
         * target.
         */
        targetBlock = GetPageWithFreeSpace(relation, targetFreeSpace);
    }
 
    /*
     * If the FSM knows nothing of the rel, try the last page before we give
     * up and extend.  This avoids one-tuple-per-page syndrome during
     * bootstrapping or in a recently-started system.
     */
    if (targetBlock == InvalidBlockNumber)
    {
        BlockNumber nblocks = RelationGetNumberOfBlocks(relation);
 
        if (nblocks > 0)
            targetBlock = nblocks - 1;
    }
 
loop:
    while (targetBlock != InvalidBlockNumber)
    {
        /*
         * Read and exclusive-lock the target block, as well as the other
         * block if one was given, taking suitable care with lock ordering and
         * the possibility they are the same block.
         *
         * If the page-level all-visible flag is set, caller will need to
         * clear both that and the corresponding visibility map bit.  However,
         * by the time we return, we'll have x-locked the buffer, and we don't
         * want to do any I/O while in that state.  So we check the bit here
         * before taking the lock, and pin the page if it appears necessary.
         * Checking without the lock creates a risk of getting the wrong
         * answer, so we'll have to recheck after acquiring the lock.
         */
        if (otherBuffer == InvalidBuffer)
        {
            /* easy case */
            buffer = ReadBufferBI(relation, targetBlock, RBM_NORMAL, bistate);
            if (PageIsAllVisible(BufferGetPage(buffer)))
                visibilitymap_pin(relation, targetBlock, vmbuffer);
 
            /*
             * If the page is empty, pin vmbuffer to set all_frozen bit later.
             */
            if ((options & HEAP_INSERT_FROZEN) &&
                (PageGetMaxOffsetNumber(BufferGetPage(buffer)) == 0))
                visibilitymap_pin(relation, targetBlock, vmbuffer);
 
            LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
        }
        else if (otherBlock == targetBlock)
        {
            /* also easy case */
            buffer = otherBuffer;
            if (PageIsAllVisible(BufferGetPage(buffer)))
                visibilitymap_pin(relation, targetBlock, vmbuffer);
            LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
        }
        else if (otherBlock < targetBlock)
        {
            /* lock other buffer first */
            buffer = ReadBuffer(relation, targetBlock);
            if (PageIsAllVisible(BufferGetPage(buffer)))
                visibilitymap_pin(relation, targetBlock, vmbuffer);
            LockBuffer(otherBuffer, BUFFER_LOCK_EXCLUSIVE);
            LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
        }
        else
        {
            /* lock target buffer first */
            buffer = ReadBuffer(relation, targetBlock);
            if (PageIsAllVisible(BufferGetPage(buffer)))
                visibilitymap_pin(relation, targetBlock, vmbuffer);
            LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
            LockBuffer(otherBuffer, BUFFER_LOCK_EXCLUSIVE);
        }
 
        /*
         * We now have the target page (and the other buffer, if any) pinned
         * and locked.  However, since our initial PageIsAllVisible checks
         * were performed before acquiring the lock, the results might now be
         * out of date, either for the selected victim buffer, or for the
         * other buffer passed by the caller.  In that case, we'll need to
         * give up our locks, go get the pin(s) we failed to get earlier, and
         * re-lock.  That's pretty painful, but hopefully shouldn't happen
         * often.
         *
         * Note that there's a small possibility that we didn't pin the page
         * above but still have the correct page pinned anyway, either because
         * we've already made a previous pass through this loop, or because
         * caller passed us the right page anyway.
         *
         * Note also that it's possible that by the time we get the pin and
         * retake the buffer locks, the visibility map bit will have been
         * cleared by some other backend anyway.  In that case, we'll have
         * done a bit of extra work for no gain, but there's no real harm
         * done.
         */
        GetVisibilityMapPins(relation, buffer, otherBuffer,
                             targetBlock, otherBlock, vmbuffer,
                             vmbuffer_other);
 
        /*
         * Now we can check to see if there's enough free space here. If so,
         * we're done.
         */
        page = BufferGetPage(buffer);
 
        /*
         * If necessary initialize page, it'll be used soon.  We could avoid
         * dirtying the buffer here, and rely on the caller to do so whenever
         * it puts a tuple onto the page, but there seems not much benefit in
         * doing so.
         */
        if (PageIsNew(page))
        {
            PageInit(page, BufferGetPageSize(buffer), 0);
            MarkBufferDirty(buffer);
        }
 
        pageFreeSpace = PageGetHeapFreeSpace(page);
        if (targetFreeSpace <= pageFreeSpace)
        {
            /* use this page as future insert target, too */
            RelationSetTargetBlock(relation, targetBlock);
            return buffer;
        }
 
        /*
         * Not enough space, so we must give up our page locks and pin (if
         * any) and prepare to look elsewhere.  We don't care which order we
         * unlock the two buffers in, so this can be slightly simpler than the
         * code above.
         */
        LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
        if (otherBuffer == InvalidBuffer)
            ReleaseBuffer(buffer);
        else if (otherBlock != targetBlock)
        {
            LockBuffer(otherBuffer, BUFFER_LOCK_UNLOCK);
            ReleaseBuffer(buffer);
        }
 
        /* Is there an ongoing bulk extension? */
        if (bistate && bistate->next_free != InvalidBlockNumber)
        {
            Assert(bistate->next_free <= bistate->last_free);
 
            /*
             * We bulk extended the relation before, and there are still some
             * unused pages from that extension, so we don't need to look in
             * the FSM for a new page. But do record the free space from the
             * last page, somebody might insert narrower tuples later.
             */
            if (use_fsm)
                RecordPageWithFreeSpace(relation, targetBlock, pageFreeSpace);
 
            targetBlock = bistate->next_free;
            if (bistate->next_free >= bistate->last_free)
            {
                bistate->next_free = InvalidBlockNumber;
                bistate->last_free = InvalidBlockNumber;
            }
            else
                bistate->next_free++;
        }
        else if (!use_fsm)
        {
            /* Without FSM, always fall out of the loop and extend */
            break;
        }
        else
        {
            /*
             * Update FSM as to condition of this page, and ask for another
             * page to try.
             */
            targetBlock = RecordAndGetPageWithFreeSpace(relation,
                                                        targetBlock,
                                                        pageFreeSpace,
                                                        targetFreeSpace);
        }
    }
 
    /* Have to extend the relation */
    buffer = RelationAddBlocks(relation, bistate, num_pages, use_fsm,
                               &unlockedTargetBuffer);
 
    targetBlock = BufferGetBlockNumber(buffer);
    page = BufferGetPage(buffer);
 
    /*
     * The page is empty, pin vmbuffer to set all_frozen bit. We don't want to
     * do IO while the buffer is locked, so we unlock the page first if IO is
     * needed (necessitating checks below).
     */
    if (options & HEAP_INSERT_FROZEN)
    {
        Assert(PageGetMaxOffsetNumber(page) == 0);
 
        if (!visibilitymap_pin_ok(targetBlock, *vmbuffer))
        {
            if (!unlockedTargetBuffer)
                LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
            unlockedTargetBuffer = true;
            visibilitymap_pin(relation, targetBlock, vmbuffer);
        }
    }
 
    /*
     * Reacquire locks if necessary.
     *
     * If the target buffer was unlocked above, or is unlocked while
     * reacquiring the lock on otherBuffer below, it's unlikely, but possible,
     * that another backend used space on this page. We check for that below,
     * and retry if necessary.
     */
    recheckVmPins = false;
    if (unlockedTargetBuffer)
    {
        /* released lock on target buffer above */
        if (otherBuffer != InvalidBuffer)
            LockBuffer(otherBuffer, BUFFER_LOCK_EXCLUSIVE);
        LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
        recheckVmPins = true;
    }
    else if (otherBuffer != InvalidBuffer)
    {
        /*
         * We did not release the target buffer, and otherBuffer is valid,
         * need to lock the other buffer. It's guaranteed to be of a lower
         * page number than the new page.  To conform with the deadlock
         * prevent rules, we ought to lock otherBuffer first, but that would
         * give other backends a chance to put tuples on our page. To reduce
         * the likelihood of that, attempt to lock the other buffer
         * conditionally, that's very likely to work.
         *
         * Alternatively, we could acquire the lock on otherBuffer before
         * extending the relation, but that'd require holding the lock while
         * performing IO, which seems worse than an unlikely retry.
         */
        Assert(otherBuffer != buffer);
        Assert(targetBlock > otherBlock);
 
        if (unlikely(!ConditionalLockBuffer(otherBuffer)))
        {
            unlockedTargetBuffer = true;
            LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
            LockBuffer(otherBuffer, BUFFER_LOCK_EXCLUSIVE);
            LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
        }
        recheckVmPins = true;
    }
 
    /*
     * If one of the buffers was unlocked (always the case if otherBuffer is
     * valid), it's possible, although unlikely, that an all-visible flag
     * became set.  We can use GetVisibilityMapPins to deal with that. It's
     * possible that GetVisibilityMapPins() might need to temporarily release
     * buffer locks, in which case we'll need to check if there's still enough
     * space on the page below.
     */
    if (recheckVmPins)
    {
        if (GetVisibilityMapPins(relation, otherBuffer, buffer,
                                 otherBlock, targetBlock, vmbuffer_other,
                                 vmbuffer))
            unlockedTargetBuffer = true;
    }
 
    /*
     * If the target buffer was temporarily unlocked since the relation
     * extension, it's possible, although unlikely, that all the space on the
     * page was already used. If so, we just retry from the start.  If we
     * didn't unlock, something has gone wrong if there's not enough space -
     * the test at the top should have prevented reaching this case.
     */
    pageFreeSpace = PageGetHeapFreeSpace(page);
    if (len > pageFreeSpace)
    {
        if (unlockedTargetBuffer)
        {
            if (otherBuffer != InvalidBuffer)
                LockBuffer(otherBuffer, BUFFER_LOCK_UNLOCK);
            UnlockReleaseBuffer(buffer);
 
            goto loop;
        }
        elog(PANIC, "tuple is too big: size %zu", len);
    }
 
    /*
     * Remember the new page as our target for future insertions.
     *
     * XXX should we enter the new page into the free space map immediately,
     * or just keep it for this backend's exclusive use in the short run
     * (until VACUUM sees it)?  Seems to depend on whether you expect the
     * current backend to make more insertions or not, which is probably a
     * good bet most of the time.  So for now, don't add it to FSM yet.
     */
    RelationSetTargetBlock(relation, targetBlock);
 
    return buffer;
}

References Assert(), BUFFER_LOCK_EXCLUSIVE, BUFFER_LOCK_UNLOCK, BufferGetBlockNumber(), BufferGetPage(), BufferGetPageSize(), ConditionalLockBuffer(), BulkInsertStateData::current_buf, elog, ereport, errcode(), errmsg(), ERROR, GetPageWithFreeSpace(), GetVisibilityMapPins(), HEAP_DEFAULT_FILLFACTOR, HEAP_INSERT_FROZEN, HEAP_INSERT_SKIP_FSM, InvalidBlockNumber, InvalidBuffer, BulkInsertStateData::last_free, len, LockBuffer(), MarkBufferDirty(), Max, MAXALIGN, MaxHeapTupleSize, MaxHeapTuplesPerPage, BulkInsertStateData::next_free, PageGetHeapFreeSpace(), PageGetMaxOffsetNumber(), PageInit(), PageIsAllVisible(), PageIsNew(), PANIC, RBM_NORMAL, ReadBuffer(), ReadBufferBI(), RecordAndGetPageWithFreeSpace(), RecordPageWithFreeSpace(), RelationAddBlocks(), RelationGetNumberOfBlocks, RelationGetTargetBlock, RelationGetTargetPageFreeSpace, RelationSetTargetBlock, ReleaseBuffer(), unlikely, UnlockReleaseBuffer(), visibilitymap_pin(), and visibilitymap_pin_ok().

Referenced by heap_insert(), heap_multi_insert(), and heap_update().

RelationPutHeapTuple()

void RelationPutHeapTuple	(	Relation	relation,
		Buffer	buffer,
		HeapTuple	tuple,
		bool	token
	)

Definition at line 35 of file hio.c.

{
    Page        pageHeader;
    OffsetNumber offnum;
 
    /*
     * A tuple that's being inserted speculatively should already have its
     * token set.
     */
    Assert(!token || HeapTupleHeaderIsSpeculative(tuple->t_data));
 
    /*
     * Do not allow tuples with invalid combinations of hint bits to be placed
     * on a page.  This combination is detected as corruption by the
     * contrib/amcheck logic, so if you disable this assertion, make
     * corresponding changes there.
     */
    Assert(!((tuple->t_data->t_infomask & HEAP_XMAX_COMMITTED) &&
             (tuple->t_data->t_infomask & HEAP_XMAX_IS_MULTI)));
 
    /* Add the tuple to the page */
    pageHeader = BufferGetPage(buffer);
 
    offnum = PageAddItem(pageHeader, tuple->t_data, tuple->t_len, InvalidOffsetNumber, false, true);
    if (offnum == InvalidOffsetNumber)
        elog(PANIC, "failed to add tuple to page");
 
    /* Update tuple->t_self to the actual position where it was stored */
    ItemPointerSet(&(tuple->t_self), BufferGetBlockNumber(buffer), offnum);
 
    /*
     * Insert the correct position into CTID of the stored tuple, too (unless
     * this is a speculative insertion, in which case the token is held in
     * CTID field instead)
     */
    if (!token)
    {
        ItemId      itemId = PageGetItemId(pageHeader, offnum);
        HeapTupleHeader item = (HeapTupleHeader) PageGetItem(pageHeader, itemId);
 
        item->t_ctid = tuple->t_self;
    }
}

References Assert(), BufferGetBlockNumber(), BufferGetPage(), elog, HEAP_XMAX_COMMITTED, HEAP_XMAX_IS_MULTI, HeapTupleHeaderIsSpeculative(), InvalidOffsetNumber, ItemPointerSet(), PageAddItem, PageGetItem(), PageGetItemId(), PANIC, HeapTupleHeaderData::t_ctid, HeapTupleData::t_data, HeapTupleHeaderData::t_infomask, HeapTupleData::t_len, and HeapTupleData::t_self.

Referenced by heap_insert(), heap_multi_insert(), and heap_update().