C++ BufferGetPageSize函数代码示例

/*
 *	_hash_getnewbuf() -- Get a new page at the end of the index.
 *
 *		This has the same API as _hash_getinitbuf, except that we are adding
 *		a page to the index, and hence expect the page to be past the
 *		logical EOF.  (However, we have to support the case where it isn't,
 *		since a prior try might have crashed after extending the filesystem
 *		EOF but before updating the metapage to reflect the added page.)
 *
 *		It is caller's responsibility to ensure that only one process can
 *		extend the index at a time.
 */
Buffer
_hash_getnewbuf(Relation rel, BlockNumber blkno, ForkNumber forkNum)
{
    BlockNumber nblocks = RelationGetNumberOfBlocksInFork(rel, forkNum);
    Buffer		buf;

    if (blkno == P_NEW)
        elog(ERROR, "hash AM does not use P_NEW");
    if (blkno > nblocks)
        elog(ERROR, "access to noncontiguous page in hash index \"%s\"",
             RelationGetRelationName(rel));

    /* smgr insists we use P_NEW to extend the relation */
    if (blkno == nblocks)
    {
        buf = ReadBufferExtended(rel, forkNum, P_NEW, RBM_NORMAL, NULL);
        if (BufferGetBlockNumber(buf) != blkno)
            elog(ERROR, "unexpected hash relation size: %u, should be %u",
                 BufferGetBlockNumber(buf), blkno);
    }
    else
        buf = ReadBufferExtended(rel, forkNum, blkno, RBM_ZERO, NULL);

    LockBuffer(buf, HASH_WRITE);

    /* ref count and lock type are correct */

    /* initialize the page */
    _hash_pageinit(BufferGetPage(buf), BufferGetPageSize(buf));

    return buf;
}

/*
 *	_hash_initbuf() -- Get and initialize a buffer by bucket number.
 */
void
_hash_initbuf(Buffer buf, uint32 max_bucket, uint32 num_bucket, uint32 flag,
			  bool initpage)
{
	HashPageOpaque pageopaque;
	Page		page;

	page = BufferGetPage(buf);

	/* initialize the page */
	if (initpage)
		_hash_pageinit(page, BufferGetPageSize(buf));

	pageopaque = (HashPageOpaque) PageGetSpecialPointer(page);

	/*
	 * Set hasho_prevblkno with current hashm_maxbucket. This value will be
	 * used to validate cached HashMetaPageData. See
	 * _hash_getbucketbuf_from_hashkey().
	 */
	pageopaque->hasho_prevblkno = max_bucket;
	pageopaque->hasho_nextblkno = InvalidBlockNumber;
	pageopaque->hasho_bucket = num_bucket;
	pageopaque->hasho_flag = flag;
	pageopaque->hasho_page_id = HASHO_PAGE_ID;
}

/*
 *	_hash_initbitmapbuffer()
 *
 *	 Initialize a new bitmap page.  All bits in the new bitmap page are set to
 *	 "1", indicating "in use".
 */
void
_hash_initbitmapbuffer(Buffer buf, uint16 bmsize, bool initpage)
{
	Page		pg;
	HashPageOpaque op;
	uint32	   *freep;

	pg = BufferGetPage(buf);

	/* initialize the page */
	if (initpage)
		_hash_pageinit(pg, BufferGetPageSize(buf));

	/* initialize the page's special space */
	op = (HashPageOpaque) PageGetSpecialPointer(pg);
	op->hasho_prevblkno = InvalidBlockNumber;
	op->hasho_nextblkno = InvalidBlockNumber;
	op->hasho_bucket = -1;
	op->hasho_flag = LH_BITMAP_PAGE;
	op->hasho_page_id = HASHO_PAGE_ID;

	/* set all of the bits to 1 */
	freep = HashPageGetBitmap(pg);
	MemSet(freep, 0xFF, bmsize);

	/*
	 * Set pd_lower just past the end of the bitmap page data.  We could even
	 * set pd_lower equal to pd_upper, but this is more precise and makes the
	 * page look compressible to xlog.c.
	 */
	((PageHeader) pg)->pd_lower = ((char *) freep + bmsize) - (char *) pg;
}

/*
 * _bitmap_init_lovpage -- initialize a new LOV page.
 */
void
_bitmap_init_lovpage(Relation rel __attribute__((unused)), Buffer buf)
{
	Page			page;

	page = (Page) BufferGetPage(buf);

	if(PageIsNew(page))
		PageInit(page, BufferGetPageSize(buf), 0);
}

void
SpGistInitMetabuffer(Buffer b, Relation index)
{
    SpGistMetaPageData   *metadata;
    Page                page = BufferGetPage(b);
    SpGistInitPage(page, SPGIST_META, BufferGetPageSize(b));
    metadata = SpGistPageGetMeta(page);
    memset(metadata, 0, sizeof(SpGistMetaPageData));
    metadata->magickNumber = SPGIST_MAGICK_NUMBER;
}

/*
 *	_hash_addovflpage
 *
 *	Add an overflow page to the bucket whose last page is pointed to by 'buf'.
 *
 *	On entry, the caller must hold a pin but no lock on 'buf'.	The pin is
 *	dropped before exiting (we assume the caller is not interested in 'buf'
 *	anymore).  The returned overflow page will be pinned and write-locked;
 *	it is guaranteed to be empty.
 *
 *	The caller must hold a pin, but no lock, on the metapage buffer.
 *	That buffer is returned in the same state.
 *
 *	The caller must hold at least share lock on the bucket, to ensure that
 *	no one else tries to compact the bucket meanwhile.	This guarantees that
 *	'buf' won't stop being part of the bucket while it's unlocked.
 *
 * NB: since this could be executed concurrently by multiple processes,
 * one should not assume that the returned overflow page will be the
 * immediate successor of the originally passed 'buf'.	Additional overflow
 * pages might have been added to the bucket chain in between.
 */
Buffer
_hash_addovflpage(Relation rel, Buffer metabuf, Buffer buf)
{
	Buffer		ovflbuf;
	Page		page;
	Page		ovflpage;
	HashPageOpaque pageopaque;
	HashPageOpaque ovflopaque;

	/* allocate and lock an empty overflow page */
	ovflbuf = _hash_getovflpage(rel, metabuf);
	ovflpage = BufferGetPage(ovflbuf);

	/*
	 * Write-lock the tail page.  It is okay to hold two buffer locks here
	 * since there cannot be anyone else contending for access to ovflbuf.
	 */
	_hash_chgbufaccess(rel, buf, HASH_NOLOCK, HASH_WRITE);

	/* loop to find current tail page, in case someone else inserted too */
	for (;;)
	{
		BlockNumber nextblkno;

		_hash_checkpage(rel, buf, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE);
		page = BufferGetPage(buf);
		pageopaque = (HashPageOpaque) PageGetSpecialPointer(page);
		nextblkno = pageopaque->hasho_nextblkno;

		if (!BlockNumberIsValid(nextblkno))
			break;

		/* we assume we do not need to write the unmodified page */
		_hash_relbuf(rel, buf);

		buf = _hash_getbuf(rel, nextblkno, HASH_WRITE);
	}

	/* now that we have correct backlink, initialize new overflow page */
	_hash_pageinit(ovflpage, BufferGetPageSize(ovflbuf));
	ovflopaque = (HashPageOpaque) PageGetSpecialPointer(ovflpage);
	ovflopaque->hasho_prevblkno = BufferGetBlockNumber(buf);
	ovflopaque->hasho_nextblkno = InvalidBlockNumber;
	ovflopaque->hasho_bucket = pageopaque->hasho_bucket;
	ovflopaque->hasho_flag = LH_OVERFLOW_PAGE;
	ovflopaque->hasho_filler = HASHO_FILL;

	MarkBufferDirty(ovflbuf);

	/* logically chain overflow page to previous page */
	pageopaque->hasho_nextblkno = BufferGetBlockNumber(ovflbuf);
	_hash_wrtbuf(rel, buf);

	return ovflbuf;
}

/*
 *	_hash_initbitmap()
 *
 *	 Initialize a new bitmap page.	The metapage has a write-lock upon
 *	 entering the function, and must be written by caller after return.
 *
 * 'blkno' is the block number of the new bitmap page.
 *
 * All bits in the new bitmap page are set to "1", indicating "in use".
 */
void
_hash_initbitmap(Relation rel, HashMetaPage metap, BlockNumber blkno)
{
	Buffer		buf;
	Page		pg;
	HashPageOpaque op;
	uint32	   *freep;

	/*
	 * It is okay to write-lock the new bitmap page while holding metapage
	 * write lock, because no one else could be contending for the new page.
	 * Also, the metapage lock makes it safe to extend the index using P_NEW,
	 * which we want to do to ensure the smgr's idea of the relation size
	 * stays in step with ours.
	 *
	 * There is some loss of concurrency in possibly doing I/O for the new
	 * page while holding the metapage lock, but this path is taken so seldom
	 * that it's not worth worrying about.
	 */
	buf = _hash_getbuf(rel, P_NEW, HASH_WRITE);
	if (BufferGetBlockNumber(buf) != blkno)
		elog(ERROR, "unexpected hash relation size: %u, should be %u",
			 BufferGetBlockNumber(buf), blkno);

	pg = BufferGetPage(buf);

	/* initialize the page */
	_hash_pageinit(pg, BufferGetPageSize(buf));
	op = (HashPageOpaque) PageGetSpecialPointer(pg);
	op->hasho_prevblkno = InvalidBlockNumber;
	op->hasho_nextblkno = InvalidBlockNumber;
	op->hasho_bucket = -1;
	op->hasho_flag = LH_BITMAP_PAGE;
	op->hasho_filler = HASHO_FILL;

	/* set all of the bits to 1 */
	freep = HashPageGetBitmap(pg);
	MemSet(freep, 0xFF, BMPGSZ_BYTE(metap));

	/* write out the new bitmap page (releasing write lock and pin) */
	_hash_wrtbuf(rel, buf);

	/* add the new bitmap page to the metapage's list of bitmaps */
	/* metapage already has a write lock */
	if (metap->hashm_nmaps >= HASH_MAX_BITMAPS)
		ereport(ERROR,
				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
				 errmsg("out of overflow pages in hash index \"%s\"",
						RelationGetRelationName(rel))));

	metap->hashm_mapp[metap->hashm_nmaps] = blkno;

	metap->hashm_nmaps++;
}

void
BloomInitMetabuffer(Buffer b, Relation index)
{
	BloomMetaPageData	*metadata;
	Page				page = BufferGetPage(b);

	BloomInitPage(page, BLOOM_META, BufferGetPageSize(b));
	metadata = BloomPageGetMeta(page);
	memset(metadata, 0, sizeof(BloomMetaPageData));
	metadata->magickNumber = BLOOM_MAGICK_NUMBER;
	metadata->opts = *makeDefaultBloomOptions((BloomOptions*)index->rd_options);
}

static void
ginRedoDeleteListPages(XLogReaderState *record)
{
	XLogRecPtr	lsn = record->EndRecPtr;
	ginxlogDeleteListPages *data = (ginxlogDeleteListPages *) XLogRecGetData(record);
	Buffer		metabuffer;
	Page		metapage;
	int			i;

	metabuffer = XLogInitBufferForRedo(record, 0);
	Assert(BufferGetBlockNumber(metabuffer) == GIN_METAPAGE_BLKNO);
	metapage = BufferGetPage(metabuffer);

	GinInitPage(metapage, GIN_META, BufferGetPageSize(metabuffer));

	memcpy(GinPageGetMeta(metapage), &data->metadata, sizeof(GinMetaPageData));
	PageSetLSN(metapage, lsn);
	MarkBufferDirty(metabuffer);

	/*
	 * In normal operation, shiftList() takes exclusive lock on all the
	 * pages-to-be-deleted simultaneously.  During replay, however, it should
	 * be all right to lock them one at a time.  This is dependent on the fact
	 * that we are deleting pages from the head of the list, and that readers
	 * share-lock the next page before releasing the one they are on. So we
	 * cannot get past a reader that is on, or due to visit, any page we are
	 * going to delete.  New incoming readers will block behind our metapage
	 * lock and then see a fully updated page list.
	 *
	 * No full-page images are taken of the deleted pages. Instead, they are
	 * re-initialized as empty, deleted pages. Their right-links don't need to
	 * be preserved, because no new___ readers can see the pages, as explained
	 * above.
	 */
	for (i = 0; i < data->ndeleted; i++)
	{
		Buffer		buffer;
		Page		page;

		buffer = XLogInitBufferForRedo(record, i + 1);
		page = BufferGetPage(buffer);
		GinInitBuffer(buffer, GIN_DELETED);

		PageSetLSN(page, lsn);
		MarkBufferDirty(buffer);

		UnlockReleaseBuffer(buffer);
	}
	UnlockReleaseBuffer(metabuffer);
}

void
GinInitMetabuffer(Buffer b)
{
	GinMetaPageData *metadata;
	Page		page = BufferGetPage(b);

	GinInitPage(page, GIN_META, BufferGetPageSize(b));

	metadata = GinPageGetMeta(page);

	metadata->head = metadata->tail = InvalidBlockNumber;
	metadata->tailFreeSize = 0;
	metadata->nPendingPages = 0;
	metadata->nPendingHeapTuples = 0;
}

static void
RTInitBuffer(Buffer b, uint32 f)
{
	RTreePageOpaque opaque;
	Page		page;
	Size		pageSize;

	pageSize = BufferGetPageSize(b);

	page = BufferGetPage(b);

	PageInit(page, pageSize, sizeof(RTreePageOpaqueData));

	opaque = (RTreePageOpaque) PageGetSpecialPointer(page);
	opaque->flags = f;
}

/*
 * Initialize a new index page
 */
void
GISTInitBuffer(Buffer b, uint32 f)
{
	GISTPageOpaque opaque;
	Page		page;
	Size		pageSize;

	pageSize = BufferGetPageSize(b);
	page = BufferGetPage(b);
	PageInit(page, pageSize, sizeof(GISTPageOpaqueData));

	opaque = GistPageGetOpaque(page);
	opaque->flags = f;
	opaque->rightlink = InvalidBlockNumber;
	/* page was already zeroed by PageInit, so this is not needed: */
	/* memset(&(opaque->nsn), 0, sizeof(GistNSN)); */
}

/*
 * _bitmap_init_bitmappage() -- initialize a new page to store the bitmap.
 */
void
_bitmap_init_bitmappage(Relation rel __attribute__((unused)), Buffer buf)
{
	Page			page;
	BMBitmapOpaque	opaque;

	page = (Page) BufferGetPage(buf);

	if(PageIsNew(page))
		PageInit(page, BufferGetPageSize(buf), sizeof(BMBitmapOpaqueData));

	/* even though page may not be new, reset all values */
	opaque = (BMBitmapOpaque) PageGetSpecialPointer(page);
	opaque->bm_hrl_words_used = 0;
	opaque->bm_bitmap_next = InvalidBlockNumber;
	opaque->bm_last_tid_location = 0;
}

/*
 *	_hash_getinitbuf() -- Get and initialize a buffer by block number.
 *
 *		This must be used only to fetch pages that are known to be before
 *		the index's filesystem EOF, but are to be filled from scratch.
 *		_hash_pageinit() is applied automatically.  Otherwise it has
 *		effects similar to _hash_getbuf() with access = HASH_WRITE.
 *
 *		When this routine returns, a write lock is set on the
 *		requested buffer and its reference count has been incremented
 *		(ie, the buffer is "locked and pinned").
 *
 *		P_NEW is disallowed because this routine can only be used
 *		to access pages that are known to be before the filesystem EOF.
 *		Extending the index should be done with _hash_getnewbuf.
 */
Buffer
_hash_getinitbuf(Relation rel, BlockNumber blkno)
{
	Buffer		buf;

	if (blkno == P_NEW)
		elog(ERROR, "hash AM does not use P_NEW");

	buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_ZERO_AND_LOCK,
							 NULL);

	/* ref count and lock type are correct */

	/* initialize the page */
	_hash_pageinit(BufferGetPage(buf), BufferGetPageSize(buf));

	return buf;
}

static void
_bt_restore_meta(XLogReaderState *record, uint8 block_id)
{
	XLogRecPtr	lsn = record->EndRecPtr;
	Buffer		metabuf;
	Page		metapg;
	BTMetaPageData *md;
	BTPageOpaque pageop;
	xl_btree_metadata *xlrec;
	char	   *ptr;
	Size		len;

	metabuf = XLogInitBufferForRedo(record, block_id);
	ptr = XLogRecGetBlockData(record, block_id, &len);

	Assert(len == sizeof(xl_btree_metadata));
	Assert(BufferGetBlockNumber(metabuf) == BTREE_METAPAGE);
	xlrec = (xl_btree_metadata *) ptr;
	metapg = BufferGetPage(metabuf);

	_bt_pageinit(metapg, BufferGetPageSize(metabuf));

	md = BTPageGetMeta(metapg);
	md->btm_magic = BTREE_MAGIC;
	md->btm_version = BTREE_VERSION;
	md->btm_root = xlrec->root;
	md->btm_level = xlrec->level;
	md->btm_fastroot = xlrec->fastroot;
	md->btm_fastlevel = xlrec->fastlevel;

	pageop = (BTPageOpaque) PageGetSpecialPointer(metapg);
	pageop->btpo_flags = BTP_META;

	/*
	 * Set pd_lower just past the end of the metadata.  This is not essential
	 * but it makes the page look compressible to xlog.c.
	 */
	((PageHeader) metapg)->pd_lower =
		((char *) md + sizeof(BTMetaPageData)) - (char *) metapg;

	PageSetLSN(metapg, lsn);
	MarkBufferDirty(metabuf);
	UnlockReleaseBuffer(metabuf);
}