Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 457 insertions, 0 deletions

diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
new file mode 100644
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+++ b/src/include/storage/bufpage.h
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+/*-------------------------------------------------------------------------
+ *
+ * bufpage.h
+ *	  Standard POSTGRES buffer page definitions.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/bufpage.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef BUFPAGE_H
+#define BUFPAGE_H
+
+#include "access/xlogdefs.h"
+#include "storage/block.h"
+#include "storage/item.h"
+#include "storage/off.h"
+
+/*
+ * A postgres disk page is an abstraction layered on top of a postgres
+ * disk block (which is simply a unit of i/o, see block.h).
+ *
+ * specifically, while a disk block can be unformatted, a postgres
+ * disk page is always a slotted page of the form:
+ *
+ * +----------------+---------------------------------+
+ * | PageHeaderData | linp1 linp2 linp3 ...           |
+ * +-----------+----+---------------------------------+
+ * | ... linpN |									  |
+ * +-----------+--------------------------------------+
+ * |		   ^ pd_lower							  |
+ * |												  |
+ * |			 v pd_upper							  |
+ * +-------------+------------------------------------+
+ * |			 | tupleN ...                         |
+ * +-------------+------------------+-----------------+
+ * |	   ... tuple3 tuple2 tuple1 | "special space" |
+ * +--------------------------------+-----------------+
+ *									^ pd_special
+ *
+ * a page is full when nothing can be added between pd_lower and
+ * pd_upper.
+ *
+ * all blocks written out by an access method must be disk pages.
+ *
+ * EXCEPTIONS:
+ *
+ * obviously, a page is not formatted before it is initialized by
+ * a call to PageInit.
+ *
+ * NOTES:
+ *
+ * linp1..N form an ItemId (line pointer) array.  ItemPointers point
+ * to a physical block number and a logical offset (line pointer
+ * number) within that block/page.  Note that OffsetNumbers
+ * conventionally start at 1, not 0.
+ *
+ * tuple1..N are added "backwards" on the page.  Since an ItemPointer
+ * offset is used to access an ItemId entry rather than an actual
+ * byte-offset position, tuples can be physically shuffled on a page
+ * whenever the need arises.  This indirection also keeps crash recovery
+ * relatively simple, because the low-level details of page space
+ * management can be controlled by standard buffer page code during
+ * logging, and during recovery.
+ *
+ * AM-generic per-page information is kept in PageHeaderData.
+ *
+ * AM-specific per-page data (if any) is kept in the area marked "special
+ * space"; each AM has an "opaque" structure defined somewhere that is
+ * stored as the page trailer.  an access method should always
+ * initialize its pages with PageInit and then set its own opaque
+ * fields.
+ */
+
+typedef Pointer Page;
+
+
+/*
+ * location (byte offset) within a page.
+ *
+ * note that this is actually limited to 2^15 because we have limited
+ * ItemIdData.lp_off and ItemIdData.lp_len to 15 bits (see itemid.h).
+ */
+typedef uint16 LocationIndex;
+
+
+/*
+ * For historical reasons, the 64-bit LSN value is stored as two 32-bit
+ * values.
+ */
+typedef struct
+{
+	uint32		xlogid;			/* high bits */
+	uint32		xrecoff;		/* low bits */
+} PageXLogRecPtr;
+
+#define PageXLogRecPtrGet(val) \
+	((uint64) (val).xlogid << 32 | (val).xrecoff)
+#define PageXLogRecPtrSet(ptr, lsn) \
+	((ptr).xlogid = (uint32) ((lsn) >> 32), (ptr).xrecoff = (uint32) (lsn))
+
+/*
+ * disk page organization
+ *
+ * space management information generic to any page
+ *
+ *		pd_lsn		- identifies xlog record for last change to this page.
+ *		pd_checksum - page checksum, if set.
+ *		pd_flags	- flag bits.
+ *		pd_lower	- offset to start of free space.
+ *		pd_upper	- offset to end of free space.
+ *		pd_special	- offset to start of special space.
+ *		pd_pagesize_version - size in bytes and page layout version number.
+ *		pd_prune_xid - oldest XID among potentially prunable tuples on page.
+ *
+ * The LSN is used by the buffer manager to enforce the basic rule of WAL:
+ * "thou shalt write xlog before data".  A dirty buffer cannot be dumped
+ * to disk until xlog has been flushed at least as far as the page's LSN.
+ *
+ * pd_checksum stores the page checksum, if it has been set for this page;
+ * zero is a valid value for a checksum. If a checksum is not in use then
+ * we leave the field unset. This will typically mean the field is zero
+ * though non-zero values may also be present if databases have been
+ * pg_upgraded from releases prior to 9.3, when the same byte offset was
+ * used to store the current timelineid when the page was last updated.
+ * Note that there is no indication on a page as to whether the checksum
+ * is valid or not, a deliberate design choice which avoids the problem
+ * of relying on the page contents to decide whether to verify it. Hence
+ * there are no flag bits relating to checksums.
+ *
+ * pd_prune_xid is a hint field that helps determine whether pruning will be
+ * useful.  It is currently unused in index pages.
+ *
+ * The page version number and page size are packed together into a single
+ * uint16 field.  This is for historical reasons: before PostgreSQL 7.3,
+ * there was no concept of a page version number, and doing it this way
+ * lets us pretend that pre-7.3 databases have page version number zero.
+ * We constrain page sizes to be multiples of 256, leaving the low eight
+ * bits available for a version number.
+ *
+ * Minimum possible page size is perhaps 64B to fit page header, opaque space
+ * and a minimal tuple; of course, in reality you want it much bigger, so
+ * the constraint on pagesize mod 256 is not an important restriction.
+ * On the high end, we can only support pages up to 32KB because lp_off/lp_len
+ * are 15 bits.
+ */
+
+typedef struct PageHeaderData
+{
+	/* XXX LSN is member of *any* block, not only page-organized ones */
+	PageXLogRecPtr pd_lsn;		/* LSN: next byte after last byte of xlog
+								 * record for last change to this page */
+	uint16		pd_checksum;	/* checksum */
+	uint16		pd_flags;		/* flag bits, see below */
+	LocationIndex pd_lower;		/* offset to start of free space */
+	LocationIndex pd_upper;		/* offset to end of free space */
+	LocationIndex pd_special;	/* offset to start of special space */
+	uint16		pd_pagesize_version;
+	TransactionId pd_prune_xid; /* oldest prunable XID, or zero if none */
+	ItemIdData	pd_linp[FLEXIBLE_ARRAY_MEMBER]; /* line pointer array */
+} PageHeaderData;
+
+typedef PageHeaderData *PageHeader;
+
+/*
+ * pd_flags contains the following flag bits.  Undefined bits are initialized
+ * to zero and may be used in the future.
+ *
+ * PD_HAS_FREE_LINES is set if there are any LP_UNUSED line pointers before
+ * pd_lower.  This should be considered a hint rather than the truth, since
+ * changes to it are not WAL-logged.
+ *
+ * PD_PAGE_FULL is set if an UPDATE doesn't find enough free space in the
+ * page for its new tuple version; this suggests that a prune is needed.
+ * Again, this is just a hint.
+ */
+#define PD_HAS_FREE_LINES	0x0001	/* are there any unused line pointers? */
+#define PD_PAGE_FULL		0x0002	/* not enough free space for new tuple? */
+#define PD_ALL_VISIBLE		0x0004	/* all tuples on page are visible to
+									 * everyone */
+
+#define PD_VALID_FLAG_BITS	0x0007	/* OR of all valid pd_flags bits */
+
+/*
+ * Page layout version number 0 is for pre-7.3 Postgres releases.
+ * Releases 7.3 and 7.4 use 1, denoting a new HeapTupleHeader layout.
+ * Release 8.0 uses 2; it changed the HeapTupleHeader layout again.
+ * Release 8.1 uses 3; it redefined HeapTupleHeader infomask bits.
+ * Release 8.3 uses 4; it changed the HeapTupleHeader layout again, and
+ *		added the pd_flags field (by stealing some bits from pd_tli),
+ *		as well as adding the pd_prune_xid field (which enlarges the header).
+ *
+ * As of Release 9.3, the checksum version must also be considered when
+ * handling pages.
+ */
+#define PG_PAGE_LAYOUT_VERSION		4
+#define PG_DATA_CHECKSUM_VERSION	1
+
+/* ----------------------------------------------------------------
+ *						page support macros
+ * ----------------------------------------------------------------
+ */
+
+/*
+ * PageIsValid
+ *		True iff page is valid.
+ */
+#define PageIsValid(page) PointerIsValid(page)
+
+/*
+ * line pointer(s) do not count as part of header
+ */
+#define SizeOfPageHeaderData (offsetof(PageHeaderData, pd_linp))
+
+/*
+ * PageIsEmpty
+ *		returns true iff no itemid has been allocated on the page
+ */
+#define PageIsEmpty(page) \
+	(((PageHeader) (page))->pd_lower <= SizeOfPageHeaderData)
+
+/*
+ * PageIsNew
+ *		returns true iff page has not been initialized (by PageInit)
+ */
+#define PageIsNew(page) (((PageHeader) (page))->pd_upper == 0)
+
+/*
+ * PageGetItemId
+ *		Returns an item identifier of a page.
+ */
+#define PageGetItemId(page, offsetNumber) \
+	((ItemId) (&((PageHeader) (page))->pd_linp[(offsetNumber) - 1]))
+
+/*
+ * PageGetContents
+ *		To be used in cases where the page does not contain line pointers.
+ *
+ * Note: prior to 8.3 this was not guaranteed to yield a MAXALIGN'd result.
+ * Now it is.  Beware of old code that might think the offset to the contents
+ * is just SizeOfPageHeaderData rather than MAXALIGN(SizeOfPageHeaderData).
+ */
+#define PageGetContents(page) \
+	((char *) (page) + MAXALIGN(SizeOfPageHeaderData))
+
+/* ----------------
+ *		macros to access page size info
+ * ----------------
+ */
+
+/*
+ * PageSizeIsValid
+ *		True iff the page size is valid.
+ */
+#define PageSizeIsValid(pageSize) ((pageSize) == BLCKSZ)
+
+/*
+ * PageGetPageSize
+ *		Returns the page size of a page.
+ *
+ * this can only be called on a formatted page (unlike
+ * BufferGetPageSize, which can be called on an unformatted page).
+ * however, it can be called on a page that is not stored in a buffer.
+ */
+#define PageGetPageSize(page) \
+	((Size) (((PageHeader) (page))->pd_pagesize_version & (uint16) 0xFF00))
+
+/*
+ * PageGetPageLayoutVersion
+ *		Returns the page layout version of a page.
+ */
+#define PageGetPageLayoutVersion(page) \
+	(((PageHeader) (page))->pd_pagesize_version & 0x00FF)
+
+/*
+ * PageSetPageSizeAndVersion
+ *		Sets the page size and page layout version number of a page.
+ *
+ * We could support setting these two values separately, but there's
+ * no real need for it at the moment.
+ */
+#define PageSetPageSizeAndVersion(page, size, version) \
+( \
+	AssertMacro(((size) & 0xFF00) == (size)), \
+	AssertMacro(((version) & 0x00FF) == (version)), \
+	((PageHeader) (page))->pd_pagesize_version = (size) | (version) \
+)
+
+/* ----------------
+ *		page special data macros
+ * ----------------
+ */
+/*
+ * PageGetSpecialSize
+ *		Returns size of special space on a page.
+ */
+#define PageGetSpecialSize(page) \
+	((uint16) (PageGetPageSize(page) - ((PageHeader)(page))->pd_special))
+
+/*
+ * Using assertions, validate that the page special pointer is OK.
+ *
+ * This is intended to catch use of the pointer before page initialization.
+ * It is implemented as a function due to the limitations of the MSVC
+ * compiler, which choked on doing all these tests within another macro.  We
+ * return true so that AssertMacro() can be used while still getting the
+ * specifics from the macro failure within this function.
+ */
+static inline bool
+PageValidateSpecialPointer(Page page)
+{
+	Assert(PageIsValid(page));
+	Assert(((PageHeader) (page))->pd_special <= BLCKSZ);
+	Assert(((PageHeader) (page))->pd_special >= SizeOfPageHeaderData);
+
+	return true;
+}
+
+/*
+ * PageGetSpecialPointer
+ *		Returns pointer to special space on a page.
+ */
+#define PageGetSpecialPointer(page) \
+( \
+	AssertMacro(PageValidateSpecialPointer(page)), \
+	(char *) ((char *) (page) + ((PageHeader) (page))->pd_special) \
+)
+
+/*
+ * PageGetItem
+ *		Retrieves an item on the given page.
+ *
+ * Note:
+ *		This does not change the status of any of the resources passed.
+ *		The semantics may change in the future.
+ */
+#define PageGetItem(page, itemId) \
+( \
+	AssertMacro(PageIsValid(page)), \
+	AssertMacro(ItemIdHasStorage(itemId)), \
+	(Item)(((char *)(page)) + ItemIdGetOffset(itemId)) \
+)
+
+/*
+ * PageGetMaxOffsetNumber
+ *		Returns the maximum offset number used by the given page.
+ *		Since offset numbers are 1-based, this is also the number
+ *		of items on the page.
+ *
+ *		NOTE: if the page is not initialized (pd_lower == 0), we must
+ *		return zero to ensure sane behavior.  Accept double evaluation
+ *		of the argument so that we can ensure this.
+ */
+#define PageGetMaxOffsetNumber(page) \
+	(((PageHeader) (page))->pd_lower <= SizeOfPageHeaderData ? 0 : \
+	 ((((PageHeader) (page))->pd_lower - SizeOfPageHeaderData) \
+	  / sizeof(ItemIdData)))
+
+/*
+ * Additional macros for access to page headers. (Beware multiple evaluation
+ * of the arguments!)
+ */
+#define PageGetLSN(page) \
+	PageXLogRecPtrGet(((PageHeader) (page))->pd_lsn)
+#define PageSetLSN(page, lsn) \
+	PageXLogRecPtrSet(((PageHeader) (page))->pd_lsn, lsn)
+
+#define PageHasFreeLinePointers(page) \
+	(((PageHeader) (page))->pd_flags & PD_HAS_FREE_LINES)
+#define PageSetHasFreeLinePointers(page) \
+	(((PageHeader) (page))->pd_flags |= PD_HAS_FREE_LINES)
+#define PageClearHasFreeLinePointers(page) \
+	(((PageHeader) (page))->pd_flags &= ~PD_HAS_FREE_LINES)
+
+#define PageIsFull(page) \
+	(((PageHeader) (page))->pd_flags & PD_PAGE_FULL)
+#define PageSetFull(page) \
+	(((PageHeader) (page))->pd_flags |= PD_PAGE_FULL)
+#define PageClearFull(page) \
+	(((PageHeader) (page))->pd_flags &= ~PD_PAGE_FULL)
+
+#define PageIsAllVisible(page) \
+	(((PageHeader) (page))->pd_flags & PD_ALL_VISIBLE)
+#define PageSetAllVisible(page) \
+	(((PageHeader) (page))->pd_flags |= PD_ALL_VISIBLE)
+#define PageClearAllVisible(page) \
+	(((PageHeader) (page))->pd_flags &= ~PD_ALL_VISIBLE)
+
+#define PageSetPrunable(page, xid) \
+do { \
+	Assert(TransactionIdIsNormal(xid)); \
+	if (!TransactionIdIsValid(((PageHeader) (page))->pd_prune_xid) || \
+		TransactionIdPrecedes(xid, ((PageHeader) (page))->pd_prune_xid)) \
+		((PageHeader) (page))->pd_prune_xid = (xid); \
+} while (0)
+#define PageClearPrunable(page) \
+	(((PageHeader) (page))->pd_prune_xid = InvalidTransactionId)
+
+
+/* ----------------------------------------------------------------
+ *		extern declarations
+ * ----------------------------------------------------------------
+ */
+
+/* flags for PageAddItemExtended() */
+#define PAI_OVERWRITE			(1 << 0)
+#define PAI_IS_HEAP				(1 << 1)
+
+/* flags for PageIsVerifiedExtended() */
+#define PIV_LOG_WARNING			(1 << 0)
+#define PIV_REPORT_STAT			(1 << 1)
+
+#define PageAddItem(page, item, size, offsetNumber, overwrite, is_heap) \
+	PageAddItemExtended(page, item, size, offsetNumber, \
+						((overwrite) ? PAI_OVERWRITE : 0) | \
+						((is_heap) ? PAI_IS_HEAP : 0))
+
+#define PageIsVerified(page, blkno) \
+	PageIsVerifiedExtended(page, blkno, \
+						   PIV_LOG_WARNING | PIV_REPORT_STAT)
+
+/*
+ * Check that BLCKSZ is a multiple of sizeof(size_t).  In
+ * PageIsVerifiedExtended(), it is much faster to check if a page is
+ * full of zeroes using the native word size.  Note that this assertion
+ * is kept within a header to make sure that StaticAssertDecl() works
+ * across various combinations of platforms and compilers.
+ */
+StaticAssertDecl(BLCKSZ == ((BLCKSZ / sizeof(size_t)) * sizeof(size_t)),
+				 "BLCKSZ has to be a multiple of sizeof(size_t)");
+
+extern void PageInit(Page page, Size pageSize, Size specialSize);
+extern bool PageIsVerifiedExtended(Page page, BlockNumber blkno, int flags);
+extern OffsetNumber PageAddItemExtended(Page page, Item item, Size size,
+										OffsetNumber offsetNumber, int flags);
+extern Page PageGetTempPage(Page page);
+extern Page PageGetTempPageCopy(Page page);
+extern Page PageGetTempPageCopySpecial(Page page);
+extern void PageRestoreTempPage(Page tempPage, Page oldPage);
+extern void PageRepairFragmentation(Page page);
+extern void PageTruncateLinePointerArray(Page page);
+extern Size PageGetFreeSpace(Page page);
+extern Size PageGetFreeSpaceForMultipleTuples(Page page, int ntups);
+extern Size PageGetExactFreeSpace(Page page);
+extern Size PageGetHeapFreeSpace(Page page);
+extern void PageIndexTupleDelete(Page page, OffsetNumber offset);
+extern void PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems);
+extern void PageIndexTupleDeleteNoCompact(Page page, OffsetNumber offset);
+extern bool PageIndexTupleOverwrite(Page page, OffsetNumber offnum,
+									Item newtup, Size newsize);
+extern char *PageSetChecksumCopy(Page page, BlockNumber blkno);
+extern void PageSetChecksumInplace(Page page, BlockNumber blkno);
+
+#endif							/* BUFPAGE_H */