There already was a macro PageGetItemId; this is now used in (almost)

all places, where pd_linp is accessed.  Also introduce new macros
SizeOfPageHeaderData and BTMaxItemSize. This is just source code
cosmetic, no behaviour changed.

Manfred Koizar

6 files changed, 58 insertions, 42 deletions

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index ebafcffd281..9a6a0b07400 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.140 2002/07/02 05:46:14 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.141 2002/07/02 05:48:44 momjian Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -2067,7 +2067,7 @@ heap_xlog_clean(bool redo, XLogRecPtr lsn, XLogRecord *record)
 
 		while ((char *) unused < unend)
 		{
-			lp = ((PageHeader) page)->pd_linp + *unused;
+			lp = PageGetItemId(page, *unused + 1);
 			lp->lp_flags &= ~LP_USED;
 			unused++;
 		}
diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c
index 4929d1d058f..c0190859b7b 100644
--- a/src/backend/access/nbtree/nbtinsert.c
+++ b/src/backend/access/nbtree/nbtinsert.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.93 2002/06/20 20:29:25 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.94 2002/07/02 05:48:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -383,10 +383,9 @@ _bt_insertonpg(Relation rel,
 	 * to 1/3 the per-page available space. Note that at this point,
 	 * itemsz doesn't include the ItemId.
 	 */
-	if (itemsz > (PageGetPageSize(page) - sizeof(PageHeaderData) - MAXALIGN(sizeof(BTPageOpaqueData))) / 3 - sizeof(ItemIdData))
+	if (itemsz > BTMaxItemSize(page))
 		elog(ERROR, "btree: index item size %lu exceeds maximum %lu",
-			 (unsigned long) itemsz,
-			 (PageGetPageSize(page) - sizeof(PageHeaderData) - MAXALIGN(sizeof(BTPageOpaqueData))) / 3 - sizeof(ItemIdData));
+			 (unsigned long) itemsz, BTMaxItemSize(page));
 
 	/*
 	 * Determine exactly where new item will go.
@@ -1020,9 +1019,8 @@ _bt_findsplitloc(Relation rel,
 
 	/* Total free space available on a btree page, after fixed overhead */
 	leftspace = rightspace =
-		PageGetPageSize(page) - sizeof(PageHeaderData) -
-		MAXALIGN(sizeof(BTPageOpaqueData))
-		+sizeof(ItemIdData);
+		PageGetPageSize(page) - SizeOfPageHeaderData -
+		MAXALIGN(sizeof(BTPageOpaqueData));
 
 	/*
 	 * Finding the best possible split would require checking all the
diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c
index dff1c0dee14..80d56f04514 100644
--- a/src/backend/access/nbtree/nbtsort.c
+++ b/src/backend/access/nbtree/nbtsort.c
@@ -35,7 +35,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsort.c,v 1.64 2002/06/20 20:29:25 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsort.c,v 1.65 2002/07/02 05:48:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -346,10 +346,9 @@ _bt_buildadd(Relation index, BTPageState *state, BTItem bti)
 	 * oversize items being inserted into an already-existing index. But
 	 * during creation of an index, we don't go through there.
 	 */
-	if (btisz > (PageGetPageSize(npage) - sizeof(PageHeaderData) - MAXALIGN(sizeof(BTPageOpaqueData))) / 3 - sizeof(ItemIdData))
+	if (btisz > BTMaxItemSize(npage))
 		elog(ERROR, "btree: index item size %lu exceeds maximum %ld",
-			 (unsigned long) btisz,
-			 (PageGetPageSize(npage) - sizeof(PageHeaderData) - MAXALIGN(sizeof(BTPageOpaqueData))) / 3 - sizeof(ItemIdData));
+			 (unsigned long) btisz, BTMaxItemSize(npage));
 
 	if (pgspc < btisz || pgspc < state->btps_full)
 	{
diff --git a/src/backend/storage/page/bufpage.c b/src/backend/storage/page/bufpage.c
index bffd403af21..e6abf3b41e4 100644
--- a/src/backend/storage/page/bufpage.c
+++ b/src/backend/storage/page/bufpage.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/page/bufpage.c,v 1.45 2002/06/20 20:29:35 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/page/bufpage.c,v 1.46 2002/07/02 05:48:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -37,13 +37,12 @@ PageInit(Page page, Size pageSize, Size specialSize)
 	specialSize = MAXALIGN(specialSize);
 
 	Assert(pageSize == BLCKSZ);
-	Assert(pageSize >
-		   specialSize + sizeof(PageHeaderData) - sizeof(ItemIdData));
+	Assert(pageSize > specialSize + SizeOfPageHeaderData);
 
 	/* Make sure all fields of page are zero, as well as unused space */
 	MemSet(p, 0, pageSize);
 
-	p->pd_lower = sizeof(PageHeaderData) - sizeof(ItemIdData);
+	p->pd_lower = SizeOfPageHeaderData;
 	p->pd_upper = pageSize - specialSize;
 	p->pd_special = pageSize - specialSize;
 	PageSetPageSize(page, pageSize);
@@ -88,7 +87,7 @@ PageAddItem(Page page,
 	/*
 	 * Be wary about corrupted page pointers
 	 */
-	if (phdr->pd_lower < (sizeof(PageHeaderData) - sizeof(ItemIdData)) ||
+	if (phdr->pd_lower < SizeOfPageHeaderData ||
 		phdr->pd_lower > phdr->pd_upper ||
 		phdr->pd_upper > phdr->pd_special ||
 		phdr->pd_special > BLCKSZ)
@@ -112,7 +111,7 @@ PageAddItem(Page page,
 			}
 			if (offsetNumber < limit)
 			{
-				itemId = &phdr->pd_linp[offsetNumber - 1];
+				itemId = PageGetItemId(phdr, offsetNumber);
 				if (((*itemId).lp_flags & LP_USED) ||
 					((*itemId).lp_len != 0))
 				{
@@ -136,7 +135,7 @@ PageAddItem(Page page,
 		/* look for "recyclable" (unused & deallocated) ItemId */
 		for (offsetNumber = 1; offsetNumber < limit; offsetNumber++)
 		{
-			itemId = &phdr->pd_linp[offsetNumber - 1];
+			itemId = PageGetItemId(phdr, offsetNumber);
 			if ((((*itemId).lp_flags & LP_USED) == 0) &&
 				((*itemId).lp_len == 0))
 				break;
@@ -150,7 +149,7 @@ PageAddItem(Page page,
 	 * alignedSize > pd_upper.
 	 */
 	if (offsetNumber > limit)
-		lower = (char *) (&phdr->pd_linp[offsetNumber]) - (char *) page;
+		lower = (char *) PageGetItemId(phdr, offsetNumber + 1) - (char *) page;
 	else if (offsetNumber == limit || needshuffle)
 		lower = phdr->pd_lower + sizeof(ItemIdData);
 	else
@@ -175,13 +174,13 @@ PageAddItem(Page page,
 			ItemId		fromitemId,
 						toitemId;
 
-			fromitemId = &phdr->pd_linp[i - 1];
-			toitemId = &phdr->pd_linp[i];
+			fromitemId = PageGetItemId(phdr, i);
+			toitemId =  PageGetItemId(phdr, i + 1);
 			*toitemId = *fromitemId;
 		}
 	}
 
-	itemId = &phdr->pd_linp[offsetNumber - 1];
+	itemId = PageGetItemId(phdr, offsetNumber);
 	(*itemId).lp_off = upper;
 	(*itemId).lp_len = size;
 	(*itemId).lp_flags = flags;
@@ -214,12 +213,12 @@ PageGetTempPage(Page page, Size specialSize)
 	memcpy(temp, page, pageSize);
 
 	/* clear out the middle */
-	size = (pageSize - sizeof(PageHeaderData)) + sizeof(ItemIdData);
+	size = pageSize - SizeOfPageHeaderData;
 	size -= MAXALIGN(specialSize);
-	MemSet((char *) &(thdr->pd_linp[0]), 0, size);
+	MemSet(PageGetContents(thdr), 0, size);
 
 	/* set high, low water marks */
-	thdr->pd_lower = sizeof(PageHeaderData) - sizeof(ItemIdData);
+	thdr->pd_lower = SizeOfPageHeaderData;
 	thdr->pd_upper = pageSize - MAXALIGN(specialSize);
 
 	return temp;
@@ -291,7 +290,7 @@ PageRepairFragmentation(Page page, OffsetNumber *unused)
 	 * pointers, lengths, etc could cause us to clobber adjacent disk
 	 * buffers, spreading the data loss further.  So, check everything.
 	 */
-	if (pd_lower < (sizeof(PageHeaderData) - sizeof(ItemIdData)) ||
+	if (pd_lower < SizeOfPageHeaderData ||
 		pd_lower > pd_upper ||
 		pd_upper > pd_special ||
 		pd_special > BLCKSZ ||
@@ -303,7 +302,7 @@ PageRepairFragmentation(Page page, OffsetNumber *unused)
 	nused = 0;
 	for (i = 0; i < nline; i++)
 	{
-		lp = ((PageHeader) page)->pd_linp + i;
+		lp = PageGetItemId(page, i + 1);
 		if ((*lp).lp_flags & LP_DELETE) /* marked for deletion */
 			(*lp).lp_flags &= ~(LP_USED | LP_DELETE);
 		if ((*lp).lp_flags & LP_USED)
@@ -317,7 +316,7 @@ PageRepairFragmentation(Page page, OffsetNumber *unused)
 		/* Page is completely empty, so just reset it quickly */
 		for (i = 0; i < nline; i++)
 		{
-			lp = ((PageHeader) page)->pd_linp + i;
+			lp = PageGetItemId(page, i + 1);
 			(*lp).lp_len = 0;	/* indicate unused & deallocated */
 		}
 		((PageHeader) page)->pd_upper = pd_special;
@@ -331,7 +330,7 @@ PageRepairFragmentation(Page page, OffsetNumber *unused)
 		totallen = 0;
 		for (i = 0; i < nline; i++)
 		{
-			lp = ((PageHeader) page)->pd_linp + i;
+			lp = PageGetItemId(page, i + 1);
 			if ((*lp).lp_flags & LP_USED)
 			{
 				itemidptr->offsetindex = i;
@@ -363,7 +362,7 @@ PageRepairFragmentation(Page page, OffsetNumber *unused)
 
 		for (i = 0, itemidptr = itemidbase; i < nused; i++, itemidptr++)
 		{
-			lp = ((PageHeader) page)->pd_linp + itemidptr->offsetindex;
+			lp = PageGetItemId(page, itemidptr->offsetindex + 1);
 			upper -= itemidptr->alignedlen;
 			memmove((char *) page + upper,
 					(char *) page + itemidptr->itemoff,
@@ -426,7 +425,7 @@ PageIndexTupleDelete(Page page, OffsetNumber offnum)
 	/*
 	 * As with PageRepairFragmentation, paranoia seems justified.
 	 */
-	if (phdr->pd_lower < (sizeof(PageHeaderData) - sizeof(ItemIdData)) ||
+	if (phdr->pd_lower < SizeOfPageHeaderData ||
 		phdr->pd_lower > phdr->pd_upper ||
 		phdr->pd_upper > phdr->pd_special ||
 		phdr->pd_special > BLCKSZ)
@@ -452,6 +451,8 @@ PageIndexTupleDelete(Page page, OffsetNumber offnum)
 	/*
 	 * First, we want to get rid of the pd_linp entry for the index tuple.
 	 * We copy all subsequent linp's back one slot in the array.
+	 * We don't use PageGetItemId, because we are manipulating the _array_,
+	 * not individual linp's.
 	 */
 	nbytes = phdr->pd_lower -
 		((char *) &phdr->pd_linp[offidx + 1] - (char *) phdr);
@@ -490,8 +491,8 @@ PageIndexTupleDelete(Page page, OffsetNumber offnum)
 		nline--;				/* there's one less than when we started */
 		for (i = nline; --i >= 0; )
 		{
-			if (phdr->pd_linp[i].lp_off <= offset)
-				phdr->pd_linp[i].lp_off += size;
+			if (PageGetItemId(phdr, i + 1)->lp_off <= offset)
+				PageGetItemId(phdr, i + 1)->lp_off += size;
 		}
 	}
 }
diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h
index 9bc86a01a82..7d279ef94d0 100644
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: nbtree.h,v 1.62 2002/06/20 20:29:43 momjian Exp $
+ * $Id: nbtree.h,v 1.63 2002/07/02 05:48:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -65,7 +65,7 @@ typedef struct BTMetaPageData
 } BTMetaPageData;
 
 #define BTPageGetMeta(p) \
-	((BTMetaPageData *) &((PageHeader) p)->pd_linp[0])
+	((BTMetaPageData *) PageGetContents(p))
 
 #define BTREE_METAPAGE	0		/* first page is meta */
 #define BTREE_MAGIC		0x053162	/* magic number of btree pages */
@@ -77,6 +77,14 @@ typedef struct BTMetaPageData
 #define BTREE_VERSION	1
 
 /*
+ * We actually need to be able to fit three items on every page,
+ * so restrict any one item to 1/3 the per-page available space.
+ */
+#define BTMaxItemSize(page) \
+	((PageGetPageSize(page) - \
+	  sizeof(PageHeaderData) - \
+	  MAXALIGN(sizeof(BTPageOpaqueData))) / 3 - sizeof(ItemIdData))
+/*
  *	BTScanOpaqueData is used to remember which buffers we're currently
  *	examining in the scan.	We keep these buffers pinned (but not locked,
  *	see nbtree.c) and recorded in the opaque entry of the scan to avoid
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
index 5c9c4a6c06a..31a858ec4ff 100644
--- a/src/include/storage/bufpage.h
+++ b/src/include/storage/bufpage.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: bufpage.h,v 1.48 2002/06/20 20:29:52 momjian Exp $
+ * $Id: bufpage.h,v 1.49 2002/07/02 05:48:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -158,12 +158,16 @@ typedef enum
 )
 
 /*
+ * line pointer does not count as part of header
+ */
+#define SizeOfPageHeaderData (offsetof(PageHeaderData, pd_linp[0]))
+
+/*
  * PageIsEmpty
  *		returns true iff no itemid has been allocated on the page
  */
 #define PageIsEmpty(page) \
-	(((PageHeader) (page))->pd_lower <= \
-	 (sizeof(PageHeaderData) - sizeof(ItemIdData)))
+	(((PageHeader) (page))->pd_lower <= SizeOfPageHeaderData)
 
 /*
  * PageIsNew
@@ -179,6 +183,13 @@ typedef enum
 #define PageGetItemId(page, offsetNumber) \
 	((ItemId) (&((PageHeader) (page))->pd_linp[(offsetNumber) - 1]))
 
+/*
+ * PageGetContents
+ *		To be used in case the page does not contain item pointers.
+ */
+#define PageGetContents(page) \
+	((char *) (&((PageHeader) (page))->pd_linp[0]))
+
 /* ----------------
  *		macros to access opaque space
  * ----------------
@@ -290,8 +301,7 @@ typedef enum
  *		That way we get -1 or so, not a huge positive number...
  */
 #define PageGetMaxOffsetNumber(page) \
-	(((int) (((PageHeader) (page))->pd_lower - \
-			 (sizeof(PageHeaderData) - sizeof(ItemIdData)))) \
+	(((int) (((PageHeader) (page))->pd_lower - SizeOfPageHeaderData)) \
 	 / ((int) sizeof(ItemIdData)))
 
 #define PageGetLSN(page) \