Further GIN refactoring.

Merge some functions that were always called together. Makes the code
little bit more readable.

Author: hlinnaka

src/backend/access/gin/ginbtree.c

@@ -52,52 +52,38 @@ ginTraverseLock(Buffer buffer, bool searchMode)
 	return access;
 }
 
-GinBtreeStack *
-ginPrepareFindLeafPage(GinBtree btree, BlockNumber blkno)
-{
-	GinBtreeStack *stack = (GinBtreeStack *) palloc(sizeof(GinBtreeStack));
-
-	stack->blkno = blkno;
-	stack->buffer = ReadBuffer(btree->index, stack->blkno);
-	stack->parent = NULL;
-	stack->predictNumber = 1;
-
-	ginTraverseLock(stack->buffer, btree->searchMode);
-
-	return stack;
-}
-
 /*
- * Locates leaf page contained tuple
+ * Descends the tree to the leaf page that contains or would contain the
+ * key we're searching for. The key should already be filled in 'btree',
+ * in tree-type specific manner. If btree->fullScan is true, descends to the
+ * leftmost leaf page.
+ *
+ * If 'searchmode' is false, on return stack->buffer is exclusively locked,
+ * and the stack represents the full path to the root. Otherwise stack->buffer
+ * is share-locked, and stack->parent is NULL.
  */
 GinBtreeStack *
-ginFindLeafPage(GinBtree btree, GinBtreeStack *stack)
+ginFindLeafPage(GinBtree btree, BlockNumber rootBlkno, bool searchMode)
 {
-	bool		isfirst = TRUE;
-	BlockNumber rootBlkno;
+	GinBtreeStack *stack;
 
-	if (!stack)
-		stack = ginPrepareFindLeafPage(btree, GIN_ROOT_BLKNO);
-	rootBlkno = stack->blkno;
+	stack = (GinBtreeStack *) palloc(sizeof(GinBtreeStack));
+	stack->blkno = rootBlkno;
+	stack->buffer = ReadBuffer(btree->index, rootBlkno);
+	stack->parent = NULL;
+	stack->predictNumber = 1;
 
 	for (;;)
 	{
 		Page		page;
 		BlockNumber child;
-		int			access = GIN_SHARE;
+		int			access;
 
 		stack->off = InvalidOffsetNumber;
 
 		page = BufferGetPage(stack->buffer);
 
-		if (isfirst)
-		{
-			if (GinPageIsLeaf(page) && !btree->searchMode)
-				access = GIN_EXCLUSIVE;
-			isfirst = FALSE;
-		}
-		else
-			access = ginTraverseLock(stack->buffer, btree->searchMode);
+		access = ginTraverseLock(stack->buffer, searchMode);
 
 		/*
 		 * ok, page is correctly locked, we should check to move right ..,
@@ -127,7 +113,7 @@ ginFindLeafPage(GinBtree btree, GinBtreeStack *stack)
 		Assert(child != InvalidBlockNumber);
 		Assert(stack->blkno != child);
 
-		if (btree->searchMode)
+		if (searchMode)
 		{
 			/* in search mode we may forget path to leaf */
 			stack->blkno = child;
@@ -251,7 +237,7 @@ ginFindParents(GinBtree btree, GinBtreeStack *stack,
 		return;
 	}
 
-	leftmostBlkno = blkno = btree->getLeftMostPage(btree, page);
+	leftmostBlkno = blkno = btree->getLeftMostChild(btree, page);
 	LockBuffer(root->buffer, GIN_UNLOCK);
 	Assert(blkno != InvalidBlockNumber);
 
@@ -263,7 +249,7 @@ ginFindParents(GinBtree btree, GinBtreeStack *stack,
 		if (GinPageIsLeaf(page))
 			elog(ERROR, "Lost path");
 
-		leftmostBlkno = btree->getLeftMostPage(btree, page);
+		leftmostBlkno = btree->getLeftMostChild(btree, page);
 
 		while ((offset = btree->findChildPtr(btree, page, stack->blkno, InvalidOffsetNumber)) == InvalidOffsetNumber)
 		{

src/backend/access/gin/gindatapage.c

@@ -54,7 +54,7 @@ dataLocateItem(GinBtree btree, GinBtreeStack *stack)
 	{
 		stack->off = FirstOffsetNumber;
 		stack->predictNumber *= GinPageGetOpaque(page)->maxoff;
-		return btree->getLeftMostPage(btree, page);
+		return btree->getLeftMostChild(btree, page);
 	}
 
 	low = FirstOffsetNumber;
@@ -680,17 +680,10 @@ createPostingTree(Relation index, ItemPointerData *items, uint32 nitems,
 	 */
 	if (nitems > nrootitems)
 	{
-		GinPostingTreeScan *gdi;
-
-		gdi = ginPrepareScanPostingTree(index, blkno, FALSE);
-		gdi->btree.isBuild = (buildStats != NULL);
-
-		ginInsertItemPointers(gdi,
+		ginInsertItemPointers(index, blkno,
 							  items + nrootitems,
 							  nitems - nrootitems,
 							  buildStats);
-
-		pfree(gdi);
 	}
 
 	return blkno;
@@ -704,76 +697,69 @@ ginPrepareDataScan(GinBtree btree, Relation index)
 	btree->index = index;
 
 	btree->findChildPage = dataLocateItem;
+	btree->getLeftMostChild = dataGetLeftMostPage;
 	btree->isMoveRight = dataIsMoveRight;
 	btree->findItem = dataLocateLeafItem;
 	btree->findChildPtr = dataFindChildPtr;
-	btree->getLeftMostPage = dataGetLeftMostPage;
 	btree->placeToPage = dataPlaceToPage;
 	btree->splitPage = dataSplitPage;
 	btree->fillRoot = ginDataFillRoot;
 
 	btree->isData = TRUE;
-	btree->searchMode = FALSE;
 	btree->isDelete = FALSE;
 	btree->fullScan = FALSE;
 	btree->isBuild = FALSE;
 }
 
-GinPostingTreeScan *
-ginPrepareScanPostingTree(Relation index, BlockNumber rootBlkno, bool searchMode)
-{
-	GinPostingTreeScan *gdi = (GinPostingTreeScan *) palloc0(sizeof(GinPostingTreeScan));
-
-	ginPrepareDataScan(&gdi->btree, index);
-
-	gdi->btree.searchMode = searchMode;
-	gdi->btree.fullScan = searchMode;
-
-	gdi->stack = ginPrepareFindLeafPage(&gdi->btree, rootBlkno);
-
-	return gdi;
-}
-
 /*
  * Inserts array of item pointers, may execute several tree scan (very rare)
  */
 void
-ginInsertItemPointers(GinPostingTreeScan *gdi,
+ginInsertItemPointers(Relation index, BlockNumber rootBlkno,
 					  ItemPointerData *items, uint32 nitem,
 					  GinStatsData *buildStats)
 {
-	BlockNumber rootBlkno = gdi->stack->blkno;
+	GinBtreeData btree;
+	GinBtreeStack *stack;
 
-	gdi->btree.items = items;
-	gdi->btree.nitem = nitem;
-	gdi->btree.curitem = 0;
+	ginPrepareDataScan(&btree, index);
+	btree.isBuild = (buildStats != NULL);
+	btree.items = items;
+	btree.nitem = nitem;
+	btree.curitem = 0;
 
-	while (gdi->btree.curitem < gdi->btree.nitem)
+	while (btree.curitem < btree.nitem)
 	{
-		if (!gdi->stack)
-			gdi->stack = ginPrepareFindLeafPage(&gdi->btree, rootBlkno);
-
-		gdi->stack = ginFindLeafPage(&gdi->btree, gdi->stack);
+		stack = ginFindLeafPage(&btree, rootBlkno, false);
 
-		if (gdi->btree.findItem(&(gdi->btree), gdi->stack))
+		if (btree.findItem(&btree, stack))
 		{
 			/*
-			 * gdi->btree.items[gdi->btree.curitem] already exists in index
+			 * btree.items[btree.curitem] already exists in index
 			 */
-			gdi->btree.curitem++;
-			LockBuffer(gdi->stack->buffer, GIN_UNLOCK);
-			freeGinBtreeStack(gdi->stack);
+			btree.curitem++;
+			LockBuffer(stack->buffer, GIN_UNLOCK);
+			freeGinBtreeStack(stack);
 		}
 		else
-			ginInsertValue(&(gdi->btree), gdi->stack, buildStats);
-
-		gdi->stack = NULL;
+			ginInsertValue(&btree, stack, buildStats);
 	}
 }
 
-Buffer
-ginScanBeginPostingTree(GinPostingTreeScan *gdi)
+/*
+ * Starts a new scan on a posting tree.
+ */
+GinBtreeStack *
+ginScanBeginPostingTree(Relation index, BlockNumber rootBlkno)
 {
-	gdi->stack = ginFindLeafPage(&gdi->btree, gdi->stack);
-	return gdi->stack->buffer;
+	GinBtreeData btree;
+	GinBtreeStack *stack;
+
+	ginPrepareDataScan(&btree, index);
+
+	btree.fullScan = TRUE;
+
+	stack = ginFindLeafPage(&btree, rootBlkno, TRUE);
+
+	return stack;
 }

src/backend/access/gin/ginentrypage.c

@@ -258,7 +258,7 @@ entryLocateEntry(GinBtree btree, GinBtreeStack *stack)
 	{
 		stack->off = FirstOffsetNumber;
 		stack->predictNumber *= PageGetMaxOffsetNumber(page);
-		return btree->getLeftMostPage(btree, page);
+		return btree->getLeftMostChild(btree, page);
 	}
 
 	low = FirstOffsetNumber;
@@ -729,16 +729,15 @@ ginPrepareEntryScan(GinBtree btree, OffsetNumber attnum,
 	btree->ginstate = ginstate;
 
 	btree->findChildPage = entryLocateEntry;
+	btree->getLeftMostChild = entryGetLeftMostPage;
 	btree->isMoveRight = entryIsMoveRight;
 	btree->findItem = entryLocateLeafEntry;
 	btree->findChildPtr = entryFindChildPtr;
-	btree->getLeftMostPage = entryGetLeftMostPage;
 	btree->placeToPage = entryPlaceToPage;
 	btree->splitPage = entrySplitPage;
 	btree->fillRoot = ginEntryFillRoot;
 
 	btree->isData = FALSE;
-	btree->searchMode = FALSE;
 	btree->fullScan = FALSE;
 	btree->isBuild = FALSE;
 

src/backend/access/gin/ginget.c

@@ -124,18 +124,16 @@ static void
 scanPostingTree(Relation index, GinScanEntry scanEntry,
 				BlockNumber rootPostingTree)
 {
-	GinPostingTreeScan *gdi;
+	GinBtreeStack *stack;
 	Buffer		buffer;
 	Page		page;
 
 	/* Descend to the leftmost leaf page */
-	gdi = ginPrepareScanPostingTree(index, rootPostingTree, TRUE);
-
-	buffer = ginScanBeginPostingTree(gdi);
+	stack = ginScanBeginPostingTree(index, rootPostingTree);
+	buffer = stack->buffer;
 	IncrBufferRefCount(buffer); /* prevent unpin in freeGinBtreeStack */
 
-	freeGinBtreeStack(gdi->stack);
-	pfree(gdi);
+	freeGinBtreeStack(stack);
 
 	/*
 	 * Loop iterates through all leaf pages of posting tree
@@ -376,8 +374,7 @@ startScanEntry(GinState *ginstate, GinScanEntry entry)
 	ginPrepareEntryScan(&btreeEntry, entry->attnum,
 						entry->queryKey, entry->queryCategory,
 						ginstate);
-	btreeEntry.searchMode = TRUE;
-	stackEntry = ginFindLeafPage(&btreeEntry, NULL);
+	stackEntry = ginFindLeafPage(&btreeEntry, GIN_ROOT_BLKNO, true);
 	page = BufferGetPage(stackEntry->buffer);
 	needUnlock = TRUE;
 
@@ -427,7 +424,7 @@ startScanEntry(GinState *ginstate, GinScanEntry entry)
 		if (GinIsPostingTree(itup))
 		{
 			BlockNumber rootPostingTree = GinGetPostingTree(itup);
-			GinPostingTreeScan *gdi;
+			GinBtreeStack *stack;
 			Page		page;
 
 			/*
@@ -439,9 +436,9 @@ startScanEntry(GinState *ginstate, GinScanEntry entry)
 			 */
 			LockBuffer(stackEntry->buffer, GIN_UNLOCK);
 			needUnlock = FALSE;
-			gdi = ginPrepareScanPostingTree(ginstate->index, rootPostingTree, TRUE);
 
-			entry->buffer = ginScanBeginPostingTree(gdi);
+			stack = ginScanBeginPostingTree(ginstate->index, rootPostingTree);
+			entry->buffer = stack->buffer;
 
 			/*
 			 * We keep buffer pinned because we need to prevent deletion of
@@ -451,7 +448,7 @@ startScanEntry(GinState *ginstate, GinScanEntry entry)
 			IncrBufferRefCount(entry->buffer);
 
 			page = BufferGetPage(entry->buffer);
-			entry->predictNumberResult = gdi->stack->predictNumber * GinPageGetOpaque(page)->maxoff;
+			entry->predictNumberResult = stack->predictNumber * GinPageGetOpaque(page)->maxoff;
 
 			/*
 			 * Keep page content in memory to prevent durable page locking
@@ -463,8 +460,7 @@ startScanEntry(GinState *ginstate, GinScanEntry entry)
 				   GinPageGetOpaque(page)->maxoff * sizeof(ItemPointerData));
 
 			LockBuffer(entry->buffer, GIN_UNLOCK);
-			freeGinBtreeStack(gdi->stack);
-			pfree(gdi);
+			freeGinBtreeStack(stack);
 			entry->isFinished = FALSE;
 		}
 		else if (GinGetNPosting(itup) > 0)

src/backend/access/gin/gininsert.c

@@ -81,7 +81,6 @@ addItemPointersToLeafTuple(GinState *ginstate,
 	{
 		/* posting list would be too big, convert to posting tree */
 		BlockNumber postingRoot;
-		GinPostingTreeScan *gdi;
 
 		/*
 		 * Initialize posting tree with the old tuple's posting list.  It's
@@ -94,12 +93,9 @@ addItemPointersToLeafTuple(GinState *ginstate,
 										buildStats);
 
 		/* Now insert the TIDs-to-be-added into the posting tree */
-		gdi = ginPrepareScanPostingTree(ginstate->index, postingRoot, FALSE);
-		gdi->btree.isBuild = (buildStats != NULL);
-
-		ginInsertItemPointers(gdi, items, nitem, buildStats);
-
-		pfree(gdi);
+		ginInsertItemPointers(ginstate->index, postingRoot,
+							  items, nitem,
+							  buildStats);
 
 		/* And build a new posting-tree-only result tuple */
 		res = GinFormTuple(ginstate, attnum, key, category, NULL, 0, true);
@@ -177,7 +173,7 @@ ginEntryInsert(GinState *ginstate,
 
 	ginPrepareEntryScan(&btree, attnum, key, category, ginstate);
 
-	stack = ginFindLeafPage(&btree, NULL);
+	stack = ginFindLeafPage(&btree, GIN_ROOT_BLKNO, false);
 	page = BufferGetPage(stack->buffer);
 
 	if (btree.findItem(&btree, stack))
@@ -189,18 +185,15 @@ ginEntryInsert(GinState *ginstate,
 		{
 			/* add entries to existing posting tree */
 			BlockNumber rootPostingTree = GinGetPostingTree(itup);
-			GinPostingTreeScan *gdi;
 
 			/* release all stack */
 			LockBuffer(stack->buffer, GIN_UNLOCK);
 			freeGinBtreeStack(stack);
 
 			/* insert into posting tree */
-			gdi = ginPrepareScanPostingTree(ginstate->index, rootPostingTree, FALSE);
-			gdi->btree.isBuild = (buildStats != NULL);
-			ginInsertItemPointers(gdi, items, nitem, buildStats);
-			pfree(gdi);
-
+			ginInsertItemPointers(ginstate->index, rootPostingTree,
+								  items, nitem,
+								  buildStats);
 			return;
 		}