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
*/
GinBtreeStack *
ginFindLeafPage(GinBtree btree, GinBtreeStack *stack)
{
bool isfirst = TRUE;
BlockNumber rootBlkno;
if (!stack)
stack = ginPrepareFindLeafPage(btree, GIN_ROOT_BLKNO);
rootBlkno = stack->blkno;
for (;;)
{
Page page;
BlockNumber child;
int access = GIN_SHARE;
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);
/*
* ok, page is correctly locked, we should check to move right ..,
* root never has a right link, so small optimization
*/
while (btree->fullScan == FALSE && stack->blkno != rootBlkno &&
btree->isMoveRight(btree, page))
{
BlockNumber rightlink = GinPageGetOpaque(page)->rightlink;
if (rightlink == InvalidBlockNumber)
/* rightmost page */
break;
stack->blkno = rightlink;
LockBuffer(stack->buffer, GIN_UNLOCK);
stack->buffer = ReleaseAndReadBuffer(stack->buffer, btree->index, stack->blkno);
LockBuffer(stack->buffer, access);
page = BufferGetPage(stack->buffer);
}
if (GinPageIsLeaf(page)) /* we found, return locked page */
return stack;
/* now we have correct buffer, try to find child */
child = btree->findChildPage(btree, stack);
LockBuffer(stack->buffer, GIN_UNLOCK);
Assert(child != InvalidBlockNumber);
Assert(stack->blkno != child);
if (btree->searchMode)
{
/* in search mode we may forget path to leaf */
stack->blkno = child;
stack->buffer = ReleaseAndReadBuffer(stack->buffer, btree->index, stack->blkno);
}
else
{
GinBtreeStack *ptr = (GinBtreeStack *) palloc(sizeof(GinBtreeStack));
ptr->parent = stack;
stack = ptr;
stack->blkno = child;
stack->buffer = ReadBuffer(btree->index, stack->blkno);
stack->predictNumber = 1;
}
}
/* keep compiler happy */
return NULL;
}
/*
* Descend 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, bool searchMode)
{
GinBtreeStack *stack;
stack = (GinBtreeStack *) palloc(sizeof(GinBtreeStack));
stack->blkno = btree->rootBlkno;
stack->buffer = ReadBuffer(btree->index, btree->rootBlkno);
stack->parent = NULL;
stack->predictNumber = 1;
for (;;)
{
Page page;
BlockNumber child;
int access;
stack->off = InvalidOffsetNumber;
page = BufferGetPage(stack->buffer);
access = ginTraverseLock(stack->buffer, searchMode);
/*
* If we're going to modify the tree, finish any incomplete splits we
* encounter on the way.
*/
if (!searchMode && GinPageIsIncompleteSplit(page))
ginFinishSplit(btree, stack, false, NULL);
/*
* ok, page is correctly locked, we should check to move right ..,
* root never has a right link, so small optimization
*/
while (btree->fullScan == FALSE && stack->blkno != btree->rootBlkno &&
btree->isMoveRight(btree, page))
{
BlockNumber rightlink = GinPageGetOpaque(page)->rightlink;
if (rightlink == InvalidBlockNumber)
/* rightmost page */
break;
stack->buffer = ginStepRight(stack->buffer, btree->index, access);
stack->blkno = rightlink;
page = BufferGetPage(stack->buffer);
if (!searchMode && GinPageIsIncompleteSplit(page))
ginFinishSplit(btree, stack, false, NULL);
}
if (GinPageIsLeaf(page)) /* we found, return locked page */
return stack;
/* now we have correct buffer, try to find child */
child = btree->findChildPage(btree, stack);
LockBuffer(stack->buffer, GIN_UNLOCK);
Assert(child != InvalidBlockNumber);
Assert(stack->blkno != child);
if (searchMode)
{
/* in search mode we may forget path to leaf */
stack->blkno = child;
stack->buffer = ReleaseAndReadBuffer(stack->buffer, btree->index, stack->blkno);
}
else
{
GinBtreeStack *ptr = (GinBtreeStack *) palloc(sizeof(GinBtreeStack));
ptr->parent = stack;
stack = ptr;
stack->blkno = child;
stack->buffer = ReadBuffer(btree->index, stack->blkno);
stack->predictNumber = 1;
}
}
}
/*
* Scan through posting tree, delete empty tuples from leaf pages.
* Also, this function collects empty subtrees (with all empty leafs).
* For parents of these subtrees CleanUp lock is taken, then we call
* ScanToDelete. This is done for every inner page, which points to
* empty subtree.
*/
static bool
ginVacuumPostingTreeLeaves(GinVacuumState *gvs, BlockNumber blkno, bool isRoot)
{
Buffer buffer;
Page page;
bool hasVoidPage = FALSE;
MemoryContext oldCxt;
buffer = ReadBufferExtended(gvs->index, MAIN_FORKNUM, blkno,
RBM_NORMAL, gvs->strategy);
page = BufferGetPage(buffer);
ginTraverseLock(buffer, false);
Assert(GinPageIsData(page));
if (GinPageIsLeaf(page))
{
oldCxt = MemoryContextSwitchTo(gvs->tmpCxt);
ginVacuumPostingTreeLeaf(gvs->index, buffer, gvs);
MemoryContextSwitchTo(oldCxt);
MemoryContextReset(gvs->tmpCxt);
/* if root is a leaf page, we don't desire further processing */
if (GinDataLeafPageIsEmpty(page))
hasVoidPage = TRUE;
UnlockReleaseBuffer(buffer);
return hasVoidPage;
}
else
{
OffsetNumber i;
bool hasEmptyChild = FALSE;
bool hasNonEmptyChild = FALSE;
OffsetNumber maxoff = GinPageGetOpaque(page)->maxoff;
BlockNumber *children = palloc(sizeof(BlockNumber) * (maxoff + 1));
/*
* Read all children BlockNumbers. Not sure it is safe if there are
* many concurrent vacuums.
*/
for (i = FirstOffsetNumber; i <= maxoff; i++)
{
PostingItem *pitem = GinDataPageGetPostingItem(page, i);
children[i] = PostingItemGetBlockNumber(pitem);
}
UnlockReleaseBuffer(buffer);
for (i = FirstOffsetNumber; i <= maxoff; i++)
{
if (ginVacuumPostingTreeLeaves(gvs, children[i], FALSE))
hasEmptyChild = TRUE;
else
hasNonEmptyChild = TRUE;
}
pfree(children);
vacuum_delay_point();
/*
* All subtree is empty - just return TRUE to indicate that parent
* must do a cleanup. Unless we are ROOT an there is way to go upper.
*/
if (hasEmptyChild && !hasNonEmptyChild && !isRoot)
return TRUE;
if (hasEmptyChild)
{
DataPageDeleteStack root,
*ptr,
*tmp;
buffer = ReadBufferExtended(gvs->index, MAIN_FORKNUM, blkno,
RBM_NORMAL, gvs->strategy);
LockBufferForCleanup(buffer);
memset(&root, 0, sizeof(DataPageDeleteStack));
root.leftBlkno = InvalidBlockNumber;
root.isRoot = TRUE;
ginScanToDelete(gvs, blkno, TRUE, &root, InvalidOffsetNumber);
ptr = root.child;
while (ptr)
{
tmp = ptr->child;
pfree(ptr);
ptr = tmp;
}
UnlockReleaseBuffer(buffer);
}
/* Here we have deleted all empty subtrees */
return FALSE;
}
}
