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Fixed a stupid bug found by accident:

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* When removing the last key from a leaf node, the node wasn't freed, but just
  emptied, and thus the whole tree structure would never combast.
* This could also cause a bug in the TreeIterator: if the last entry was not
  in the last node, every second readdir() after the last one would return
  the last entry again. I only found this because that happens to be what
  Tracker does (which would run in an endless loop while scanning the directory
  then).
* Minor cleanup.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@18992 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler
2006-10-03 17:51:22 +00:00
parent 65bf7e89c9
commit 0d01edbaba
1 changed files with 15 additions and 12 deletions
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src/add-ons/kernel/file_systems/bfs/BPlusTree.cpp
+13 -10
View File
@@ -1641,11 +1641,9 @@ BPlusTree::Remove(Transaction &transaction, const uint8 *key, uint16 keyLength,
return B_IO_ERROR; return B_IO_ERROR;
// if it's an empty root node, we have to convert it // if it's an empty root node, we have to convert it
// to a leaf node by dropping the overflow link, or, // to a leaf node by dropping the overflow link
// if it's a leaf node, just empty it
if (nodeAndKey.nodeOffset == fHeader->RootNode() if (nodeAndKey.nodeOffset == fHeader->RootNode()
&& node->NumKeys() == 0 && node->NumKeys() == 0) {
|| node->NumKeys() == 1 && node->IsLeaf()) {
writableNode->overflow_link = HOST_ENDIAN_TO_BFS_INT64((uint64)BPLUSTREE_NULL); writableNode->overflow_link = HOST_ENDIAN_TO_BFS_INT64((uint64)BPLUSTREE_NULL);
writableNode->all_key_count = 0; writableNode->all_key_count = 0;
writableNode->all_key_length = 0; writableNode->all_key_length = 0;
@@ -1883,8 +1881,11 @@ TreeIterator::Traverse(int8 direction, void *key, uint16 *keyLength, uint16 maxL
{ {
if (fTree == NULL) if (fTree == NULL)
return B_INTERRUPTED; return B_INTERRUPTED;
bool forward = direction == BPLUSTREE_FORWARD;
if (fCurrentNodeOffset == BPLUSTREE_NULL if (fCurrentNodeOffset == BPLUSTREE_NULL
&& Goto(direction == BPLUSTREE_FORWARD ? BPLUSTREE_BEGIN : BPLUSTREE_END) < B_OK) && Goto(forward ? BPLUSTREE_BEGIN : BPLUSTREE_END) < B_OK)
RETURN_ERROR(B_ERROR); RETURN_ERROR(B_ERROR);
// if the tree was emptied since the last call // if the tree was emptied since the last call
@@ -1928,6 +1929,8 @@ TreeIterator::Traverse(int8 direction, void *key, uint16 *keyLength, uint16 maxL
} }
off_t savedNodeOffset = fCurrentNodeOffset; off_t savedNodeOffset = fCurrentNodeOffset;
int32 savedKey = fCurrentKey;
if ((node = cached.SetTo(fCurrentNodeOffset)) == NULL) if ((node = cached.SetTo(fCurrentNodeOffset)) == NULL)
RETURN_ERROR(B_ERROR); RETURN_ERROR(B_ERROR);
@@ -1937,9 +1940,9 @@ TreeIterator::Traverse(int8 direction, void *key, uint16 *keyLength, uint16 maxL
fCurrentKey += direction; fCurrentKey += direction;
// is the current key in the current node? // is the current key in the current node?
while ((direction == BPLUSTREE_FORWARD && fCurrentKey >= node->NumKeys()) while ((forward && fCurrentKey >= node->NumKeys())
|| (direction == BPLUSTREE_BACKWARD && fCurrentKey < 0)) { || (!forward && fCurrentKey < 0)) {
fCurrentNodeOffset = direction == BPLUSTREE_FORWARD ? node->RightLink() : node->LeftLink(); fCurrentNodeOffset = forward ? node->RightLink() : node->LeftLink();
// are there any more nodes? // are there any more nodes?
if (fCurrentNodeOffset != BPLUSTREE_NULL) { if (fCurrentNodeOffset != BPLUSTREE_NULL) {
@@ -1948,11 +1951,11 @@ TreeIterator::Traverse(int8 direction, void *key, uint16 *keyLength, uint16 maxL
RETURN_ERROR(B_ERROR); RETURN_ERROR(B_ERROR);
// reset current key // reset current key
fCurrentKey = direction == BPLUSTREE_FORWARD ? 0 : node->NumKeys(); fCurrentKey = forward ? 0 : node->NumKeys();
} else { } else {
// there are no nodes left, so turn back to the last key // there are no nodes left, so turn back to the last key
fCurrentNodeOffset = savedNodeOffset; fCurrentNodeOffset = savedNodeOffset;
fCurrentKey = direction == BPLUSTREE_FORWARD ? node->NumKeys() : -1; fCurrentKey = savedKey;
return B_ENTRY_NOT_FOUND; return B_ENTRY_NOT_FOUND;
} }