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Fix for AMQ-2757 - leaf nodes were not properly getting linked together in some cases. 

git-svn-id: https://svn.apache.org/repos/asf/activemq/trunk@956741 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Hiram R. Chirino 2010-06-21 23:56:35 +00:00
parent d8440f8610
commit 9ae41192a9
1 changed files with 66 additions and 7 deletions
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69
kahadb/src/main/java/org/apache/kahadb/index/BTreeNode.java
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@ -101,6 +101,7 @@ public final class BTreeNode<Key,Value> {
// we need to roll to the next leaf..
if( current.next >= 0 ) {
current = index.loadNode(tx, current.next, null);
assert !current.isBranch() : "Should have linked to the next leaf node.";
nextIndex=0;
} else {
break;
@ -228,6 +229,52 @@ public final class BTreeNode<Key,Value> {
}
}
/**
* Returns the right most leaf from the current btree graph.
* @throws IOException
*/
private BTreeNode<Key,Value> getRightLeaf(Transaction tx) throws IOException {
BTreeNode<Key,Value> cur = this;
while(cur.isBranch()) {
cur = cur.getChild(tx, keys.length);
}
return cur;
}
/**
* Returns the left most leaf from the current btree graph.
* @throws IOException
*/
private BTreeNode<Key,Value> getLeftLeaf(Transaction tx) throws IOException {
BTreeNode<Key,Value> cur = this;
while(cur.isBranch()) {
cur = cur.getChild(tx, 0);
}
return cur;
}
/**
* Returns the left most leaf from the current btree graph.
* @throws IOException
*/
private BTreeNode<Key,Value> getLeftPeer(Transaction tx, BTreeNode<Key,Value> x) throws IOException {
BTreeNode<Key,Value> cur = x;
while( cur.parent !=null ) {
if( cur.parent.children[0] == cur.getPageId() ) {
cur = cur.parent;
} else {
for( int i=0; i < cur.parent.children.length; i ++) {
if( cur.parent.children[i]==cur.getPageId() ) {
return cur.parent.getChild(tx, i-1);
}
}
throw new AssertionError("page "+x+" was decendent of "+cur.getPageId());
}
}
return null;
}
public Value remove(Transaction tx, Key key) throws IOException {
if(isBranch()) {
@ -249,12 +296,24 @@ public final class BTreeNode<Key,Value> {
} else {
// The child was a leaf. Then we need to actually remove it from this branch node..
// and relink the previous leaf to skip to the next leaf.
// We need to update the previous child's next pointer to skip over the child being removed....
if( idx > 0 && children.length > 1) {
BTreeNode<Key, Value> previousChild = getChild(tx, idx-1);
previousChild.next = child.next;
index.storeNode(tx, previousChild, true);
BTreeNode<Key, Value> previousLeaf = null;
if( idx > 0 ) {
// easy if we this node hold the previous child.
previousLeaf = getChild(tx, idx-1).getRightLeaf(tx);
} else {
// less easy if we need to go to the parent to find the previous child.
BTreeNode<Key, Value> lp = getLeftPeer(tx, this);
if( lp!=null ) {
previousLeaf = lp.getRightLeaf(tx);
}
// lp will be null if there was no previous child.
}
if( previousLeaf !=null ) {
previousLeaf.next = child.next;
index.storeNode(tx, previousLeaf, true);
}
if( idx < children.length-1 ) {