/**
* Remove a key-value pair.
*
* @param p the page (may not be null)
* @param writeVersion the write version
* @param key the key
* @return the old value, or null if the key did not exist
*/
protected Object remove(Page p, long writeVersion, Object key) {
int index = p.binarySearch(key);
Object result = null;
if (p.isLeaf()) {
if (index >= 0) {
result = p.getValue(index);
p.remove(index);
if (p.getKeyCount() == 0) {
removePage(p.getPos());
}
}
return result;
}
// node
if (index < 0) {
index = -index - 1;
} else {
index++;
}
Page cOld = p.getChildPage(index);
Page c = copyOnWrite(cOld, writeVersion);
result = remove(c, writeVersion, key);
if (result == null) {
return null;
}
if (c.getTotalCount() == 0) {
// this child was deleted
if (p.getKeyCount() == 0) {
p.setChild(index, c);
p.setCounts(index, c);
removePage(p.getPos());
} else {
p.remove(index);
}
} else {
p.setChild(index, c);
p.setCounts(index, c);
}
return result;
}
