private void fetchNext() {
while (fetchNextKey()) {
if (pos1 == null || pos2 == null) {
break;
}
@SuppressWarnings("unchecked")
V v1 = (V) map.binarySearch(root1, current);
@SuppressWarnings("unchecked")
V v2 = (V) map.binarySearch(root2, current);
if (!v1.equals(v2)) {
break;
}
}
}
@SuppressWarnings("unchecked")
private CursorPos fetchNext(CursorPos p) {
while (p != null) {
if (p.index < p.page.getKeyCount()) {
current = (K) p.page.getKey(p.index++);
return p;
}
p = p.parent;
if (p == null) {
break;
}
if (p.index + 1 < map.getChildPageCount(p.page)) {
p = new CursorPos(p.page.getChildPage(++p.index), 0, p);
p = min(p);
}
}
current = null;
return p;
}
private boolean fetchNextKey() {
while (true) {
if (state == 3) {
return false;
}
if (state == 1) {
// read from root1
pos1 = fetchNext(pos1);
if (pos1 == null) {
// reached the end of pos1
state = 2;
pos2 = null;
continue;
}
pos2 = find(root2, current);
if (pos2 == null) {
// not found in root2
return true;
}
if (!pos1.page.equals(pos2.page)) {
// the page is different,
// so the entry has possibly changed
return true;
}
while (true) {
pos1 = pos1.parent;
if (pos1 == null) {
// reached end of pos1
state = 2;
pos2 = null;
break;
}
pos2 = pos2.parent;
if (pos2 == null || !pos1.page.equals(pos2.page)) {
if (pos1.index + 1 < map.getChildPageCount(pos1.page)) {
pos1 = new CursorPos(pos1.page.getChildPage(++pos1.index), 0, pos1);
pos1 = min(pos1);
break;
}
}
}
}
if (state == 2) {
if (pos2 == null) {
// init reading from root2
pos2 = new CursorPos(root2, 0, null);
pos2 = min(pos2);
}
// read from root2
pos2 = fetchNext(pos2);
if (pos2 == null) {
// reached the end of pos2
state = 3;
current = null;
continue;
}
pos1 = find(root1, current);
if (pos1 != null) {
// found a corresponding record
// so it was not deleted
// but now we may need to skip pages
if (!pos1.page.equals(pos2.page)) {
// the page is different
pos1 = null;
continue;
}
while (true) {
pos2 = pos2.parent;
if (pos2 == null) {
// reached end of pos1
state = 3;
current = null;
pos1 = null;
break;
}
pos1 = pos1.parent;
if (pos1 == null || !pos2.page.equals(pos1.page)) {
if (pos2.index + 1 < map.getChildPageCount(pos2.page)) {
pos2 = new CursorPos(pos2.page.getChildPage(++pos2.index), 0, pos2);
pos2 = min(pos2);
break;
}
}
}
pos1 = null;
continue;
}
// found no corresponding record
// so it was deleted
return true;
}
}
}
