org.h2.index.PageDataCursor Maven / Gradle / Ivy
/*
* Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.index;
import java.util.Iterator;
import org.h2.engine.Session;
import org.h2.message.DbException;
import org.h2.result.Row;
import org.h2.result.SearchRow;
/**
* The cursor implementation for the page scan index.
*/
class PageDataCursor implements Cursor {
private PageDataLeaf current;
private int idx;
private final long maxKey;
private Row row;
private final boolean multiVersion;
private final Session session;
private Iterator delta;
PageDataCursor(Session session, PageDataLeaf current, int idx, long maxKey,
boolean multiVersion) {
this.current = current;
this.idx = idx;
this.maxKey = maxKey;
this.multiVersion = multiVersion;
this.session = session;
if (multiVersion) {
delta = current.index.getDelta();
}
}
@Override
public Row get() {
return row;
}
@Override
public SearchRow getSearchRow() {
return get();
}
@Override
public boolean next() {
if (!multiVersion) {
nextRow();
return checkMax();
}
while (true) {
if (delta != null) {
if (!delta.hasNext()) {
delta = null;
row = null;
continue;
}
row = delta.next();
if (!row.isDeleted() || row.getSessionId() == session.getId()) {
continue;
}
} else {
nextRow();
if (row != null && row.getSessionId() != 0 &&
row.getSessionId() != session.getId()) {
continue;
}
}
break;
}
return checkMax();
}
private boolean checkMax() {
if (row != null) {
if (maxKey != Long.MAX_VALUE) {
long x = current.index.getKey(row, Long.MAX_VALUE, Long.MAX_VALUE);
if (x > maxKey) {
row = null;
return false;
}
}
return true;
}
return false;
}
private void nextRow() {
if (idx >= current.getEntryCount()) {
current = current.getNextPage();
idx = 0;
if (current == null) {
row = null;
return;
}
}
row = current.getRowAt(idx);
idx++;
}
@Override
public boolean previous() {
throw DbException.throwInternalError();
}
}