package com.taobao.tddl.executor.cursor.impl;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import com.taobao.tddl.common.exception.TddlException;
import com.taobao.tddl.common.utils.GeneralUtil;
import com.taobao.tddl.executor.common.DuplicateKVPair;
import com.taobao.tddl.executor.cursor.Cursor;
import com.taobao.tddl.executor.cursor.ISchematicCursor;
import com.taobao.tddl.executor.record.CloneableRecord;
import com.taobao.tddl.executor.rowset.IRowSet;
import com.taobao.tddl.executor.utils.ExecUtils;
/**
* n个cursor的归并排序，假设子cursor都是有序的
*
* @author mengshi.sunmengshi 2013-12-3 上午10:57:02
* @since 5.0.0
*/
public class MergeSortedCursors extends SortCursor {
private ValueMappingIRowSetConvertor valueMappingIRowSetConvertor;
private final List<ISchematicCursor> cursors;
/**
* 保存每个cursor当前的值得wrapper
*/
private List<IRowSet> values;
private boolean templateIsLeft = true;
public MergeSortedCursors(List<ISchematicCursor> cursors, boolean duplicated) throws TddlException{
super(cursors.get(0), null);
this.cursors = cursors;
this.allowDuplicated = duplicated;
values = new ArrayList(cursors.size());
this.orderBys = cursors.get(0).getOrderBy();
}
public MergeSortedCursors(ISchematicCursor cursor, boolean duplicated) throws TddlException{
super(cursor, null);
List<ISchematicCursor> cursors = new ArrayList(1);
cursors.add(cursor);
this.cursors = cursors;
this.allowDuplicated = duplicated;
values = new ArrayList(cursors.size());
}
@Override
public void beforeFirst() throws TddlException {
inited = false;
values.clear();
values = new ArrayList(cursors.size());
for (Cursor cursor : cursors) {
cursor.beforeFirst();
}
}
boolean allowDuplicated = false;
IRowSet current = null;
boolean inited = false;
@Override
public void init() throws TddlException {
if (inited) {
return;
}
inited = true;
for (int i = 0; i < cursors.size(); i++) {
IRowSet row = cursors.get(i).next();
row = convertToIRowSet(row, i == 0);
values.add(row);
}
}
IRowSet currentMaxOrMin = null;
/**
* values中存着每个cursor的当前值 每次调用next，从values中找出最小的值，并且将对应的cursor前移 将新值存到values中
* 如果去重，需要将重复的值略过
*/
@Override
public IRowSet next() throws TddlException {
init();
int indexOfCurrentMaxOrMin = 0;
currentMaxOrMin = null;
for (int i = 0; i < this.values.size(); i++) {
IRowSet row = this.values.get(i);
if (row == null) {
continue;
}
if (currentMaxOrMin == null) {
currentMaxOrMin = row;
indexOfCurrentMaxOrMin = i;
continue;
}
super.initComparator(orderBys, row.getParentCursorMeta());
int n = kvPairComparator.compare(row, currentMaxOrMin);
if (n < 0) {
currentMaxOrMin = row;
indexOfCurrentMaxOrMin = i;
} else if (n == 0) {
if (!this.allowDuplicated) {
// 去重
// 把其他cursor中重复的记录消耗光
IRowSet rowToRemoveDuplicate = currentMaxOrMin;
while (true) {
rowToRemoveDuplicate = this.cursors.get(i).next();
if (rowToRemoveDuplicate == null) {
break;
}
rowToRemoveDuplicate = convertToIRowSet(rowToRemoveDuplicate, i == 0);
if (kvPairComparator.compare(rowToRemoveDuplicate, currentMaxOrMin) != 0) {
break;
}
}
this.values.set(i, rowToRemoveDuplicate);
}
}
}
if (currentMaxOrMin != null) {
currentMaxOrMin = ExecUtils.fromIRowSetToArrayRowSet(currentMaxOrMin);
IRowSet rowToRemoveDuplicate = currentMaxOrMin;
// 选中的cursor消费一行记录，往前移动，如果有需要，还要去重
while (true) {
rowToRemoveDuplicate = this.cursors.get(indexOfCurrentMaxOrMin).next();
if (rowToRemoveDuplicate == null) {
break;
}
rowToRemoveDuplicate = convertToIRowSet(rowToRemoveDuplicate, indexOfCurrentMaxOrMin == 0);
if (this.allowDuplicated) {
break;
}
super.initComparator(orderBys, rowToRemoveDuplicate.getParentCursorMeta());
if (kvPairComparator.compare(rowToRemoveDuplicate, currentMaxOrMin) != 0) {
break;
}
}
this.values.set(indexOfCurrentMaxOrMin, rowToRemoveDuplicate);
}
setCurrent(currentMaxOrMin);
return currentMaxOrMin;
}
private IRowSet convertToIRowSet(IRowSet rowSet, boolean left) {
if (rowSet == null) {
return null;
}
if (valueMappingIRowSetConvertor == null) {// 认为是初始化
valueMappingIRowSetConvertor = new ValueMappingIRowSetConvertor();
valueMappingIRowSetConvertor.wrapValueMappingIRowSetIfNeed(rowSet);
valueMappingIRowSetConvertor.reset();
templateIsLeft = left;
}
if (templateIsLeft == left) {
// template is left and current is left
// template is right and current is right
return rowSet;
} else {
// template is left but current is right
// or template is right but current is left
return valueMappingIRowSetConvertor.wrapValueMappingIRowSetIfNeed(rowSet);
}
}
private void setCurrent(IRowSet current) {
this.current = current;
}
@Override
public IRowSet current() throws TddlException {
return current;
}
@Override
public IRowSet first() throws TddlException {
for (int i = 0; i < this.cursors.size(); i++) {
cursors.get(i).beforeFirst();
}
this.values.clear();
this.inited = false;
this.init();
return next();
}
@Override
public void put(CloneableRecord key, CloneableRecord value) throws TddlException {
throw new UnsupportedOperationException("should not be here");
}
@Override
public Cursor getCursor() {
return cursor;
}
@Override
public Map<CloneableRecord, DuplicateKVPair> mgetWithDuplicate(List<CloneableRecord> keys, boolean prefixMatch,
boolean keyFilterOrValueFilter) throws TddlException {
throw new UnsupportedOperationException("should not be here");
}
@Override
public List<DuplicateKVPair> mgetWithDuplicateList(List<CloneableRecord> keys, boolean prefixMatch,
boolean keyFilterOrValueFilter) throws TddlException {
throw new UnsupportedOperationException("should not be here");
}
@Override
public String toStringWithInden(int inden) {
String tabTittle = GeneralUtil.getTab(inden);
String tabContent = GeneralUtil.getTab(inden + 1);
StringBuilder sb = new StringBuilder();
GeneralUtil.printlnToStringBuilder(sb, tabTittle + "MergeSortedCursor ");
GeneralUtil.printAFieldToStringBuilder(sb, "orderBy", this.orderBys, tabContent);
for (Cursor sub : this.cursors) {
sb.append(sub.toStringWithInden(inden + 1));
}
return sb.toString();
}
@Override
public List<TddlException> close(List<TddlException> exs) {
for (Cursor c : this.cursors) {
if (c != null) {
exs = c.close(exs);
}
}
return exs;
}
@Override
public String toString() {
return toStringWithInden(0);
}
}