/*
* Copyright 2004-2013 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.lealone.result;
import java.util.ArrayList;
import org.lealone.constant.Constants;
import org.lealone.engine.Database;
import org.lealone.engine.Session;
import org.lealone.store.Data;
import org.lealone.store.FileStore;
import org.lealone.util.New;
import org.lealone.value.Value;
/**
* A list of rows. If the list grows too large, it is buffered to disk
* automatically.
*/
public class RowList {
private final Session session;
private final ArrayList<Row> list = New.arrayList();
private int size;
private int index, listIndex;
private FileStore file;
private Data rowBuff;
private ArrayList<Value> lobs;
private final int maxMemory;
private int memory;
private boolean written;
private boolean readUncached;
/**
* Construct a new row list for this session.
*
* @param session the session
*/
public RowList(Session session) {
this.session = session;
if (session.getDatabase().isPersistent()) {
maxMemory = session.getDatabase().getMaxOperationMemory();
} else {
maxMemory = 0;
}
}
private void writeRow(Data buff, Row r) {
buff.checkCapacity(1 + Data.LENGTH_INT * 8);
buff.writeByte((byte) 1);
buff.writeInt(r.getMemory());
int columnCount = r.getColumnCount();
buff.writeInt(columnCount);
buff.writeLong(r.getKey());
buff.writeInt(r.getVersion());
buff.writeInt(r.isDeleted() ? 1 : 0);
buff.writeInt(r.getSessionId());
for (int i = 0; i < columnCount; i++) {
Value v = r.getValue(i);
buff.checkCapacity(1);
if (v == null) {
buff.writeByte((byte) 0);
} else {
buff.writeByte((byte) 1);
if (v.getType() == Value.CLOB || v.getType() == Value.BLOB) {
// need to keep a reference to temporary lobs,
// otherwise the temp file is deleted
if (v.getSmall() == null && v.getTableId() == 0) {
if (lobs == null) {
lobs = New.arrayList();
}
// need to create a copy, otherwise,
// if stored multiple times, it may be renamed
// and then not found
v = v.copyToTemp();
lobs.add(v);
}
}
buff.checkCapacity(buff.getValueLen(v));
buff.writeValue(v);
}
}
}
private void writeAllRows() {
if (file == null) {
Database db = session.getDatabase();
String fileName = db.createTempFile();
file = db.openFile(fileName, "rw", false);
file.setCheckedWriting(false);
file.seek(FileStore.HEADER_LENGTH);
rowBuff = Data.create(db, Constants.DEFAULT_PAGE_SIZE);
file.seek(FileStore.HEADER_LENGTH);
}
Data buff = rowBuff;
initBuffer(buff);
for (int i = 0, size = list.size(); i < size; i++) {
if (i > 0 && buff.length() > Constants.IO_BUFFER_SIZE) {
flushBuffer(buff);
initBuffer(buff);
}
Row r = list.get(i);
writeRow(buff, r);
}
flushBuffer(buff);
file.autoDelete();
list.clear();
memory = 0;
}
private static void initBuffer(Data buff) {
buff.reset();
buff.writeInt(0);
}
private void flushBuffer(Data buff) {
buff.checkCapacity(1);
buff.writeByte((byte) 0);
buff.fillAligned();
buff.setInt(0, buff.length() / Constants.FILE_BLOCK_SIZE);
file.write(buff.getBytes(), 0, buff.length());
}
/**
* Add a row to the list.
*
* @param r the row to add
*/
public void add(Row r) {
list.add(r);
memory += r.getMemory() + Constants.MEMORY_POINTER;
if (maxMemory > 0 && memory > maxMemory) {
writeAllRows();
}
size++;
}
/**
* Remove all rows from the list.
*/
public void reset() {
index = 0;
if (file != null) {
listIndex = 0;
if (!written) {
writeAllRows();
written = true;
}
list.clear();
file.seek(FileStore.HEADER_LENGTH);
}
}
/**
* Check if there are more rows in this list.
*
* @return true it there are more rows
*/
public boolean hasNext() {
return index < size;
}
private Row readRow(Data buff) {
if (buff.readByte() == 0) {
return null;
}
int mem = buff.readInt();
int columnCount = buff.readInt();
long key = buff.readLong();
int version = buff.readInt();
if (readUncached) {
key = 0;
}
boolean deleted = buff.readInt() == 1;
int sessionId = buff.readInt();
Value[] values = new Value[columnCount];
for (int i = 0; i < columnCount; i++) {
Value v;
if (buff.readByte() == 0) {
v = null;
} else {
v = buff.readValue();
if (v.isLinked()) {
// the table id is 0 if it was linked when writing
// a temporary entry
if (v.getTableId() == 0) {
session.unlinkAtCommit(v);
}
}
}
values[i] = v;
}
Row row = new Row(values, mem);
row.setKey(key);
row.setVersion(version);
row.setDeleted(deleted);
row.setSessionId(sessionId);
return row;
}
/**
* Get the next row from the list.
*
* @return the next row
*/
public Row next() {
Row r;
if (file == null) {
r = list.get(index++);
} else {
if (listIndex >= list.size()) {
list.clear();
listIndex = 0;
Data buff = rowBuff;
buff.reset();
int min = Constants.FILE_BLOCK_SIZE;
file.readFully(buff.getBytes(), 0, min);
int len = buff.readInt() * Constants.FILE_BLOCK_SIZE;
buff.checkCapacity(len);
if (len - min > 0) {
file.readFully(buff.getBytes(), min, len - min);
}
while (true) {
r = readRow(buff);
if (r == null) {
break;
}
list.add(r);
}
}
index++;
r = list.get(listIndex++);
}
return r;
}
/**
* Get the number of rows in this list.
*
* @return the number of rows
*/
public int size() {
return size;
}
/**
* Do not use the cache.
*/
public void invalidateCache() {
readUncached = true;
}
/**
* Close the result list and delete the temporary file.
*/
public void close() {
if (file != null) {
file.autoDelete();
file.closeAndDeleteSilently();
file = null;
rowBuff = null;
}
}
}