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/*
* Copyright 2004-2018 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.engine;
import org.h2.api.ErrorCode;
import org.h2.message.DbException;
import org.h2.result.Row;
import org.h2.store.Data;
import org.h2.store.FileStore;
import org.h2.table.Table;
import org.h2.value.Value;
/**
* An entry in a undo log.
*/
public class UndoLogRecord {
/**
* Operation type meaning the row was inserted.
*/
public static final short INSERT = 0;
/**
* Operation type meaning the row was deleted.
*/
public static final short DELETE = 1;
private static final int IN_MEMORY = 0, STORED = 1, IN_MEMORY_INVALID = 2;
private Table table;
private Row row;
private short operation;
private short state;
private int filePos;
/**
* Create a new undo log record
*
* @param table the table
* @param op the operation type
* @param row the row that was deleted or inserted
*/
UndoLogRecord(Table table, short op, Row row) {
this.table = table;
this.row = row;
this.operation = op;
this.state = IN_MEMORY;
}
/**
* Check if the log record is stored in the file.
*
* @return true if it is
*/
boolean isStored() {
return state == STORED;
}
/**
* Check if this undo log record can be store. Only record can be stored if
* the table has a unique index.
*
* @return if it can be stored
*/
boolean canStore() {
// if large transactions are enabled, this method is not called
return table.getUniqueIndex() != null;
}
/**
* Un-do the operation. If the row was inserted before, it is deleted now,
* and vice versa.
*
* @param session the session
*/
void undo(Session session) {
Database db = session.getDatabase();
switch (operation) {
case INSERT:
if (state == IN_MEMORY_INVALID) {
state = IN_MEMORY;
}
if (db.getLockMode() == Constants.LOCK_MODE_OFF) {
if (row.isDeleted()) {
// it might have been deleted by another thread
return;
}
}
try {
row.setDeleted(false);
table.removeRow(session, row);
table.fireAfterRow(session, row, null, true);
} catch (DbException e) {
if (session.getDatabase().getLockMode() == Constants.LOCK_MODE_OFF
&& e.getErrorCode() == ErrorCode.ROW_NOT_FOUND_WHEN_DELETING_1) {
// it might have been deleted by another thread
// ignore
} else {
throw e;
}
}
break;
case DELETE:
try {
table.addRow(session, row);
table.fireAfterRow(session, null, row, true);
// reset session id, otherwise other sessions think
// that this row was inserted by this session
row.commit();
} catch (DbException e) {
if (session.getDatabase().getLockMode() == Constants.LOCK_MODE_OFF
&& e.getSQLException().getErrorCode() == ErrorCode.DUPLICATE_KEY_1) {
// it might have been added by another thread
// ignore
} else {
throw e;
}
}
break;
default:
DbException.throwInternalError("op=" + operation);
}
}
/**
* Append the row to the buffer.
*
* @param buff the buffer
* @param log the undo log
*/
void append(Data buff, UndoLog log) {
int p = buff.length();
buff.writeInt(0);
buff.writeInt(operation);
buff.writeByte(row.isDeleted() ? (byte) 1 : (byte) 0);
buff.writeInt(log.getTableId(table));
buff.writeLong(row.getKey());
buff.writeInt(row.getSessionId());
int count = row.getColumnCount();
buff.writeInt(count);
for (int i = 0; i < count; i++) {
Value v = row.getValue(i);
buff.checkCapacity(buff.getValueLen(v));
buff.writeValue(v);
}
buff.fillAligned();
buff.setInt(p, (buff.length() - p) / Constants.FILE_BLOCK_SIZE);
}
/**
* Save the row in the file using a buffer.
*
* @param buff the buffer
* @param file the file
* @param log the undo log
*/
void save(Data buff, FileStore file, UndoLog log) {
buff.reset();
append(buff, log);
filePos = (int) (file.getFilePointer() / Constants.FILE_BLOCK_SIZE);
file.write(buff.getBytes(), 0, buff.length());
row = null;
state = STORED;
}
/**
* Load an undo log record row using a buffer.
*
* @param buff the buffer
* @param log the log
* @return the undo log record
*/
static UndoLogRecord loadFromBuffer(Data buff, UndoLog log) {
UndoLogRecord rec = new UndoLogRecord(null, (short) 0, null);
int pos = buff.length();
int len = buff.readInt() * Constants.FILE_BLOCK_SIZE;
rec.load(buff, log);
buff.setPos(pos + len);
return rec;
}
/**
* Load an undo log record row using a buffer.
*
* @param buff the buffer
* @param file the source file
* @param log the log
*/
void load(Data buff, FileStore file, UndoLog log) {
int min = Constants.FILE_BLOCK_SIZE;
log.seek(filePos);
buff.reset();
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);
}
int oldOp = operation;
load(buff, log);
if (SysProperties.CHECK) {
if (operation != oldOp) {
DbException.throwInternalError("operation=" + operation + " op=" + oldOp);
}
}
}
private void load(Data buff, UndoLog log) {
operation = (short) buff.readInt();
boolean deleted = buff.readByte() == 1;
table = log.getTable(buff.readInt());
long key = buff.readLong();
int sessionId = buff.readInt();
int columnCount = buff.readInt();
Value[] values = new Value[columnCount];
for (int i = 0; i < columnCount; i++) {
values[i] = buff.readValue();
}
row = getTable().getDatabase().createRow(values, Row.MEMORY_CALCULATE);
row.setKey(key);
row.setDeleted(deleted);
row.setSessionId(sessionId);
state = IN_MEMORY_INVALID;
}
/**
* Get the table.
*
* @return the table
*/
public Table getTable() {
return table;
}
/**
* Get the position in the file.
*
* @return the file position
*/
public long getFilePos() {
return filePos;
}
/**
* This method is called after the operation was committed.
* It commits the change to the indexes.
*/
void commit() {
table.commit(operation, row);
}
/**
* Get the row that was deleted or inserted.
*
* @return the row
*/
public Row getRow() {
return row;
}
/**
* Change the state from IN_MEMORY to IN_MEMORY_INVALID. This method is
* called if a later record was read from the temporary file, and therefore
* the position could have changed.
*/
void invalidatePos() {
if (this.state == IN_MEMORY) {
state = IN_MEMORY_INVALID;
}
}
}
