/*
* Copyright (C) 2006 http://www.chaidb.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
package org.chaidb.db.log.logrecord;
import org.apache.log4j.Logger;
import org.chaidb.db.exception.ChaiDBException;
import org.chaidb.db.log.Lsn;
/**
* This is the checkpoint record. It contains the lsn that the checkpoint
* guarantees and a pointer to the last checkpoint so we can walk backwards
* by checkpoint.
* <p/>
* last_ckp:
* The previous checkpoint.
* <p/>
* timestamp:
* timestamps while doing fuzzy checkpoint
* <p/>
* smallestLsn:
* Smallest first Lsn of all active TXN
*/
public class TxnFuzzyCkpLogRecord extends TxnCkpLogRecord {
private static final Logger logger = Logger.getLogger(TxnFuzzyCkpLogRecord.class);
/* if no active txn while doing fuzzy checkpoint,smallestLsn is equals to
current checkpoint log lsn,if has active txns,it's euqals to smallest
first_lsn of all active txns. */
private Lsn smallestLsn;
/**
* Default Constructor
*/
public TxnFuzzyCkpLogRecord() {
super();
smallestLsn = new Lsn();
super.setType(LOG_TXN_FUZZY_CHECKPOINT);
}
/**
* Constructor
*
* @param newLastCkpLsn
* @param newTimeStamp
*/
public TxnFuzzyCkpLogRecord(Lsn newLastCkpLsn, long newTimeStamp, byte flag, Lsn newSmallestLsn) {
super(newLastCkpLsn, newTimeStamp, flag);
this.smallestLsn = newSmallestLsn;//it's null while no active txns
super.setType(LOG_TXN_FUZZY_CHECKPOINT);
}
/**
* Constructor
*
* @param newLastCkpLsn
* @param newTimeStamp
* @param newTxnId
*/
public TxnFuzzyCkpLogRecord(Lsn newLastCkpLsn, long newTimeStamp, int newTxnId, byte flag, Lsn newSmallestLsn) {
super(newLastCkpLsn, newTimeStamp, newTxnId, flag);
this.smallestLsn = newSmallestLsn;//it's null while no active txns
super.setType(LOG_TXN_FUZZY_CHECKPOINT);
}
/**
* get smallestLsn of current TxnFuzzyCkpLogRecord Object
*
* @return Lsn smallestLsn
*/
public Lsn getSmallestLsn() {
if (smallestLsn == null) {
return null;
}
return new Lsn(smallestLsn);
}
/**
* set smallestLsn of current TxnFuzzyCkpLogRecord Object
* while no active txns,smallestLsn is equals to current checkpoint log Lsn,
* it will be set while putting to log buffer in LogManagerImpl.
*
* @param smallestLsn
*/
public void setSmallestLsn(Lsn smallestLsn) {
this.smallestLsn = smallestLsn;
}
/**
* converts a byte array into a log record instance
*/
public boolean read(byte[] bArr, int start) throws ChaiDBException {
/* construct a new LogRecord instance */
super.read(bArr, start);
/* get the values of TxnFuzzyCkpLogRecord Object */
int step = start + super.getRecordLength();
smallestLsn.read(bArr, step);
return true;
}
/**
* redo or undo the operation for recovery
*/
public boolean recover(short flag) throws ChaiDBException {
return true;
}
/**
* print data and help in debugging log files
*/
public void print() throws ChaiDBException {
//logger.debug(
//"begin: printing the information of TxnFuzzyCkpLogRecord object......");
super.print();
logger.debug("smallestLsn's file id:" + this.getSmallestLsn().getFileId());
logger.debug("smallestLsn's offset:" + Integer.toHexString(this.getSmallestLsn().getOffset()));
//logger.debug(
//"end: printing the information of TxnFuzzyCkpLogRecord object.");
}
/**
* converts a log record instance into a byte array.
* The byte array has the following format:
* ----------------------------------------------------------------
* | hdr | type | txnId | prevLsn | lastCkpLsn | timeStamp | flag
* ----------------------------------------------------------------
* hdr: 12 bytes,the byte array of the header,generated by Hdr.toBytes().
* type: 4 bytes.
* txnId: 4 bytes.
* prevLsn: 8 bytes,the byte array of the header of lsn,generated by Lsn.toBytes().
* <p/>
* lastCkpLsn: 8 bytes,generated by Lsn.toBytes().
* timeStamp: 8 bytes.
* flag : 1 byte
* smallestLsn: 8 bytes,generated by Lsn.toBytes().
*/
public void toBytes(byte[] byteArray, int start) throws ChaiDBException {
super.toBytes(byteArray, start);
int step = start + super.getRecordLength();
smallestLsn.toBytes(byteArray, step);
}
/**
* get current log record type total length
*
* @return int total lenth
*/
public int getRecordLength() {
return super.getRecordLength() + Lsn.getLsnLength();
}
}