/*
* Copyright (c) 2008 - 2011, Jan Stender, Bjoern Kolbeck, Mikael Hoegqvist,
* Felix Hupfeld, Zuse Institute Berlin
*
* Licensed under the BSD License, see LICENSE file for details.
*
*/
package de.mxro.thrd.babudb05.log;
import java.util.zip.Checksum;
import de.mxro.thrd.babudb05.lsmdb.LSMDBRequest;
import de.mxro.thrd.babudb05.lsmdb.LSN;
import de.mxro.thrd.xstreemfs.foundation.buffer.BufferPool;
import de.mxro.thrd.xstreemfs.foundation.buffer.ReusableBuffer;
import de.mxro.thrd.xstreemfs.foundation.logging.Logging;
/**
*
* @author bjko
*/
public class LogEntry {
/**
* length of the entry's header (excluding the length field itself)
*/
protected static final int headerLength = Integer.SIZE / 8 * 4 +
Long.SIZE / 8 + Byte.SIZE / 8;
public static final boolean USE_CHECKSUMS = true;
public static final byte PAYLOAD_TYPE_INSERT = 0;
public static final byte PAYLOAD_TYPE_SNAP = 1;
public static final byte PAYLOAD_TYPE_CREATE = 2;
public static final byte PAYLOAD_TYPE_COPY = 3;
public static final byte PAYLOAD_TYPE_DELETE = 4;
public static final byte PAYLOAD_TYPE_SNAP_DELETE = 5;
public static final byte PAYLOAD_TYPE_TRANSACTION = 6;
/**
* view ID of the log entry. The view ID is an epoch number which creates a
* total order on the log entries (viewId.logSequenceNo).
*/
protected int viewId = -1;
protected long logSequenceNo = -1L;
protected int checksum;
protected ReusableBuffer payload;
protected SyncListener listener;
private LSMDBRequest<?> attachment;
protected byte payloadType;
private LogEntry() {
}
public LogEntry(ReusableBuffer payload, SyncListener l, byte payloadType) {
assert(payload != null);
this.payload = payload;
this.listener = l;
this.payloadType = payloadType;
}
public void assignId(int viewId, long logSequenceNo) {
this.viewId = viewId;
this.logSequenceNo = logSequenceNo;
}
public ReusableBuffer serialize(Checksum csumAlgo) {
assert (viewId > 0);
assert (logSequenceNo > 0);
final int bufSize = headerLength + payload.remaining();
ReusableBuffer buf = BufferPool.allocate(bufSize);
buf.putInt(bufSize);
buf.putInt(checksum);
buf.putInt(viewId);
buf.putLong(logSequenceNo);
buf.put(payloadType);
buf.put(payload);
payload.flip(); // otherwise payload is not reusable
buf.putInt(bufSize);
buf.flip();
if (USE_CHECKSUMS) {
// reset the old checksum to 0, before calculating a new one
buf.position(Integer.SIZE / 8);
buf.putInt(0);
buf.position(0);
csumAlgo.update(buf.array(), 0, bufSize);
int cPos = buf.position();
// write the checksum to the buffer
buf.position(Integer.SIZE / 8);
buf.putInt((int) csumAlgo.getValue());
buf.position(cPos);
}
return buf;
}
public void setListener(SyncListener listener) {
this.listener = listener;
}
public SyncListener getListener() {
return listener;
}
public ReusableBuffer getPayload() {
return this.payload;
}
public int getViewId() {
return this.viewId;
}
public long getLogSequenceNo() {
return this.logSequenceNo;
}
public LSN getLSN() {
if (this.viewId == -1 && this.logSequenceNo == -1L) return null;
else return new LSN(this.viewId, this.logSequenceNo);
}
public static void checkIntegrity(ReusableBuffer data)
throws LogEntryException {
int cPos = data.position();
if (data.remaining() < Integer.SIZE / 8)
throw new LogEntryException("Empty data. Cannot read log entry.");
int length1 = data.getInt();
if ((length1 - Integer.SIZE / 8) > data.remaining()) {
data.position(cPos);
Logging.logMessage(Logging.LEVEL_DEBUG, null, "not long enough");
throw new LogEntryException("The log entry is incomplete. " +
"The length indicated in the header exceeds the " +
"available data.");
}
data.position(cPos + length1 - Integer.SIZE / 8);
int length2 = data.getInt();
data.position(cPos);
if (length1 != length2) {
throw new LogEntryException("Invalid Frame. The length entries do" +
" not match; length1=" + length1 + ", length2=" +
length2);
}
}
public static LogEntry deserialize(ReusableBuffer data, Checksum csumAlgo)
throws LogEntryException {
checkIntegrity(data);
final int startPos = data.position();
final int bufSize = data.getInt();
LogEntry e = new LogEntry();
e.checksum = data.getInt();
e.viewId = data.getInt();
e.logSequenceNo = data.getLong();
e.payloadType = data.get();
final int payloadSize = bufSize - headerLength;
int payloadPosition = data.position();
ReusableBuffer payload = data.createViewBuffer();
payload.range(payloadPosition, payloadSize);
e.payload = payload;
if (USE_CHECKSUMS) {
// reset the old checksum to 0, before calculating a new one
data.position(startPos + Integer.SIZE / 8);
data.putInt(0);
data.position(startPos);
csumAlgo.update(data.array(), startPos, bufSize);
int csum = (int) csumAlgo.getValue();
// write back the checksum to the buffer
data.position(startPos + Integer.SIZE / 8);
data.putInt((int) e.checksum);
if (csum != e.checksum) {
throw new LogEntryException(
"Invalid Checksum. Checksum in log entry and calculated " +
"checksum do not match.");
}
}
data.position(startPos);
return e;
}
public void free() {
BufferPool.free(payload);
payload = null;
}
public LSMDBRequest<?> getAttachment() {
return attachment;
}
public void setAttachment(LSMDBRequest<?> attachment) {
this.attachment = attachment;
}
public byte getPayloadType() {
return payloadType;
}
/* (non-Javadoc)
* @see java.lang.Object#clone()
*/
@Override
public LogEntry clone() {
LogEntry result = new LogEntry(payload.createViewBuffer(), listener, payloadType);
result.assignId(viewId, logSequenceNo);
result.attachment = attachment;
result.checksum = checksum;
return result;
}
/* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
return "LSN(" + viewId + ":" + logSequenceNo + ") with " + payload.remaining() +
" bytes of payload.";
}
}