/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2002, 2011 Oracle and/or its affiliates. All rights reserved.
*
*/
package com.sleepycat.je.log;
import java.nio.ByteBuffer;
import java.util.Calendar;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.EnvironmentFailureException;
import com.sleepycat.je.VersionMismatchException;
import com.sleepycat.je.dbi.EnvironmentFailureReason;
import com.sleepycat.je.dbi.EnvironmentImpl;
import com.sleepycat.je.utilint.Timestamp;
/**
* A FileHeader embodies the header information at the beginning of each log
* file.
*/
public class FileHeader implements Loggable {
/*
* fileNum is the number of file, starting at 0. An unsigned int, so stored
* in a long in memory, but in 4 bytes on disk
*/
private long fileNum;
private long lastEntryInPrevFileOffset;
private Timestamp time;
private int logVersion;
FileHeader(long fileNum, long lastEntryInPrevFileOffset) {
this.fileNum = fileNum;
this.lastEntryInPrevFileOffset = lastEntryInPrevFileOffset;
Calendar now = Calendar.getInstance();
time = new Timestamp(now.getTimeInMillis());
logVersion = LogEntryType.LOG_VERSION;
}
/**
* For logging only.
*/
public FileHeader() {
}
public int getLogVersion() {
return logVersion;
}
/**
* @return file header log version.
*/
int validate(EnvironmentImpl envImpl,
String fileName,
long expectedFileNum)
throws DatabaseException {
if (logVersion > LogEntryType.LOG_VERSION) {
throw new VersionMismatchException
(envImpl,
"Expected log version " + LogEntryType.LOG_VERSION +
" or earlier but found " + logVersion);
}
if (fileNum != expectedFileNum) {
throw new EnvironmentFailureException
(envImpl, EnvironmentFailureReason.LOG_INTEGRITY,
"Wrong filenum in header for file " +
fileName + " expected " +
expectedFileNum + " got " + fileNum);
}
return logVersion;
}
/**
* @return the offset of the last entry in the previous file.
*/
long getLastEntryInPrevFileOffset() {
return lastEntryInPrevFileOffset;
}
/*
* Logging support
*/
/**
* A header is always a known size.
*/
public static int entrySize() {
return
LogUtils.LONG_BYTES + // time
LogUtils.UNSIGNED_INT_BYTES + // file number
LogUtils.LONG_BYTES + // lastEntryInPrevFileOffset
LogUtils.INT_BYTES; // logVersion
}
/**
* @see Loggable#getLogSize
* @return number of bytes used to store this object
*/
public int getLogSize() {
return entrySize();
}
/**
* @see Loggable#writeToLog
* Serialize this object into the buffer. Update cksum with all
* the bytes used by this object
* @param logBuffer is the destination buffer
*/
public void writeToLog(ByteBuffer logBuffer) {
LogUtils.writeLong(logBuffer, time.getTime());
LogUtils.writeUnsignedInt(logBuffer, fileNum);
LogUtils.writeLong(logBuffer, lastEntryInPrevFileOffset);
LogUtils.writeInt(logBuffer, logVersion);
}
/**
* @see Loggable#readFromLog
* Initialize this object from the data in itemBuf.
* @param itemBuf the source buffer
*/
public void readFromLog(ByteBuffer logBuffer, int unusableEntryVersion) {
/* Timestamp is always unpacked. */
time = LogUtils.readTimestamp(logBuffer, true/*unpacked*/);
fileNum = LogUtils.readUnsignedInt(logBuffer);
lastEntryInPrevFileOffset = LogUtils.readLong(logBuffer);
logVersion = LogUtils.readInt(logBuffer);
/*
* The log version is unknown until reading it. If there are
* version-specific fields in this entry, they must follow the log
* version and use it, not the entryVersion param, for conditionals.
*/
}
/**
* @see Loggable#dumpLog
* @param sb destination string buffer
* @param verbose if true, dump the full, verbose version
*/
public void dumpLog(StringBuilder sb, boolean verbose) {
sb.append("<FileHeader num=\"0x");
sb.append(Long.toHexString(fileNum));
sb.append("\" lastEntryInPrevFileOffset=\"0x");
sb.append(Long.toHexString(lastEntryInPrevFileOffset));
sb.append("\" logVersion=\"0x");
sb.append(Integer.toHexString(logVersion));
sb.append("\" time=\"").append(time);
sb.append("\"/>");
}
/**
* @see Loggable#getTransactionId
*/
public long getTransactionId() {
return 0;
}
/**
* @see Loggable#logicalEquals
* Always return false, this item should never be compared.
*/
public boolean logicalEquals(Loggable other) {
return false;
}
/**
* Print in xml format
*/
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
dumpLog(sb, true);
return sb.toString();
}
}