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//----------------------------------------------------------------------------
//
// Module: LogLSN.java
//
// Description: Log sequence number.
//
// Product: com.sun.jts.CosTransactions
//
// Author: Simon Holdsworth
//
// Date: March, 1997
//
// Copyright (c): 1995-1997 IBM Corp.
//
// The source code for this program is not published or otherwise divested
// of its trade secrets, irrespective of what has been deposited with the
// U.S. Copyright Office.
//
// This software contains confidential and proprietary information of
// IBM Corp.
//----------------------------------------------------------------------------
package com.sun.jts.CosTransactions;
// Import required classes
import java.io.*;
/**A structure containing 2 unsigned integers.
* extent: the extent file number
* offset: the offset within the extent file
*
* @version 0.01
*
* @author Simon Holdsworth, IBM Corporation
*
* @see
*/
//----------------------------------------------------------------------------
// CHANGE HISTORY
//
// Version By Change Description
// 0.01 SAJH Initial implementation.
//-----------------------------------------------------------------------------
class LogLSN implements Serializable {
/**Constants for particular LSN values.
*/
static final LogLSN HEAD_LSN = new LogLSN(0xFFFFFFFF, 0xFFFFFFFF);
static final LogLSN TAIL_LSN = new LogLSN(0xFFFFFFFF, 0xFFFFFFFE);
static final LogLSN NULL_LSN = new LogLSN(0x00000000, 0x00000000);
static final LogLSN FIRST_LSN = new LogLSN(0x00000001, 0x00000000);
/**This constant holds the size of the LogRecordEnding object.
*/
static final int SIZEOF = 8;
/**Internal instance members.
*/
int offset = 0;
int extent = 0;
/**Default LogLSN constructor
*
* @param
*
* @return
*
* @see
*/
LogLSN() {
offset = 0;
extent = 0;
}
/**LogLSN constructor
*
* @param ext Extent for new LSN.
* @param off Offset for new LSN.
*
* @return
*
* @see
*/
LogLSN( int ext,
int off ) {
offset = off;
extent = ext;
}
/**LogLSN constructor
*
* @param lsn Other LSN to be copied.
*
* @return
*
* @see
*/
LogLSN( LogLSN lsn ) {
offset = lsn.offset;
extent = lsn.extent;
}
/**Constructs a LogLSN from the given byte array.
*
* @param bytes The array of bytes from which the LogLSN is to be constructed.
* @param index The index in the array where copy is to start.
*
* @return
*
* @see
*/
LogLSN( byte[] bytes,
int index ) {
offset = (bytes[index++]&255) +
((bytes[index++]&255) << 8) +
((bytes[index++]&255) << 16) +
((bytes[index++]&255) << 24);
extent = (bytes[index++]&255) +
((bytes[index++]&255) << 8) +
((bytes[index++]&255) << 16) +
((bytes[index++]&255) << 24);
}
/**Determines whether the target LSN is NULL.
*
* @param
*
* @return
*
* @see
*/
final boolean isNULL() {
return offset == 0 && extent == 0;
}
/**Determines whether the given LSN is equal to the target.
*
* @param other The other LogLSN to be compared.
*
* @return
*
* @see
*/
final boolean equals( LogLSN other ) {
return offset == other.offset && extent == other.extent;
}
/**Determines whether the target LSN is less than the parameter.
*
* @param other The other LogLSN to be compared.
*
* @return
*
* @see
*/
final boolean lessThan( LogLSN other ) {
return ( (offset < other.offset && extent == other.extent) ||
extent < other.extent);
}
/**Determines whether the target LSN is greater than the parameter.
*
* @param other The other LogLSN to be compared.
*
* @return
*
* @see
*/
final boolean greaterThan( LogLSN other ) {
return ( (offset > other.offset && extent == other.extent) ||
extent > other.extent);
}
/**makes the target LSN a copy of the parameter.
*
* @param LogLSN The LSN to be copied.
*
* @return
*
* @see
*/
final void copy( LogLSN other ) {
extent = other.extent;
offset = other.offset;
}
/**Makes a byte representation of the LogLSN.
*
* @param bytes The array of bytes into which the LogLSN is to be copied.
* @param index The index in the array where copy is to start.
*
* @return Number of bytes copied.
*
* @see
*/
final int toBytes( byte[] bytes,
int index ) {
bytes[index++] = (byte) offset;
bytes[index++] = (byte)(offset >> 8);
bytes[index++] = (byte)(offset >> 16);
bytes[index++] = (byte)(offset >> 24);
bytes[index++] = (byte) extent;
bytes[index++] = (byte)(extent >> 8);
bytes[index++] = (byte)(extent >> 16);
bytes[index++] = (byte)(extent >> 24);
return SIZEOF;
}
/**This method is called to direct the object to format its state to a String.
*
* @param
*
* @return The formatted representation of the object.
*
* @see
*/
public final String toString() {
return "LSN(ext="/*#Frozen*/+extent+",off="/*#Frozen*/+offset+")"/*#Frozen*/;
}
}