Glassfish example source code file (LogFileHandle.java)
The Glassfish LogFileHandle.java source code/*
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*
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//----------------------------------------------------------------------------
//
// Module: LogFileHandle.java
//
// Description: Physical log file operations.
//
// 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 com.sun.enterprise.util.i18n.StringManager;
import java.io.*;
/**This class encapsulates file I/O operations and the file handle.
*
* @version 0.01
*
* @author Simon Holdsworth, IBM Corporation
*
* @see
*/
//----------------------------------------------------------------------------
// CHANGE HISTORY
//
// Version By Change Description
// 0.01 SAJH Initial implementation.
//-----------------------------------------------------------------------------
class LogFileHandle {
private static final StringManager sm = StringManager.getManager(LogFileHandle.class);
/**The log file should be accessed in read only mode.
*/
final static int OPEN_RDONLY = 0x00000001;
/**The log file should be accessed in read/write mode.
*/
final static int OPEN_RDWR = 0x00000002;
/**The log file should be opened as a new file if necessary.
*/
final static int OPEN_CREAT = 0x00000004;
/**The log file should be synchronized with the file system.
*/
final static int OPEN_SYNC = 0x00000008;
/**Seek relative location to the current position.
*/
final static int SEEK_RELATIVE = 0;
/**Seek absolute location in the file.
*/
final static int SEEK_ABSOLUTE = 1;
/**Open options string for file read only.
*/
final static String MODE_READONLY = "r"/*#Frozen*/; // rb
/**Open options string for file read/write, old file.
*/
static String MODE_READWRITEOLD = "rw"/*#Frozen*/; // wb-
/**open options string for file read/write, new file.
*/
static String MODE_READWRITENEW = "rw"/*#Frozen*/; // wb+
static String dsyncProp = null;
final static String DSYNC_PROPERTY = "com.sun.appserv.transaction.nofdsync";
/**The maximum length of a file name.
*/
//!final static int LOG_FNAME_MAX = FILENAME_MAX;
final static int LOG_FNAME_MAX = 252;
/**The size of a block in the file system.
*/
final static int FILESYSTEM_BLOCKSIZE = 4096;
/**Instance information.
*/
private RandomAccessFile fhandle = null;
private FileDescriptor fd = null;
private byte[] bufferData = null;
boolean buffered = false;
int bufferUpdateStart = -1;
int bufferUpdateEnd = -1;
int buffPos = 0;
static {
dsyncProp = System.getProperty(DSYNC_PROPERTY);
if (dsyncProp != null) {
MODE_READWRITEOLD = "rwd";
MODE_READWRITENEW = "rwd";
}
}
/**Default LogFileHandle constructor.
*
* @param
*
* @return
*
* @see
*/
LogFileHandle() {
fhandle = null;
fd = null; //@MA
}
/**Creates a new file handle for the given file.
*
* @param file The File to be opened.
* @param int Open options
*
* @return
*
* @exception LogException Opening the file failed.
*
* @see
*/
LogFileHandle( File file,
int openOptions )
throws LogException {
// Perform buffering depending on the flag.
if (dsyncProp == null) {
if( (openOptions & OPEN_SYNC) == 0 )
buffered = true;
}
// Change the OpenOptions to the format expected by CLOSE
if( (openOptions & OPEN_RDONLY) != 0 )
fileOpen(file,MODE_READONLY);
else
try {
fileOpen(file,MODE_READWRITEOLD);
} catch( LogException e ) {
if( (openOptions & OPEN_CREAT) != 0 )
fileOpen(file,MODE_READWRITENEW);
}
}
/**Destroys the FileHandle, closing the file, if open.
*
* @param
*
* @return
*
* @exception LogException The close of the file failed.
*
* @see
*/
public void finalize()
throws LogException {
// Ensure that the file is closed.
// If the file is buffered, this ensures that the buffer is written out
// if necessary.
if( fhandle != null )
fileClose();
// Discard the buffer.
bufferData = null;
}
/**Reads from the file.
*
* @param buffer Buffer for file read.
*
* @return Number of bytes read.
*
* @exception LogException The read failed.
*
* @see
*/
int fileRead( byte[] buffer )
throws LogException{
int bytesRead = 0;
if( buffer.length > 0 )
try {
// If buffered, then copy the file buffer into the required array.
if( buffered ) {
// If the current position is beyond the end of the buffer then the read fails.
if( buffPos >= bufferData.length )
bytesRead = -1;
// Otherwise if the buffer is not big enough for all the bytes, return those that
// it does contain, else return all the bytes asked for.
else {
if( buffPos + buffer.length >= bufferData.length )
bytesRead = bufferData.length - buffPos;
else
bytesRead = buffer.length;
System.arraycopy(bufferData,buffPos,buffer,0,bytesRead);
buffPos += bytesRead;
}
}
// Otherwise read the data from the file.
else {
bytesRead = fhandle.read(buffer);
if( bytesRead == -1 ) bytesRead = 0;
}
} catch( Throwable exc ) {
throw new LogException(LogException.LOG_READ_FAILURE, 1,
sm.getString("jts.log_read_failed_bytes", bytesRead), exc);
}
return bytesRead;
}
/**Writes to the file.
*
* @param buffer The bytes to write.
*
* @return The number of bytes written.
*
* @exception LogException The write failed.
*
* @see
*/
int fileWrite( byte[] buffer )
throws LogException {
if( buffer.length > 0 )
try {
// If buffered, then copy the array into the file buffer.
if( buffered ) {
// If the array copy requires more bytes than exist in the buffer, then the
// buffer must be extended to the required size.
if( buffPos + buffer.length >= bufferData.length ) {
byte[] newBufferData = new byte[buffPos+buffer.length];
if( bufferData.length > 0 )
System.arraycopy(bufferData,0,newBufferData,0,bufferData.length);
bufferData = newBufferData;
}
// Copy the data.
System.arraycopy(buffer,0,bufferData,buffPos,buffer.length);
// Remember how much of the buffer has been updated, and increase the current
// buffer position.
if( bufferUpdateStart == -1 ||
buffPos < bufferUpdateStart )
bufferUpdateStart = buffPos;
buffPos += buffer.length;
if( buffPos > bufferUpdateEnd )
bufferUpdateEnd = buffPos;
}
// Otherwise write the data to the file.
// For non-buffered writes, we always sync to the file system.
else {
fhandle.write(buffer);
if (dsyncProp == null)
fd.sync();
}
} catch( Throwable e ) {
int errCode = LogException.LOG_WRITE_FAILURE;
//$ if( errno == ENOSPC )
//$ retCode = LogControl.LOG_NO_SPACE;
throw new LogException(errCode, 1, sm.getString("jts.log_write_failed"), e);
}
return buffer.length;
}
/**Opens the given file.
*
* @param file The name of the file.
* @param fileMode The mode to open in.
*
* @return
*
* @exception LogException The open failed.
*
* @see
*/
void fileOpen( File file,
String fileMode )
throws LogException {
fhandle = null;
try {
fhandle = new RandomAccessFile(file,fileMode);
fd = fhandle.getFD();
// If buffering, and the opened file has contents, then allocate the buffer
// and read the file contents in. Otherwise make the buffer an empty array.
if( buffered )
if( fhandle.length() > 0 ) {
bufferData = new byte[(int)fhandle.length()];
fhandle.readFully(bufferData);
}
else
bufferData = new byte[0];
} catch( Throwable e ) {
throw new LogException(LogException.LOG_OPEN_FAILURE,1,
sm.getString("jts.log_open_failed", file), e);
}
}
/**Closes the file.
*
* @param
*
* @return
*
* @exception LogException The close failed
*
* @see
*/
void fileClose()
throws LogException {
try {
// If buffered, then ensure that the buffer is stored and synced with the
// file system.
if( bufferUpdateStart != -1 )
fileSync();
// Close the file.
fhandle.close();
} catch( Throwable e ) {
throw new LogException(LogException.LOG_CLOSE_FAILURE,1,
sm.getString("jts.log_close_failed"), e);
}
// Reset the file handle and descriptor values.
fhandle = null;
fd = null; //@MA
}
/**Seeks the given position in the file.
*
* @param position Position to seek.
* @param seekMode Mode of seek.
*
* @return
*
* @exception LogException The seek failed.
*
* @see
*/
void fileSeek( long position,
int seekMode )
throws LogException {
// Adjust the position being sought if it is relative to the current position.
long absPos = position;
try {
// If buffered, then simply set the buffer position.
// If the position is beyond the end of the buffer, then the buffer will be
// extended when the next write occurs.
if( buffered ) {
if( seekMode == SEEK_RELATIVE )
absPos = buffPos + position;
buffPos = (int)absPos;
}
// Otherwise seek the position in the file.
else {
if( seekMode == SEEK_RELATIVE )
absPos = fhandle.getFilePointer() + position;
fhandle.seek(absPos);
}
} catch( Throwable e ) {
throw new LogException(LogException.LOG_READ_FAILURE,1,
sm.getString("jts.log_file_seek_failed"), e);
}
}
/**Synchronises (flushes) the file to the file system.
*
* @param
*
* @return
*
* @exception LogException The sync failed
*
* @see
*/
void fileSync() throws LogException {
// Synchronization is only done for buffered files which have been updated.
// Non-buffered files have every write synchronized with the file system.
if( bufferUpdateStart != -1 )
try {
fhandle.seek(bufferUpdateStart);
fhandle.write(bufferData,bufferUpdateStart,bufferUpdateEnd-bufferUpdateStart);
if (dsyncProp == null)
fd.sync();
bufferUpdateStart = -1;
bufferUpdateEnd = -1;
} catch (Throwable e) {
throw new LogException(LogException.LOG_READ_FAILURE,1,
sm.getString("jts.log_file_sync_failed"), e);
}
}
/**Reads a vector of records from the file.
*
* @param vector The vector to contain the records to be read.
*
* @return The total number of bytes read.
*
* @exception LogException The read failed.
*
* @see
*/
int readVector( byte[][] vector )
throws LogException {
int bytesRead = 0;
for( int i = 0; i < vector.length; i++ )
bytesRead += fileRead(vector[i]);
return bytesRead;
}
/**Allocates more storage for the file.
*
* @param bytesToClear Number of bytes to allocate for the file.
*
* @return
*
* @exception LogException The allocation failed.
*
* @see
*/
void allocFileStorage( int bytesToClear )
throws LogException {
int numberOfBlocks; // Number of blocks to write
int bytesRemaining; // Remaining bytes
//byte[] singleChar1 = new byte[1];
byte[] singleChar2 = new byte[1];
long bytesWritten;
if( bytesToClear == 0 ) {
return;
}
/* Don't bother with the compilcated version. Just write out a byte at the
appropriate place.
// Calculate the number of blocks and remaining bytes
numberOfBlocks = bytesToClear / FILESYSTEM_BLOCKSIZE;
bytesRemaining = bytesToClear % FILESYSTEM_BLOCKSIZE;
// Initialise the single characters to be written to force allocation.
singleChar1[0] = (byte)0x01;
singleChar2[0] = (byte)0xff;
// For each block, write a single char and seek to the next block
// multiple from the current position
for( int i = 1; i <= numberOfBlocks; i++ )
{
// Write the single char at start of the file block
fileWrite(singleChar1);
// Now seek to the end of block
fileSeek(FILESYSTEM_BLOCKSIZE-2,SEEK_RELATIVE);
// Write the single char at end of the file block
fileWrite(singleChar2);
}
// If there are still bytes remaining, get them allocated too.
if( bytesRemaining > 0 )
{
// Now write out a byte at the beginning and end of the remaining
// area to be allocated
fileWrite(singleChar1);
if( --bytesRemaining > 0 )
{
// Seek to end of area and write the last char
fileSeek(bytesRemaining-1,SEEK_RELATIVE);
// Now write a byte at the end of the remaining area to be allocated.
fileWrite(singleChar2);
}
}
This is the quick version which only does one write.
*/
fileSeek(bytesToClear-1,SEEK_RELATIVE);
fileWrite(singleChar2);
// Move the file pointer back to its original location on the file
// by seeking -BytesToClear
fileSeek(-bytesToClear,SEEK_RELATIVE);
// If the file is buffered, make sue the space is really allocated.
if( buffered )
fileSync();
}
}
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