com.continuent.tungsten.replicator.thl.log
Class LogFile

java.lang.Object
  com.continuent.tungsten.replicator.thl.log.LogFile

public class LogFile
extends java.lang.Object

This class manages I/O on a physical log file. It handles streams to read or write from the underlying file.

Version:

1.0

Author:

Stephane Giron, Robert Hodges

Field Summary

static int	HEADER_LENGTH
static int	NO_WAIT Return immediately from write when there are no data.

Constructor Summary

LogFile(java.io.File file)
Creates a log file from a simple file.

LogFile(java.io.File parentDirectory, java.lang.String fileName)
Creates a file from a parent directory and child filename.

Method Summary

protected void	assertAnyMode() Returns only if log file is in read or write mode.
protected void	assertReadMode() Returns only if log file is in read mode.
protected void	assertWriteMode() Returns only if log file is in write mode.
void	close() Flush and close file.
void	create(long seqno) Create a new log file.
void	flush() Synchronizes file writes using flush with optional fsync.
long	getBaseSeqno() Returns the base sequence number from the file header.
int	getBufferSize()
java.io.File	getFile() Returns the log file.
long	getFlushIntervalMillis()
long	getLength() Returns the length of the file, including any unbuffered writes.
LogFlushTask	getLogFlushTask() Returns the current log flush task, if any.
long	getOffset() Returns the current position in the log file.
boolean	isFsyncOnFlush()
void	openRead() Open the log file for reading.
void	openWrite() Prepare the log file for writing.
protected int	readInt() Read a single integer.
protected long	readLong() Reads a single long.
LogRecord	readRecord(int waitMillis) Reads a record from the file into a byte array.
protected short	readShort() Reads a single short.
void	seekOffset(long offset) Seeks to a particular offset in the file.
void	setBufferSize(int bufferSize)
void	setFlushIntervalMillis(long flushIntervalMillis)
void	setFsyncOnFlush(boolean fsyncOnFlush)
void	setLength(long length) Truncate the file to the provided length.
void	setLogSyncTask(LogFlushTask logFlushTask) Sets the log flush task.
java.lang.String	toString() Returns a nicely formatting description of the file.
protected void	write(int myInt)
protected void	write(long seqno)
protected void	write(short myShort)
boolean	writeRecord(LogRecord record, int logFileSize) Writes a buffer to the log file and returns true if we have exceeded the log file size.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

HEADER_LENGTH

public static final int HEADER_LENGTH

See Also:

Constant Field Values

NO_WAIT

public static final int NO_WAIT

Return immediately from write when there are no data.

See Also:

Constant Field Values

Constructor Detail

LogFile

public LogFile(java.io.File parentDirectory,
               java.lang.String fileName)

Creates a file from a parent directory and child filename. The file must exist.

Parameters:

parentDirectory - Log file directory

fileName - Log file name

LogFile

public LogFile(java.io.File file)

Creates a log file from a simple file. The file must exist.

Parameters:

file - Log file specification

Method Detail

getFile

public java.io.File getFile()

Returns the log file.

getLogFlushTask

public LogFlushTask getLogFlushTask()

Returns the current log flush task, if any.

setLogSyncTask

public void setLogSyncTask(LogFlushTask logFlushTask)

Sets the log flush task. This enables delayed flush/fsync using flushIntervalMillis.

getFlushIntervalMillis

public long getFlushIntervalMillis()

setFlushIntervalMillis

public void setFlushIntervalMillis(long flushIntervalMillis)

isFsyncOnFlush

public boolean isFsyncOnFlush()

setFsyncOnFlush

public void setFsyncOnFlush(boolean fsyncOnFlush)

getBufferSize

public int getBufferSize()

setBufferSize

public void setBufferSize(int bufferSize)

openRead

public void openRead()
              throws ReplicatorException,
                     java.lang.InterruptedException

Open the log file for reading. The log cannot be written.

Throws:

ReplicatorException - Thrown if file cannot be opened

java.lang.InterruptedException - Thrown if thread is interrupted

openWrite

public void openWrite()
               throws ReplicatorException,
                      java.lang.InterruptedException

Prepare the log file for writing. The write offset is automatically set to the end of the file.

Throws:

ReplicatorException - Thrown if file cannot be opened

java.lang.InterruptedException - Thrown if we are interrupted

create

public void create(long seqno)
            throws ReplicatorException,
                   java.lang.InterruptedException

Create a new log file. We must write a header with a base sequence number. NOTE: The file offset is positioned after the header.

Parameters:

seqno - Base sequence number of this file (written to header)

Throws:

ReplicatorException

java.lang.InterruptedException

close

public void close()

Flush and close file. It should be called after all other methods as part of a clean shutdown.

assertAnyMode

protected void assertAnyMode()
                      throws ReplicatorException

Returns only if log file is in read or write mode.

Throws:

ReplicatorException

assertWriteMode

protected void assertWriteMode()
                        throws ReplicatorException,
                               java.lang.InterruptedException

Returns only if log file is in write mode. If we are in read mode, this will switch over to write mode and position at the end of the file.

Throws:

ReplicatorException

java.lang.InterruptedException

assertReadMode

protected void assertReadMode()
                       throws ReplicatorException,
                              java.lang.InterruptedException

Returns only if log file is in read mode.

Throws:

ReplicatorException

java.lang.InterruptedException

getBaseSeqno

public long getBaseSeqno()

Returns the base sequence number from the file header.

getLength

public long getLength()
               throws ReplicatorException

Returns the length of the file, including any unbuffered writes.

Throws:

ReplicatorException

getOffset

public long getOffset()
               throws ReplicatorException

Returns the current position in the log file.

Throws:

ReplicatorException

seekOffset

public void seekOffset(long offset)
                throws java.io.IOException,
                       ReplicatorException,
                       java.lang.InterruptedException

Seeks to a particular offset in the file.

Throws:

java.io.IOException - If positioning results in an error.

ReplicatorException

java.lang.InterruptedException

readRecord

public LogRecord readRecord(int waitMillis)
                     throws java.io.IOException,
                            java.lang.InterruptedException,
                            LogTimeoutException,
                            ReplicatorException

Reads a record from the file into a byte array. We may encounter a number of unpredictable conditions at this point that we need to report accurately to layers above us that will decide whether it represents a problem.

Parameters:

waitMillis - Number of milliseconds to wait for data to be available. 0 means do not wait.

Returns:

A log record if we can read one before timing out

Throws:

java.io.IOException - Thrown if there is an I/O error

java.lang.InterruptedException - Thrown if we are interrupted

LogTimeoutException - Thrown if we timeout while waiting for data to appear

ReplicatorException

readShort

protected short readShort()
                   throws java.io.IOException,
                          ReplicatorException,
                          java.lang.InterruptedException

Reads a single short.

Throws:

java.io.IOException

ReplicatorException

java.lang.InterruptedException

readInt

protected int readInt()
               throws java.io.IOException,
                      ReplicatorException,
                      java.lang.InterruptedException

Read a single integer.

Throws:

java.io.IOException

ReplicatorException

java.lang.InterruptedException

readLong

protected long readLong()
                 throws java.io.IOException,
                        ReplicatorException,
                        java.lang.InterruptedException

Reads a single long.

Throws:

java.io.IOException

ReplicatorException

java.lang.InterruptedException

setLength

public void setLength(long length)
               throws ReplicatorException,
                      java.lang.InterruptedException

Truncate the file to the provided length. Performs an automatic fsync.

Parameters:

length - New file length

Throws:

ReplicatorException

java.lang.InterruptedException

write

protected void write(int myInt)
              throws java.io.IOException,
                     ReplicatorException,
                     java.lang.InterruptedException

Throws:

java.io.IOException

ReplicatorException

java.lang.InterruptedException

write

protected void write(long seqno)
              throws java.io.IOException,
                     ReplicatorException,
                     java.lang.InterruptedException

Throws:

java.io.IOException

ReplicatorException

java.lang.InterruptedException

write

protected void write(short myShort)
              throws java.io.IOException,
                     ReplicatorException,
                     java.lang.InterruptedException

Throws:

java.io.IOException

ReplicatorException

java.lang.InterruptedException

writeRecord

public boolean writeRecord(LogRecord record,
                           int logFileSize)
                    throws java.io.IOException,
                           java.lang.InterruptedException,
                           ReplicatorException

Writes a buffer to the log file and returns true if we have exceeded the log file size.

Parameters:

record - Log record to write

logFileSize - Maximum log file size

Returns:

true if log file size exceeded

Throws:

java.io.IOException

java.lang.InterruptedException

ReplicatorException

flush

public void flush()
           throws java.io.IOException,
                  ReplicatorException,
                  java.lang.InterruptedException

Synchronizes file writes using flush with optional fsync. You must call this method to commit data.

Throws:

java.io.IOException

ReplicatorException

java.lang.InterruptedException

toString

public java.lang.String toString()

Returns a nicely formatting description of the file.

Overrides:

toString in class java.lang.Object