com.bigdata.ha.althalog

Class HALogFile

java.lang.Object

com.bigdata.ha.althalog.HALogFile

public class HALogFile
extends Object

Author:

Martyn Cutcher

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	HALogFile.HALogWriter

Field Summary

Fields

Modifier and Type	Field and Description
static long	START_DATA

Constructor Summary

Constructors

Constructor and Description
HALogFile(File file) This constructor creates a read only view of the log file and can be used independently of the HALogManager.
HALogFile(IRootBlockView rbv, com.bigdata.ha.althalog.HALogManager.IHALogManagerCallback callback) This constructor is called by the log manager to create the file.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Attempts to close the file; will only succeed if there are no readers and writers.
void	delete() Requests that the underlying log file is deleted.
void	disable() Called from the LogManager to disable the current log file for writing.
long	getCommitCounter()
File	getFile()
static File	getHALogFileName(File dir, long commitCounter) Return the local name of the HA Log file associated with the commitCounter.
IHALogReader	getReader()
HALogFile.HALogWriter	getWriter()
boolean	isEmpty()
boolean	isOpen()

Methods inherited from class java.lang.Object

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

Field Detail

START_DATA

public static final long START_DATA

See Also:

Constant Field Values

Constructor Detail

HALogFile

public HALogFile(IRootBlockView rbv,
         com.bigdata.ha.althalog.HALogManager.IHALogManagerCallback callback)
          throws IOException

This constructor is called by the log manager to create the file. A writer is created at the same time, and its presence indicates that the file is open for writing.

Throws:

IOException

HALogFile

public HALogFile(File file)

This constructor creates a read only view of the log file and can be used independently of the HALogManager. The opening and closing root blocks are examined to confirm the file has fully committed writes and can be opened for read only access.

Parameters:

readonlyLog -

Throws:

FileNotFoundException

Method Detail

close

public void close()
           throws IOException

Attempts to close the file; will only succeed if there are no readers and writers.

Throws:

IOException

delete

public void delete()
            throws IOException

Requests that the underlying log file is deleted.

Throws:

IOException

isEmpty

public boolean isEmpty()

Returns:

true if the file is complete and its size indicates no content

getCommitCounter

public long getCommitCounter()

getWriter

public HALogFile.HALogWriter getWriter()

Returns:

the open writer for the file if any

getReader

public IHALogReader getReader()
                       throws IOException

Returns:

a new reader for the file

Throws:

IOException

disable

public void disable()
             throws IOException

Called from the LogManager to disable the current log file for writing. We need not worry about concurrent access to the writer since another threads access to the writer is non-deterministic, the important state is that the calling thread would receive a null writer if it requested one.

Throws:

IOException

getHALogFileName

public static File getHALogFileName(File dir,
                    long commitCounter)

Return the local name of the HA Log file associated with the commitCounter.

Parameters:

commitCounter -

Returns:

isOpen

public boolean isOpen()

getFile

public File getFile()

Returns:

the File object for this HALogFile