com.bigdata.journal

Class FileMetadata

java.lang.Object

com.bigdata.journal.FileMetadata

public class FileMetadata
extends Object

Helper object used when opening or creating journal file in any of the file-based modes.

Version:

$Id$

Author:

Bryan Thompson

Field Summary

Fields

Modifier and Type	Field and Description
static int	CURRENT_VERSION The current journal version number.
protected static boolean	DEBUG
File	file The file that was opened.
static int	headerSize0 The size of the journal header, including MAGIC, version, and both root blocks.
protected static boolean	INFO
protected static org.apache.log4j.Logger	log Logger.
static int	MAGIC Magic value for journal (the root blocks have their own magic value).
static int	OFFSET_ROOT_BLOCK0 Offset of the first root block in the file.
static int	OFFSET_ROOT_BLOCK1 Offset of the second root block in the file.
boolean	readOnly True iff the file was opened in a read-only mode.
IRootBlockView	rootBlock The current root block.
static int	VERSION1 The original journal version number (version 1).
int	writeCacheBufferCount The #of write cache buffers to be used if the write cache is enabled.

Method Summary

Methods

Modifier and Type	Method and Description
static FileMetadata	createInstance(Properties properties, boolean isScaleout, long quorumToken) Prepare a journal file for use by an IBufferStrategy.
BufferMode	getBufferMode()
protected static String	getProperty(Properties properties, String name, String defaultValue)
protected static <E> E	getProperty(Properties properties, String name, String defaultValue, IValidator<E> validator)
String	getProperty(String name, String defaultValue) retrieve the property value from the properties object used to initialize this object.
RandomAccessFile	getRandomAccessFile() The interface for IO performed on that file.

Methods inherited from class java.lang.Object

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

Field Detail

log

protected static final org.apache.log4j.Logger log

Logger.

INFO

protected static final boolean INFO

DEBUG

protected static final boolean DEBUG

MAGIC

public static final int MAGIC

Magic value for journal (the root blocks have their own magic value).

See Also:

Constant Field Values

VERSION1

public static final int VERSION1

The original journal version number (version 1).

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Constant Field Values

CURRENT_VERSION

public static final int CURRENT_VERSION

The current journal version number.

Note: This could be used to create major versioning changes of the file structure. There is only one version to date.

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Constant Field Values

file

public final File file

The file that was opened.

writeCacheBufferCount

public final int writeCacheBufferCount

The #of write cache buffers to be used if the write cache is enabled.

readOnly

public final boolean readOnly

True iff the file was opened in a read-only mode.

OFFSET_ROOT_BLOCK0

public static final int OFFSET_ROOT_BLOCK0

Offset of the first root block in the file.

See Also:

Constant Field Values

OFFSET_ROOT_BLOCK1

public static final int OFFSET_ROOT_BLOCK1

Offset of the second root block in the file.

See Also:

Constant Field Values

headerSize0

public static final int headerSize0

The size of the journal header, including MAGIC, version, and both root blocks. This is used as an offset when computing the index of a record in the journal.

See Also:

Constant Field Values

rootBlock

public final IRootBlockView rootBlock

The current root block. For a new file, this is "rootBlock0". For an existing file it is based on an examination of both root blocks.

Method Detail

getRandomAccessFile

public RandomAccessFile getRandomAccessFile()

The interface for IO performed on that file.

Note: this method is only safe for use during the initial file create/open. It is not safe to use once a file has been closed, whether directly or by an interrupt during an IO operation.

createInstance

public static FileMetadata createInstance(Properties properties,
                          boolean isScaleout,
                          long quorumToken)

Prepare a journal file for use by an IBufferStrategy. The file will be created if necessary as permitted and instructed by the specified Options. The root blocks will be created or read from the file and verified. A variety of interesting properties are set on the returned FileMetadata object.

getProperty

protected static String getProperty(Properties properties,
                 String name,
                 String defaultValue)

getProperty

protected static <E> E getProperty(Properties properties,
                String name,
                String defaultValue,
                IValidator<E> validator)

getProperty

public String getProperty(String name,
                 String defaultValue)

retrieve the property value from the properties object used to initialize this object.

getBufferMode

public BufferMode getBufferMode()