com.bigdata.journal

Class RootBlockUtility

java.lang.Object

com.bigdata.journal.RootBlockUtility

public class RootBlockUtility
extends Object

Utility class will read both root blocks of a file and indicate which one is current.

Version:

$Id$

Author:

Bryan Thompson

Field Summary

Fields

Modifier and Type	Field and Description
IRootBlockView	rootBlock The current root block.
IRootBlockView	rootBlock0 The 1st root block.
IRootBlockView	rootBlock1 The 2nd root block.

Constructor Summary

Constructors

Constructor and Description
RootBlockUtility(BufferMode bufferMode, int offsetBits, long createTime, long quorumToken, UUID storeUUID) Generate the root blocks.
RootBlockUtility(IReopenChannel<FileChannel> opener, File file, boolean validateChecksum, boolean alternateRootBlock, boolean ignoreBadRootBlock)
RootBlockUtility(IRootBlockView rb0, IRootBlockView rb1)

Method Summary

Methods

Modifier and Type	Method and Description
IRootBlockView	chooseRootBlock() Return the chosen root block.
static IRootBlockView	chooseRootBlock(IRootBlockView rootBlock0, IRootBlockView rootBlock1) Return the chosen root block.
static IRootBlockView	chooseRootBlock(IRootBlockView rootBlock0, IRootBlockView rootBlock1, boolean alternateRootBlock, boolean ignoreBadRootBlock) Return the chosen root block.
static void	main(String[] args) Dumps the root blocks for the specified file.

Methods inherited from class java.lang.Object

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

Field Detail

rootBlock0

public final IRootBlockView rootBlock0

The 1st root block.

rootBlock1

public final IRootBlockView rootBlock1

The 2nd root block.

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.

Constructor Detail

RootBlockUtility

public RootBlockUtility(IReopenChannel<FileChannel> opener,
                File file,
                boolean validateChecksum,
                boolean alternateRootBlock,
                boolean ignoreBadRootBlock)
                 throws IOException

Parameters:

opener -

file -

validateChecksum -

alternateRootBlock - When true, the alternate root block will be chosen. This flag only makes sense when you have two root blocks to choose from and you want to choose the other one.

ignoreBadRootBlock - When true, a bad root block will be ignored.

Throws:

IOException

See Also:

Options.ALTERNATE_ROOT_BLOCK, Options.IGNORE_BAD_ROOT_BLOCK

RootBlockUtility

public RootBlockUtility(IRootBlockView rb0,
                IRootBlockView rb1)

RootBlockUtility

public RootBlockUtility(BufferMode bufferMode,
                int offsetBits,
                long createTime,
                long quorumToken,
                UUID storeUUID)

Generate the root blocks. They are for all practical purposes identical.

Parameters:

bufferMode -

offsetBits -

createTime -

quorumToken -

storeUUID -

Method Detail

chooseRootBlock

public static IRootBlockView chooseRootBlock(IRootBlockView rootBlock0,
                             IRootBlockView rootBlock1)

Return the chosen root block. The root block having the greater commit counter is chosen by default.

Note: For historical compatibility, rootBlock1 is chosen if both root blocks have the same IRootBlockView.getCommitCounter().

Parameters:

rootBlock0 - Root block 0 (may be null if this root block is bad).

rootBlock1 - Root block 1 (may be null if this root block is bad).

Returns:

The chosen root block.

Throws:

RuntimeException - if no root block satisfies the criteria.

chooseRootBlock

public IRootBlockView chooseRootBlock()

Return the chosen root block. The root block having the greater commit counter is chosen by default.

Note: For historical compatibility, rootBlock1 is chosen if both root blocks have the same IRootBlockView.getCommitCounter().

Returns:

The chosen root block.

Throws:

RuntimeException - if no root block satisfies the criteria.

chooseRootBlock

public static IRootBlockView chooseRootBlock(IRootBlockView rootBlock0,
                             IRootBlockView rootBlock1,
                             boolean alternateRootBlock,
                             boolean ignoreBadRootBlock)

Return the chosen root block. The root block having the greater commit counter is chosen by default.

Note: For historical compatibility, rootBlock1 is chosen if both root blocks have the same IRootBlockView.getCommitCounter().

Parameters:

rootBlock0 - Root block 0 (may be null if this root block is bad).

rootBlock1 - Root block 1 (may be null if this root block is bad).

alternateRootBlock - When true, the alternate root block will be chosen. This flag only makes sense when you have two root blocks to choose from and you want to choose the other one.

ignoreBadRootBlock - When true, a bad root block will be ignored.

Returns:

The chosen root block.

Throws:

RuntimeException - if no root block satisfies the criteria.

main

public static void main(String[] args)
                 throws IOException

Dumps the root blocks for the specified file.

Parameters:

args - filename

Throws:

IOException