org.apache.hadoop.hdfs.protocol

类 LayoutVersion

java.lang.Object

org.apache.hadoop.hdfs.protocol.LayoutVersion

@InterfaceAudience.Private
public class LayoutVersion
extends Object

This class tracks changes in the layout version of HDFS. Layout version is changed for following reasons:

1. The layout of how namenode or datanode stores information on disk changes.
2. A new operation code is added to the editlog.
3. Modification such as format of a record, content of a record in editlog or fsimage.

How to update layout version:
When a change requires new layout version, please add an entry into LayoutVersion.Feature with a short enum name, new layout version and description of the change. Please see LayoutVersion.Feature for further details.

嵌套类概要

嵌套类

限定符和类型	类和说明
static class	LayoutVersion.Feature Enums for features that change the layout version.

字段概要

字段

限定符和类型	字段和说明
static int	BUGFIX_HDFS_2991_VERSION Version in which HDFS-2991 was fixed.

构造器概要

构造器

构造器和说明
LayoutVersion()

方法概要

方法

限定符和类型	方法和说明
static int	getCurrentLayoutVersion() Get the current layout version
static String	getString() Gets formatted string that describes LayoutVersion information.
static boolean	supports(LayoutVersion.Feature f, int lv) Returns true if a given feature is supported in the given layout version

从类继承的方法 java.lang.Object

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

字段详细资料

BUGFIX_HDFS_2991_VERSION

public static final int BUGFIX_HDFS_2991_VERSION

Version in which HDFS-2991 was fixed. This bug caused OP_ADD to sometimes be skipped for append() calls. If we see such a case when loading the edits, but the version is known to have that bug, we workaround the issue. Otherwise we should consider it a corruption and bail.

另请参阅:

常量字段值

构造器详细资料

LayoutVersion

public LayoutVersion()

方法详细资料

getString

public static String getString()

Gets formatted string that describes LayoutVersion information.

supports

public static boolean supports(LayoutVersion.Feature f,
               int lv)

Returns true if a given feature is supported in the given layout version

参数:

f - Feature

lv - LayoutVersion

返回:

true if f is supported in layout version lv

getCurrentLayoutVersion

public static int getCurrentLayoutVersion()

Get the current layout version