Package org.apache.hadoop.hdfs.server.namenode

Enum NameNodeLayoutVersion.Feature

java.lang.Object

java.lang.Enum<NameNodeLayoutVersion.Feature>

org.apache.hadoop.hdfs.server.namenode.NameNodeLayoutVersion.Feature

All Implemented Interfaces:

java.io.Serializable, java.lang.Comparable<NameNodeLayoutVersion.Feature>, LayoutVersion.LayoutFeature

Enclosing class:

NameNodeLayoutVersion

public static enum NameNodeLayoutVersion.Feature
extends java.lang.Enum<NameNodeLayoutVersion.Feature>
implements LayoutVersion.LayoutFeature

Enums for features that change the layout version.

To add a new layout version:

• Define a new enum constant with a short enum name, the new layout version and description of the added feature.
• When adding a layout version with an ancestor that is not same as its immediate predecessor, use the constructor where a specific ancestor can be passed.
• Specify a minimum compatible layout version. The minimum compatible layout version is the earliest prior version to which a downgrade is possible after initiating rolling upgrade. If the feature cannot satisfy compatibility with any prior version, then set its minimum compatible layout version to itself to indicate that downgrade is impossible. Satisfying compatibility might require adding logic to the new feature to reject operations or handle them differently while rolling upgrade is in progress. In general, it's possible to satisfy compatibility for downgrade if the new feature just involves adding new edit log ops. Deeper structural changes, such as changing the way we place files in the metadata directories, might be incompatible. Feature implementations should strive for compatibility, because it's in the best interest of our users to support downgrade.

Enum Constant Summary

Enum Constants

Enum Constant	Description
APPEND_NEW_BLOCK
BLOCK_STORAGE_POLICY
CREATE_OVERWRITE
EDITLOG_LENGTH
ERASURE_CODING
EXPANDED_STRING_TABLE
NVDIMM_SUPPORT
QUOTA_BY_STORAGE_TYPE
ROLLING_UPGRADE
SNAPSHOT_MODIFICATION_TIME
TRUNCATE
XATTRS
XATTRS_NAMESPACE_EXT

Method Summary

Modifier and Type	Method	Description
LayoutVersion.FeatureInfo	getInfo()
static NameNodeLayoutVersion.Feature	valueOf(java.lang.String name)	Returns the enum constant of this type with the specified name.
static NameNodeLayoutVersion.Feature[]	values()	Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

ROLLING_UPGRADE

public static final NameNodeLayoutVersion.Feature ROLLING_UPGRADE

EDITLOG_LENGTH

public static final NameNodeLayoutVersion.Feature EDITLOG_LENGTH

XATTRS

public static final NameNodeLayoutVersion.Feature XATTRS

CREATE_OVERWRITE

public static final NameNodeLayoutVersion.Feature CREATE_OVERWRITE

XATTRS_NAMESPACE_EXT

public static final NameNodeLayoutVersion.Feature XATTRS_NAMESPACE_EXT

BLOCK_STORAGE_POLICY

public static final NameNodeLayoutVersion.Feature BLOCK_STORAGE_POLICY

TRUNCATE

public static final NameNodeLayoutVersion.Feature TRUNCATE

APPEND_NEW_BLOCK

public static final NameNodeLayoutVersion.Feature APPEND_NEW_BLOCK

QUOTA_BY_STORAGE_TYPE

public static final NameNodeLayoutVersion.Feature QUOTA_BY_STORAGE_TYPE

ERASURE_CODING

public static final NameNodeLayoutVersion.Feature ERASURE_CODING

EXPANDED_STRING_TABLE

public static final NameNodeLayoutVersion.Feature EXPANDED_STRING_TABLE

SNAPSHOT_MODIFICATION_TIME

public static final NameNodeLayoutVersion.Feature SNAPSHOT_MODIFICATION_TIME

NVDIMM_SUPPORT

public static final NameNodeLayoutVersion.Feature NVDIMM_SUPPORT

Method Detail

values

public static NameNodeLayoutVersion.Feature[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (NameNodeLayoutVersion.Feature c : NameNodeLayoutVersion.Feature.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static NameNodeLayoutVersion.Feature valueOf(java.lang.String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

java.lang.IllegalArgumentException - if this enum type has no constant with the specified name

java.lang.NullPointerException - if the argument is null

getInfo

public LayoutVersion.FeatureInfo getInfo()

Specified by:

getInfo in interface LayoutVersion.LayoutFeature