Package org.apache.hadoop.fs.impl

Class FlagSet<E extends java.lang.Enum<E>>

java.lang.Object

org.apache.hadoop.fs.impl.FlagSet<E>

All Implemented Interfaces:

StreamCapabilities

public final class FlagSet<E extends java.lang.Enum<E>>
extends java.lang.Object
implements StreamCapabilities

A set of flags, constructed from a configuration option or from a string, with the semantics of ConfigurationHelper.parseEnumSet(String, String, Class, boolean) and implementing StreamCapabilities.

Thread safety: there is no synchronization on a mutable FlagSet. Once declared immutable, flags cannot be changed, so they becomes implicitly thread-safe.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.fs.StreamCapabilities

StreamCapabilities.StreamCapability

Field Summary

Fields inherited from interface org.apache.hadoop.fs.StreamCapabilities

ABORTABLE_STREAM, DROPBEHIND, HFLUSH, HSYNC, IOSTATISTICS, IOSTATISTICS_CONTEXT, PREADBYTEBUFFER, READAHEAD, READBYTEBUFFER, UNBUFFER, VECTOREDIO

Method Summary

Modifier and Type	Method	Description
static <E extends java.lang.Enum<E>> FlagSet<E>	buildFlagSet(java.lang.Class<E> enumClass, Configuration conf, java.lang.String key, boolean ignoreUnknown)	Build a FlagSet from a comma separated list of values.
FlagSet<E>	copy()	Create a copy of the FlagSet.
static <E extends java.lang.Enum<E>> FlagSet<E>	createFlagSet(java.lang.Class<E> enumClass, java.lang.String prefix, E... enabled)	Create a FlagSet from a list of enum values.
static <E extends java.lang.Enum<E>> FlagSet<E>	createFlagSet(java.lang.Class<E> enumClass, java.lang.String prefix, java.util.EnumSet<E> flags)	Create a FlagSet.
void	disable(E flag)	Disable a flag.
void	enable(E flag)	Enable a flag.
boolean	enabled(E flag)	Is a flag enabled?
boolean	equals(java.lang.Object o)	Equality is based on the value of enumClass and prefix and the contents of the set, which must match.
java.util.EnumSet<E>	flags()	Get a copy of the flags.
java.lang.Class<E>	getEnumClass()	Get the enum class.
boolean	hasCapability(java.lang.String capability)	Is a flag enabled?
int	hashCode()	Hash code is based on the flags.
boolean	isEmpty()	Probe for the FlagSet being empty.
boolean	isImmutable()	Is the FlagSet immutable?
void	makeImmutable()	Make immutable; no-op if already set.
java.util.List<java.lang.String>	pathCapabilities()	Generate the list of capabilities.
void	set(E flag, boolean state)	Set a flag to the chosen value.
java.lang.String	toConfigurationString()	Convert to a string which can be then set in a configuration.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

flags

public java.util.EnumSet<E> flags()

Get a copy of the flags.

This is immutable.

Returns:

the flags.

isEmpty

public boolean isEmpty()

Probe for the FlagSet being empty.

Returns:

true if there are no flags set.

enabled

public boolean enabled(E flag)

Is a flag enabled?

Parameters:

flag - flag to check

Returns:

true if it is in the set of enabled flags.

enable

public void enable(E flag)

Enable a flag.

Parameters:

flag - flag to enable.

disable

public void disable(E flag)

Disable a flag.

Parameters:

flag - flag to disable

set

public void set(E flag,
                boolean state)

Set a flag to the chosen value.

Parameters:

flag - flag

state - true to enable, false to disable.

hasCapability

public boolean hasCapability(java.lang.String capability)

Is a flag enabled?

Specified by:

hasCapability in interface StreamCapabilities

Parameters:

capability - string to query the stream support for.

Returns:

true if the capability maps to an enum value and that value is set.

makeImmutable

public void makeImmutable()

Make immutable; no-op if already set.

isImmutable

public boolean isImmutable()

Is the FlagSet immutable?

Returns:

true iff the FlagSet is immutable.

getEnumClass

public java.lang.Class<E> getEnumClass()

Get the enum class.

Returns:

the enum class.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

pathCapabilities

public java.util.List<java.lang.String> pathCapabilities()

Generate the list of capabilities.

Returns:

a possibly empty list.

equals

public boolean equals(java.lang.Object o)

Equality is based on the value of enumClass and prefix and the contents of the set, which must match.

The immutability flag is not considered, nor is the namesToValues map, though as that is generated from the enumeration and prefix, it is implicitly equal if the prefix and enumClass fields are equal.

Overrides:

equals in class java.lang.Object

Parameters:

o - other object

Returns:

true iff the equality condition is met.

hashCode

public int hashCode()

Hash code is based on the flags.

Overrides:

hashCode in class java.lang.Object

Returns:

a hash code.

copy

public FlagSet<E> copy()

Create a copy of the FlagSet.

Returns:

a new mutable instance with a separate copy of the flags

toConfigurationString

public java.lang.String toConfigurationString()

Convert to a string which can be then set in a configuration. This is effectively a marshalled form of the flags.

Returns:

a comma separated list of flag names.

createFlagSet

public static <E extends java.lang.Enum<E>> FlagSet<E> createFlagSet(java.lang.Class<E> enumClass,
                                                                     java.lang.String prefix,
                                                                     java.util.EnumSet<E> flags)

Create a FlagSet.

Type Parameters:

E - enum type

Parameters:

enumClass - class of enum

prefix - prefix (with trailing ".") for path capabilities probe

flags - flags

Returns:

a mutable FlagSet

createFlagSet

@SafeVarargs
public static <E extends java.lang.Enum<E>> FlagSet<E> createFlagSet(java.lang.Class<E> enumClass,
                                                                     java.lang.String prefix,
                                                                     E... enabled)

Create a FlagSet from a list of enum values.

Type Parameters:

E - enum type

Parameters:

enumClass - class of enum

prefix - prefix (with trailing ".") for path capabilities probe

enabled - varags list of flags to enable.

Returns:

a mutable FlagSet

buildFlagSet

public static <E extends java.lang.Enum<E>> FlagSet<E> buildFlagSet(java.lang.Class<E> enumClass,
                                                                    Configuration conf,
                                                                    java.lang.String key,
                                                                    boolean ignoreUnknown)

Build a FlagSet from a comma separated list of values. Case independent. Special handling of "*" meaning: all values.

Type Parameters:

E - enumeration type

Parameters:

enumClass - class of enum

conf - configuration

key - key to look for

ignoreUnknown - should unknown values raise an exception?

Returns:

a mutable FlagSet

Throws:

java.lang.IllegalArgumentException - if one of the entries was unknown and ignoreUnknown is false, or there are two entries in the enum which differ only by case.