org.apache.hadoop.hdfs.util
Class EnumCounters<E extends Enum<E>>

java.lang.Object
  org.apache.hadoop.hdfs.util.EnumCounters<E>

Type Parameters:

E - the enum type

Direct Known Subclasses:

Content.Counts, Quota.Counts

public class EnumCounters<E extends Enum<E>>
extends Object

Counters for an enum type. For example, suppose there is an enum type

 enum Fruit { APPLE, ORANGE, GRAPE }
 

An EnumCounters object can be created for counting the numbers of APPLE, ORANGLE and GRAPE.

Nested Class Summary

static interface	EnumCounters.Factory<E extends Enum<E>,C extends EnumCounters<E>> A factory for creating counters.
static class	EnumCounters.Map<K,E extends Enum<E>,C extends EnumCounters<E>> A key-value map which maps the keys to EnumCounters.

Constructor Summary

EnumCounters(E[] enumConstants)
Construct counters for the given enum constants.

Method Summary

void	add(E e, long value) Add the given value to counter e.
void	add(EnumCounters<E> that) Add that counters to this counters.
long	get(E e)
void	negation() Negate all counters.
void	set(E e, long value) Set counter e to the given value.
void	subtract(E e, long value) Subtract the given value from counter e.
void	subtract(EnumCounters<E> that) Subtract that counters from this counters.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

EnumCounters

public EnumCounters(E[] enumConstants)

Construct counters for the given enum constants.

Parameters:

enumConstants - an array of enum constants such that, for all i, enumConstants[i].ordinal() == i.

Method Detail

get

public final long get(E e)

Returns:

the value of counter e.

negation

public final void negation()

Negate all counters.

set

public final void set(E e,
                      long value)

Set counter e to the given value.

add

public final void add(E e,
                      long value)

Add the given value to counter e.

add

public final void add(EnumCounters<E> that)

Add that counters to this counters.

subtract

public final void subtract(E e,
                           long value)

Subtract the given value from counter e.

subtract

public final void subtract(EnumCounters<E> that)

Subtract that counters from this counters.

toString

public String toString()

Overrides:

toString in class Object