org.apache.hadoop.mapreduce.counters

Class AbstractCounters<C extends Counter,G extends CounterGroupBase<C>>

java.lang.Object

org.apache.hadoop.mapreduce.counters.AbstractCounters<C,G>

Type Parameters:

C - type of counter inside the counters

G - type of group inside the counters

All Implemented Interfaces:

Iterable<G>, Writable

Direct Known Subclasses:

Counters, Counters

@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class AbstractCounters<C extends Counter,G extends CounterGroupBase<C>>
extends Object
implements Writable, Iterable<G>

An abstract class to provide common implementation for the Counters container in both mapred and mapreduce packages.

Field Summary

Fields

Modifier and Type	Field and Description
protected static org.apache.commons.logging.Log	LOG

Constructor Summary

Constructors

Constructor and Description
AbstractCounters(AbstractCounters<C1,G1> counters, org.apache.hadoop.mapreduce.counters.CounterGroupFactory<C,G> groupFactory) Construct from another counters object.
AbstractCounters(org.apache.hadoop.mapreduce.counters.CounterGroupFactory<C,G> gf)

Method Summary

Methods

Modifier and Type	Method and Description
int	countCounters() Returns the total number of counters, by summing the number of counters in each group.
boolean	equals(Object genericRight)
C	findCounter(Enum<?> key) Find the counter for the given enum.
C	findCounter(String groupName, String counterName) Find a counter, create one if necessary
G	getGroup(String groupName) Returns the named counter group, or an empty group if there is none with the specified name.
Iterable<String>	getGroupNames() Returns the names of all counter classes.
int	hashCode()
void	incrAllCounters(AbstractCounters<C,G> other) Increments multiple counters by their amounts in another Counters instance.
Iterator<G>	iterator()
void	readFields(DataInput in) Deserialize the fields of this object from in.
String	toString() Return textual representation of the counter values.
void	write(DataOutput out) Write the set of groups.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

protected static final org.apache.commons.logging.Log LOG

Constructor Detail

AbstractCounters

@InterfaceAudience.Private
public AbstractCounters(org.apache.hadoop.mapreduce.counters.CounterGroupFactory<C,G> gf)

AbstractCounters

@InterfaceAudience.Private
public AbstractCounters(AbstractCounters<C1,G1> counters,
                                          org.apache.hadoop.mapreduce.counters.CounterGroupFactory<C,G> groupFactory)

Construct from another counters object.

Type Parameters:

C1 - type of the other counter

G1 - type of the other counter group

Parameters:

counters - the counters object to copy

groupFactory - the factory for new groups

Method Detail

findCounter

public C findCounter(String groupName,
            String counterName)

Find a counter, create one if necessary

Parameters:

groupName - of the counter

counterName - name of the counter

Returns:

the matching counter

findCounter

public C findCounter(Enum<?> key)

Find the counter for the given enum. The same enum will always return the same counter.

Parameters:

key - the counter key

Returns:

the matching counter object

getGroupNames

public Iterable<String> getGroupNames()

Returns the names of all counter classes.

Returns:

Set of counter names.

iterator

public Iterator<G> iterator()

Specified by:

iterator in interface Iterable<G extends CounterGroupBase<C>>

getGroup

public G getGroup(String groupName)

Returns the named counter group, or an empty group if there is none with the specified name.

Parameters:

groupName - name of the group

Returns:

the group

countCounters

public int countCounters()

Returns the total number of counters, by summing the number of counters in each group.

Returns:

the total number of counters

write

public void write(DataOutput out)
           throws IOException

Write the set of groups. Counters ::= version #fgroups (groupId, group)* #groups (group)*

Specified by:

write in interface Writable

Parameters:

out - DataOuput to serialize this object into.

Throws:

IOException

readFields

public void readFields(DataInput in)
                throws IOException

Description copied from interface: Writable

Deserialize the fields of this object from in.

For efficiency, implementations should attempt to re-use storage in the existing object where possible.

Specified by:

readFields in interface Writable

Parameters:

in - DataInput to deseriablize this object from.

Throws:

IOException

toString

public String toString()

Return textual representation of the counter values.

Overrides:

toString in class Object

Returns:

the string

incrAllCounters

public void incrAllCounters(AbstractCounters<C,G> other)

Increments multiple counters by their amounts in another Counters instance.

Parameters:

other - the other Counters instance

equals

public boolean equals(Object genericRight)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object