org.apache.hadoop.mapred
Class Counters

java.lang.Object
  org.apache.hadoop.mapreduce.counters.AbstractCounters<Counters.Counter,Counters.Group>
      org.apache.hadoop.mapred.Counters

All Implemented Interfaces:

Iterable<Counters.Group>, Writable

@InterfaceAudience.Public
@InterfaceStability.Stable
public class Counters
extends AbstractCounters<Counters.Counter,Counters.Group>

A set of named counters.

Counters represent global counters, defined either by the Map-Reduce framework or applications. Each Counter can be of any Enum type.

Counters are bunched into Counters.Groups, each comprising of counters from a particular Enum class.

Nested Class Summary

static class	Counters.Counter A counter record, comprising its name and value.
static class	Counters.Group Group of counters, comprising of counters from a particular counter Enum class.

Field Summary

static int	MAX_COUNTER_LIMIT
static int	MAX_GROUP_LIMIT

Fields inherited from class org.apache.hadoop.mapreduce.counters.AbstractCounters

LOG

Constructor Summary

Counters()

Counters(Counters newCounters)

Method Summary

Counters.Counter	findCounter(String group, int id, String name) Deprecated. use findCounter(String, String) instead
Counters.Counter	findCounter(String group, String name) Find a counter, create one if necessary
static Counters	fromEscapedCompactString(String compactString) Convert a stringified (by makeEscapedCompactString() counter representation into a counter object.
long	getCounter(Enum<?> key) Returns current value of the specified counter, or 0 if the counter does not exist.
Counters.Group	getGroup(String groupName) Returns the named counter group, or an empty group if there is none with the specified name.
Collection<String>	getGroupNames() Returns the names of all counter classes.
void	incrAllCounters(Counters other) Increments multiple counters by their amounts in another Counters instance.
void	incrCounter(Enum<?> key, long amount) Increments the specified counter by the specified amount, creating it if it didn't already exist.
void	incrCounter(String group, String counter, long amount) Increments the specified counter by the specified amount, creating it if it didn't already exist.
void	log(org.apache.commons.logging.Log log) Logs the current counter values.
String	makeCompactString()
String	makeEscapedCompactString() Represent the counter in a textual format that can be converted back to its object form
int	size() Deprecated. use AbstractCounters.countCounters() instead
static Counters	sum(Counters a, Counters b) Convenience method for computing the sum of two sets of counters.

Methods inherited from class org.apache.hadoop.mapreduce.counters.AbstractCounters

countCounters, equals, findCounter, hashCode, incrAllCounters, iterator, readFields, toString, write

Methods inherited from class java.lang.Object

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

Field Detail

MAX_COUNTER_LIMIT

public static int MAX_COUNTER_LIMIT

MAX_GROUP_LIMIT

public static int MAX_GROUP_LIMIT

Constructor Detail

Counters

public Counters()

Counters

public Counters(Counters newCounters)

Method Detail

getGroup

public Counters.Group getGroup(String groupName)

Description copied from class: AbstractCounters

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

Overrides:

getGroup in class AbstractCounters<Counters.Counter,Counters.Group>

Parameters:

groupName - name of the group

Returns:

the group

getGroupNames

public Collection<String> getGroupNames()

Description copied from class: AbstractCounters

Returns the names of all counter classes.

Overrides:

getGroupNames in class AbstractCounters<Counters.Counter,Counters.Group>

Returns:

Set of counter names.

makeCompactString

public String makeCompactString()

findCounter

public Counters.Counter findCounter(String group,
                                    String name)

Description copied from class: AbstractCounters

Find a counter, create one if necessary

Overrides:

findCounter in class AbstractCounters<Counters.Counter,Counters.Group>

Parameters:

group - of the counter

name - name of the counter

Returns:

the matching counter

findCounter

@Deprecated
public Counters.Counter findCounter(String group,
                                               int id,
                                               String name)

Deprecated. use findCounter(String, String) instead

Find a counter by using strings

Parameters:

group - the name of the group

id - the id of the counter within the group (0 to N-1)

name - the internal name of the counter

Returns:

the counter for that name

incrCounter

public void incrCounter(Enum<?> key,
                        long amount)

Increments the specified counter by the specified amount, creating it if it didn't already exist.

Parameters:

key - identifies a counter

amount - amount by which counter is to be incremented

incrCounter

public void incrCounter(String group,
                        String counter,
                        long amount)

Increments the specified counter by the specified amount, creating it if it didn't already exist.

Parameters:

group - the name of the group

counter - the internal name of the counter

amount - amount by which counter is to be incremented

getCounter

public long getCounter(Enum<?> key)

Returns current value of the specified counter, or 0 if the counter does not exist.

Parameters:

key - the counter enum to lookup

Returns:

the counter value or 0 if counter not found

incrAllCounters

public void incrAllCounters(Counters other)

Increments multiple counters by their amounts in another Counters instance.

Parameters:

other - the other Counters instance

size

public int size()

Deprecated. use AbstractCounters.countCounters() instead

Returns:

the total number of counters

sum

public static Counters sum(Counters a,
                           Counters b)

Convenience method for computing the sum of two sets of counters.

Parameters:

a - the first counters

b - the second counters

Returns:

a new summed counters object

log

public void log(org.apache.commons.logging.Log log)

Logs the current counter values.

Parameters:

log - The log to use.

makeEscapedCompactString

public String makeEscapedCompactString()

Represent the counter in a textual format that can be converted back to its object form

Returns:

the string in the following format {(groupName)(group-displayName)[(counterName)(displayName)(value)][]*}*

fromEscapedCompactString

public static Counters fromEscapedCompactString(String compactString)
                                         throws ParseException

Convert a stringified (by makeEscapedCompactString() counter representation into a counter object.

Parameters:

compactString - to parse

Returns:

a new counters object

Throws:

ParseException