Counters (Hadoop 1.2.2-SNAPSHOT API)

java.lang.Object
- org.apache.hadoop.mapred.Counters

所有已实现的接口:

Iterable<Counters.Group>, Writable
```
public class Counters
extends Object
implements Writable, Iterable<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.

嵌套类概要

嵌套类
限定符和类型	类和说明
`static class`	`Counters.Counter` A counter record, comprising its name and value.
`static class`	`Counters.CountersExceededException` Counter exception thrown when the number of counters exceed the limit
`class`	`Counters.Group` `Group` of counters, comprising of counters from a particular counter `Enum` class.

字段概要

字段
限定符和类型字段和说明

static int MAX_COUNTER_LIMIT
limit on counters

static int MAX_GROUP_LIMIT
the max groups allowed

字段
限定符和类型	字段和说明
`static int`	`MAX_COUNTER_LIMIT` limit on counters
`static int`	`MAX_GROUP_LIMIT` the max groups allowed

构造器概要

构造器
构造器和说明

Counters()

构造器
构造器和说明
`Counters()`

方法概要

方法
限定符和类型	方法和说明
`boolean`	`equals(Object obj)`
`Counters.Counter`	`findCounter(Enum key)` Find the counter for the given enum.
`Counters.Counter`	`findCounter(String group, int id, String name)` 已过时。
`Counters.Counter`	`findCounter(String group, String name)` Find a counter given the group and the name.
`static Counters`	`fromEscapedCompactString(String compactString)` Convert a stringified 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.
`int`	`hashCode()`
`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.
`Iterator<Counters.Group>`	`iterator()`
`void`	`log(org.apache.commons.logging.Log log)` Logs the current counter values.
`String`	`makeCompactString()` Convert a counters object into a single line that is easy to parse.
`String`	`makeEscapedCompactString()` Represent the counter in a textual format that can be converted back to its object form
`void`	`readFields(DataInput in)` Read a set of groups.
`int`	`size()` Returns the total number of counters, by summing the number of counters in each group.
`static Counters`	`sum(Counters a, Counters b)` Convenience method for computing the sum of two sets of counters.
`String`	`toString()` Return textual representation of the counter values.
`void`	`write(DataOutput out)` Write the set of groups.

从类继承的方法 java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- 字段详细资料
  - MAX_COUNTER_LIMIT
```
public static int MAX_COUNTER_LIMIT
```
    limit on counters
  - MAX_GROUP_LIMIT
```
public static final int MAX_GROUP_LIMIT
```
    the max groups allowed
- 构造器详细资料
  - Counters
```
public Counters()
```
- 方法详细资料
  - getGroupNames
```
public Collection<String> getGroupNames()
```
    Returns the names of all counter classes.
    
    返回:
    Set of counter names.
  - iterator
```
public Iterator<Counters.Group> iterator()
```
    指定者:
    
    iterator 在接口中 Iterable<Counters.Group>
  - getGroup
```
public Counters.Group getGroup(String groupName)
```
    Returns the named counter group, or an empty group if there is none with the specified name.
  - findCounter
```
public Counters.Counter findCounter(Enum key)
```
    Find the counter for the given enum. The same enum will always return the same counter.
    
    参数:
    key - the counter key
    
    返回:
    the matching counter object
  - findCounter
```
public Counters.Counter findCounter(String group,
                           String name)
```
    Find a counter given the group and the name.
    
    参数:
    group - the name of the group
    name - the internal name of the counter
    
    返回:
    the counter for that name
  - findCounter
```
@Deprecated
public Counters.Counter findCounter(String group,
                                      int id,
                                      String name)
```
    已过时。
    
    Find a counter by using strings
    
    参数:
    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
    
    返回:
    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.
    
    参数:
    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.
    
    参数:
    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.
  - incrAllCounters
```
public void incrAllCounters(Counters other)
```
    Increments multiple counters by their amounts in another Counters instance.
    
    参数:
    other - the other Counters instance
  - sum
```
public static Counters sum(Counters a,
           Counters b)
```
    Convenience method for computing the sum of two sets of counters.
  - size
```
public int size()
```
    Returns the total number of counters, by summing the number of counters in each group.
  - write
```
public void write(DataOutput out)
           throws IOException
```
    Write the set of groups. The external format is: #groups (groupName group)* i.e. the number of groups followed by 0 or more groups, where each group is of the form: groupDisplayName #counters (false | true counter)* where each counter is of the form: name (false | true displayName) value
    
    指定者:
    
    write 在接口中 Writable
    
    参数:
    out - DataOuput to serialize this object into.
    
    抛出:
    
    IOException
  - readFields
```
public void readFields(DataInput in)
                throws IOException
```
    Read a set of groups.
    
    指定者:
    
    readFields 在接口中 Writable
    
    参数:
    in - DataInput to deseriablize this object from.
    
    抛出:
    
    IOException
  - log
```
public void log(org.apache.commons.logging.Log log)
```
    Logs the current counter values.
    
    参数:
    log - The log to use.
  - toString
```
public String toString()
```
    Return textual representation of the counter values.
    
    覆盖:
    
    toString 在类中 Object
  - makeCompactString
```
public String makeCompactString()
```
    Convert a counters object into a single line that is easy to parse.
    
    返回:
    the string with "name=value" for each counter and separated by ","
  - makeEscapedCompactString
```
public String makeEscapedCompactString()
```
    Represent the counter in a textual format that can be converted back to its object form
    
    返回:
    the string in the following format {(groupname)(group-displayname)[(countername)(displayname)(value)][][]}{}{}
  - fromEscapedCompactString
```
public static Counters fromEscapedCompactString(String compactString)
                                         throws ParseException
```
    Convert a stringified counter representation into a counter object. Note that the counter can be recovered if its stringified using makeEscapedCompactString().
    
    返回:
    a Counter
    
    抛出:
    
    ParseException
  - hashCode
```
public int hashCode()
```
    覆盖:
    
    hashCode 在类中 Object
  - equals
```
public boolean equals(Object obj)
```
    覆盖:
    
    equals 在类中 Object

类 Counters

嵌套类概要

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

MAX_COUNTER_LIMIT

MAX_GROUP_LIMIT

构造器详细资料

Counters

方法详细资料

getGroupNames

iterator

getGroup

findCounter

findCounter

findCounter

incrCounter

incrCounter

getCounter

incrAllCounters

sum

size

write

readFields

log

toString

makeCompactString

makeEscapedCompactString

fromEscapedCompactString

hashCode

equals