org.apache.hadoop.mapred.join

类 WrappedRecordReader<K extends WritableComparable,U extends Writable>

java.lang.Object

org.apache.hadoop.mapred.join.WrappedRecordReader<K,U>

所有已实现的接口:

Comparable<ComposableRecordReader<K,?>>, ComposableRecordReader<K,U>, RecordReader<K,U>

public class WrappedRecordReader<K extends WritableComparable,U extends Writable>
extends Object
implements ComposableRecordReader<K,U>

Proxy class for a RecordReader participating in the join framework. This class keeps track of the "head" key-value pair for the provided RecordReader and keeps a store of values matching a key when this source is participating in a join.

方法概要

方法

限定符和类型	方法和说明
void	accept(org.apache.hadoop.mapred.join.CompositeRecordReader.JoinCollector i, K key) Add an iterator to the collector at the position occupied by this RecordReader over the values in this stream paired with the key provided (ie register a stream of values from this source matching K with a collector).
void	close() Forward close request to proxied RR.
int	compareTo(ComposableRecordReader<K,?> other) Implement Comparable contract (compare key at head of proxied RR with that of another).
K	createKey() Request new key from proxied RR.
U	createValue() Request new value from proxied RR.
boolean	equals(Object other) Return true iff compareTo(other) retn true.
long	getPos() Request position from proxied RR.
float	getProgress() Request progress from proxied RR.
int	hashCode()
boolean	hasNext() Return true if the RR- including the k,v pair stored in this object- is exhausted.
int	id() Return the position in the collector this class occupies.
K	key() Return the key at the head of this RR.
void	key(K qkey) Clone the key at the head of this RR into the object supplied.
protected boolean	next() Read the next k,v pair into the head of this object; return true iff the RR and this are exhausted.
boolean	next(K key, U value) Write key-value pair at the head of this stream to the objects provided; get next key-value pair from proxied RR.
void	skip(K key) Skip key-value pairs with keys less than or equal to the key provided.

从类继承的方法 java.lang.Object

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

方法详细资料

id

public int id()

Return the position in the collector this class occupies.

指定者:

id 在接口中 ComposableRecordReader<K extends WritableComparable,U extends Writable>

key

public K key()

Return the key at the head of this RR.

指定者:

key 在接口中 ComposableRecordReader<K extends WritableComparable,U extends Writable>

key

public void key(K qkey)
         throws IOException

Clone the key at the head of this RR into the object supplied.

指定者:

key 在接口中 ComposableRecordReader<K extends WritableComparable,U extends Writable>

抛出:

IOException

hasNext

public boolean hasNext()

Return true if the RR- including the k,v pair stored in this object- is exhausted.

指定者:

hasNext 在接口中 ComposableRecordReader<K extends WritableComparable,U extends Writable>

skip

public void skip(K key)
          throws IOException

Skip key-value pairs with keys less than or equal to the key provided.

指定者:

skip 在接口中 ComposableRecordReader<K extends WritableComparable,U extends Writable>

抛出:

IOException

next

protected boolean next()
                throws IOException

Read the next k,v pair into the head of this object; return true iff the RR and this are exhausted.

抛出:

IOException

accept

public void accept(org.apache.hadoop.mapred.join.CompositeRecordReader.JoinCollector i,
          K key)
            throws IOException

Add an iterator to the collector at the position occupied by this RecordReader over the values in this stream paired with the key provided (ie register a stream of values from this source matching K with a collector).

指定者:

accept 在接口中 ComposableRecordReader<K extends WritableComparable,U extends Writable>

抛出:

IOException

next

public boolean next(K key,
           U value)
             throws IOException

Write key-value pair at the head of this stream to the objects provided; get next key-value pair from proxied RR.

指定者:

next 在接口中 RecordReader<K extends WritableComparable,U extends Writable>

参数:

key - the key to read data into

value - the value to read data into

返回:

true iff a key/value was read, false if at EOF

抛出:

IOException

createKey

public K createKey()

Request new key from proxied RR.

指定者:

createKey 在接口中 RecordReader<K extends WritableComparable,U extends Writable>

返回:

a new key object.

createValue

public U createValue()

Request new value from proxied RR.

指定者:

createValue 在接口中 RecordReader<K extends WritableComparable,U extends Writable>

返回:

a new value object.

getProgress

public float getProgress()
                  throws IOException

Request progress from proxied RR.

指定者:

getProgress 在接口中 RecordReader<K extends WritableComparable,U extends Writable>

返回:

progress from 0.0 to 1.0.

抛出:

IOException

getPos

public long getPos()
            throws IOException

Request position from proxied RR.

指定者:

getPos 在接口中 RecordReader<K extends WritableComparable,U extends Writable>

返回:

the current position in the input.

抛出:

IOException

close

public void close()
           throws IOException

Forward close request to proxied RR.

指定者:

close 在接口中 RecordReader<K extends WritableComparable,U extends Writable>

抛出:

IOException

compareTo

public int compareTo(ComposableRecordReader<K,?> other)

Implement Comparable contract (compare key at head of proxied RR with that of another).

指定者:

compareTo 在接口中 Comparable<ComposableRecordReader<K extends WritableComparable,?>>

equals

public boolean equals(Object other)

Return true iff compareTo(other) retn true.

覆盖:

equals 在类中 Object

hashCode

public int hashCode()

覆盖:

hashCode 在类中 Object