CompositeRecordReader (Apache Hadoop Main 3.0.0-alpha2-SNAPSHOT API)

java.lang.Object
- org.apache.hadoop.mapreduce.RecordReader<K,V>
- - org.apache.hadoop.mapreduce.lib.join.ComposableRecordReader<K,X>
  - - org.apache.hadoop.mapreduce.lib.join.CompositeRecordReader<K,V,X>

すべての実装されたインタフェース:

Closeable, AutoCloseable, Comparable<ComposableRecordReader<K,?>>, Configurable

直系の既知のサブクラス:

JoinRecordReader, MultiFilterRecordReader
```
@InterfaceAudience.Public
 @InterfaceStability.Stable
public abstract class CompositeRecordReader<K extends WritableComparable<?>,V extends Writable,X extends Writable>
extends ComposableRecordReader<K,X>
implements Configurable
```
A RecordReader that can effect joins of RecordReaders sharing a common key type and partitioning.

フィールドのサマリー

フィールド
修飾子とタイプ	フィールドと説明
`protected Configuration`	`conf`
`protected org.apache.hadoop.mapreduce.lib.join.CompositeRecordReader.JoinCollector`	`jc`
`protected K`	`key`
`protected Class<? extends WritableComparable>`	`keyclass`
`protected ComposableRecordReader<K,? extends V>[]`	`kids`
`protected X`	`value`

コンストラクタのサマリー

コンストラクタ
コンストラクタと説明
`CompositeRecordReader(int id, int capacity, Class<? extends WritableComparator> cmpcl)` Create a RecordReader with `capacity` children to position `id` in the parent reader.

メソッドのサマリー

すべてのメソッドインスタンス・メソッド abstractメソッド concreteメソッド
修飾子とタイプ	メソッドと説明
`void`	`accept(org.apache.hadoop.mapreduce.lib.join.CompositeRecordReader.JoinCollector jc, K key)` If key provided matches that of this Composite, give JoinCollector iterator over values it may emit.
`void`	`add(ComposableRecordReader<K,? extends V> rr)` Add a RecordReader to this collection.
`void`	`close()` Close all child RRs.
`protected abstract boolean`	`combine(Object[] srcs, TupleWritable value)`
`int`	`compareTo(ComposableRecordReader<K,?> other)` Implement Comparable contract (compare key of join or head of heap with that of another).
`protected K`	`createKey()` Create a new key common to all child RRs.
`protected TupleWritable`	`createTupleWritable()` Create a value to be used internally for joins.
`protected void`	`fillJoinCollector(K iterkey)` For all child RRs offering the key provided, obtain an iterator at that position in the JoinCollector.
`protected WritableComparator`	`getComparator()` Return comparator defining the ordering for RecordReaders in this composite.
`Configuration`	`getConf()` Return the configuration used by this object.
`K`	`getCurrentKey()` Get the current key
`X`	`getCurrentValue()` Get the current value.
`protected abstract ResetableIterator<X>`	`getDelegate()` Obtain an iterator over the child RRs apropos of the value type ultimately emitted from this join.
`float`	`getProgress()` Report progress as the minimum of all child RR progress.
`protected PriorityQueue<ComposableRecordReader<K,?>>`	`getRecordReaderQueue()` Return sorted list of RecordReaders for this composite.
`boolean`	`hasNext()` Return true if it is possible that this could emit more values.
`int`	`id()` Return the position in the collector this class occupies.
`void`	`initialize(InputSplit split, TaskAttemptContext context)` Called once at initialization.
`K`	`key()` Return the key for the current join or the value at the top of the RecordReader heap.
`void`	`key(K key)` Clone the key at the top of this RR into the given object.
`void`	`setConf(Configuration conf)` Set the configuration to be used by this object.
`void`	`skip(K key)` Pass skip key to child RRs.

クラスから継承されたメソッド org.apache.hadoop.mapreduce.RecordReader
nextKeyValue

クラスから継承されたメソッド java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- フィールドの詳細
  - conf
```
protected Configuration conf
```
  - keyclass
```
protected Class<? extends WritableComparable> keyclass
```
  - jc
```
protected final org.apache.hadoop.mapreduce.lib.join.CompositeRecordReader.JoinCollector jc
```
  - kids
```
protected final ComposableRecordReader<K extends WritableComparable<?>,? extends V extends Writable>[] kids
```
  - key
```
protected K extends WritableComparable<?> key
```
  - value
```
protected X extends Writable value
```
- コンストラクタの詳細
  - CompositeRecordReader
```
public CompositeRecordReader(int id,
                             int capacity,
                             Class<? extends WritableComparator> cmpcl)
                      throws IOException
```
    Create a RecordReader with capacity children to position id in the parent reader. The id of a root CompositeRecordReader is -1 by convention, but relying on this is not recommended.
    
    例外:
    
    IOException
- メソッドの詳細
  - combine
```
protected abstract boolean combine(Object[] srcs,
                                   TupleWritable value)
```
  - initialize
```
public void initialize(InputSplit split,
                       TaskAttemptContext context)
                throws IOException,
                       InterruptedException
```
    クラスからコピーされた説明: RecordReader
    
    Called once at initialization.
    
    定義:
    
    initialize クラス内 RecordReader<K extends WritableComparable<?>,X extends Writable>
    
    パラメータ:
    
    split - the split that defines the range of records to read
    
    context - the information about the task
    
    例外:
    
    IOException
    
    InterruptedException
  - id
```
public int id()
```
    Return the position in the collector this class occupies.
  - setConf
```
public void setConf(Configuration conf)
```
    Set the configuration to be used by this object.
    
    定義:
    
    setConf インタフェース内 Configurable
  - getConf
```
public Configuration getConf()
```
    Return the configuration used by this object.
    
    定義:
    
    getConf インタフェース内 Configurable
  - getRecordReaderQueue
```
protected PriorityQueue<ComposableRecordReader<K,?>> getRecordReaderQueue()
```
    Return sorted list of RecordReaders for this composite.
  - getComparator
```
protected WritableComparator getComparator()
```
    Return comparator defining the ordering for RecordReaders in this composite.
  - add
```
public void add(ComposableRecordReader<K,? extends V> rr)
         throws IOException,
                InterruptedException
```
    Add a RecordReader to this collection. The id() of a RecordReader determines where in the Tuple its entry will appear. Adding RecordReaders with the same id has undefined behavior.
    
    例外:
    
    IOException
    
    InterruptedException
  - key
```
public K key()
```
    Return the key for the current join or the value at the top of the RecordReader heap.
  - key
```
public void key(K key)
         throws IOException
```
    Clone the key at the top of this RR into the given object.
    
    例外:
    
    IOException
  - getCurrentKey
```
public K getCurrentKey()
```
    クラスからコピーされた説明: RecordReader
    
    Get the current key
    
    定義:
    
    getCurrentKey クラス内 RecordReader<K extends WritableComparable<?>,X extends Writable>
    
    戻り値:
    
    the current key or null if there is no current key
  - hasNext
```
public boolean hasNext()
```
    Return true if it is possible that this could emit more values.
  - skip
```
public void skip(K key)
          throws IOException,
                 InterruptedException
```
    Pass skip key to child RRs.
    
    例外:
    
    IOException
    
    InterruptedException
  - getDelegate
```
protected abstract ResetableIterator<X> getDelegate()
```
    Obtain an iterator over the child RRs apropos of the value type ultimately emitted from this join.
  - accept
```
public void accept(org.apache.hadoop.mapreduce.lib.join.CompositeRecordReader.JoinCollector jc,
                   K key)
            throws IOException,
                   InterruptedException
```
    If key provided matches that of this Composite, give JoinCollector iterator over values it may emit.
    
    例外:
    
    IOException
    
    InterruptedException
  - fillJoinCollector
```
protected void fillJoinCollector(K iterkey)
                          throws IOException,
                                 InterruptedException
```
    For all child RRs offering the key provided, obtain an iterator at that position in the JoinCollector.
    
    例外:
    
    IOException
    
    InterruptedException
  - compareTo
```
public int compareTo(ComposableRecordReader<K,?> other)
```
    Implement Comparable contract (compare key of join or head of heap with that of another).
    
    定義:
    
    compareTo インタフェース内 Comparable<ComposableRecordReader<K extends WritableComparable<?>,?>>
  - createKey
```
protected K createKey()
```
    Create a new key common to all child RRs.
    
    例外:
    
    ClassCastException - if key classes differ.
  - createTupleWritable
```
protected TupleWritable createTupleWritable()
```
    Create a value to be used internally for joins.
  - getCurrentValue
```
public X getCurrentValue()
                  throws IOException,
                         InterruptedException
```
    Get the current value.
    
    定義:
    
    getCurrentValue クラス内 RecordReader<K extends WritableComparable<?>,X extends Writable>
    
    戻り値:
    
    the object that was read
    
    例外:
    
    IOException
    
    InterruptedException
  - close
```
public void close()
           throws IOException
```
    Close all child RRs.
    
    定義:
    
    close インタフェース内 Closeable
    
    定義:
    
    close インタフェース内 AutoCloseable
    
    定義:
    
    close クラス内 RecordReader<K extends WritableComparable<?>,X extends Writable>
    
    例外:
    
    IOException
  - getProgress
```
public float getProgress()
                  throws IOException,
                         InterruptedException
```
    Report progress as the minimum of all child RR progress.
    
    定義:
    
    getProgress クラス内 RecordReader<K extends WritableComparable<?>,X extends Writable>
    
    戻り値:
    
    a number between 0.0 and 1.0 that is the fraction of the data read
    
    例外:
    
    IOException
    
    InterruptedException

クラス CompositeRecordReader<K extends WritableComparable<?>,V extends Writable,X extends Writable>

フィールドのサマリー

コンストラクタのサマリー

メソッドのサマリー

クラスから継承されたメソッド org.apache.hadoop.mapreduce.RecordReader

クラスから継承されたメソッド java.lang.Object

フィールドの詳細

conf

keyclass

jc

kids

key

value

コンストラクタの詳細

CompositeRecordReader

メソッドの詳細

combine

initialize

id

setConf

getConf

getRecordReaderQueue

getComparator

add

key

key

getCurrentKey

hasNext

skip

getDelegate

accept

fillJoinCollector

compareTo

createKey

createTupleWritable

getCurrentValue

close

getProgress