public abstract class CompositeRecordReader<K extends WritableComparable,V extends Writable,X extends Writable> extends Object implements Configurable
限定符和类型 | 字段和说明 |
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protected org.apache.hadoop.mapred.join.CompositeRecordReader.JoinCollector |
jc |
protected ComposableRecordReader<K,? extends V>[] |
kids |
构造器和说明 |
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CompositeRecordReader(int id,
int capacity,
Class<? extends WritableComparator> cmpcl)
Create a RecordReader with capacity children to position
id in the parent reader.
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限定符和类型 | 方法和说明 |
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void |
accept(org.apache.hadoop.mapred.join.CompositeRecordReader.JoinCollector jc,
K key)
If key provided matches that of this Composite, give JoinCollector
iterator over values it may emit.
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void |
add(ComposableRecordReader<K,? extends V> rr)
Add a RecordReader to this collection.
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void |
close()
Close all child RRs.
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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).
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protected TupleWritable |
createInternalValue()
Create a value to be used internally for joins.
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K |
createKey()
Create a new key value common to all child RRs.
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protected void |
fillJoinCollector(K iterkey)
For all child RRs offering the key provided, obtain an iterator
at that position in the JoinCollector.
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protected WritableComparator |
getComparator()
Return comparator defining the ordering for RecordReaders in this
composite.
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Configuration |
getConf()
Return the configuration used by this object.
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protected abstract ResetableIterator<X> |
getDelegate()
Obtain an iterator over the child RRs apropos of the value type
ultimately emitted from this join.
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long |
getPos()
Unsupported (returns zero in all cases).
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float |
getProgress()
Report progress as the minimum of all child RR progress.
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protected PriorityQueue<ComposableRecordReader<K,?>> |
getRecordReaderQueue()
Return sorted list of RecordReaders for this composite.
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boolean |
hasNext()
Return true if it is possible that this could emit more values.
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int |
id()
Return the position in the collector this class occupies.
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K |
key()
Return the key for the current join or the value at the top of the
RecordReader heap.
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void |
key(K key)
Clone the key at the top of this RR into the given object.
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void |
setConf(Configuration conf)
Set the configuration to be used by this object.
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void |
skip(K key)
Pass skip key to child RRs.
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protected final org.apache.hadoop.mapred.join.CompositeRecordReader.JoinCollector jc
protected final ComposableRecordReader<K extends WritableComparable,? extends V extends Writable>[] kids
public CompositeRecordReader(int id, int capacity, Class<? extends WritableComparator> cmpcl) throws IOException
IOException
protected abstract boolean combine(Object[] srcs, TupleWritable value)
public int id()
public void setConf(Configuration conf)
setConf
在接口中 Configurable
public Configuration getConf()
getConf
在接口中 Configurable
protected PriorityQueue<ComposableRecordReader<K,?>> getRecordReaderQueue()
protected WritableComparator getComparator()
public void add(ComposableRecordReader<K,? extends V> rr) throws IOException
IOException
public K key()
public void key(K key) throws IOException
IOException
public boolean hasNext()
public void skip(K key) throws IOException
IOException
protected abstract ResetableIterator<X> getDelegate()
public void accept(org.apache.hadoop.mapred.join.CompositeRecordReader.JoinCollector jc, K key) throws IOException
IOException
protected void fillJoinCollector(K iterkey) throws IOException
IOException
public int compareTo(ComposableRecordReader<K,?> other)
public K createKey()
ClassCastException
- if key classes differ.protected TupleWritable createInternalValue()
public long getPos() throws IOException
IOException
public void close() throws IOException
IOException
public float getProgress() throws IOException
IOException
Copyright © 2009 The Apache Software Foundation