org.apache.hadoop.tools.distcp2.mapred.lib

类 DynamicRecordReader<K,V>

java.lang.Object

org.apache.hadoop.mapreduce.RecordReader<K,V>

org.apache.hadoop.tools.distcp2.mapred.lib.DynamicRecordReader<K,V>

所有已实现的接口:

Closeable, AutoCloseable

public class DynamicRecordReader<K,V>
extends RecordReader<K,V>

The DynamicRecordReader is used in conjunction with the DynamicInputFormat to implement the "Worker pattern" for DistCp. The DynamicRecordReader is responsible for: 1. Presenting the contents of each chunk to DistCp's mapper. 2. Acquiring a new chunk when the current chunk has been completely consumed, transparently.

构造器概要

构造器

构造器和说明
DynamicRecordReader()

方法概要

方法

限定符和类型	方法和说明
void	close() Implementation of RecordReader::close().
K	getCurrentKey() Implementation of RecordReader::getCurrentKey().
V	getCurrentValue() Implementation of RecordReader::getCurrentValue().
float	getProgress() Implementation of RecordReader::getProgress().
void	initialize(InputSplit inputSplit, TaskAttemptContext taskAttemptContext) Implementation for RecordReader::initialize().
boolean	nextKeyValue() Implementation of RecordReader::nextValue().

从类继承的方法 java.lang.Object

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

构造器详细资料

DynamicRecordReader

public DynamicRecordReader()

方法详细资料

initialize

public void initialize(InputSplit inputSplit,
              TaskAttemptContext taskAttemptContext)
                throws IOException,
                       InterruptedException

Implementation for RecordReader::initialize(). Initializes the internal RecordReader to read from chunks.

指定者:

initialize 在类中 RecordReader<K,V>

参数:

inputSplit - The InputSplit for the map. Ignored entirely.

taskAttemptContext - The AttemptContext.

抛出:

IOException, - on failure.

InterruptedException

IOException

nextKeyValue

public boolean nextKeyValue()
                     throws IOException,
                            InterruptedException

Implementation of RecordReader::nextValue(). Reads the contents of the current chunk and returns them. When a chunk has been completely exhausted, an new chunk is acquired and read, transparently.

指定者:

nextKeyValue 在类中 RecordReader<K,V>

返回:

True, if the nextValue() could be traversed to. False, otherwise.

抛出:

IOException, - on failure.

InterruptedException

IOException

getCurrentKey

public K getCurrentKey()
                throws IOException,
                       InterruptedException

Implementation of RecordReader::getCurrentKey().

指定者:

getCurrentKey 在类中 RecordReader<K,V>

返回:

The key of the current record. (i.e. the source-path.)

抛出:

IOException, - on failure.

InterruptedException

IOException

getCurrentValue

public V getCurrentValue()
                  throws IOException,
                         InterruptedException

Implementation of RecordReader::getCurrentValue().

指定者:

getCurrentValue 在类中 RecordReader<K,V>

返回:

The value of the current record. (i.e. the target-path.)

抛出:

IOException, - on failure.

InterruptedException

IOException

getProgress

public float getProgress()
                  throws IOException,
                         InterruptedException

Implementation of RecordReader::getProgress().

指定者:

getProgress 在类中 RecordReader<K,V>

返回:

A fraction [0.0,1.0] indicating the progress of a DistCp mapper.

抛出:

IOException, - on failure.

InterruptedException

IOException

close

public void close()
           throws IOException

Implementation of RecordReader::close(). Closes the RecordReader.

指定者:

close 在接口中 Closeable

指定者:

close 在接口中 AutoCloseable

指定者:

close 在类中 RecordReader<K,V>

抛出:

IOException, - on failure.

IOException