org.apache.hudi.io.hfile

Class HFileReaderImpl

java.lang.Object

org.apache.hudi.io.hfile.HFileReaderImpl

All Implemented Interfaces:

Closeable, AutoCloseable, HFileReader

public class HFileReaderImpl
extends Object
implements HFileReader

An implementation a HFileReader.

Field Summary

Fields inherited from interface org.apache.hudi.io.hfile.HFileReader

SEEK_TO_BEFORE_FIRST_KEY, SEEK_TO_EOF, SEEK_TO_FOUND, SEEK_TO_IN_RANGE

Constructor Summary

Constructors

Constructor and Description
HFileReaderImpl(SeekableDataInputStream stream, long fileSize)

Method Summary

Modifier and Type	Method and Description
void	close()
Option<KeyValue>	getKeyValue()
Option<ByteBuffer>	getMetaBlock(String metaBlockName) Gets the content of a meta block from HFile.
Option<byte[]>	getMetaInfo(UTF8StringKey key) Gets info entry from file info block of a HFile.
long	getNumKeyValueEntries()
void	initializeMetadata() Initializes metadata based on a HFile before other read operations.
boolean	isSeeked()
boolean	next() Scans to the next entry in the file.
boolean	seekTo() Positions this reader at the start of the file.
int	seekTo(Key key) seekTo or just before the passed Key.

Methods inherited from class java.lang.Object

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

Constructor Detail

HFileReaderImpl

public HFileReaderImpl(SeekableDataInputStream stream,
                       long fileSize)

Method Detail

initializeMetadata

public void initializeMetadata()
                        throws IOException

Description copied from interface: HFileReader

Initializes metadata based on a HFile before other read operations.

Specified by:

initializeMetadata in interface HFileReader

Throws:

IOException - upon read errors.

getMetaInfo

public Option<byte[]> getMetaInfo(UTF8StringKey key)
                           throws IOException

Description copied from interface: HFileReader

Gets info entry from file info block of a HFile.

Specified by:

getMetaInfo in interface HFileReader

Parameters:

key - meta key.

Returns:

the content in bytes if present.

Throws:

IOException - upon read errors.

getMetaBlock

public Option<ByteBuffer> getMetaBlock(String metaBlockName)
                                throws IOException

Description copied from interface: HFileReader

Gets the content of a meta block from HFile.

Specified by:

getMetaBlock in interface HFileReader

Parameters:

metaBlockName - meta block name.

Returns:

the content in bytes if present.

Throws:

IOException - upon read errors.

getNumKeyValueEntries

public long getNumKeyValueEntries()

Specified by:

getNumKeyValueEntries in interface HFileReader

Returns:

total number of key value entries in the HFile.

seekTo

public int seekTo(Key key)
           throws IOException

Description copied from interface: HFileReader

seekTo or just before the passed Key. Examine the return code to figure whether we found the key or not. Consider the key-value pairs in the file, kv[0] .. kv[n-1], where there are n KV pairs in the file.

The position only moves forward so the caller has to make sure the keys are sorted before making multiple calls of this method.

Specified by:

seekTo in interface HFileReader

Parameters:

key - Key to seek to.

Returns:

-1, if key < kv[0], no position; 0, such that kv[i].key = key and the reader is left in position i; and 1, such that kv[i].key < key if there is no exact match, and the reader is left in position i. The reader will position itself between kv[i] and kv[i+1] where kv[i].key < key <= kv[i+1].key; 2, if there is no KV greater than or equal to the input key, and the reader positions itself at the end of the file and next() will return false when it is called.

Throws:

IOException - upon read errors.

seekTo

public boolean seekTo()
               throws IOException

Description copied from interface: HFileReader

Positions this reader at the start of the file.

Specified by:

seekTo in interface HFileReader

Returns:

false if empty file; i.e. a call to next would return false and the current key and value are undefined.

Throws:

IOException - upon read errors.

next

public boolean next()
             throws IOException

Description copied from interface: HFileReader

Scans to the next entry in the file.

Specified by:

next in interface HFileReader

Returns:

false if the current position is at the end; otherwise true if more in file.

Throws:

IOException - upon read errors.

getKeyValue

public Option<KeyValue> getKeyValue()
                             throws IOException

Specified by:

getKeyValue in interface HFileReader

Returns:

The KeyValue instance at current position.

Throws:

IOException

isSeeked

public boolean isSeeked()

Specified by:

isSeeked in interface HFileReader

Returns:

true if the reader has had one of the seek calls invoked; i.e. HFileReader.seekTo() or HFileReader.seekTo(Key). Otherwise, false.

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException