org.apache.hadoop.hbase.regionserver.wal

Class ReaderBase

java.lang.Object

org.apache.hadoop.hbase.regionserver.wal.ReaderBase

All Implemented Interfaces:

HLog.Reader

Direct Known Subclasses:

ProtobufLogReader, SequenceFileLogReader

@InterfaceAudience.LimitedPrivate(value={"Coprocesssor","Phoenix"})
public abstract class ReaderBase
extends Object
implements HLog.Reader

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.hadoop.hbase.regionserver.wal.CompressionContext	compressionContext Compression context to use reading.
protected org.apache.hadoop.conf.Configuration	conf
protected long	edit
protected boolean	emptyCompressionContext
protected long	fileLength
protected org.apache.hadoop.fs.FileSystem	fs
protected org.apache.hadoop.fs.Path	path
protected WALProtos.WALTrailer	trailer
protected int	trailerWarnSize

Constructor Summary

Constructors

Constructor and Description
ReaderBase() Default constructor.

Method Summary

Methods

Modifier and Type	Method and Description
WALProtos.WALTrailer	getWALTrailer()
protected abstract boolean	hasCompression()
protected abstract boolean	hasTagCompression()
void	init(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path, org.apache.hadoop.conf.Configuration conf, org.apache.hadoop.fs.FSDataInputStream stream)
protected abstract void	initAfterCompression() Initializes the compression after the shared stuff has been initialized.
protected abstract void	initAfterCompression(String cellCodecClsName) Initializes the compression after the shared stuff has been initialized.
protected abstract String	initReader(org.apache.hadoop.fs.FSDataInputStream stream) Initializes the log reader with a particular stream (may be null).
HLog.Entry	next()
HLog.Entry	next(HLog.Entry reuse)
protected abstract boolean	readNext(HLog.Entry e) Read next entry.
void	seek(long pos)
protected abstract void	seekOnFs(long pos) Performs a filesystem-level seek to a certain position in an underlying file.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.hbase.regionserver.wal.HLog.Reader

close, getPosition, reset

Field Detail

conf

protected org.apache.hadoop.conf.Configuration conf

fs

protected org.apache.hadoop.fs.FileSystem fs

path

protected org.apache.hadoop.fs.Path path

edit

protected long edit

fileLength

protected long fileLength

trailer

protected WALProtos.WALTrailer trailer

trailerWarnSize

protected int trailerWarnSize

compressionContext

protected org.apache.hadoop.hbase.regionserver.wal.CompressionContext compressionContext

Compression context to use reading. Can be null if no compression.

emptyCompressionContext

protected boolean emptyCompressionContext

Constructor Detail

ReaderBase

public ReaderBase()

Default constructor.

Method Detail

init

public void init(org.apache.hadoop.fs.FileSystem fs,
        org.apache.hadoop.fs.Path path,
        org.apache.hadoop.conf.Configuration conf,
        org.apache.hadoop.fs.FSDataInputStream stream)
          throws IOException

Specified by:

init in interface HLog.Reader

Parameters:

fs - File system.

path - Path.

conf - Configuration.

stream - Input stream that may have been pre-opened by the caller; may be null.

Throws:

IOException

next

public HLog.Entry next()
                throws IOException

Specified by:

next in interface HLog.Reader

Throws:

IOException

next

public HLog.Entry next(HLog.Entry reuse)
                throws IOException

Specified by:

next in interface HLog.Reader

Throws:

IOException

seek

public void seek(long pos)
          throws IOException

Specified by:

seek in interface HLog.Reader

Throws:

IOException

initReader

protected abstract String initReader(org.apache.hadoop.fs.FSDataInputStream stream)
                              throws IOException

Initializes the log reader with a particular stream (may be null). Reader assumes ownership of the stream if not null and may use it. Called once.

Returns:

the class name of cell Codec, null if such information is not available

Throws:

IOException

initAfterCompression

protected abstract void initAfterCompression()
                                      throws IOException

Initializes the compression after the shared stuff has been initialized. Called once.

Throws:

IOException

initAfterCompression

protected abstract void initAfterCompression(String cellCodecClsName)
                                      throws IOException

Initializes the compression after the shared stuff has been initialized. Called once.

Parameters:

cellCodecClsName - class name of cell Codec

Throws:

IOException

hasCompression

protected abstract boolean hasCompression()

Returns:

Whether compression is enabled for this log.

hasTagCompression

protected abstract boolean hasTagCompression()

Returns:

Whether tag compression is enabled for this log.

readNext

protected abstract boolean readNext(HLog.Entry e)
                             throws IOException

Read next entry.

Parameters:

e - The entry to read into.

Returns:

Whether there was anything to read.

Throws:

IOException

seekOnFs

protected abstract void seekOnFs(long pos)
                          throws IOException

Performs a filesystem-level seek to a certain position in an underlying file.

Throws:

IOException

getWALTrailer

public WALProtos.WALTrailer getWALTrailer()

Specified by:

getWALTrailer in interface HLog.Reader

Returns:

the WALTrailer of the current HLog. It may be null in case of legacy or corrupt WAL files.