com.pervasive.datarush.io

Class SplitReader

java.lang.Object

java.io.Reader

com.pervasive.datarush.io.SplitReader

All Implemented Interfaces:

Closeable, AutoCloseable, Readable

public class SplitReader
extends Reader

A character based reader for splits. A SplitReader provides a text view of split data, handling conversion from bytes to characters.

Because splits may fall at arbitrary points within a file, consumers may need to perform additional processing to place themselves in a valid position. SplitReader supports this case by allowing a character sequence to be provided for use as a synchronization marker at the beginning and end of splits.

Normally, reading begins at the beginning of the split, but can be configured to start at the first character after the synchronization marker. Care should be taken when reading at the split beginning, as split boundaries may occur in the middle of an encoded character sequence.

Similarly, reads can continue beyond the end of the split. Readers can either manage this themselves or auto-terminate after the first complete synchronization marker beyond the end of split.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_BUFFER Default buffer size for input to the character decoder, in bytes

Fields inherited from class java.io.Reader

lock

Constructor Summary

Constructors

Constructor and Description
SplitReader(SplitInputStream in, CharsetEncoding charset) Creates a new reader on the specified stream, using the given encoding properties.
SplitReader(SplitInputStream in, CharsetEncoding charset, int buffer) Creates a new reader on the specified stream, using the given encoding properties.
SplitReader(SplitInputStream in, CharsetEncoding charset, int buffer, String syncMarker, boolean doInitialSync) Creates a new reader on the specified stream, using the given encoding properties and synchronization marker.
SplitReader(SplitInputStream in, CharsetEncoding charset, String syncMarker, boolean doInitialSync) Creates a new reader on the specified stream, using the given encoding properties and synchronization marker.

Method Summary

Modifier and Type	Method and Description
long	charsRead() Gets the character offset into the underlying split.
void	close()
boolean	hasOverrun() Indicates whether the reader has passed the end of the underlying split.
void	mark(int readAheadLimit)
boolean	markSupported()
int	read()
int	read(char[] cbuf)
int	read(char[] cbuf, int off, int len)
int	read(CharBuffer target)
boolean	readIfPresent(char[] chars) Conditionally reads the input to see if the specified characters are present.
boolean	readLine(Appendable lineBuffer) Reads a line of text into the specified buffer.
boolean	ready()
void	reset()
long	skip(long n)
boolean	skipTo(char[] bytes) Advances the position of the stream to the first character after the specified pattern.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_BUFFER

public static final int DEFAULT_BUFFER

Default buffer size for input to the character decoder, in bytes

See Also:

Constant Field Values

Constructor Detail

SplitReader

public SplitReader(SplitInputStream in,
                   CharsetEncoding charset)

Creates a new reader on the specified stream, using the given encoding properties. The default decoding buffer size is used.

Parameters:

in - the input stream on the split being read

charset - character set encoding properties

SplitReader

public SplitReader(SplitInputStream in,
                   CharsetEncoding charset,
                   int buffer)

Creates a new reader on the specified stream, using the given encoding properties. The decoding buffer is the requested size.

Parameters:

in - the input stream on the split being read

charset - character set encoding properties

buffer - the size of the decoding input buffer, in bytes

SplitReader

public SplitReader(SplitInputStream in,
                   CharsetEncoding charset,
                   String syncMarker,
                   boolean doInitialSync)
            throws IOException

Creates a new reader on the specified stream, using the given encoding properties and synchronization marker. The default decoding buffer size is used.

The reader will stop providing data after the first complete synchronization marker appearing after the end of the split.

Parameters:

in - the input stream on the split being read

charset - character set encoding properties

syncMarker - the character sequence to use to synchronize the read positions

doInitialSync - indicates whether to synchronize the read position before the first read

Throws:

IOException - if an I/O error occurs while performing initial position synchronization

SplitReader

public SplitReader(SplitInputStream in,
                   CharsetEncoding charset,
                   int buffer,
                   String syncMarker,
                   boolean doInitialSync)
            throws IOException

Creates a new reader on the specified stream, using the given encoding properties and synchronization marker. The decoding buffer is the requested size.

The reader will stop providing data after the first complete synchronization marker appearing after the end of the split.

Parameters:

in - the input stream on the split being read

charset - character set encoding properties

buffer - the size of the decoding input buffer, in bytes

syncMarker - the character sequence to use to synchronize the read positions

doInitialSync - indicates whether to synchronize the read position before the first read

Throws:

IOException - if an I/O error occurs while performing initial position synchronization

Method Detail

read

public int read()
         throws IOException

Overrides:

read in class Reader

Throws:

IOException

read

public int read(char[] cbuf)
         throws IOException

Overrides:

read in class Reader

Throws:

IOException

read

public int read(char[] cbuf,
                int off,
                int len)
         throws IOException

Specified by:

read in class Reader

Throws:

IOException

read

public int read(CharBuffer target)
         throws IOException

Specified by:

read in interface Readable

Overrides:

read in class Reader

Throws:

IOException

skip

public long skip(long n)
          throws IOException

Overrides:

skip in class Reader

Throws:

IOException

ready

public boolean ready()

Overrides:

ready in class Reader

markSupported

public boolean markSupported()

Overrides:

markSupported in class Reader

mark

public void mark(int readAheadLimit)
          throws IOException

Overrides:

mark in class Reader

Throws:

IOException

reset

public void reset()
           throws IOException

Overrides:

reset in class Reader

Throws:

IOException

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in class Reader

hasOverrun

public boolean hasOverrun()

Indicates whether the reader has passed the end of the underlying split.

Because character encodings may be multiple bytes, the split may fall in the middle of a character. Overrun is flagged with the first character whose encoding has a byte beyond the end of the split.

Returns:

true if the current read position is beyond the end of the split, false otherwise

readIfPresent

public boolean readIfPresent(char[] chars)
                      throws IOException

Conditionally reads the input to see if the specified characters are present. If they are, the read position is advanced to the first character following the sequence. Otherwise, the read position is unchanged.

Parameters:

chars - the character sequence which is to be checked

Returns:

true if the sequence was found, false otherwise

Throws:

IOException - if an I/O error occurs during the read

charsRead

public long charsRead()

Gets the character offset into the underlying split. This is measured from the first full character within the split, in case the split begins in the middle of a character encoding.

Returns:

the number of characters read so far in the split

skipTo

public boolean skipTo(char[] bytes)
               throws IOException

Advances the position of the stream to the first character after the specified pattern.

Parameters:

bytes - the pattern to find in the stream

Returns:

false if end of data is reached, true otherwise.

Throws:

IOException - if an I/O error occurs while reading the stream

readLine

public boolean readLine(Appendable lineBuffer)
                 throws IOException

Reads a line of text into the specified buffer. A line is considered to be terminated by any one of a line feed ('\n'), a carriage return ('\r'), or a carriage return followed immediately by a linefeed.

Parameters:

lineBuffer - the buffer to which to append line data.

Returns:

false if end of file has been reached during the read

Throws:

IOException

See Also:

BufferedReader#readLine()