org.terrier.structures.indexing.singlepass
Class RunWriter

java.lang.Object
  org.terrier.structures.indexing.singlepass.RunWriter

Direct Known Subclasses:

HadoopRunWriter

public class RunWriter
extends Object

This class writes a run to disk. The data written depends on the specific subclass. This one, writes the Nt, TF and the sequence. It also writes the max frequency of a term in the run (useful for allocating memory during the merging phase).

Author:

Roi Blanco

Field Summary

protected BitOutputStream	bos Underlying BitOutputStream to write the compressed objects
protected String	info Debug String representation of this RunWriter
protected DataOutputStream	stringDos Underlying DataOutputStream to write the term Strings

Constructor Summary

protected	RunWriter()
protected	RunWriter(BitOutputStream _bos, DataOutputStream _stringDos) other constructor for use by subclasses
	RunWriter(String fileName, String termsFile) Instanciates a RunWriter, given the filenames to write.

Method Summary

void	beginWrite(int maxSize, int size) Writes the headers of the run.
void	finishWrite() Closes the output streams.
String	toString()
boolean	writeSorted() Returns true if this RunWriter needs writeTerm() to be called sorted by term
void	writeTerm(String term, Posting post) Writes the information for a given term.

Methods inherited from class java.lang.Object

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

Field Detail

bos

protected final BitOutputStream bos

Underlying BitOutputStream to write the compressed objects

stringDos

protected final DataOutputStream stringDos

Underlying DataOutputStream to write the term Strings

info

protected String info

Debug String representation of this RunWriter

Constructor Detail

RunWriter

protected RunWriter()

RunWriter

protected RunWriter(BitOutputStream _bos,
                    DataOutputStream _stringDos)
             throws IOException

other constructor for use by subclasses

Throws:

IOException

RunWriter

public RunWriter(String fileName,
                 String termsFile)
          throws IOException

Instanciates a RunWriter, given the filenames to write.

Parameters:

fileName - name of the file to write the posting lists data.

termsFile - name of the file to write the terms.

Throws:

IOException - if an I/O error occurs.

Method Detail

writeSorted

public boolean writeSorted()

Returns true if this RunWriter needs writeTerm() to be called sorted by term

beginWrite

public void beginWrite(int maxSize,
                       int size)
                throws IOException

Writes the headers of the run.

Parameters:

maxSize - max size of a posting.

size - number of postings in the run.

Throws:

IOException - if an I/O error occurs.

writeTerm

public void writeTerm(String term,
                      Posting post)
               throws IOException

Writes the information for a given term.

Parameters:

term - the term to write.

post - the Posting with the data of the term.

Throws:

IOException - if an I/O error occurs.

finishWrite

public void finishWrite()
                 throws IOException

Closes the output streams.

Throws:

IOException - if an I/O error occurs.

toString

public String toString()

Overrides:

toString in class Object