org.egothor.store

Class Documents

java.lang.Object

org.egothor.store.Documents

public class Documents
extends Object

Documents implements a documents DB structure on disc. The structure consists of two files: the first one is used as an index, and the second one as a data store. When you want to read the element with key uid the algorithm works as follows:

1. Read an offset of the element: firstfile.seek( uid*SIZEOFOFFSET ); offset = firstfile.read();
2. Read the element: secondfile.seek( offset ); object = secondfile.readTheObject();

Author:

Leo Galambos

Constructor Summary

Constructors

Constructor and Description
Documents(String location) Constructor for the Documents object.

Method Summary

Modifier and Type	Method and Description
void	close() Closes the structure.
void	destroy() Destroy this data structure.
static void	destroy(String location)
DocumentData	elementAt(long uid) Return the element with the given uid.
IMetaReader	getReader(Bitmap map) Open this structure for sequential reading.
long	size()

Methods inherited from class java.lang.Object

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

Constructor Detail

Documents

public Documents(String location)
          throws IOException

Constructor for the Documents object. Open the structure in the given directory. Three files are created, all with the name doc , with varying extensions depending on the file's function: information about removed elements is stored in doc.btm , the first file of offsets in doc.idx , and the second file with elements data in doc.dta .

Parameters:

location - the location where the files will be created

Throws:

IOException - if an I/O error occurs

Method Detail

getReader

public IMetaReader getReader(Bitmap map)

Open this structure for sequential reading.

Parameters:

map -

Returns:

an IndexDataReader

destroy

public void destroy()

Destroy this data structure. First, it calls close(). Then it removes these files from the directory where the structure is stored: bitmap, idocs, docs.

destroy

public static void destroy(String location)

elementAt

public DocumentData elementAt(long uid)

Return the element with the given uid.

Parameters:

uid - the key of the element to fetch

Returns:

the element

close

public void close()

Closes the structure.

See Also:

Documents(String)

size

public long size()