Package com.github.dagnelies.filemap

Class AbstractFileMap<K,V>

java.lang.Object

com.github.dagnelies.filemap.AbstractFileMap<K,V>

Type Parameters:

K -

V -

All Implemented Interfaces:

FileMap<K,V>, Map<K,V>

Direct Known Subclasses:

CachedFileMap, IndexedFileMap

public abstract class AbstractFileMap<K,V>
extends Object
implements FileMap<K,V>

This abstract class is a utility to easily manipulate lines in a random access file and converting text lines into key/value format and vice-versa.

Author:

dagnelies

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
class	AbstractFileMap.LineEntry

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K extends Object,V extends Object>

Field Summary

Fields

Modifier and Type	Field	Description
protected File	file
protected BufferedRandomAccessFile	fileio

Constructor Summary

Constructors

Constructor	Description
AbstractFileMap(File file, Class<K> keyType, Class<V> valueType)

Method Summary

Modifier and Type	Method	Description
protected void	clearLines()
void	close()
long	diskSize()
protected long	getEntriesWritten()
File	getFile()
double	getFragmentation()	Returns an estimate of the file's content fragmentation.
protected abstract void	init()
protected abstract void	loadEntry(long offset, String line)
protected K	parseKey(String line)
protected Map.Entry<K,V>	parseLine(String line)
protected V	parseValue(String line)
void	putAll(Map<? extends K,? extends V> m)
protected String	readLine(long offset)
protected long	writeLine(K key, V value)

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

clear, compute, computeIfAbsent, computeIfPresent, containsKey, containsValue, entrySet, equals, forEach, get, getOrDefault, hashCode, isEmpty, keySet, merge, put, putIfAbsent, remove, remove, replace, replace, replaceAll, size, values

Field Detail

file

protected File file

fileio

protected BufferedRandomAccessFile fileio

Constructor Detail

AbstractFileMap

public AbstractFileMap(File file,
                       Class<K> keyType,
                       Class<V> valueType)
                throws IOException

Throws:

IOException

Method Detail

getEntriesWritten

protected long getEntriesWritten()

init

protected abstract void init()
                      throws IOException

Throws:

IOException

loadEntry

protected abstract void loadEntry(long offset,
                                  String line)
                           throws IOException

Throws:

IOException

getFile

public File getFile()

Specified by:

getFile in interface FileMap<K,V>

parseLine

protected Map.Entry<K,V> parseLine(String line)
                                  throws IOException

Throws:

IOException

parseKey

protected K parseKey(String line)
              throws IOException

Throws:

IOException

parseValue

protected V parseValue(String line)
                throws IOException

Throws:

IOException

readLine

protected String readLine(long offset)
                   throws IOException

Throws:

IOException

writeLine

protected long writeLine(K key,
                         V value)

putAll

public void putAll(Map<? extends K,? extends V> m)

Specified by:

putAll in interface Map<K,V>

clearLines

protected void clearLines()

getFragmentation

public double getFragmentation()

Returns an estimate of the file's content fragmentation. It is the ratio of obsolete data in the file. When entries are frequently updated and removed, the old entries are still stored in the file. For example, a fragmentation of 2/3 would mean that roughly 2/3 of the file is filled with obsolete content.

Returns:

diskSize

public long diskSize()

Specified by:

diskSize in interface FileMap<K,V>

close

public void close()
           throws IOException

Specified by:

close in interface FileMap<K,V>

Throws:

IOException