Package com.storedobject.common

Class FileBuffer

java.lang.Object

com.storedobject.common.FileBuffer

All Implemented Interfaces:

ResourceOwner

public class FileBuffer
extends Object
implements ResourceOwner

A file-mapped data buffer with index-based access to data for writing and then, for reading. Data is just byte arrays of arbitrary length.

Author:

Syam

Constructor Summary

Constructors

Constructor	Description
FileBuffer()	Constructor.

Method Summary

Modifier and Type	Method	Description
void	begin()	This method must be called before writing anything.
void	close()	Close this buffer.
void	end()	This method must be called when writing is completed.
FileBuffer	filter(Predicate<byte[]> filter)	Apply a filter to the buffer.
AutoCloseable	getResource()	Get the "resource" owned by this buffer.
byte[]	read(int index)	Read data from a specified index.
int	size()	Get the size of this buffer in terms of number of indices it holds.
FileBuffer	sort(Comparator<byte[]> comparator)	Sort the data according the comparator passed.
void	swap(int firstIndex, int secondIndex)	Swap positions of 2 data chunks.
void	write(byte[] data)	Write something at the current index.

Methods inherited from class java.lang.Object

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

Constructor Details

FileBuffer

public FileBuffer()

Constructor.

Method Details

getResource

public AutoCloseable getResource()

Get the "resource" owned by this buffer.

Specified by:

getResource in interface ResourceOwner

Returns:

The "resource" owned by this buffer.

begin

public void begin()

This method must be called before writing anything.

end

public void end()

This method must be called when writing is completed. After this, the buffer will be in read-only mode and any attempt to write will cause errors.

write

public void write(byte[] data)
           throws Exception

Write something at the current index. The data could be of any length. The first index is zero.

Parameters:

data - Data to write.

Throws:

Exception - Throws if any error occurs.

close

public void close()

Close this buffer. No more reading or writing is possible after this.

size

public int size()

Get the size of this buffer in terms of number of indices it holds. Each index may be pointing to varying chunks of data.

Returns:

Number of indices written available in the buffer.

read

public byte[] read(int index)

Read data from a specified index.

Parameters:

index - Index.

Returns:

Data read.

swap

public void swap(int firstIndex,
 int secondIndex)

Swap positions of 2 data chunks.

Parameters:

firstIndex - First index.

secondIndex - Second index.

sort

public FileBuffer sort(Comparator<byte[]> comparator)

Sort the data according the comparator passed.

Parameters:

comparator - Comparator to compare the data chunks.

Returns:

Sorter buffer.

filter

public FileBuffer filter(Predicate<byte[]> filter)

Apply a filter to the buffer.

Parameters:

filter - Filter to be applied.

Returns:

Filtered buffer (if the filter is null or if all the data chunks are satisfying the filter, then, the same buffer will be returned).