org.lastbamboo.common.download
Class DefaultRangeSizeSelector

java.lang.Object
  org.lastbamboo.common.download.DefaultRangeSizeSelector

All Implemented Interfaces:

RangeSizeSelector

public class DefaultRangeSizeSelector
extends Object
implements RangeSizeSelector

Class for selecting the size of download ranges based on the size of a file and the number of available sources.

Field Summary

static long	DIFFERENTIAL_SPEED_FACTOR This is the factor that takes into account that different sources provide different download speeds.
static long	MAX_CHUNK_SIZE The maximum size for chunks.
static long	MIN_CHUNK_SIZE The minimum size for chunks.

Constructor Summary

DefaultRangeSizeSelector()

Method Summary

long	selectSize(long fileSize, int numSources) Selects the size of ranges based on the file size and the number of sources for the download.

Methods inherited from class java.lang.Object

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

Field Detail

MAX_CHUNK_SIZE

public static final long MAX_CHUNK_SIZE

The maximum size for chunks.

See Also:

Constant Field Values

MIN_CHUNK_SIZE

public static final long MIN_CHUNK_SIZE

The minimum size for chunks.

See Also:

Constant Field Values

DIFFERENTIAL_SPEED_FACTOR

public static final long DIFFERENTIAL_SPEED_FACTOR

This is the factor that takes into account that different sources provide different download speeds. The extreme of this is a centralized CDN source versus a peer on a modem link, for example. We need to choose small enough chunks so that slower downloaders don't screw things up for the download as a whole.

See Also:

Constant Field Values

Constructor Detail

DefaultRangeSizeSelector

public DefaultRangeSizeSelector()

Method Detail

selectSize

public long selectSize(long fileSize,
                       int numSources)

Description copied from interface: RangeSizeSelector

Selects the size of ranges based on the file size and the number of sources for the download.

Specified by:

selectSize in interface RangeSizeSelector

Parameters:

fileSize - The size of the file.

numSources - The number of sources for the download.

Returns:

The size to use for each chunk.