Naanou.ResourceExchange
Class RangeGetter

Downloads a specific range of a file using multiple sources simulatenously

This class will attempt to `swarm' or multi-source download a given range. Each range has a specified list of sources available for it, and RangeGetter will randomly choose from among them to spread load. A range could be an entire file or some subset, so the class does not attempt to download it all at once. Instead, it will cut the range up into chunks, their size being the powers of two above 8 kilobytes. Which sized chunk that is attempted depends on the source. RangeGetter aims to fetch small chunks (say, 512KB) from slower hosts and larger chunks (upto 16MB) from faster hosts. This heuristic reduces unnecessary communication bandwidth if there was a set chunk size, and maximises the ability for slower hosts to participate fully in the resource exchanging. Multiple chunks are then transferred from sources simultaneously. When the process is over, RangeGetter signals via its completetion via the Naanou.ResourceExchange.RangeGetter.Complete event.

blocksDownloaded

private System.Collections.ArrayList blocksDownloaded

bytesDownloaded

private long bytesDownloaded

bytesRequired

private long bytesRequired

completed

private bool completed

downloader

private Naanou.ResourceExchange.Downloader downloader

error

private System.Exception error

failedRanges

private System.Collections.ArrayList failedRanges

internalWorker

private Naanou.ResourceExchange.RangeGetter.RangeGetterWorker internalWorker

An internal worker that gets set by DownloadChunk

lastStatus

private Naanou.ResourceExchange.WorkStatusArgs lastStatus

miniPool

private System.Collections.ArrayList miniPool

Synchronised arraylist

originalRange

private Naanou.ResourceExchange.ByteRange originalRange

random

private System.Random random

range

private Naanou.ResourceExchange.ResourceAvailRange range

thread

private System.Threading.Thread thread

workerStatus

private System.Collections.Hashtable workerStatus

RangeGetter

public RangeGetter(Naanou.ResourceExchange.Downloader downloader,
                   Naanou.ResourceExchange.ResourceAvailRange range)

Constructor

Parameters:

downloader - Downloader

range - Range to get

BytesDownloaded

public long BytesDownloaded

Gets the number of bytes downloaded in this range

Error

public string Error

Gets the error message if any

WereErrors

public bool WereErrors

Gets a value indicating if there were errors while running

Abort

public void Abort()

Aborts a get

DownloadChunk

private void DownloadChunk(Naanou.ResourceExchange.Source.Manifest source,
                           Naanou.ResourceExchange.ResourceAvailRange chunk)

Downloads a chunk. Either spawns off work in new thread and is async, or does work in own thread and blocks until done.

Parameters:

source - Source

chunk - Chunk

GetStats

private void GetStats()

GetStats

private void GetStats(System.Drawing.Graphics g,
                      System.Drawing.Rectangle rect)

Join

public void Join()

Waits for getter to complete

Join

public void Join(System.TimeSpan timeout)

Waits a finite time for getter to complete

Parameters:

timeout -

OnWorkerComplete

private void OnWorkerComplete(Naanou.ResourceExchange.IWorker sender,
                              Naanou.ResourceExchange.WorkCompleteArgs args)

Notification by a worker it has completed (successfully or not)

Parameters:

sender - Worker

args - Completion args

OnWorkerStatus

private void OnWorkerStatus(Naanou.ResourceExchange.IWorker worker,
                            Naanou.ResourceExchange.WorkStatusArgs args)

PaintStatus

public void PaintStatus(System.Drawing.Graphics g,
                        System.Drawing.Rectangle rect)

Paints status of range getter

Parameters:

g -

rect -

Start

public void Start()

Starts downloading (async)

StartImpl

private void StartImpl()

StartWrapper

private void StartWrapper()

ToString

public string ToString()

Gets a string representation of range

Returns:

String representation of range

WaitForWorkers

private void WaitForWorkers(bool abort)

Complete

public Naanou.ResourceExchange.WorkCompleteHandler Complete

Signal that the range has been downloaded, or all sources have been exhausted. Args contains an ArrayList of all blocks downloaded

Status

public Naanou.ResourceExchange.WorkStatusHandler Status

Status