/// <summary>
/// Downloads the torrent of the piece and write it to
/// </summary>
/// <param name="nameSpace">The name space.</param>
/// <param name="name">The name.</param>
/// <param name="wholeTorrent">The whole torrent.</param>
/// <param name="pieceIndex">Index of the piece.</param>
byte[] DownloadPieceTorrent(string nameSpace, string name, Torrent wholeTorrent,
int pieceIndex)
{
var wholeTorrentDhtKeyStr = ServiceUtil.GetDictKeyString(nameSpace, name);
var pieceKeyStr = MakePieceTorrentKey(wholeTorrentDhtKeyStr, pieceIndex);
var torrentFilePath = _bittorrentCache.GetTorrentFilePath(nameSpace, name);
byte[] pieceTorrentBytes;
bool succ = _torrentHelper.TryReadOrDownloadTorrent(
nameSpace, name, _dhtProxy, out pieceTorrentBytes);
if (succ)
{
// Somebody else already requested this piece.
return(pieceTorrentBytes);
}
else
{
// We need to request the seeder to make a new piece.
IEnumerable <PeerEntry> peers = _dhtProxy.GetPeers(wholeTorrent.InfoHash.ToArray());
bool foundCompletePeer = false;
// The list most likely has only one entry.
var trackerIPs = new List <string>();
foreach (var tiers in wholeTorrent.AnnounceUrls)
{
foreach (var trackerUrl in tiers)
{
// Given that we don't use domain names for hosts.
trackerIPs.Add(new Uri(trackerUrl).Host);
}
}
// Completed -> Downloader has the whole data.
// PeerIP == Tracker -> Original Seeder(s).
var peerIPs = (from peer in peers
where (peer.PeerState == TorrentEvent.Completed ||
trackerIPs.Contains(peer.PeerIP))
select peer.PeerIP).Distinct();
Logger.WriteLineIf(LogLevel.Verbose, _log_props, string.Format(
"{0} peers to try for piece info.", peerIPs.Count()));
foreach (var peerIP in peerIPs)
{
foundCompletePeer = true;
// The first complete peer should be able to serve the piece we want.
bool succPieceInfo = TryDownloadPieceTorrentFromPeer(nameSpace,
name, pieceIndex, peerIP, _pieceInfoServerPort,
out pieceTorrentBytes);
if (succPieceInfo)
{
Logger.WriteLineIf(LogLevel.Verbose, _log_props,
string.Format("Piece info downloaded from {0}", peerIP));
return(pieceTorrentBytes);
}
else
{
// Try the next completePeer
continue;
}
}
if (!foundCompletePeer)
{
throw new DictionaryKeyNotFoundException("No peer is complete.");
}
else if (pieceTorrentBytes == null)
{
throw new DictionaryKeyNotFoundException(
"No complete peer(s) can return the piece Info");
}
else
{
// This shouldn't happen
return(pieceTorrentBytes);
}
}
}