MonoTorrent 0.20 has just been shoved unwillingly out of it's cosy spot in SVN into full public view. The last time i tagged and released was way back on July 4th. Far too long ago! Full details of the release can be read here. Download links here aswell.

Here's the changelog:
Client
Features
Linear piece picking possible
- This mode of operation chooses pieces towards the start of the file where possible. This should not be a publicly settable option in a GUI. It could be automatically set until the first 20 pieces in a torrent are received to allow for previewing. For general usage, this is a very inefficient way to download.
Full choke/unchoke algorithm implemented (Andy Henderson)
- Full tit-for-tat algorithm implemented. This improves download rates and upload rates and is pretty slick.
Sub-optimal implementation of code used to connect to peers made optimal
- Fixed corner case where a connection wouldn't be cleaned up correctly
- Significantly faster startup performance in cases where remote peers don't support encryption and encryption is enabled
Rate limiting for Disk IO implemented
Configurable amount of open filestreams
Reduced disk thrashing when multiple torrents hashing simultaneously
Files are not preallocated anymore
TorrentManager will never block when .Start() is called
The Tracker base class made more extensible (Eric Butler)
- An example usage would be if a person had peer details stored in a database. They could implement a 'DataBaseTracker' class, register it with the engine, then monotorrent could announce to that tracker and retrieve peers from the database. Thanks to Eric, this is hugely simplified and is now trivial to implement.




Bug Fixes
Piece Requesting
Fixed bug where a piece could be requested twice
When a corrupt piece is received, ensure all contributing peers are marked
Fixed a possible null ref when removing pending piece requests when a connection is closed

Torrent Creator
When creating an (optional) MD5 hash in the torrent creator, open the files in read-only mode (Roger Zander)
Creating torrents no longer spins up an extra thread when using the synchronous method (Eric Butler)
Fixed possible race conditions when creating a torrent using the asynchronous methods
Private key is retained when creating torrents

Misc
Per-file progress is updated correctly.
Fixed detection of when a tracker supports scrape - It should have been case insensitive
Added extra check to make sure a scrape request is only performed if the tracker supports scraping
Added extra logic checks to help prevent the loading of incorrect fastresume data
When a peer sends a HaveAll message - it is correctly marked as being a seeder
PieceHashed event fired under all circumstances



Tracker
The MonoTorrent.Tracker got a major rewrite. Highlights include:
- more than 1000x memory reduction for trackers hosting a large number of torrents. 1000 torrents can be hosted in ~30kB. Previously would have required ~30MB.
- Faster more efficient announce handling. For large trackers, lookups are significantly faster
- Vastly simplified announce handling. It is now trivial to write code to handle incoming connections from differing sources. A typical example would be to create an AspNetHandler to handle connections in an ASP.NEt project. It requires less than 20 lines of code to be written.



It should be fairly solid, with a lot of cool feature enhancements under the hood. There are a few cool things which i managed to implement this time round like rate limiting disk IO, not pre-allocating 100% of the file on startup, being able to properly handle a torrent with 100,000 files in it. Good stuff.

Plans for the future are pretty cool aswell. I'll blog more about that later though.