Chord
===========

Swiftcore::Chord

This is an implementation of the Chord protocol, a description of which
can be found here:
  http://pdos.csail.mit.edu/chord/papers/chord.pdf
  http://pdos.csail.mit.edu/chord/papers/paper-ton.pdf
  http://en.wikipedia.org/wiki/Chord_%28peer-to-peer%29

The implementation is based on the psuedocode and implementation suggestions
in the MIT papers, but it has some modifications.

As it stands currently, nodes can balance their workload with their
successor. It currently does this by comparing its workload to the load
of the successor. If the successor has a sufficiently larger load, as
determined by the Swiftcore::Chord::Node#calculate_allowable_difference
method, then the node will advance its ID, and thus, the keyspace that it
is responsible for, towards that of its successor. It then tells its
successor to reallocate data that lies in the new keyspace to it.

By only moving towards a successor, without ever changing relative
positions, changing a node's id/keyspace coverage doesn't harm the ability
of the the chord to find the data in any given node, and the balancing
algorithm will eventually result in well distributed nodes, even as data
changes and nodes are added or removed from the chord.

Features
--------



Examples
--------


Requirements
------------


Install
-------


Author
------

Kirk Haines ([email protected])


License
-------

(The MIT License) FIXME (different license?)

Copyright (c) 2011 Kirk Haines

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.