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Consistent hashing for Python. http://www.joachim-bauch.de/projects/…
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python-continuum - Consistent hashing ======================================================================== Copyright (c) 2010 by Joachim Bauch, email@example.com http://www.joachim-bauch.de/projects/python-continuum/ python-continuum provides a function to do consistent hashing. See wikipedia _ for more informations about this technique. First we need the continuum object that serves as storage for server informations and can later be used to resolve keys:: >>> from continuum import Continuum >>> c = Continuum() Empty continuums obviously can't be queried:: >>> c.resolve('my-key1') Traceback (most recent call last): ... IndexError: empty continuum Add the server objects that are available as backends:: >>> c.add_server('192.168.0.1', 8080) <Server "192.168.0.1:8080", capacity=1> >>> c.add_server('192.168.0.2', 8080) <Server "192.168.0.2:8080", capacity=1> You can also specify different capacities of the server to priorize them (this defaults to 1):: >>> c.add_server('192.168.0.3', 8080, 2) <Server "192.168.0.3:8080", capacity=2> Server objects can also be removed:: >>> server = c.add_server('192.168.0.4', 8080) >>> c.remove_server(server) >>> len(c) 3 Please note that a server can only be added once:: >>> c.add_server('192.168.0.2', 8080) Traceback (most recent call last): ... TypeError: server already added After all servers have been added, the continuum can be queried for the server that should be used for a given (string) key:: >>> c.resolve('my-first-key') <Server "192.168.0.1:8080", capacity=1> >>> c.resolve('my-other-key') <Server "192.168.0.3:8080", capacity=2> ..  http://en.wikipedia.org/wiki/Consistent_hashing