[Sugar-devel] GSoC Groupthink Update: SharedTextDemo-2
bobbypowers at gmail.com
Sun Jun 14 19:52:54 EDT 2009
On Sat, Jun 13, 2009 at 3:45 PM, Benjamin M.
Schwartz<bmschwar at fas.harvard.edu> wrote:
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> SharedTextDemo-2 is now available at
> This version is functionally identical to (and even protocol-compatible
> with) version 1. However, I have redesigned the entire operational
> transformation engine. The new algorithms are still O(N), and the demo is
> still too slow to write a whole essay. However, I can now recommend
> Groupthink's SharedTextView to anyone who wants instant collaboration in a
> GTK TextView, and is editing less than 1 Kilobyte of text (on an XO-1, or
> proportionally more on more powerful machines).
Sounds great! Are you expecting more performance gains in the future?
Is there a git repository somewhere I could check out?
> Please contact me if you would like help using Groupthink in your activity.
> The new algorithms are moderately interesting. I have completely removed
> all explicit trees, and all walking of trees. Instead, the new algorithm
> maintains two Lists, and a Dict for their inverted index. This allows
> determining the Nth character, locating an existing edit, or computing a
> new edit, in constant time. Actually performing an edit requires O(N)
> time, but the O(N) component is now a small, simple loop. I am hopeful
> that these algorithms are amenable to integration with a self-balancing
> tree (most likely a customized variant of a Rope), for log-time
> performance on all operations. Time permitting, I may implement this.
> - --Ben
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