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https://bro-tracker.atlassian.net/browse/BIT-1043?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jon Siwek updated BIT-1043:
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Fix Version/s: (was: 2.4)
2.5
> LRU Table implementation
> ------------------------
>
> Key: BIT-1043
> URL: https://bro-tracker.atlassian.net/browse/BIT-1043
> Project: Bro Issue Tracker
> Issue Type: Improvement
> Components: Bro
> Affects Versions: git/master
> Reporter: Jordi Ros-Giralt
> Fix For: 2.5
>
>
> Attaching below the email description i exchanged with Seth and Robin
> describing this work.
> ------
> Hi Seth and Robin,
> We got the repo up, you can get to our branch as follows:
> git clone --recursive https://github.com/giralt/bro.git
> cd bro/
> git checkout lru-table
> We would be happy to contribute this code to the Bro community. This is what
> it does:
> - It implements LRU tables for Bro
> - A Bro table can be enhanced with the LRU functionality with the following
> new table attributes:
> &lru_table: enhance the table with LRU functionality
> &size_limit=n: if adding an element to the table makes the size of the table
> larger than n, then drop the LRU element from that table before inserting the
> new element. n=0 means table size can be infinite (so don't drop elements
> from it)
> &drop_func=callback_func: defines a programmable callback function that gets
> called automatically every time an element from the LRU table is dropped due
> to hitting the size_limit. The prototype of this callback must be as follows:
> function callback_func(t: table[keytype] of valuetype, key: keytype, val:
> valuetype): count
> - It adds the following bif functions:
> function get_lru%(v: any%): any
> function get_mru%(v: any%): any
> function get_lru_key%(v: any%): any
> function get_mru_key%(v: any%): any
> - Example:
> function freed(t: table[port] of string, key: port, val: string): count {
> print "Dropped"; }
> local port_names: table[port] of string &lru &size_limit=2 &drop_func=freed;
> In terms of applications, we are currently using this feature for the
> chimera-to-bro compiler we are working on:
> http://www.chimera-query.org/index.html
> We thought that we could also use this feature to provide a sort of memory
> management facility for Bro. I had a talk with Seth some weeks ago about
> this. Something like the LRU implementation allows programmers to put bounds
> on the size of tables and prioritize which elements can be dropped first upon
> memory exhaustion scenarios. Perhaps an idea here would be to develop a
> garbage collector (could be done using Bro language itself, perhaps as a
> framework) which would be run upon hitting a certain memory usage watermark
> and which would mainly run through the set of tables marked as "garbage
> collectable" dropping LRU elements from them to help reduce/eliminate the
> risk of running out of memory.
> Should this be something interesting, what are the steps we would need to do
> to open source the LRU code into Bro?
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