[Bug translator/6872] module cache cleaner

[Bug translator/6872] module cache cleaner

[ksebasti at redhat dot com]

------- Additional Comments From ksebasti at redhat dot com  2008-09-19 17:58 -------
Created an attachment (id=2957)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2957&action=view)
Shell script to clean oldest modules when cache folder is above a certain size

This is a small shell script which will remove the folder of the oldest modules
in the cache dir (based on access time) until it is below the max cache size,
which can be an environment variable $SYSTEMTAP_MAX_CACHE_SIZE or defaults to
16MiB (2^24 bytes).

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6872

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[Bug translator/6872] module cache cleaner

[ksebasti at redhat dot com]

------- Additional Comments From ksebasti at redhat dot com  2008-09-26 18:11 -------
Created an attachment (id=2962)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2962&action=view)
patch to integrate cache clean script into main.cxx

This patch adds the clean script to main.cxx, after the temp directory is
removed. I tested it on a local build and it works nicely.

The current limit is defined in a macro in cache.h, set to 20mb. This is just a
random guess at an appropriate size.

Ideas:
* modify the script to output the name/path of the removed folder to be extra
verbose
(these 2 would probably require more members in struct systemtap_session)
* there should probably be a cl switch to disable (or enable?) the cache
clearing
* specify the max cache size as a cl switch 
* a better eviction policy than oldest by access time ?

If any of those sound good let me know and I can work on it.

-- 
           What    |Removed                     |Added
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Attachment #2957 is|0                           |1
           obsolete|                            |


http://sourceware.org/bugzilla/show_bug.cgi?id=6872

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Re: [Bug translator/6872] module cache cleaner

[Frank Ch. Eigler]

Hi -

This is looking better and better.  The code seems like it could go in
as it is right now, though I'd like to make (or see made) some minor
changes to it as style matters:

* The main.cxx code that runs get_cache_max() then clean_cache() could
  just go into cache.cxx:add_to_cache().

* Status messages could get printed in situ, rather than indirectly
  via returned result codes and then if/else checks.

* get_cache_max() could bypass the stringstream / getline business
  and just 
      std::ifstream foo ("cache_max_mb");
      unsigned num; foo >> num;
  You wouldn't need a separate function.  Plus, if merged with
  clean_cache(), you wouldn't need a new session variable either.

* Consider adding the cache_ent_info to a set<> (parametrized with the
  weight-comparer function for implicit sorting -- which should take
  const-refs by the way), rather than a vector<> that's later sorted.
  Then you get a sorted iteration later from begin()..end().


- FChE