[collectd-changes] collectd, the system statistics collection daemon: Changes to 'master'

[Florian Forster]

 src/utils_cache.c |  115 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/utils_cache.h |    5 ++
 2 files changed, 120 insertions(+), 0 deletions(-)

New commits:
commit 5472038917e3fbf19e4706e488c1522018c51749
Author: Florian Forster <octo at noris.net>
Date:   Wed Jul 22 09:55:21 2009 +0200

    src/utils_cache.[ch]: Add uc_get_history[_by_name].
    
    These two new functions can be used to get historical data of values in
    the cache. This can be used to calculate floating averages, hysteresis
    and a shipload of other aggregation and consolidation functions.
    
    The current implementation is probably not yet perfect:
    
     - If not enough values are available to satisfy the request, the buffer
       will be enlarged and NaNs will be returned in the newly allocated
       cells. The caller has no way to recognize this case.
    
     - If a value is missing, no NaNs will be added to the cache. It's
       unclear if this was desirable.
    
     - The returned values are reversed, i. e. val[0] will be the newest
       value, val[n-1] will be the oldest. Here, too, I'm unsure which way
       is easier to comprehend / use. I went for this implementation because
       it was easier to write.