(ITS#8054) Operation duration logging

[ebackes@symas.com]

Full_Name: Emily Backes
Version: master, 2.4
OS: 
URL: 
Submission from: (NULL) (50.113.67.84)


Here is a patch to add duration logging for operations that appears in the
standard result messages of statslog.  It's a reasonably small change with
negligible performance implications except under pathological benchmarking
conditions.  It does change the quasi-machine-parsable statslog format, however,
so it might not be appropriate for general 2.4 release.  Example line:

54d8298c conn=1000 op=1 SEARCH RESULT tag=101 err=0 duration=0.170ms nentries=1
text=

As written, it uses a separate field in struct Operation and is entirely
independent of the o_tincr functionality.  Merging those has further portability
problems, and is out of the scope of this feature.  As a result, the overhead is
two additional gettimeofday() calls per operation.  The change is wrapped in
#ifdef HAVE_GETTIMEOFDAY, so architectures lacking that will see no change.

I have patches versus both the master branch (which likely covers 2.5), and
OPENLDAP_REL_ENG_2_4.  They'll be attached momentarily, outside jitterbug's web
interface.
%ThThese modifications are the sole work of myself (Emily Backes) on behalf of
Symas Corporation based on existing log features of OpenLDAP.  Therefore, these
modifications are:

Copyright 2014-2015 Symas Corporation
Redistribution and use in source and binary forms, with or without modification,
are permitted only as authorized by the OpenLDAP Public License.