ndoutils with zlib

[Tilo Renz]

Hello Developers,

we are happily using ndomod on more than 1000 machines distributed to multiple locations, but the traffic (over leased lines) is tremendous. To reduce this traffic I was told to embed zlib into ndoutils (ndoutils-1.4b7).

What did I do?

To make ndomod.c more readable, I refactored some of its functionality.

First, I moved the option-parsing to extra files parseopt.[c|h]
parseopt.h defines a struct to hold all configuration data for ndomod, replacing various global variables in ndomod.c.
parseopt.c does the option-parsing with parameters given by nagios and the configuration file. It also contains the default values, formerly kept in ndomod.c.
For zipped tcp Streams, the option output_type now understands the new value 'tcpsocketzip'.

Second, I refactored io.[c|h].
Handing filedescriptors around is no option, when you need a gz_file-Structure.
In order to fix this I declared a new struct ndo_sink_description_struct, which is holding the filedescriptor, the pointer to gz_file and some status-variables, intended to replace sink-related global variables in ndomod.c (is_open, previously_open).
Also io.h defines the new sink-type NDO_SINK_TCPSOCKETZIP.

I replaced all sink-related functions (ndo_sink_open, ndo_sink_write, ndo_sink_write_newline, ndo_sink_flush, ndo_sink_close) by new functions (ndo_sink_init2, ndo_sink_open2, ndo_sink_write2, ndo_sink_write_newline2, ndo_sink_flush2, ndo_sink_close2) which take a pointer to a ndo_sink_description_struct as their first argument.
I admit, this is kind of object-oriented, but not knowing all compilers and target platforms of nagios I resisted zo use real Objects. I also tried to keep the strange indention scheme, although editor & brain support seems broken, as the mixed usage of tabs and spaces in the given sources prooves. (In real life I'm a wimpy java programmer, so I prefer KR)

Compression works best, if there is a some amount of data to compress, so I introcduced some slight changes to ndomod.c concerning the (re-)opening of the sink:
If the sink-Buffer is empty (and if the sink prefers blockwise data, as zipped tcp does) the connection will be closed. It will be reopened after the usual reconnect interval. (src/ndomod.c line 596ff)
This implies that reconnect_time and output_buffer_items should be set to reasonable values, otherwise data will get lost. Also the logfile may contain some unnecessary warnings.

I patched all other programs (ndo2db, file2sock, log2ndo) according to the new possiblities.
ndo2db will automatically detect a zipped tcp stream, file2sock and log2ndo both have changed command line parameters. I also altered their help-texts.

Finally I _tried_ to fix the build-process. (Here I need help)
I managed to extend src/Makefile.in and include/config.h.in.
config.h.in now has a section for zlib, similar to those for the databases.
I peppered the whole project with #ifdef HAVE_ZLIBs, so that it will compile (and work!) with and without HAVE_ZLIB.

This is where I need your help:
I was unable to adapt the configure-Script, so that it automatically recognizes if zlib-support could be built in.
Currently, after ./configure, I have to fix the created include/config.h to #define USE_ZLIB 1 (line  272 ff)

Please help me to fix this issue.

I would be happy if these changes would be included into a new version of ndoutils. Also I am open to your comments and further improvements. Beyond the configure-issue the code is working in our current setup for several days.

I tried to build a .diff-file, but I doubt the attached file is really usefull.
I published the whole changed ndoutils at http://joey.in-ulm.de/2008/ndoutils 
Please have a look at it.


anticipating your comments,
Joey5337
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