Object structure change

[Eric Stanley]

On 2/26/13 5:05 AM, Andreas Ericsson wrote:
> On 02/25/2013 07:11 PM, Ton Voon wrote:
>> Hi,
>>
>> Looking through recent commits, I came across 2601, which is a port
>> of 2600, to fix a downtime issue.
>>
>> There is a change to downtime.h to add a new attribute to the
>> downtime object.
>>
>> Am I right in saying that this is a object structure change and thus
>> will affect the binary compatibility of all broker modules? If so,
>> this is a problem for Nagios 4 which is in a structure freeze before
>> release, but more seriously it is a problem in the Nagios 3.4 branch
>> which will silently break lots of broker modules.
>>
> It's an ABI incompatibility, so it requires a recompile of affected
> modules. No modules use the modified function calls, so for that part
> it doesn't matter in practical terms, although it's academically
> horribly (which is to say; It only matters if you're interested in
> intellectual masturbation). Nagios 3 with the patch should really be
> released as 3.5 though. For Nagios 4 it's ok to make this change
> (although I'm not very happy about it).
>
> On a side-note, the downtime handling needs to be rewritten more or
> less completely. I've started it, but the old code has to remain in
> place (as a shim, preferrably) until 5.0 to retain api compatibility.
>
> To clarify, here are the "rules" which we try to adhere to:
> API change (requires major release):
>   * remove things from structs
>   * remove or modify existing functions
>   * remove existing types
>   * rename existing types without backwards compatibility hacks
>    ("#define comment nagios_comment" is the compat hack)
>
> ABI change (requires minor release and module recompilation):
>   * add stuff to structs
>   * reorder structs
>
> API addendum (requires API minor-version extension marker):
>   * add new types
>   * add new API's
>   * add functions to API's
>
> Shimming (requires nothing at all):
>   * Add new API
>   * Rewrite old API in ABI-compatible way to front the new API
>   * Use new API in core code
>
> Normally, ABI change and API addendum go hand in hand when doing
> optimizations, and sometimes when doing bugfixes.
>
My apologies. I did not realize the trunk was in a code freeze. I've 
been going through the bug list on tracker and fixing things in the core 
3 code, most of which apply to the core 4 code as well. I will be 
careful until core 4 is released.

Thanks, too, for the "rules" reminder. I will be happy to make the next 
release 3.5.0 and will include an ABI change notice with the release notes.

-- 
Eric Stanley
___
Developer
Nagios Enterprises, LLC
Email:  estanley at nagios.com
Web:    www.nagios.com


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