Rework comment handling

[sni]

rework comment handling

This PR reworks the comment handling to improve performance when having lots of comments.

• it add a prev pointer to the comments list so we don't have to iterate over the complete list when removing an item
• it replaces the hash lookup to quickly access comments for specific hosts/services in favor of a new host/service attribute which holds links to the comments
• it avoids duplicate host/service lookups for DEL_ALL_HOST_COMMENTS/DEL_ALL_SVC_COMMENTS command
• it removes hash functions which are now unused

In general, it tries to adopt the downtime handling over to comments.

This PR is based on and includes #375.

Since the internal object structure changes, all NEB modules have to be rebuild. (We therefor increase CURRENT_NEB_API_VERSION to 6)

Signed-off-by: Sven Nierlein sven@consol.de

[jdumalaonITRS]

Hi, Not sure if I missed something but doesn't it look like we need the comment_list even less? We can still have the host/service attribute which holds links to the comments and have a hashtable.

I am just not 100% sure what needs to happen for the sorting code for comment_list though. Does anyone know why we need to sort?

[sni]

I assumed the comment_list is required for livestatus, but i did a quick search and did not find any reference. It seems like comments are soley add/removed from broker callbacks. I can try to remove it completely. And if it's removed, we don't have to order it.

[sni]

Alright, i completely removed the comments_list now.

[jdumalaonITRS]

Nice thanks for this. The code looks good. Let me try some manual tests for this. I'll try to feedback by next week.

[nook24]

I have tested this with 400k comments, works as promised.

[0.0079 (+0.0000)] Initialized retention data
[0.0079 (+0.0000)] Reading initial state information
[2.4028 (+2.3948)] Read initial state information
[2.4029 (+0.0002)] Restored 0 downtimes
[2.4029 (+0.0000)] Restored 400000 comments
[2.4030 (+0.0000)] Initializing performance data