Re: [GNUnet-developers] Re: [Help-gnunet] trouble with cvs

[Christian Grothoff]

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On Friday 07 November 2003 05:57 pm, Igor Wronsky wrote:
> Btw, in insertContent(), whats this supposed to achieve,
>
>   if ( ( sender != NULL) &&
>        ( randomi(2 + importance) == 0) ) {
>     return SYSERR; /* don't bother... */
>   }
>
> ? Yes, I can read what it does. Whats the reasoning?

Ok, let me recap what it does first (since it is out-of-context...).

If we're not processing content originating from the local user (sender != 
NULL) and the content has been decided to be of low value, we 
probabilistically do not even bother going to the database to see if we have 
space to store it.

Reasoning: processing the database (find lowest-priority content or find that 
we have enough space, do the insertion, etc) costs us many disk-accesses.  If 
the content additionally has a rather low priority, it is likely that this 
whole process will fail (lowest-priority content has higher or equal priority 
to new content).  So we just don't do it all the time.  Which also makes it 
slightly harder to predict whether or not a given peer will cache content 
floating by.  Now, the exact formula (2+importance) comes from that even 
importance == 0 should have a chance to be added to the local DB.

Christian
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