which outweigh the trouble it causes.

The original idea was to allow intelligent purging for space reason
in a size-constrained storage.

In practice, storage is seldomly constrained.

In the cases where it is, I have yet to see any documented benefit
from using vcl_discard{}, likely because of the fragmentation such
use would cause.

The implementation of the vcl_discard callback had severe costs in
code complexity (not fully unrolled by this commit) and locking
activity.

The straw that breaks the camels back, is that faithfull implementation
of vcl_discard{} in -spersistence would force us to relocate objects,
at a cost likely higher than picking them up from the backend.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4099 d4fa192b-c00b-0410-8231-f00ffab90ce4