[boehms-gc] support for cache hash tables (gt_ggc_cache_rtab)

Tom Tromey tromey@redhat.com
Wed Aug 2 21:21:00 GMT 2006


>>>>> "Laurynas" == Laurynas Biveinis <laurynas.biveinis@gmail.com> writes:

Laurynas> If the objects pointed to by them are collected, they are
Laurynas> automatically set to NULL by the collector, which looks like
Laurynas> HTAB_EMPTY_ENTRY to others. By comparison, current
Laurynas> collectors set them to HTAB_DELETED_ENTRY, is this
Laurynas> difference important, or just for statistics?


The general idea is that you don't want to re-hash all the entries in
a hash table when one entry is deleted.  But, if you mark a deleted
entry as "empty", then future searches may stop there instead of
proceeding on to find the real entry.

So, it matters quite a bit.

I only skimmed hashtab.c.  But, this is a pretty ordinary way to
implement hash tables, and by my reading hashtab.c does it this way as
well.

Tom



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