On Apr 14, 2009, at 7:57 PM, Rémi Coulom <remi.cou...@univ-lille3.fr>
wrote:
Jason House wrote:
Out of curiosity, how do you intelligently delete old nodes?
Reference counting won't always work due to cycles, and a nieve
scan of the tree could block all threads.
I store a date of birth in every node. At the beginning of a new
search, I increment time, and refresh the date of birth of all the
descendants of the new root. When allocating a new node, I can reuse
old hash entries.
Reuse hash entries? I assume you don't mean reuse entries because a
later hash value matches (should be quite rare, even with 32 bit hash
codes). The lockless hash you gave links to does not handle ever
changing a hash value once it's set.
If you CAS the tombstone value before the key, I guess it'd be
reasonably safe, but not guaranteed. Did you add any new states to
guarantee safety?
Or am I thinking about this the wrong way?
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