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Re^8: RFC: Is there a solution to the flaw in my hash mechanism? ($o != $i)

by BrowserUk (Patriarch)
on Jun 03, 2015 at 11:57 UTC ( [id://1128939]=note: print w/replies, xml ) Need Help??


in reply to Re^7: RFC: Is there a solution to the flaw in my hash mechanism? ($o != $i)
in thread RFC: Is there a solution to the flaw in my hash mechanism? (And are there any others?)

I'm not convinced that either of those is required. But I'll refrain from trying to make a case stronger than that at least at this point.

How would you distinguish between an empty slot and one that is in use other than by reserving one value from the input range (0 .. 2**64-1) as a sentinel or tell tale value?

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Re^9: RFC: Is there a solution to the flaw in my hash mechanism? (sentinel)
by tye (Sage) on Jun 03, 2015 at 13:49 UTC

    Sorry, I mistook the context of that statement due to lazy reading.

    Another approach would be a bitmap.

    You could even avoid a bitmap by, for example, sharding odd hash values into one hash table and even hash values into a second hash table. Then the 0 bit could indicate "empty" though the meaning of the value of that bit would be reversed between the two tables.

    - tye        

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