1057928 - Use |ops| instead of other fields to indicate PL_DHashTable liveness

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Nicholas Nethercote [inactive]]

SpanningCellSorter has a hash table. It zeroes the |entryCount| field to
indicate when the hash table is not live. This goes against the standard idiom
of using the |ops| field for this purpose, and blocks my goal of making
|entryCount| private (see bug 1057914).

Comment 1

[Nicholas Nethercote [inactive]]

Attachment: In SpanningCellSorter, use |ops| instead of |entryCount| to indicate table liveness

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I think at the time I wrote this I was trying to change the idiom from using null-ops to using 0-entryCount, although I don't remember why.

Comment 3

[Nicholas Nethercote [inactive]]

Thanks for the fast review, dbaron!

Comment 4

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Sure.

I didn't see any clues in bug 363329 as to why I was using entryCount.

Comment 5

[Nicholas Nethercote [inactive]]

Attachment: (part 2) - In nsTHashtable, use |ops| instead of |entryCount| to indicate table liveness

I found another case to convert. (Nb: if you're wondering, there are dozens and
dozens of places that use |ops| to indicate liveness, as opposed to the two
that use |entryStore|.)

Comment 6

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 8478084 [details] [diff] [review]
(part 2) - In nsTHashtable, use |ops| instead of |entryCount| to indicate table liveness

You also need to adjust the assertions in nsBaseHashtable::EnumerateRead and nsBaseHashtable::Enumerate.

You should also fix the commit message to refer to entrySize instead of entryCount, since that's what was being used here.

r=dbaron with that

Comment 7

[Nicholas Nethercote [inactive]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/c4d86cfb8fa2
https://hg.mozilla.org/integration/mozilla-inbound/rev/a17805b07d4f

Comment 8

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/c4d86cfb8fa2
https://hg.mozilla.org/mozilla-central/rev/a17805b07d4f