1376117 - RestyleManager::mRestyleGeneration should be a uint64_t

Status: RESOLVED DUPLICATE of bug 1421197

(Core :: CSS Parsing and Computation, defect, P5)

Description

[Cameron McCormack (:heycam)]

RestyleManager::mRestyleGeneration is currently a uint32_t, but exposed from nsPresContext::GetRestyleGeneration as a uint64_t.  This is probably from me only partially addressing bz's review comment in bug 1203766 comment 13.

Comment 1

[Mats Palmgren (inactive)]

Or GetRestyleGeneration could return uint32_t...
Does using 64 bits for the field really have any benefits?

Comment 2

[Cameron McCormack (:heycam)]

Depends how likely it is someone will call getComputedStyle on an element in a display:none subtree, cause 2^32 restyles, and then inspect a property on the nsComputedDOMStyle object.  On a page doing, say, restyles at 60 Hz, it would take 828.5 days to wrap around to the same value.  So I suppose it's pretty unlikely...

Comment 4

[Jeremy Chen ([e-mail])]

Attachment: Bug 1376117 - use 64-bit for restyle generation counters to avoid overflow issues.

It is expected to use 64-bit for all the restyle generation counters, since the
getter methods all return uint64_t type at present. However, we're using uint32_t
for the actual counter variables, which means the potential overflow issue is not
avoided.

In this patch, we use 64-bit for all the restyle generation counters, so the
overflow issue can be avoided as expected.

Review commit: https://reviewboard.mozilla.org/r/203438/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/203438/

Comment 5

[Jeremy Chen ([e-mail])]

try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=75af66e6a371f30a2b60b592a35bae8921ad6670

Comment 6

[Jeremy Chen ([e-mail])]

Normally we don't dup the originally filed bug to a newly filed one. Since this issue is a relatively simple one, and the patch in Bug 1421197 has been r+ ed, I'm going to land the patch there.