1380410 - Add mozilla::NeverAllocPolicy

Status: RESOLVED FIXED

(Core :: MFBT, enhancement)

Description

[Nika Layzell [:nika] (ni? for response)]

For some situations, such as in bug 1380096, it's useful to use MFBT types like Vector in situations where it would be Very Bad(tm) to allocate any memory.

For those situations, I suggest we add mozilla::NeverAllocPolicy, which is an alloc policy like MallocAllocPolicy, except it always fails to allocate, returning `nullptr`.

Comment 1

[Nika Layzell [:nika] (ni? for response)]

Attachment: Add NeverAllocPolicy

MozReview-Commit-ID: 8U38Oj3vyaF

Comment 2

[Eric Rahm [:erahm]]

Comment on attachment 8885833 [details] [diff] [review]
Add NeverAllocPolicy

Review of attachment 8885833 [details] [diff] [review]:
-----------------------------------------------------------------

LGTM, but we should get a mfbt peer to sign off. Mike this is pretty straightforward and came out of a discussion in another bug, a simplified version of the usage we were talking about would be to replace something like:

> char buffer[kMax];
> size_t used = std::min(str.len, kMax);
> memcpy(buffer, str, used);

with:

> Vector<char, kMax, NeverAllocPolicy> buffer;
> buffer.append(str, used);

Comment 3

[Nika Layzell [:nika] (ni? for response)]

(In reply to Eric Rahm [:erahm] (please no mozreview requests) from comment #2)
> LGTM, but we should get a mfbt peer to sign off.

Oops. for some reason in my head you were a mfbt peer ^.^.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/0318e26f75c8
Add NeverAllocPolicy, r=erahm

Comment 5

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/0318e26f75c8