On 2014-08-04, 7:09 PM, Kyle Huey wrote:
On Mon, Aug 4, 2014 at 4:06 PM, Mike Hommey <m...@glandium.org> wrote:
On Mon, Aug 04, 2014 at 03:42:07PM -0700, Kyle Huey wrote:
On Mon, Aug 4, 2014 at 3:09 PM, Mike Hommey <m...@glandium.org> wrote:
On Mon, Aug 04, 2014 at 11:33:55AM -0700, Kyle Huey wrote:
On Sun, Aug 3, 2014 at 11:01 PM, Nicholas Nethercote
<n.netherc...@gmail.com> wrote:
On Sun, Aug 3, 2014 at 10:18 PM, Kyle Huey <m...@kylehuey.com> wrote:
Static*Ptrs are there to avoid
static constructors and destructors so they can't clear themselves at
shutdown. That means that they behave quite differently than
"regular" smart pointers. Am I the only one who is bothered by this?
To use them correctly, is it the case that you need to do one of the following?
- null them at some point, or
- call ClearOnShutdown() on them at some point.
The comments in StaticPtr.h don't make this clear. And
ClearOnShutdown.h is a separate file, and ClearOnShutdown() isn't
mentioned in StaticPtr.h.
So I think they're useful -- being able to avoid static constructors
is important. But the documentation on how to use them could be much
clearer.
Nick
Yes, that's correct. You have to clear them somehow before the
process exits or we leak.
Which, besides accounting, is not really a problem, since the process is
exiting anyways. It can be a problem if desctructor code is actively
doing import stuff like persisting state.
Mike
That accounting is useful though. We need to fix the leaks that don't
matter in order to catch the ones that do, so that the latter don't
get lost in the noise of the former.
That accounting is useful on debug builds. Arguably, debug builds don't
have to care about avoiding static initializers. So we could add a
destructor to Static*Ptrs on debug builds that:
- sends a error that ClearOnShutdown was not called on them
or
- clears them to clear the leak
or
- both (replacing the error with a warning)
Mike
Yeah, we could do that. But turning on leak checking does the same
thing as (a) so (b) is the only useful code change to make.
Not only that, but it also makes our code correct. There is nothing to
guarantee that one of those destrcutors we're skipping right now would
not have observable side effects passed shutdown. So until somone comes
up with an idea on how to enforce that, we should clear these on all
builds. Please make it so. :-)
Cheers,
Ehsan
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