[Interest] QMap and thread-safe.

[Mandeep Sandhu]

On Wed, Jul 24, 2013 at 12:20 PM, André Somers <andre at familiesomers.nl>wrote:

> Op 23-7-2013 13:34, Giuseppe D'Angelo schreef:
> > On 23 July 2013 13:25, Bill Crocker <william.crocker at analog.com> wrote:
> >> Hi all:
> >>
> >> The QMap class states that all member functons are reentrant, but
> >> if I populate a map at program start-up (with QStrings, let's say) and I
> >> do not change its contents from then on... I should be able to treat the
> >> member function ::contains() and any other member function which does
> not
> >> modify the map as thread-safe.
> >>
> >> Is true?
> > Probably yes, although totally undocumented. (There has been some
> > discussion before the release of 5.0 -- about whether we should make
> > it official that using only "const" methods on containers makes them
> > thread safe, but I don't remember the outcome...)
> >
> > HTH,
> Well, if I understood Herb Sutters talk[1] on this correctly, that
> basically *is* the meaning of const nowadays...
>
> André
>
> [1]
>
> http://channel9.msdn.com/posts/C-and-Beyond-2012-Herb-Sutter-You-dont-know-blank-and-blank
>

Thanks for sharing this link. It was very informative. (BTW, this applies
only to C++11)

Also, doesn't a "const" (old sense of the word) member function mean - "I'm
not going to alter the state of the object" ?

If so, that would make it thread-safe in the special scenario (mentioned by
OP) where only "reads" are being attempted, right? Can an implementation
make it thread-unsafe while still being const (again considering only the
special "read-only" scenario)?

-mandeep



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