On 2/24/15 8:17 AM, Michel Fortin wrote:
On 2015-02-23 22:15:46 +0000, Walter Bright said:
int* count;
[...] if (count && --*count == 0) [...]
Careful!
This isn't memory safe and you have to thank the GC for it. If you ever
use RCArray as a member variable in a class, the RCArray destructor is
going to be called from a random thread when the class destructor is
run. If some thread has a stack reference to the array you have a race.
You have to use an atomic counter unless you can prove the RCArray
struct will never be put in a GC-managed context. It is rather sad that
the language has no way to enforce such a restriction, and also that
@safe cannot detect that this is a problem here.
Actually, RCArray can never be allocated on GC, or you may corrupt
memory. count may be non-null, and point at invalid memory when the dtor
is called.
Only safe way to do this is to C malloc/free the count. And yes, at that
point, you need atomics.
-Steve
