Re: need array of shared ptrs to shared structs

• Previous message: Steve Reinhardt: "need array of shared ptrs to shared structs"
• In reply to: Steve Reinhardt: "need array of shared ptrs to shared structs"

On Sun, Dec 04, 2005 at 08:21:26AM -0600, Steve Reinhardt wrote:
> 
> typedef struct {
>         int a;
>         int b;
> } gink;
> 
> typedef struct {
>         int a;
>         int b;
>         shared gink *c;         // private ptr to shared object
>         shared gink *shared d;  // shared ptr to shared object
>         shared int *e;          // private ptr to shared object
>         shared int *shared f;   // shared ptr to shared object
> } gink2;
> 
> shared gink2 aa[10][THREADS];
> shared gink2 *shared cc[10][THREADS];
 
 
> Having played with variations on this theme, it appears that UPC 
> doesn't support a member of a structure that's a shared pointer to a 
> shared object.  Is this so?

Since UPC, like C, makes some guarantees about memory layout within
structs, it can't create a struct in which some members are shared and
some aren't.  So the 'shared' keyword is illegal for a member
declaration, unless it qualifies a type that is pointed to.

But this doesn't mean you can't have shared structs--you just have to
make the entire struct shared.  You've done this already, here:
 
     shared gink2 aa[10][THREADS];

Each struct in aa can be accessed by any thread, and any 'c' member can
be manipulated by any thread.  So in effect 'c' *is* a 'shared gink
*shared'.  

Does that suffice for your purposes, or are you running into type issues
(i.e. do you need to treat the address of 'c' fields as 'shared gink
*shared')?

-- 
Jason Duell             Future Technologies Group
<jcduell_at_lbl_dot_gov>       Computational Research Division
Tel: +1-510-495-2354    Lawrence Berkeley National Laboratory

• Previous message: Steve Reinhardt: "need array of shared ptrs to shared structs"
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