On Mon, Oct 22, 2018 at 6:00 AM Timon Gehr via Digitalmars-d
<digitalmars-d@puremagic.com> wrote:
>
> On 22.10.18 12:26, Timon Gehr wrote:
> > ---
> > module borked;
> >
> > void atomicIncrement(int* p)@system{
> > import core.atomic;
> > atomicOp!("+=",int,int)(*cast(shared(int)*)p,1);
> > }
> >
> > struct Atomic(T){
> > private T val;
> > void opUnary(string op : "++")() shared @trusted {
> > atomicIncrement(cast(T*)&val);
> > }
> > }
> > void main()@safe{
> > Atomic!int i;
> > auto a=&[i][0];// was: Atomic!int* a = &i;
> > import std.concurrency;
> > spawn((shared(Atomic!int)* a){ ++*a; }, a);
> > ++i.val; // race
> > }
> > ---
>
> Obviously, this should have been:
>
> ---
> module borked;
>
> void atomicIncrement(int*p)@system{
> import core.atomic;
> atomicOp!"+="(*cast(shared(int)*)p,1);
> }
> struct Atomic(T){
> private T val;
> void opUnary(string op:"++")()shared @trusted{
> atomicIncrement(cast(T*)&val);
> }
> }
> void main()@safe{
> auto a=new Atomic!int;
> import std.concurrency;
> spawn((shared(Atomic!int)* a){ ++*a; }, a);
> ++a.val; // race
> }
> ---
>
> (I was short on time and had to fix Manu's code because it was not
> actually compilable.)
Nitpick; atomicOp does not receive a shared arg under my proposal,
it's not a threadsafe function by definition as discussed a few times.
