Re: Online enabling of checksums

On 2018-04-06 02:28:17 +0200, Daniel Gustafsson wrote:
> Looking into the isolationtester failure on piculet, which builds using
> --disable-atomics, and locust which doesn’t have atomics, the code for
> pg_atomic_test_set_flag seems a bit odd.
>
> TAS() is defined to return zero if successful, and pg_atomic_test_set_flag()
> defined to return True if it could set. When running without atomics, don’t we
> need to do something like the below diff to make these APIs match? :
>
> --- a/src/backend/port/atomics.c
> +++ b/src/backend/port/atomics.c
> @@ -73,7 +73,7 @@ pg_atomic_init_flag_impl(volatile pg_atomic_flag *ptr)
> bool
> pg_atomic_test_set_flag_impl(volatile pg_atomic_flag *ptr)
> {
> - return TAS((slock_t *) &ptr->sema);
> + return TAS((slock_t *) &ptr->sema) == 0;
> }

Yes, this looks wrong.

Greetings,

Andres Freund