On 2014-06-25 20:22:31 -0400, Robert Haas wrote: > On Wed, Jun 25, 2014 at 5:42 PM, Heikki Linnakangas > <hlinnakan...@vmware.com> wrote: > > I think having a separate file for each architecture is nice. I totally > > agree that they don't belong in src/include/storage, though. s_lock.h has > > always been misplaced there, but we've let it be for historical reasons, but > > now that we're adding a dozen new files, it's time to move them out. > > I find the current organization pretty confusing, but maybe that could > be solved by better documentation of what's supposed to go in each > architecture or compiler-dependent file.
The idea is that first a architecture specific file (atomics-arch-*.h) is included. That file can provide a (partial) implementation for the specific architecture. Or it can do pretty much nothing. After that a compiler specific file is included (atomics-generic-*.h). If atomics aren't yet implemented that can provide an intrinsics based implementation if the compiler version has support for it. At the very least a compiler barrier should be provided. After that the spinlock based fallback implementation (atomics-fallback.h) provides atomics and barriers if not yet available. By here we're sure that nothing else will provide them. Then we can provide operations (atomics-generic.h) that build ontop of the provided functions. E.g. implement _sub, _and et al. I'll include some more of that explanation in the header. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
