Peter Dimov escribió:
Ion Gaztañaga:
Peter Dimov escribió:
Last I looked at the various implementations, most of the routines did not provide these guarantees, though. Willing to help on these implementations? We also need to write our own versions to avoid license issues with the original Apache implementation (basically we need our implementation of gcc Intel & PowerPC asm versions).
There are various sp_counted_base implementations in boost/detail that can be used as a starting point. But if you want help for the implementation, you need to specify an interface first. I'm not particularly fond of
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2393.html
preferring something along the lines of
http://open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2195.html
I basically need to write (some) functions described here: http://svn.boost.org/trac/boost/browser/trunk/boost/interprocess/detail/atom... Not all functions are necessary (some are not used, so I'm going to remove them). Full barrier semantics would be a safe bet for a non-expert like me, although I'm not sure if they should be applied to atomic_read or atomic_write: //! Atomically increment an apr_uint32_t by 1 //! "mem": pointer to the object //! Returns the old value pointed to by mem inline boost::uint32_t atomic_inc32(volatile boost::uint32_t *mem); //! Atomically decrement an boost::uint32_t by 1 //! "mem": pointer to the atomic value //! Returns false if the value becomes zero on decrement, otherwise true inline bool atomic_dec32(volatile boost::uint32_t *mem); //! Atomically read an boost::uint32_t from memory inline boost::uint32_t atomic_read32(volatile boost::uint32_t *mem); //! Atomically set an boost::uint32_t in memory //! "mem": pointer to the object //! "param": val value that the object will assume inline void atomic_write32(volatile boost::uint32_t *mem, boost::uint32_t val); //! Compare an boost::uint32_t's value with "cmp". //! If they are the same swap the value with "with" //! "mem": pointer to the value //! "with": what to swap it with //! "cmp": the value to compare it to //! Returns the old value of *mem inline boost::uint32_t atomic_cas32 (volatile boost::uint32_t *mem, boost::uint32_t with, boost::uint32_t cmp);
but no matter what (if any) style you choose to follow, you need to be explicit about the constraints. At the very least, the functions should contain the constraint as a suffix, i.e. atomic_add_acqrel instead of atomic_add.
If you prefer to change the names, there is no problem. This is an internal header. Maybe it's better to place them somewhere in boost/detail if someone wants to reuse them, but I think that would require a review. Regards, Ion