Something needs to happen with shared, and soon.

[Andrei Alexandrescu]

On 11/14/12 4:23 AM, David Nadlinger wrote:
> On Wednesday, 14 November 2012 at 00:04:56 UTC, deadalnix wrote:
>> That is what java's volatile do. It have several uses cases, including
>> valid double check locking (It has to be noted that this idiom is used
>> incorrectly in druntime ATM, which proves both its usefullness and
>> that it require language support) and disruptor which I wanted to
>> implement for message passing in D but couldn't because of lack of
>> support at the time.
>
> What stops you from using core.atomic.{atomicLoad, atomicStore}? I don't
> know whether there might be a weird spec loophole which could
> theoretically lead to them being undefined behavior, but I'm sure that
> they are guaranteed to produce the right code on all relevant compilers.
> You can even specify the memory order semantics if you know what you are
> doing (although this used to trigger a template resolution bug in the
> frontend, no idea if it works now).
>
> David

This is a simplification of what should be going on. The 
core.atomic.{atomicLoad, atomicStore} functions must be intrinsics so 
the compiler generate sequentially consistent code with them (i.e. not 
perform certain reorderings). Then there are loads and stores with 
weaker consistency semantics (acquire, release, acquire/release, and 
consume).

Andrei