[cpp-threads] Temporal models

[Jeremy Manson]

Hi all,

My name is Jeremy Manson, and I was involved with the Java memory model 
effort.  I have been sporadically following the conversation, but I am 
mostly just jumping in here without a lot of context, so forgive me if I 
get the wrong end of the stick.

Nick Maclaren wrote:
> 
> Note that I am NOT asking for any more precision in when events are
> serialised - i.e. the current lack of definition on when dubious memory
> actions take place can stay.  What I am saying is that, WHEN the
> language provides a construction that states that A causes B, then A
> happens before B.  Where this differs from the current approaches is
> that it permits the use of causality as a sequencing operator, which I
> assert is what almost all users will expect.
> 

What do you mean by "a construction that states that A causes B"?  This 
was one of the toughest things to define in Java, because traditional 
control and data dependences can be (often trivially) removed by the 
compiler.  It was completely impractical to use them to guarantee an 
ordering between memory operations.

I can talk about that more, if that is something that interests the 
folks here, but I'm not sure you were referring to that.  You might have 
been just referring to causation implied by external actions.

Forgive me if this is well-known to the readers of the list.

					Jeremy