Hi Peter, On 10/19/06, Peter Dimov <pdimov@mmltd.net> wrote:
Dean Michael Berris wrote:
I had been more or less influenced by Herb Sutter's presentation on the Concur project and the idea of:
[snipped code example]
It isn't clear to me how this simple model can handle synchronization constraints; do all "active calls" run in parallel? Sequentially? What if I want some of them to run in parallel and some of them to obey sequential consistency?
It seems that the simplistic approach leaves a lot to the (compiler) implementation to decide (barring any more additional keywords aside from `active' to be added just for modifying the concurrency implementation). However for all intents and purposes, it seems to me that behind the scenes (and adhering to the Active Object Pattern) there would be a single scheduler for a single active object (perhaps using something similar to io_service).
Given an appropriate Executor (as in N2096), it's easy to emulate asynchronous calls as
future<int> r = ex.execute( bind( &my_class::f, &instance ) );
or maybe even
future<int> r = active( &my_class::f, &instance );
// future<int> r = active { instance.f() } in Concur?
if we trust the implementation to provide an optimal default executor (an adaptive thread pool, most likely.)
I like the above examples a lot, and would like to be able to do something even like: future<int> r = active<new_thread>(&my_class::f, &instance); future<int> r = active<queued>(&my_class::f_other, &instance);
But the real world is usually not as simple.
Indeed. That's why we had to hand-roll our own solution and profile-optimize for our specific situation, though it would be nice to have something flexible and generic enough for a good subset of the very many cases in which you'd want concurrency support in C++ written applications. -- Dean Michael C. Berris C++ Software Architect Orange and Bronze Software Labs, Ltd. Co. web: http://software.orangeandbronze.com/ email: dean@orangeandbronze.com mobile: +63 928 7291459 phone: +63 2 8943415 other: +1 408 4049532 blogs: http://mikhailberis.blogspot.com http://3w-agility.blogspot.com http://cplusplus-soup.blogspot.com