alt Hacker NewsThis seems to omit the main point of it, though? That the compiler turns a function into a state machine that can restart from any of its suspension points. I guess that's the "state" variable, but what I'm talking about is what it contains and the partially compiler-generated code that deals with it.
C++ async is unfortunately a "bring your own runtime" sort of model (for now), but it does handle the part that would be incredibly tedious by hand, building above mentioned state machine.
Replies
If the objective with using async is performance and scalability then you should almost always "bring your own runtime". Bringing your own runtime is the main reason you might want to use async.
Delegating the runtime nerfs many of the benefits that async can offer. If you are going to delegate the runtime it offers relatively little compared to just using threads.
You are confusing it with coroutines. This is just a plain library feature that the compiler doesn’t necessarily have special support for.
C++ async model is too complicated (and not cost free as claimed, since it allocates memory for the coroutine state) and as such it wasn't widely adopted. I don't see any code using C++ async (apart from libraries implementing "tasks" in various forms). At this point I view it as a failed experiment. My bet is that executors are going to replace async completely.
That's the co_await/co_yield/co_routine stuff, which this isn't talking about--this is talking about the std::future-et-al logic, which predates C++ coroutines by almost a decade.