Re: Q: tasks and recursion, binary tree

[Bob Duff <bobduff@theworld.com>]

gautier_niouzes@hotmail.com writes:

>     count: Natural:= 0;
>     pragma Volatile(count);
...
>         count:= count + 1;

You need an atomic increment.  Volatile doesn't do that (see the RM for
what it actually does).  Pragma Atomic doesn't do that either.
So the code has a data race, which makes it erroneous, which means
anything could happen (the program might crash, or might get wrong
answers, or might get correct answers).

You could create a protected object that encapsulates Count.
Or with GNAT you could look at System.Atomic_Counters.

- Bob