On 13/05/2012, at 12:50 AM, john skaller wrote:
>
> On 13/05/2012, at 12:24 AM, john skaller wrote:
>>
>> Anyhow, Felix shouldn't terminate with the writer still on the
>> fibre stack (the reader put it there when it read the channel).
>
>
> Oh.. interesting. Very interesting!!
Oh yes, bitten by my semantics again. Dang that Cat, he is too smart,
he used to belong to Schroedinger, that's the problem here:
This fails to do what you expect.
var x = mk_schannel[int]();
proc reader() {
println$ "R1 ";
var u = read x;
println$ "R2 ";
u = read x;
println$ "R3 ";
}
proc writer() {
println$ "W1";
write (x,1);
println$ "W2";
write (x,2);
println$ "W3";
}
spawn_fthread reader;
spawn_fthread writer;
print "Done"; endl;
// OUTPUT:
Done
W1
R1
R2
R3
Weird eh? Three reads but only one write? How can that be??
Is it really reading or is there a bug? Lets add some debugging:
var x = mk_schannel[int]();
proc reader() {
println$ "R1 ";
var u = read x;
println$ "R2 "+ str u;
u = read x;
println$ "R3 " + str u;
}
proc writer() {
println$ "W1";
write (x,1);
println$ "W2";
write (x,2);
println$ "W3";
}
spawn_fthread reader;
spawn_fthread writer;
print "Done"; endl;
// OUTPUT:
Done
W1
R1
R2 1
W2
R3 2
W3
Crap! Now its working!
What's going on? Where's the bug??
The bug is never there when you look for it.
It's quantum mechanics.
yes indeed! There's no bug. It's Schroedingers Cat
playing with my mind.
[Do you see the problem yet??]
[No? Hint: what did I last improve in the compiler?]
[Still don't see it? State Heisenberg's uncertainty principle
and its obvious!]
--
john skaller
[email protected]
http://felix-lang.org
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