I've been playing around with concurrency lately, and I brought
up a limitation (which I feel is very strong): Basically, each
MessageBox are thread-global objects.
Because of this, it is not possible (or at least, very difficult)
to create *objects* that own other threads and communicate with
said threads, all from the same master thread.
It turns out the limitation is mostly artificial. I added a
couple of lines to concurrency, and I was able to *very* easily
deploy code such as:
//--------
import std.stdio;
import std.concurrency;
import core.thread;
import core.time;
void job(Tid ownerTid, string s, Duration duration)
{
Thread.sleep(duration);
ownerTid.send("Job " ~ s ~ " has finished.");
}
struct Manager
{
string name;
Tid myTid;
this(string name, Duration duration)
{
this.name = name;
myTid = generateMessageBox(); //New in concurrency
spawn(&job, myTid, name, duration);
}
void get()
{
myTid.receive( //Specific member function to Tid
(string s){writefln("Manager %s say: %s", name, s);}
);
}
}
void main()
{
auto a = Manager("a", seconds(5));
auto b = Manager("b", seconds(1));
auto c = Manager("c", seconds(3));
Thread.sleep(seconds(10));
a.get();
b.get();
c.get();
}
//--------
Manager a say: Job a has finished.
Manager b say: Job b has finished.
Manager c say: Job c has finished.
//--------
As you can see, my main has created 3 Managers, all of which
spawned their own thread. Each manager can easily speak to its
job, via its own private MessageBox, with no risk of collateral
noise.
Most importantly, deploying this code was *bafflinggly* easy and
straight forward. Furthermore, it reduces to *nothing* end user
message management.
In particular, imagine if "Manager" was instead:
struct AssyncFileCopier
{
this(string origin, string target);
bool areYouDoneYet();
}
Again, implementation would be VERY straight forward.
Without such local MessageBoxes, I don't know how you'd tackle
the problem.
One thing is for sure, I don't think it would be very pretty...
--------
The question is: I'd like to put a bit more work into this, flesh
it out, maybe write a DIP, and submit to phobos for inclusion.
Does anybody have any preliminary feedback, objections, remarks?
