[Vala] [Valum]help with process async method.

[Matrix <pigex zhang gmail com>]

Hi:

i'm writing a server side program with valum framework...

in one entry point,  the server will send a http request to a remote 
server,

i copy the https://wiki.gnome.org/Projects/Vala/AsyncSamples in my code 
to test


async double do_calc_in_bg(double val) throws ThreadError {
   SourceFunc callback = do_calc_in_bg.callback;
   double[] output = new double[1];

   // Hold reference to closure to keep it from being freed whilst
   // thread is active.
   ThreadFunc<void*> run = () => {
       // Perform a dummy slow calculation.
       // (Insert real-life time-consuming algorithm here.)
       double result = 0;
       for (int a = 0; a<10000000; a++)
           result += val * a;

       // Pass back result and schedule callback
       output[0] = result;
       Idle.add((owned) callback);
       return null;
   };
   Thread.create<void*>(run, false);

   // Wait for background thread to schedule our callback
   yield;
   return output[0];
}

void test(Request request, Response response) {

        do_calc_in_bg.begin(0.001, (obj, res) => {
                try {
                        double result = do_calc_in_bg.end(res);
                        response.write_all(@"yes, the result is $result".data, null);
                } catch (ThreadError e) {
                        string msg = e.message;
                        stderr.printf(@"Thread error: $msg\n");
                }
        });
}


but when the thread finished,  call the response.write_all, it fails ...

2015-11-24 20:37:32: (mod_fastcgi.c.2391) unexpected end-of-file 
(perhaps the fastcgi process died): pid: 6667 socket: 
unix:/opt/projects/platformX/install/valum.sock-0
2015-11-24 20:37:32: (mod_fastcgi.c.3172) response not received, 
request sent: 548 on socket: 
unix:/opt/projects/platformX/install/valum.sock-0 for 
/verify_code?phone=13300000000, closing connection

how to implement async method ?

3ks a lot!!!