On Mon, 25 Feb 2013, Brammert Ottens wrote:

...

Hi,

I want to be able to put a time out on the r_c_shortest_paths, and still be able to get the optimal paths that have been found so far. Currently, I changed the REF such that it always returns false as soon as the time out has reach, in effect emptying the unprocessed_labels queue. The problem with this is that the algorithm still needs quite some time to actually empty the queue.

I tried to have the on_label_popped(cur_label) throw an exception when the timeout has been reached. The timeout itself works like a charm, but because the pareto_optimal_solutions container is only filled after the while loop I can't access the already found optimal solutions.

You might want to have on_label_popped(l, g) take l by reference and set l.b_is_dominated to true. You'll still need to empty the queue, but (if that approach works) it should be faster that way.

-- Jeremiah Willcock

Hi Jeremiah,

Thanks for your suggestion, but if I understand correctly it would mean a change to the code. I do not want to change the code, because if ever there is an update to boost I just want to be able to replace the old libraries with the new ones. If I would change the code, I would keep the exception and put a try/catch statement around the while-loop. Then you go around the problem of having to empty the queue.

Is there any change to get something like a graceful timeout supported in the boost graph algorithms?

Brammert Ottens

Hi,

I've had a closer look and I was too quick in dismissing your solution. however, the on_label_popped(cur_label) gets a const reference to the label. I've used a const_cast to remove the const (see code below), but now the code crashes when cleaning up the labels using deallocate. Any ideas on what could be wrong?

template void QRCSPPVisitor::on_label_popped( const Label& label, const Graph& graph ) { RCSPPVisitorData().IncrementLabelsPopped();

if ( TimedOut() || GetMillis(StartTime()) > MaxMillis() ) { this->SetTimedOut(); const_cast(label).b_is_dominated = true; } }

I think you can just change the parameter declaration to be a non-const reference. Can you please check where the crash occurs and whatever information you can get about the cause? Thanks. -- Jeremiah Willcock