Subject: Re: [boost] [thread] Exception based timed locks
From: vicente.botet (vicente.botet_at_[hidden])
Date: 2009-01-19 19:47:51
----- Original Message -----
From: "vicente.botet" <vicente.botet_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Tuesday, January 20, 2009 1:03 AM
Subject: [boost] [thread] Exception based timed locks
>
> Hi,
>
> I've read recently about timed locks throwing an exception when there is a timeout.
> What do you think about this behaviour?
> Could the thread library provide both?
>
> Next follows a piece of code without exceptions
>
> while (polling) {
> t=now()+100;
> boost::unique_lock<boost::mutex> l1(m1, t);
> if (l1.has_lock() {
> boost::unique_lock<boost::mutex> l2(m2, t);
> if (l2.has_lock() {
> boost::unique_lock<boost::mutex> l3(m3, t);
> if (l2.has_lock() {
> foo();
> polling = false;
> } else execute_on_failed();
> } else execute_on_failed();
> } else execute_on_failed();
> }
>
> and now with exceptions
>
> while (polling)
> try {
> t=now()+100;
> boost::exception_unique_lock<boost::mutex> l1(m1, t);
> boost::exception_unique_lock<boost::mutex> l2(m2, t);
> boost::exception_unique_lock<boost::mutex> l3(m3, t);
> foo();
> polling = false;
> } catch (timeout_exception& ex) {execute_on_failed(); }
>
> What do you think about a try_lock_until, try_lock_for functions
>
> while (polling)
> try {
> boost::try_lock_for(100, m1, m2, m3);
> foo();
> polling = false;
> } catch (timeout_exception& ex) {execute_on_failed(); }
>
Sorry, in order to be exception safe we need a kind of scoped lock for tuples
while (polling)
try {
exception_unique_lock_tuple<mutex, shared_mutex, mutex>(100, m1, m2, m3);
foo();
polling = false;
} catch (timeout_exception& ex) {execute_on_failed(); }
Independent of the exception timeout, what do you think of a unique_lock_tuple?
Regards,
Vicente