Oops. Left some name mangling in there. Fixed now. On 3 February 2011 12:16, John Ky <newhoggy@gmail.com> wrote:
Hi boost users,
I've discovered that the following doesn't compile.
using namespace boost::interprocess; interprocess_upgradable_mutex mutex; interprocess_condition cv; boost::posix_time::ptime deadline;
{ scoped_lock<interprocess_upgradable_mutex> lock(mutex); sharable_lock<interprocess_upgradable_mutex> lock2(mutex); cv.wait(lock); // doesn't compile cv.timed_wait(lock, deadline); // doesn't compile. }
It is failing because boost doesn't define the following methods:
void interprocess_condition::do_wait(interprocess_upgradable_mutex &mut);
bool interprocess_condition::do_timed_wait(const boost::posix_time::ptime &abs_time, interprocess_upgradable_mutex &mut);
I was thinking of making a basic implementation like so:
Define a scoped_unlock class, which behaves just like scoped_lock except the constructor unlocks and the destructor locks.
Then define the following:
inline void interprocess_condition::do_wait(interprocess_upgradable_mutex &mut) { scoped_unlock<interprocess_upgradable_mutex> unlock(mut); interprocess_mutex &internal_mutex = mut.m_mut; scoped_lock<interprocess_mutex> internal_lock(internal_mutex); this->wait(internal_lock); }
inline bool interprocess_condition::do_timed_wait (const boost::posix_time::ptime &abs_time, interprocess_upgradable_mutex &mut) { scoped_unlock<interprocess_upgradable_mutex> unlock(mut); interprocess_mutex &internal_mutex = mut.m_mut; scoped_lock<interprocess_mutex> internal_lock(internal_mutex); return this->timed_wait(internal_lock, abs_time); }
These functions simply do the following:
- unlock the exclusive lock on the interprocess_upgradable_mutex (which is emulated with an internal interprocess_mutex) - then lock the internal interprocess_mutex - Call interprocess_condition::wait or interprocess_condition::time_ wait on the implementation lock which does all the work - unlock the internal interprocess_mutex - relock the exclusive lock on the interprocess_upgradable_mutex
Intuitively, this should work.
Is there anything I missed that would make this an incorrect implementation?
Cheers,
-John