[Boost-users] boost::condition questions

From: Adam M (boost_at_[hidden])
Date: 2005-11-04 12:36:44

Hi,

I have a couple questions regarding boost::condition.

You can view the condition.hpp here:
http://www.boost.org/boost/thread/condition.hpp

1) wait() starts out as follows:
--------------------------------
    void wait(L& lock)
    {
        if (!lock)
            throw lock_error();
...
--------------------------------

This "if (!lock)" seems to be checking if the lock is NULL, not if the
mutex is actually locked.

In the documentation, it says:
"Throws: lock_error if !lock.locked()"

However, even this seems to be a bit dubious, because that checks to see
if the given lock is the one that locked the mutex, and *not* if the
mutex itself is locked. 

Remember that the scoped_lock constructor can take a second parameter to
indicate whether or not to actually lock the mutex. One might use this
as an alternative to recursive locking, so that a synchronized function
may call another synchronized function and indicate with a flag that the
scoped_lock "initially_locked" parameter should be 'false'. If that
function then called to wait(), lock.locked() would return 'false', when
the mutex is in fact actually locked. Am I wrong?

2) In the boost::condition documentation:
http://boost.org/doc/html/condition.html

#4 on "condition waiting" is wrong; they left out the boost::xtime
parameter.

Thanks,
Adam