All,
(Note: I'm not critiquing the design choices, just trying to
understand the choices and the behavior of the implementation)
I read in the docs that simultaneous reads are ok, but simultaneous
read/write or write/write are not. Ok, seems like a valid set up.
When I looked at the implementation, it looks like the reference
counter uses a mutex when BOOST_HAS_THREADS is defined.
Does that mean that if I have thread capability on my boost
installation (which I do), I pay for the mutex regardless of whether I
am actually using threads?
Secondly, if I'm paying for the cost of a mutex for the reference
count, why couldn't the shared_ptr also be protected by a mutex?
Thereby making the simultaneous read/write safe (safe in that no
memory would be leaked b/c the pointers written/read).
Which brings me to a third question.
Let's say I've got a class (e.g. shared_count) that I sometimes want
to be protected by a mutex, and sometimes not. Say, for instance, I
want it to be protected by default, but sometimes I want to avoid that
overhead b/c I know I'll be using it in an environment that's already
protected by a mutex (and can avoid the extra mutex overhead).
Question: is the following design a reasonable one?
It appears to work for me.
template<class LockingStrategy>
class mySuperLockedClass : public LockingStrategy
{
public:
void read()
{
LockingStrategy::readlock();
// do stuff
}
void write()
{
LockingStrategy::writelock();
// do stuff
}
};
struct
EmptyLockingStrategy
{
void readlock()
{
// Just a no-op
}
void writelock()
{
// Just a no-op
}
};
struct
MutexLockingStrategy
{
boost::mutex m_;
void readlock()
{
boost::mutex::scoped_lock l(m_);
}
void writelock()
{
boost::mutex::scoped_lock l(m_);
}
};
struct
ReaderWriterLockingStrategy
{
boost::unimplemented::rwmutex m_;
void readlock()
{
boost::unimplemented::rwmutex::scoped_read_lock l(m_);
}
void writelock()
{
boost::unimplemented::rwmutex::scoped_write_lock l(m_);
}
};
Just wondering if the above strategy could be used in the case of
shared_count, and if not, why not?
thanks,
TJ
--
Trey Jackson
[EMAIL PROTECTED]
"A life lived in fear is a life half lived."
-- No Fear
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