Date: 2001-06-29 08:15:46
I have a wedding to attend today so I wasn't around yesterday and
won't be around again until monday. However, I had a thought about
the design that I'd like to share (hopefully no one else has posted
the same thought... I've not caught up on the thread yet). There's a
third design which I think solves most of the problems and leaves us
with a design that I think is pretty consistent with C++ design.
class thread : noncopyable
// Constructs a thread object for the currently running
// thread of execution. A form of the self() method
// that I thought would be needed and would make Design 1
// Constructs a thread object for a new thread of execution
// that runs threadproc().
// Cleans up any appropriate state information.
// Checks for equality between thread objects.
bool operator==(const thread& other) const;
bool operator!=(const thread& other) const;
// Polls to see if the thread is still running.
bool is_alive() const;
// Blocks until the thread is no longer running.
// Causes the current thread of execution to block
// for a period of time.
static void sleep(const xtime& xt);
// Relinquishes a thread's current time slice on
// preemptive implementations and allows another
// thread to run on non-preemptive implementations.
static void yield();
This design appears to be an easier design to implement, is more in
line with other C++ designs and doesn't suffer from some of the
problems pointed out about the other two designs. The only thing I
see as possibly wrong is that there's not exactly a one-to-one
relationship between the class and the thread of execution. In other
words there can be multiple thread objects for a single thread of
execution. I don't think this is wrong as far as the design is
concerned, but it does lead back to a question about the name.
Personally, I find calling this class design a "thread" is less
confusing than the original since you can't directly copy thread
objects, but technically it's still suffering from the same problem
as Beman originally pointed out. Thoughts?
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk