Hallo Phil!

Antwort auf eine Message von Phil Crown an Mario Semo:


 PC> But, is the overhead of creating the mutex semaphore trivial?  My code
 PC> has two threads calling this semaphore VERY often.

the difference are just a few machine statement . I'm not creating the
sema4 multiple times (which wouldn't work), i'm just creating a sema4
Request object whenever i need it. and i just create it inline. so the only
difference is a initialization of a local variable. 

 PC> Also, say one thread has created the sem and is pre-empted before
 PC> deleteing it, what happens when the second thread tries to create a
 PC> sem with the same name?  Error code or exception or blocks until the
 PC> first thread deletes the sem?

again: i do:

LCtMutexSema4 mySem("sema");        // eq. global

and the code to be protected is doing:

  {
   LCtMutexSema4::Request x(mySema);               
     // store mySema handle to x and perform a mySema.request();
   code to be protected.
  }  
   // end of block automatically (C++!!) destroys all local objects
(objects on the stack)
  // so '~x' is called and this performs a mySem.release();
  

Servus, Mario!

--- FleetStreet 1.18 PR#2