"Richard Seaman, Jr." wrote: > > On Fri, Jan 22, 1999 at 09:49:23AM -0800, Kurt D. Zeilenga wrote: > > "Richard Seaman, Jr." wrote: > > > _THREAD_SAFE is only used in stdio.h. Looking at what's there, it could > > > be rewritten to eliminate _THREAD_SAFE entirely, at a (very slight) > > > performance penalty. You'd have to check __isthreaded (could be done > > > once, instead of twice, as in the code now) each time you call one > > > of the functions defined within the _THREAD_SAFE switch. All > > > _THREAD_SAFE does is let you avoid checking __isthreaded when you're > > > not threaded. > > > > So, if I want to produce a library which can be safely used by both > > threaded and non-threaded applications I should NOT define -D_THREAD_SAFE > > such that __isthreaded is always checked by the library. > > I guess I was a little unclear. > > 1) I think you would have to rewrite a little bit of the header to > use the __isthreaded test on a couple of more functions. > > 2) If you always define -D_THREAD_SAFE, __isthreaded will be > checked whether you're threaded or not.
I would think that most third party libraries (from Ports) do not compile with -D_THREAD_SAFE. As such, __isthreaded won't be checked and the library cannot be safely used in a threaded environment. > You could also just eliminate _THREAD_SAFE entirely by letting > __isthreaded get checked on each relevant call. I would much prefer this. Then third party libraries compiled without -D_THREAD_SAFE can be used in threaded environments (though they might require external synchronization). Kurt To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-current" in the body of the message
