Date: Thu, 16 Oct 2008 09:46:28 +0800 From: David Xu <davidxu@freebsd.org> To: Daniel Eischen <deischen@freebsd.org> Cc: threads@freebsd.org, John Hein <jhein@timing.com> Subject: Re: pthread_cleanup_push & pthread_cleanup_pop usage Message-ID: <48F69CF4.9050905@freebsd.org> In-Reply-To: <Pine.GSO.4.64.0810080215150.3378@sea.ntplx.net> References: <18668.10465.699531.162573@gromit.timing.com> <20081008045447.GY36572@elvis.mu.org> <Pine.GSO.4.64.0810080215150.3378@sea.ntplx.net>
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Daniel Eischen wrote: > On Tue, 7 Oct 2008, Alfred Perlstein wrote: > >> * John Hein <jhein@timing.com> [081007 21:45] wrote: >>> In June pthread_cleanup_push & pthread_cleanup_pop were changed to >>> macros >>> that look like so... >> >> Hey John, I found the same problem when working on QNX a while back, >> however that is really how it's supposed to be set up. >> >> I would suggest the following construct to fix the problem, >> make your own per-thread stack of destructors that are callable >> as functions and not macros. >> >> It's not too hard to do. >> >> Just use a pthread_key and pthread_once thingy to write a library >> to do it, shouldn't take more than a hundred lines of code. >> >> FWIW, OS X and QNX have the same set of macros, not sure about >> other OSes. > > Solaris as well. > > Just conditionally undef them before you use them. > > #ifdef pthread_cleanup_push > #undef pthread_cleanup_push > #endif > #ifdef pthread_cleanup_pop > #undef pthread_cleanup_pop > #endif > > The library versions are still there (they have to be in order > to be callable from non-C/C++ languages). > One of possible solutions is we define a C++ class in pthread.h: #ifdef __cplusplus class __pthread_cleanup_obj { void (*__f)(void *); void *__a; int __execeute; public: __pthread_cleanup_obj(void (*__cleanup_routine)(void *), void *__arg) { f = __cleanup_routine; a = __arg; __execute = 0; } ~__pthread_cleanup_obj() { if (__execute) __f(__a); } void __set_execute(int __e) { __execute = __e; } }; #define pthread_cleanup_push(f, a) { \ __pthread_cleanup_obj __cleanup(f, a); \ { #define pthread_cleanup_pop(e) \ __cleanup.__set_execute(e); \ } \ } #endif but because there is no specification for C++ and threading, it is unknown which behavior is desired. David Xu
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