An important thing (which you would consider to be reasonable) is that no multiple threads access the very same connection object. This causes at least problems with MySQL, but I would expect also with other database engines. It may be worth adding that to a piece of doc.
Rainer > -----Original Message----- > From: Markus Hoenicka [mailto:[EMAIL PROTECTED] > Sent: Tuesday, November 25, 2008 11:57 AM > To: [EMAIL PROTECTED] > Cc: [email protected] > Subject: Re: [libdbi-devel] Thread Safety question > > Quoting Artyom <[EMAIL PROTECTED]>: > > > I'm mostly interested in accessing different dbi_conn objects > > from same thread in safe way. > > > > So, it is quite reasonable to call dbi_initialize from single thread > > and call dbi_shutdown from single thread. > > > > This is perfectly reasonable. However, if we advertise libdbi as > thread-safe, we must also accommodate programmers who use one instance > per thread, for whatever reason. > > > gmtime_r, readdir_r exists on both Linux and Cygwin platforms and > > according to man mages exists in FreeBSD as well: > > > > Yes, I've mentioned those as I do have access to them and positively > know they support the reentrant versions. I'm more concerned about the > systems that I don't run myself, like OSX, the other *BSDs, Solaris > and so on. > > > However readdir_r is less important because it is quite reasonable > > to load shared objects from single thread. > > > > Once again, it is reasonable, but we must not rely on users doing only > things that we assume as reasonable. > > > Also, I had seen that gmtime used from timegm only if it > > is not implemented. (Undef cygwin/Linux it is implemented > > as GNU extension). Thus, gmttime shoudn't be called. > > > > It is called whenever a platform does not implement timegm. We've had > at least one such platform, otherwise there wouldn't be a workaround. > > There is another function in dbi_result.c which uses gmtime: > dbi_result_get_as_string_copy_idx(). This needs to be fixed too. > > > > Is there other points where non reenterable functions are used? > > To the best of my knowledge, not in libdbi. > > > > > I started to use the library for CppCMS project that naively > > runs in multiple threads. I assumed that the library is thread > > safe, however if I'm wrong it may be quite problematic for me. > > > > This is a good excuse to make libdbi thread-safe :-) > > > It would be great, at least it is possible to know what > > backends are not safe. > > > > For the record I had seen in sqlite (not sqlite3) backend > > usage of strtok. So it should be thread unsafe. > > > > What happens with others? > > > > I'll start reviewing the drivers as soon as time permits. We may end > up labelling individual drivers as thread-safe if we can't get all of > them fixed. We may also end up claiming thread-safety only for a > subset of platforms (i.e. those which implement reentrant versions of > functions which we cannot do without). > > regards, > Markus > > -- > Markus Hoenicka > [EMAIL PROTECTED] > (Spam-protected email: replace the quadrupeds with "mhoenicka") > http://www.mhoenicka.de > > > ----------------------------------------------------------------------- > -- > This SF.Net email is sponsored by the Moblin Your Move Developer's > challenge > Build the coolest Linux based applications with Moblin SDK & win great > prizes > Grand prize is a trip for two to an Open Source event anywhere in the > world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > libdbi-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/libdbi-devel ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ libdbi-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libdbi-devel
