On 19 Aug 2007, at 4:09 PM, Adam R. Maxwell wrote: > > On Aug 19, 2007, at 03:10, Christiaan Hofman wrote: > >> >> On 19 Aug 2007, at 1:50 AM, Adam R. Maxwell wrote: >> >>> I was looking at some of the refactoring in Skim, and noticed that >>> the >>> file functions are supposed to be thread safe. Isn't there a >>> potential race condition in SKTemporaryDirectoryCreating, if >>> multiple >>> threads are creating baseTmpDir or incrementing a counter to find a >>> unique name? In BibDesk's NSFileManager method we use >>> @synchronized(self) to guard against that, but the function might >>> need >>> a mutex created in an __attribute__((constructor)) (or use CFUUID to >>> make a unique name). >>> >>> -- >>> adam >> >> @synchronize actually is completely useless here, as this only works >> when it's used always, which is certainly not true here. Note that >> NSFileManager itself is not thread safe. > > @synchronized() works fine here; it's a category method that only we > call, so the mutex /is/ always used. And yes, I know NSFileManager is > not thread safe...that's why I wrote many of the category methods for > BibDesk. Looking at BibDesk again, it still suffers from a race > condition, since it returns a path without creating it, so subsequent > parallel calls can easily get the same name. > > -- > adam
Well, @synchronized is OK for getting the unique number, but I'm not sure if accessing defaultManager itself is thread safe. Moreover the call to createDirectoryAtPath:attributes: may not be thread safe. As for the race condition, this probably is not a big problem. If the file is not created, it has a pretty arbitrary file name. Chances that two files with the same base name are created are pretty small. Christiaan ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ skim-app-develop mailing list skim-app-develop@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/skim-app-develop
