Even if there were an atomic method how would that help? It wouldn't eliminate the race condition, because it would still be illegal to call the method simultaneously on multiple threads. (FileStream's documentation says it's illegal to do that.) So you'd still need to use locking or some other synchronization method to make sure your threads take it in turns even if there were an atomic method.
I agree it would be cleaner to have a random access method if random access is what you're doing - a stream isn't really the right abstraction in that case. (Sadly it's the only one we're offered AFAIK.) But is this a defect? It's a bug to use a stream from multiple threads without synchronization. It would still be a bug even with the atomic method you propose. -- Ian Griffiths http://www.interact-sw.co.uk/iangblog/ > -----Original Message----- > From: John Davis > > >Are you saying that locking, Seeking, BeginWriteing, and unlocking is > not good enough? > > Well, I guess it is good enough, just doesn't seem very elegant. Would be > nice if there was an offset in there so one "atomic" call could be made. > Same as with Win32 overlapped io. > > >Does the BeginWrite not in effect take a snapshot of > the seek location when the operation starts? > > I don't know for certain if it does, I certainly hope so. Time to go > digging with reflector I guess. > > Ian Griffiths <[EMAIL PROTECTED]> wrote: > The documentation says that members of this class are not thread safe, > so multiple threads shouldn't be using this at any given instance. You > need to do some kind of locking if you have multiple threads using it. > > Are you saying that locking, Seeking, BeginWriteing, and unlocking is > not good enough? Does the BeginWrite not in effect take a snapshot of > the seek location when the operation starts? > > > > -----Original Message----- > > From: John Davis > > > > The way I understand it, the current BeginWrite on the > > FileStream object will write out it's buffer at the location of > > the last Seek. The problem comes when there are multiple threads > > using the same FileStream instance. > > > > Each one is looking to write to a different offset in the file. This > > means each thread must call FileStream.Seek followed by > > FileStream.BeginWrite Obviously, this creates a race condition. > > > > Why isn't there an async BeginWrite, on the FileStream, with an > > argument which specifies the offset within the file to write to. > > It's possible to call WriteFileEx within the Win32 API with an > > OVERLAPPED struct which specifies the offset. Why isn't this > > exposed through the framework? =================================== This list is hosted by DevelopMentor� http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com
