Yep that addresses my concerns... On Mar 3, 2014 4:47 PM, "Ben Langmuir" <[email protected]> wrote:
> > On Feb 27, 2014, at 8:00 AM, Argyrios Kyrtzidis <[email protected]> > wrote: > > > On Feb 27, 2014, at 4:43 AM, Manuel Klimek <[email protected]> wrote: > > On Thu, Feb 27, 2014 at 1:37 PM, Manuel Klimek <[email protected]> wrote: > >> On Wed, Feb 12, 2014 at 11:22 PM, Douglas Gregor <[email protected]> >> wrote: >> >>> >>> On Feb 12, 2014, at 2:21 PM, Rafael Ávila de Espíndola < >>> [email protected]> wrote: >>> >>> > >>> > >>> > ================ >>> > Comment at: include/clang/Basic/FileManager.h:122 >>> > @@ -121,2 +121,3 @@ >>> > class FileManager : public RefCountedBase<FileManager> { >>> > + IntrusiveRefCntPtr<AbstractFileSystem> FS; >>> > FileSystemOptions FileSystemOpts; >>> > ---------------- >>> > Why is the reference count necessary? Given its nature I would expect >>> the FS to outlive the file manger, in which case the FileManager could have >>> just a pointer to the FileSystem. >>> >>> >>> The FS is likely to get shared among a number of FileManagers in >>> different compiler instances within a thread. Yes, we could try to >>> establish and maintain relationships among these, but it’s simpler and >>> costs us effectively nothing to make this ref-counted. >>> >> >> Just to follow up: >> I found one more argument against making this ref-counted: >> The constructor of FileManager that uses the default "real" file system >> is now actively thread hostile (you cannot create a FileManager per thread >> without locking). I think that's rather unexpected. >> > > And even worse, because RealFileSystem is an implementation detail, and > getRealFileSystem returns a ref counted pointer by value, I cannot see any > way to get me a RealFileSystem without locking. > > > I propose we introduce a RefCountedBase that is using atomic reference > count (either change RefCountedBase or add a new class), and have > FileSystem use that. > > > Makes sense to me. Manuel, does this address your concern? > > Ben > > Cheers, > /Manuel > > >
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