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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