localrepo: unify tag related info into a tagscache class

localrepo: make invalidate() walk _filecache

localrepo: decorate manifest() with filecache

localrepo: decorate _bookmarks/current with filecache nodebookmarks() can be cached as well, leaving for later

localrepo: decorate changelog() with filecache

localrepo: refresh filecache entries after releasing a repo.lock()

localrepo: decorate dirstate() with filecache We refresh the stat info when releasing repo.wlock(), right after writing it. Also, invalidate the dirstate by deleting its attribute. This will force a stat by the decorator that actually checks if anything changed, rather than reading it again every time. Note that prior to this, there was a single dirstate instance created for a localrepo. It was invalidated by calling dirstate.invalidated(), clearing its internal attributes. As a consequence, the following construct is no longer safe: ds = repo.dirstate # keep a reference to the repo's dirstate wlock = repo.wlock() try: ds.setparents(...) finally: wlock.release() # dirstate should be written here Since it's possible that the dirstate was modified between lines #1 and #2, therefore changes to the old dirstate won't get written when the lock releases, because a new instance was created by the decorator.

localrepo: add a cache with stat info for files under .hg/

scmutil: introduce filecache The idea is being able to associate a file with a property, and watch that file stat info for modifications when we decide it's important for it to be up-to-date. Once it changes, we recreate the object. On filesystems that can't uniquely identify a file, we always recreate. As a consequence, localrepo.invalidate() will become much less expensive in the case where nothing changed on-disk.

posix, windows: introduce cachestat This class contains a stat result, and possibly other file info to reliably determine between two points in time whether a file has changed. Uniquely identifying a file gives us that reliability because we either atomic rename or append. So one of two will happen: the file 'id' will change, or the size of the file will change. posix implements it simply by calling os.stat() and checking if the result has st_ino. For now on Windows we always assume the path is uncacheable. This can be improved on NTFS due to file IDs: http://msdn.microsoft.com/en-us/library/aa363788(v=vs.85).aspx So we need to find out if a file path is on an NTFS drive, for that we have: - GetVolumeInformation, which unfortunately only works with a root path (but is available on XP) - GetVolumeInformationByHandleW, works on a full file path but requires Vista or higher