dblink: add hooks to sync disk for bug #439584

diff --git a/pym/portage/dbapi/vartree.py b/pym/portage/dbapi/vartree.py
index 46afea5724b68ed79923c27b97ff418f5b270373..cb7b39b02f8c86037426cb5eeaf2c652b053f375 100644 (file)
--- a/pym/portage/dbapi/vartree.py
+++ b/pym/portage/dbapi/vartree.py
@@ -1486,6 +1486,7 @@ class dblink(object):
                self._contents_inodes = None
                self._contents_basenames = None
                self._linkmap_broken = False
+               self._device_path_map = {}
                self._hardlink_merge_map = {}
                self._hash_key = (self._eroot, self.mycpv)
                self._protect_obj = None
@@ -1533,7 +1534,11 @@ class dblink(object):
                """
                Remove this entry from the database
                """
-               if not os.path.exists(self.dbdir):
+               try:
+                       os.lstat(self.dbdir)
+               except OSError as e:
+                       if e.errno not in (errno.ENOENT, errno.ENOTDIR, errno.ESTALE):
+                               raise
                        return
 
                # Check validity of self.dbdir before attempting to remove it.
@@ -1550,6 +1555,14 @@ class dblink(object):
                        pass
                self.vartree.dbapi._remove(self)
 
+               # Use self.dbroot since we need an existing path for syncfs.
+               try:
+                       self._merged_path(self.dbroot, os.lstat(self.dbroot))
+               except OSError:
+                       pass
+
+               self._post_merge_sync()
+
        def clearcontents(self):
                """
                For a given db entry (self), erase the CONTENTS values.
@@ -2135,6 +2148,12 @@ class dblink(object):
                                        self._eerror("postrm", 
                                                ["Could not chmod or unlink '%s': %s" % \
                                                (file_name, ose)])
+                               else:
+                                       try:
+                                               self._merged_path(file_name, lstatobj)
+                                       except OSError:
+                                               pass
+
                                finally:
                                        if bsd_chflags and pflags != 0:
                                                # Restore the parent flags we saved before unlinking
@@ -4048,6 +4067,7 @@ class dblink(object):
                try:
                        self.delete()
                        _movefile(self.dbtmpdir, self.dbpkgdir, mysettings=self.settings)
+                       self._merged_path(self.dbpkgdir, os.lstat(self.dbpkgdir))
                finally:
                        self.unlockdb()
 
@@ -4163,6 +4183,7 @@ class dblink(object):
                # For gcc upgrades, preserved libs have to be removed after the
                # the library path has been updated.
                self._prune_plib_registry()
+               self._post_merge_sync()
 
                return os.EX_OK
 
@@ -4412,6 +4433,12 @@ class dblink(object):
                                mymtime = movefile(mysrc, mydest, newmtime=thismtime,
                                        sstat=mystat, mysettings=self.settings,
                                        encoding=_encodings['merge'])
+
+                               try:
+                                       self._merged_path(mydest, os.lstat(mydest))
+                               except OSError:
+                                       pass
+
                                if mymtime != None:
                                        showMessage(">>> %s -> %s\n" % (mydest, myto))
                                        if sys.hexversion >= 0x3030000:
@@ -4511,6 +4538,12 @@ class dblink(object):
                                        os.chmod(mydest, mystat[0])
                                        os.chown(mydest, mystat[4], mystat[5])
                                        showMessage(">>> %s/\n" % mydest)
+
+                               try:
+                                       self._merged_path(mydest, os.lstat(mydest))
+                               except OSError:
+                                       pass
+
                                outfile.write("dir "+myrealdest+"\n")
                                # recurse and merge this directory
                                if self.mergeme(srcroot, destroot, outfile, secondhand,
@@ -4610,6 +4643,11 @@ class dblink(object):
                                        hardlink_candidates.append(mydest)
                                        zing = ">>>"
 
+                                       try:
+                                               self._merged_path(mydest, os.lstat(mydest))
+                                       except OSError:
+                                               pass
+
                                if mymtime != None:
                                        if sys.hexversion >= 0x3030000:
                                                outfile.write("obj "+myrealdest+" "+mymd5+" "+str(mymtime // 1000000000)+"\n")
@@ -4625,6 +4663,12 @@ class dblink(object):
                                                sstat=mystat, mysettings=self.settings,
                                                encoding=_encodings['merge']) is not None:
                                                zing = ">>>"
+
+                                               try:
+                                                       self._merged_path(mydest, os.lstat(mydest))
+                                               except OSError:
+                                                       pass
+
                                        else:
                                                return 1
                                if stat.S_ISFIFO(mymode):
@@ -4633,6 +4677,19 @@ class dblink(object):
                                        outfile.write("dev %s\n" % myrealdest)
                                showMessage(zing + " " + mydest + "\n")
 
+       def _merged_path(self, path, lstatobj):
+               previous_path = self._device_path_map.get(lstatobj.st_dev)
+               if previous_path is None or len(path) < len(previous_path):
+                       self._device_path_map[lstatobj.st_dev] = path
+
+       def _post_merge_sync(self):
+               """
+               Call this after merge or unmerge, in order to sync relevant files to
+               disk and avoid data-loss in the event of a power failure. This method
+               does nothing if FEATURES=merge-sync is disabled.
+               """
+               pass
+
        def merge(self, mergeroot, inforoot, myroot=None, myebuild=None, cleanup=0,
                mydbapi=None, prev_mtimes=None, counter=None):
                """