--- a/mercurial/revlog.py	Fri Sep 06 23:26:30 2019 -0700
+++ b/mercurial/revlog.py	Thu Aug 08 01:12:48 2019 +0200
@@ -261,7 +261,7 @@
             p = versionformat_pack(version) + p[4:]
         return p
 
-class revlog(object):
+class revlog(flagutil.flagprocessorsmixin):
     """
     the underlying revision storage object
 
@@ -1715,69 +1715,6 @@
         """
         return storageutil.hashrevisionsha1(text, p1, p2)
 
-    def _processflags(self, text, flags, operation, raw=False):
-        """Inspect revision data flags and applies transforms defined by
-        registered flag processors.
-
-        ``text`` - the revision data to process
-        ``flags`` - the revision flags
-        ``operation`` - the operation being performed (read or write)
-        ``raw`` - an optional argument describing if the raw transform should be
-        applied.
-
-        This method processes the flags in the order (or reverse order if
-        ``operation`` is 'write') defined by REVIDX_FLAGS_ORDER, applying the
-        flag processors registered for present flags. The order of flags defined
-        in REVIDX_FLAGS_ORDER needs to be stable to allow non-commutativity.
-
-        Returns a 2-tuple of ``(text, validatehash)`` where ``text`` is the
-        processed text and ``validatehash`` is a bool indicating whether the
-        returned text should be checked for hash integrity.
-
-        Note: If the ``raw`` argument is set, it has precedence over the
-        operation and will only update the value of ``validatehash``.
-        """
-        # fast path: no flag processors will run
-        if flags == 0:
-            return text, True
-        if not operation in ('read', 'write'):
-            raise error.ProgrammingError(_("invalid '%s' operation") %
-                                         operation)
-        # Check all flags are known.
-        if flags & ~flagutil.REVIDX_KNOWN_FLAGS:
-            raise error.RevlogError(_("incompatible revision flag '%#x'") %
-                                    (flags & ~flagutil.REVIDX_KNOWN_FLAGS))
-        validatehash = True
-        # Depending on the operation (read or write), the order might be
-        # reversed due to non-commutative transforms.
-        orderedflags = REVIDX_FLAGS_ORDER
-        if operation == 'write':
-            orderedflags = reversed(orderedflags)
-
-        for flag in orderedflags:
-            # If a flagprocessor has been registered for a known flag, apply the
-            # related operation transform and update result tuple.
-            if flag & flags:
-                vhash = True
-
-                if flag not in self._flagprocessors:
-                    message = _("missing processor for flag '%#x'") % (flag)
-                    raise error.RevlogError(message)
-
-                processor = self._flagprocessors[flag]
-                if processor is not None:
-                    readtransform, writetransform, rawtransform = processor
-
-                    if raw:
-                        vhash = rawtransform(self, text)
-                    elif operation == 'read':
-                        text, vhash = readtransform(self, text)
-                    else: # write operation
-                        text, vhash = writetransform(self, text)
-                validatehash = validatehash and vhash
-
-        return text, validatehash
-
     def checkhash(self, text, node, p1=None, p2=None, rev=None):
         """Check node hash integrity.