revlog: move `revisioninfo` in `revlogutils`

We will need it in other utility module. So lets extract it from `revlog.py`,
the module is too large already anyway.

Differential Revision: https://phab.mercurial-scm.org/D10797

mercurial/revlog.py

@@ -167,27 +167,6 b' HAS_FAST_PERSISTENT_NODEMAP = rustrevlog'
 )
 
 
-@attr.s(slots=True, frozen=True)
-class _revisioninfo(object):
-    """Information about a revision that allows building its fulltext
-    node:       expected hash of the revision
-    p1, p2:     parent revs of the revision
-    btext:      built text cache consisting of a one-element list
-    cachedelta: (baserev, uncompressed_delta) or None
-    flags:      flags associated to the revision storage
-
-    One of btext[0] or cachedelta must be set.
-    """
-
-    node = attr.ib()
-    p1 = attr.ib()
-    p2 = attr.ib()
-    btext = attr.ib()
-    textlen = attr.ib()
-    cachedelta = attr.ib()
-    flags = attr.ib()
-
-
 @interfaceutil.implementer(repository.irevisiondelta)
 @attr.s(slots=True)
 class revlogrevisiondelta(object):
@@ -2534,7 +2513,15 b' class revlog(object):'
         if deltacomputer is None:
             deltacomputer = deltautil.deltacomputer(self)
 
-        revinfo = _revisioninfo(node, p1, p2, btext, textlen, cachedelta, flags)
+        revinfo = revlogutils.revisioninfo(
+            node,
+            p1,
+            p2,
+            btext,
+            textlen,
+            cachedelta,
+            flags,
+        )
 
         deltainfo = deltacomputer.finddeltainfo(revinfo, fh)
 

mercurial/revlogutils/__init__.py

@@ -7,6 +7,7 b''
 
 from __future__ import absolute_import
 
+from ..thirdparty import attr
 from ..interfaces import repository
 
 # See mercurial.revlogutils.constants for doc
@@ -56,3 +57,24 b' def entry('
         data_compression_mode,
         sidedata_compression_mode,
     )
+
+
+@attr.s(slots=True, frozen=True)
+class revisioninfo(object):
+    """Information about a revision that allows building its fulltext
+    node:       expected hash of the revision
+    p1, p2:     parent revs of the revision
+    btext:      built text cache consisting of a one-element list
+    cachedelta: (baserev, uncompressed_delta) or None
+    flags:      flags associated to the revision storage
+
+    One of btext[0] or cachedelta must be set.
+    """
+
+    node = attr.ib()
+    p1 = attr.ib()
+    p2 = attr.ib()
+    btext = attr.ib()
+    textlen = attr.ib()
+    cachedelta = attr.ib()
+    flags = attr.ib()

mercurial/revlogutils/deltas.py

@@ -932,7 +932,7 b' class deltacomputer(object):'
     def buildtext(self, revinfo, fh):
         """Builds a fulltext version of a revision
 
-        revinfo: _revisioninfo instance that contains all needed info
+        revinfo: revisioninfo instance that contains all needed info
         fh:      file handle to either the .i or the .d revlog file,
                  depending on whether it is inlined or not
         """