issue6528: implement _is_revision_affected_fast using callback

The delta comming from a bundle/stream does not exists in the revlog yet, so we
will need other way to retrieve the same information.

To prepare for this we split the function to use callbacks in the core logic.

Differential Revision: https://phab.mercurial-scm.org/D11268

mercurial/revlogutils/rewrite.py

@@ -598,6 +598,32 b' def _is_revision_affected_inner('
 
 
 def _is_revision_affected_fast(repo, fl, filerev, metadata_cache):
+    rl = fl._revlog
+    is_censored = lambda: rl.iscensored(filerev)
+    delta_base = lambda: rl.deltaparent(filerev)
+    delta = lambda: rl._chunk(filerev)
+    full_text = lambda: rl.rawdata(filerev)
+    parent_revs = lambda: rl.parentrevs(filerev)
+    return _is_revision_affected_fast_inner(
+        is_censored,
+        delta_base,
+        delta,
+        full_text,
+        parent_revs,
+        filerev,
+        metadata_cache,
+    )
+
+
+def _is_revision_affected_fast_inner(
+    is_censored,
+    delta_base,
+    delta,
+    full_text,
+    parent_revs,
+    filerev,
+    metadata_cache,
+):
     """Optimization fast-path for `_is_revision_affected`.
 
     `metadata_cache` is a dict of `{rev: has_metadata}` which allows any
@@ -605,24 +631,27 b' def _is_revision_affected_fast(repo, fl,'
     text, instead looking at the current delta.
 
     This optimization only works if the revisions are looked at in order."""
-    rl = fl._revlog
 
-    if rl.iscensored(filerev):
+    if is_censored():
         # Censored revisions don't contain metadata, so they cannot be affected
         metadata_cache[filerev] = False
         return False
 
-    p1, p2 = rl.parentrevs(filerev)
+    p1, p2 = parent_revs()
     if p1 == nullrev or p2 != nullrev:
         return False
 
-    delta_parent = rl.deltaparent(filerev)
+    delta_parent = delta_base()
     parent_has_metadata = metadata_cache.get(delta_parent)
     if parent_has_metadata is None:
-        is_affected = _is_revision_affected(fl, filerev, metadata_cache)
-        return is_affected
+        return _is_revision_affected_inner(
+            full_text,
+            parent_revs,
+            filerev,
+            metadata_cache,
+        )
 
-    chunk = rl._chunk(filerev)
+    chunk = delta()
     if not len(chunk):
         # No diff for this revision
         return parent_has_metadata
@@ -636,7 +665,12 b' def _is_revision_affected_fast(repo, fl,'
     if start < 2:  # len(b'\x01\n') == 2
         # This delta does *something* to the metadata marker (if any).
         # Check it the slow way
-        is_affected = _is_revision_affected(fl, filerev, metadata_cache)
+        is_affected = _is_revision_affected_inner(
+            full_text,
+            parent_revs,
+            filerev,
+            metadata_cache,
+        )
         return is_affected
 
     # The diff did not remove or add the metadata header, it's then in the same