revlog: replace revlog._io.size with a new revlog.index.entry_size The `revlogio` class is mostly a relic from the past. Once in charge of the full revlog related Input/Output code, that class gradually lost responsibilities to the point where more IO are now done by `revlog.index` objects or revlog objects themself. I would like to ultimately remove the `revlogio` class, to do so I start simple with move the "entry size" information on the index. (The index is already responsible of the binary unpacking, so it knows the size. Differential Revision: https://phab.mercurial-scm.org/D10309

--- a/contrib/perf.py	Wed Apr 14 20:32:53 2021 +0200
+++ b/contrib/perf.py	Mon Apr 05 12:22:25 2021 +0200
@@ -3228,7 +3228,10 @@
         start = r.start
         length = r.length
         inline = r._inline
-        iosize = r._io.size
+        try:
+            iosize = r.index.entry_size
+        except AttributeError:
+            iosize = r._io.size
         buffer = util.buffer
 
         chunks = []