diff mercurial/revlogutils/constants.py @ 47234:616b8f412676

revlogv2: introduce a very basic docket file

This is the first stone toward using a docket file in revlogv2. Right now the
docket is very basic and only store the version number (which is -also- stored
into the index file…) and the other files have fixed name. This new
implementation break transactionally… but they are no test checking
transactionally for revlogv2… So I take this as an opportunity to start small.
They are no usage of revlogv2 outside of tests anyway.

The docket keeps the `.i` naming used by previous version index to preserve a
unique entry point. We could decide to use a different name and look it up
first, or to fully rework this in a future "store" version. However that does
not seems necessary right now.

We will re-introduces transactionality (and associated testing…) in a later
changesets.


A long list of TODOs have been added to the relevant comment.

Differential Revision: https://phab.mercurial-scm.org/D10624

--- a/mercurial/revlogutils/constants.py	Mon May 17 15:05:24 2021 +0200
+++ b/mercurial/revlogutils/constants.py	Mon May 03 12:34:11 2021 +0200
@@ -133,20 +133,22 @@
         b'inline': _no,
         b'generaldelta': _no,
         b'sidedata': False,
+        b'docket': False,
     },
     REVLOGV1: {
         b'inline': _from_flag(FLAG_INLINE_DATA),
         b'generaldelta': _from_flag(FLAG_GENERALDELTA),
         b'sidedata': False,
+        b'docket': False,
     },
     REVLOGV2: {
-        # There is a bug in the transaction handling when going from an
-        # inline revlog to a separate index and data file. Turn it off until
-        # it's fixed, since v2 revlogs sometimes get rewritten on exchange.
-        # See issue6485
+        # The point of inline-revlog is to reduce the number of files used in
+        # the store. Using a docket defeat this purpose. So we needs other
+        # means to reduce the number of files for revlogv2.
         b'inline': _no,
         b'generaldelta': _yes,
         b'sidedata': True,
+        b'docket': True,
     },
 }