diff mercurial/revlogutils/constants.py @ 41202:e7a2cc84dbc0

revlog: always enable generaldelta on version 2 revlogs

This commit starts the process of diverging version 2 revlogs
from version 1 revlogs.

generaldelta is a useful feature and has been enabled by
default for ages. I can't think of a good reason why the
feature should be disabled. Yes, it is true changelogs
today don't have generaldelta enabled. But that's because
they don't have delta chains enabled, so generaldelta makes
no sense there.

This commit makes generaldelta always enabled on version 2
revlogs.

As part of this, one-off code in changelog.py mucking with
revlog.version had to be made conditional on the revlog
version, as we don't want to change revlog feature
flags on version 2 revlogs. The fact this code exists
is horrible and stems from revlog options being shared by
the opener. We probably want a better API here. But that can
wait for another patch.

Differential Revision: https://phab.mercurial-scm.org/D5561

--- a/mercurial/revlogutils/constants.py	Wed Jan 09 15:45:17 2019 -0800
+++ b/mercurial/revlogutils/constants.py	Wed Jan 09 17:41:36 2019 -0800
@@ -20,13 +20,15 @@
 # Dummy value until file format is finalized.
 # Reminder: change the bounds check in revlog.__init__ when this is changed.
 REVLOGV2 = 0xDEAD
+# Shared across v1 and v2.
 FLAG_INLINE_DATA = (1 << 16)
+# Only used by v1, implied by v2.
 FLAG_GENERALDELTA = (1 << 17)
 REVLOG_DEFAULT_FLAGS = FLAG_INLINE_DATA
 REVLOG_DEFAULT_FORMAT = REVLOGV1
 REVLOG_DEFAULT_VERSION = REVLOG_DEFAULT_FORMAT | REVLOG_DEFAULT_FLAGS
 REVLOGV1_FLAGS = FLAG_INLINE_DATA | FLAG_GENERALDELTA
-REVLOGV2_FLAGS = REVLOGV1_FLAGS
+REVLOGV2_FLAGS = FLAG_INLINE_DATA
 
 # revlog index flags