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revlog: always enable generaldelta on version 2 revlogs

Authored by indygreg on Jan 10 2019, 7:32 PM.



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

As part of this, one-off code in 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.

Diff Detail

rHG Mercurial
Automatic diff as part of commit; lint not applicable.
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

indygreg created this revision.Jan 10 2019, 7:32 PM
yuja added a subscriber: yuja.Jan 12 2019, 10:24 PM
  • if self._initempty:
  • # changelogs don't benefit from generaldelta

+ if self._initempty and (self.version & 0xFFFF == revlog.REVLOGV1):
+ # changelogs don't benefit from generaldelta.

Perhaps, debugdeltachain() and debugrevlog() has to be updated as well.
They peek .version attribute.

This revision was automatically updated to reflect the committed changes.