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view tests/test-convert-tla.t @ 32697:19b9fc40cc51
revlog: skeleton support for version 2 revlogs
There are a number of improvements we want to make to revlogs
that will require a new version - version 2. It is unclear what the
full set of improvements will be or when we'll be done with them.
What I do know is that the process will likely take longer than a
single release, will require input from various stakeholders to
evaluate changes, and will have many contentious debates and
bikeshedding.
It is unrealistic to develop revlog version 2 up front: there
are just too many uncertainties that we won't know until things
are implemented and experiments are run. Some changes will also
be invasive and prone to bit rot, so sitting on dozens of patches
is not practical.
This commit introduces skeleton support for version 2 revlogs in
a way that is flexible and not bound by backwards compatibility
concerns.
An experimental repo requirement for denoting revlog v2 has been
added. The requirement string has a sub-version component to it.
This will allow us to declare multiple requirements in the course
of developing revlog v2. Whenever we change the in-development
revlog v2 format, we can tweak the string, creating a new
requirement and locking out old clients. This will allow us to
make as many backwards incompatible changes and experiments to
revlog v2 as we want. In other words, we can land code and make
meaningful progress towards revlog v2 while still maintaining
extreme format flexibility up until the point we freeze the
format and remove the experimental labels.
To enable the new repo requirement, you must supply an experimental
and undocumented config option. But not just any boolean flag
will do: you need to explicitly use a value that no sane person
should ever type. This is an additional guard against enabling
revlog v2 on an installation it shouldn't be enabled on. The
specific scenario I'm trying to prevent is say a user with a
4.4 client with a frozen format enabling the option but then
downgrading to 4.3 and accidentally creating repos with an
outdated and unsupported repo format. Requiring a "challenge"
string should prevent this.
Because the format is not yet finalized and I don't want to take
any chances, revlog v2's version is currently 0xDEAD. I figure
squatting on a value we're likely never to use as an actual revlog
version to mean "internal testing only" is acceptable. And
"dead" is easily recognized as something meaningful.
There is a bunch of cleanup that is needed before work on revlog
v2 begins in earnest. I plan on doing that work once this patch
is accepted and we're comfortable with the idea of starting down
this path.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 19 May 2017 20:29:11 -0700 |
parents | 561a019c0268 |
children |
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#require tla symlink $ tla my-id "mercurial <mercurial@mercurial-scm.org>" $ echo "[extensions]" >> $HGRCPATH $ echo "convert=" >> $HGRCPATH create tla archive $ tla make-archive tla@mercurial--convert `pwd`/hg-test-convert-tla initialize tla repo $ mkdir tla-repo $ cd tla-repo/ $ tla init-tree tla@mercurial--convert/tla--test--0 $ tla import * creating version tla@mercurial--convert/tla--test--0 * imported tla@mercurial--convert/tla--test--0 create initial files $ echo 'this is a file' > a $ tla add a $ mkdir src $ tla add src $ cd src $ dd count=1 if=/dev/zero of=b > /dev/null 2> /dev/null $ tla add b $ tla commit -s "added a file, src and src/b (binary)" A/ .arch-ids A/ src A/ src/.arch-ids A .arch-ids/a.id A a A src/.arch-ids/=id A src/.arch-ids/b.id A src/b * update pristine tree (tla@mercurial--convert/tla--test--0--base-0 => tla--test--0--patch-1) * committed tla@mercurial--convert/tla--test--0--patch-1 create link file and modify a $ ln -s ../a a-link $ tla add a-link $ echo 'this a modification to a' >> ../a $ tla commit -s "added link to a and modify a" A src/.arch-ids/a-link.id A src/a-link M a * update pristine tree (tla@mercurial--convert/tla--test--0--patch-1 => tla--test--0--patch-2) * committed tla@mercurial--convert/tla--test--0--patch-2 create second link and modify b $ ln -s ../a a-link-2 $ tla add a-link-2 $ dd count=1 seek=1 if=/dev/zero of=b > /dev/null 2> /dev/null $ tla commit -s "added second link and modify b" A src/.arch-ids/a-link-2.id A src/a-link-2 Mb src/b * update pristine tree (tla@mercurial--convert/tla--test--0--patch-2 => tla--test--0--patch-3) * committed tla@mercurial--convert/tla--test--0--patch-3 b file to link and a-link-2 to regular file $ rm -f a-link-2 $ echo 'this is now a regular file' > a-link-2 $ ln -sf ../a b $ tla commit -s "file to link and link to file test" fl src/b lf src/a-link-2 * update pristine tree (tla@mercurial--convert/tla--test--0--patch-3 => tla--test--0--patch-4) * committed tla@mercurial--convert/tla--test--0--patch-4 move a-link-2 file and src directory $ cd .. $ tla mv src/a-link-2 c $ tla mv src test $ tla commit -s "move and rename a-link-2 file and src directory" D/ src/.arch-ids A/ test/.arch-ids /> src test => src/.arch-ids/a-link-2.id .arch-ids/c.id => src/a-link-2 c => src/.arch-ids/=id test/.arch-ids/=id => src/.arch-ids/a-link.id test/.arch-ids/a-link.id => src/.arch-ids/b.id test/.arch-ids/b.id * update pristine tree (tla@mercurial--convert/tla--test--0--patch-4 => tla--test--0--patch-5) * committed tla@mercurial--convert/tla--test--0--patch-5 $ cd .. converting tla repo to Mercurial $ hg convert tla-repo tla-repo-hg initializing destination tla-repo-hg repository analyzing tree version tla@mercurial--convert/tla--test--0... scanning source... sorting... converting... 5 initial import 4 added a file, src and src/b (binary) 3 added link to a and modify a 2 added second link and modify b 1 file to link and link to file test 0 move and rename a-link-2 file and src directory $ tla register-archive -d tla@mercurial--convert $ glog() > { > hg log -G --template '{rev} "{desc|firstline}" files: {files}\n' "$@" > } show graph log $ glog -R tla-repo-hg o 5 "move and rename a-link-2 file and src directory" files: c src/a-link src/a-link-2 src/b test/a-link test/b | o 4 "file to link and link to file test" files: src/a-link-2 src/b | o 3 "added second link and modify b" files: src/a-link-2 src/b | o 2 "added link to a and modify a" files: a src/a-link | o 1 "added a file, src and src/b (binary)" files: a src/b | o 0 "initial import" files: $ hg up -q -R tla-repo-hg $ hg -R tla-repo-hg manifest --debug c4072c4b72e1cabace081888efa148ee80ca3cbb 644 a 0201ac32a3a8e86e303dff60366382a54b48a72e 644 c c0067ba5ff0b7c9a3eb17270839d04614c435623 644 @ test/a-link 375f4263d86feacdea7e3c27100abd1560f2a973 644 @ test/b