Goal
~~~~
We want to make it possible to use the split-index feature
automatically by just setting a new "core.splitIndex" configuration
variable to true.
This can be valuable as split-index can help significantly speed up
`git rebase` especially along with the current work to libify `git
apply`.
Design
~~~~~~
The design is similar as the previous work that introduced
"core.untrackedCache".
The new "core.splitIndex" configuration option can be either true,
false or undefined which is the default.
When it is true, the split index is created, if it does not already
exists, when the index is read. When it is false, the split index is
removed if it exists, when the index is read. Otherwise it is left as
is.
Highlevel view of the patches in the series
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Patches 1/8 to 4/8 introduce the functions that are reading the
configuration variable and tweaking the split index depending on
its value.
- Patches 5/8 and 6/8 add some documentation for the new feature.
- Patch 7/8 adds a few simple tests.
- Patch 8/8 cleans up the old "sharedindex.XXXX" previously
created by split-index.
Future work
~~~~~~~~~~~
One thing that is probably missing is a mechanism to avoid having too
many changes accumulating in the (split) index while in split index
mode. The git-update-index documentation says:
If split-index mode is already enabled and `--split-index` is
given again, all changes in $GIT_DIR/index are pushed back to
the shared index file.
but it is probably better to not expect the user to think about it and
to have a mechanism that pushes back all changes to the shared index
file automatically when some threshold is reached. The threshold could
be for example when $GIT_DIR/index size is larger than 25% of the
shared index size. Opinions, test results or test ideas are welcome on
this.
Links
~~~~~
The last iteration of the git apply libification patch series is
there:
http://thread.gmane.org/gmane.comp.version-control.git/298344/
This patch series is also available here:
https://github.com/chriscool/git/commits/config-split-index
Christian Couder (8):
config: add git_config_get_split_index()
split-index: add {add,remove}_split_index() functions
read-cache: add and then use tweak_split_index()
update-index: warn in case of split-index incoherency
Documentation/config: add information for core.splitIndex
Documentation/git-update-index: talk about core.splitIndex config var
t1700: add tests for core.splitIndex
read-cache: unlink old sharedindex files
Documentation/config.txt | 4 ++++
Documentation/git-update-index.txt | 6 ++++++
builtin/update-index.c | 20 ++++++++---------
cache.h | 1 +
config.c | 10 +++++++++
read-cache.c | 44 +++++++++++++++++++++++++++++++++++++-
split-index.c | 18 ++++++++++++++++
split-index.h | 2 ++
t/t1700-split-index.sh | 44 ++++++++++++++++++++++++++++++++++++++
9 files changed, 138 insertions(+), 11 deletions(-)
--
2.9.0.250.g7087ccc.dirty
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