The parent and recursive patterns allowed by the "cone mode"
option in sparse-checkout are restrictive enough that we
can avoid using the regex parsing. Everything is based on
prefix matches, so we can use hashsets to store the prefixes
from the sparse-checkout file. When checking a path, we can
strip path entries from the path and check the hashset for
an exact match.
As a test, I created a cone-mode sparse-checkout file for the
Linux repository that actually includes every file. This was
constructed by taking every folder in the Linux repo and creating
the pattern pairs here:
/$folder/
!/$folder/*/
This resulted in a sparse-checkout file sith 8,296 patterns.
Running 'git read-tree -mu HEAD' on this file had the following
performance:
core.sparseCheckout=false: 0.21 s (0.00 s)
core.sparseCheckout=true: 3.75 s (3.50 s)
core.sparseCheckoutCone=true: 0.23 s (0.01 s)
The times in parentheses above correspond to the time spent
in the first clear_ce_flags() call, according to the trace2
performance traces.
While this example is contrived, it demonstrates how these
patterns can slow the sparse-checkout feature.
Helped-by: Eric Wong <e@80x24.org>
Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The sparse-checkout feature can have quadratic performance as
the number of patterns and number of entries in the index grow.
If there are 1,000 patterns and 1,000,000 entries, this time can
be very significant.
Create a new Boolean config option, core.sparseCheckoutCone, to
indicate that we expect the sparse-checkout file to contain a
more limited set of patterns. This is a separate config setting
from core.sparseCheckout to avoid breaking older clients by
introducing a tri-state option.
The config option does nothing right now, but will be expanded
upon in a later commit.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The instructions for disabling a sparse-checkout to a full
working directory are complicated and non-intuitive. Add a
subcommand, 'git sparse-checkout disable', to perform those
steps for the user.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'git sparse-checkout set' subcommand takes a list of patterns
and places them in the sparse-checkout file. Then, it updates the
working directory to match those patterns. For a large list of
patterns, the command-line call can get very cumbersome.
Add a '--stdin' option to instead read patterns over standard in.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'git sparse-checkout set' subcommand takes a list of patterns
as arguments and writes them to the sparse-checkout file. Then, it
updates the working directory using 'git read-tree -mu HEAD'.
The 'set' subcommand will replace the entire contents of the
sparse-checkout file. The write_patterns_and_update() method is
extracted from cmd_sparse_checkout() to make it easier to implement
'add' and/or 'remove' subcommands in the future.
If the core.sparseCheckout config setting is disabled, then enable
the config setting in the worktree config. If we set the config
this way and the sparse-checkout fails, then re-disable the config
setting.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When someone wants to clone a large repository, but plans to work
using a sparse-checkout file, they either need to do a full
checkout first and then reduce the patterns they included, or
clone with --no-checkout, set up their patterns, and then run
a checkout manually. This requires knowing a lot about the repo
shape and how sparse-checkout works.
Add a new '--sparse' option to 'git clone' that initializes the
sparse-checkout file to include the following patterns:
/*
!/*/
These patterns include every file in the root directory, but
no directories. This allows a repo to include files like a
README or a bootstrapping script to grow enlistments from that
point.
During the 'git sparse-checkout init' call, we must first look
to see if HEAD is valid, since 'git clone' does not have a valid
HEAD at the point where it initializes the sparse-checkout. The
following checkout within the clone command will create the HEAD
ref and update the working directory correctly.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Getting started with a sparse-checkout file can be daunting. Help
users start their sparse enlistment using 'git sparse-checkout init'.
This will set 'core.sparseCheckout=true' in their config, write
an initial set of patterns to the sparse-checkout file, and update
their working directory.
Make sure to use the `extensions.worktreeConfig` setting and write
the sparse checkout config to the worktree-specific config file.
This avoids confusing interactions with other worktrees.
The use of running another process for 'git read-tree' is sub-
optimal. This will be removed in a later change.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The sparse-checkout feature is mostly hidden to users, as its
only documentation is supplementary information in the docs for
'git read-tree'. In addition, users need to know how to edit the
.git/info/sparse-checkout file with the right patterns, then run
the appropriate 'git read-tree -mu HEAD' command. Keeping the
working directory in sync with the sparse-checkout file requires
care.
Begin an effort to make the sparse-checkout feature a porcelain
feature by creating a new 'git sparse-checkout' builtin. This
builtin will be the preferred mechanism for manipulating the
sparse-checkout file and syncing the working directory.
The documentation provided is adapted from the "git read-tree"
documentation with a few edits for clarity in the new context.
Extra sections are added to hint toward a future change to
a more restricted pattern set.
Helped-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Derrick Stolee