If we have a full index, then we can convert it to a sparse index by
replacing directories outside of the sparse cone with sparse directory
entries. The convert_to_sparse() method does this, when the situation is
appropriate.
For now, we avoid converting the index to a sparse index if:
1. the index is split.
2. the index is already sparse.
3. sparse-checkout is disabled.
4. sparse-checkout does not use cone mode.
Finally, we currently limit the conversion to when the
GIT_TEST_SPARSE_INDEX environment variable is enabled. A mode using Git
config will be added in a later change.
The trickiest thing about this conversion is that we might not be able
to mark a directory as a sparse directory just because it is outside the
sparse cone. There might be unmerged files within that directory, so we
need to look for those. Also, if there is some strange reason why a file
is not marked with CE_SKIP_WORKTREE, then we should give up on
converting that directory. There is still hope that some of its
subdirectories might be able to convert to sparse, so we keep looking
deeper.
The conversion process is assisted by the cache-tree extension. This is
calculated from the full index if it does not already exist. We then
abandon the cache-tree as it no longer applies to the newly-sparse
index. Thus, this cache-tree will be recalculated in every
sparse-full-sparse round-trip until we integrate the cache-tree
extension with the sparse index.
Some Git commands use the index after writing it. For example, 'git add'
will update the index, then write it to disk, then read its entries to
report information. To keep the in-memory index in a full state after
writing, we re-expand it to a full one after the write. This is wasteful
for commands that only write the index and do not read from it again,
but that is only the case until we make those commands "sparse aware."
We can compare the behavior of the sparse-index in
t1092-sparse-checkout-compability.sh by using GIT_TEST_SPARSE_INDEX=1
when operating on the 'sparse-index' repo. We can also compare the two
sparse repos directly, such as comparing their indexes (when expanded to
full in the case of the 'sparse-index' repo). We also verify that the
index is actually populated with sparse directory entries.
The 'checkout and reset (mixed)' test is marked for failure when
comparing a sparse repo to a full repo, but we can compare the two
sparse-checkout cases directly to ensure that we are not changing the
behavior when using a sparse index.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We will use 'test-tool read-cache --table' to check that a sparse
index is written as part of init_repos. Since we will no longer always
expand a sparse index into a full index, add an '--expand' parameter
that adds a call to ensure_full_index() so we can compare a sparse index
directly against a full index, or at least what the in-memory index
looks like when expanded in this way.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a new 'sparse-index' repo alongside the 'full-checkout' and
'sparse-checkout' repos in t1092-sparse-checkout-compatibility.sh. Also
add run_on_sparse and test_sparse_match helpers. These helpers will be
used when the sparse index is implemented.
Add the GIT_TEST_SPARSE_INDEX environment variable to enable the
sparse-index by default. This can be enabled across all tests, but that
will only affect cases where the sparse-checkout feature is enabled.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This test was introduced in 19a0acc83e (t1092: test interesting
sparse-checkout scenarios, 2021-01-23), but it contains issues with quoting
that were not noticed until starting this follow-up series. The old
mechanism would drop quoting such as in
test_all_match git commit -m "touch README.md"
The above happened to work because README.md is a file in the
repository, so 'git commit -m touch REAMDE.md' would succeed by
accident.
Other cases included quoting for no good reason, so clean that up now.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
These also document some behaviors that differ from a full checkout, and
possibly in a way that is not intended.
The test is designed to be run with "--run=1,X" where 'X' is an
interesting test case. Each test uses 'init_repos' to reset the full and
sparse copies of the initial-repo that is created by the first test
case. This also makes it possible to have test cases leave the working
directory or index in unusual states without disturbing later cases.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
