When running 'read-tree' with a single tree and no prefix,
'prime_cache_tree()' is called after the tree is unpacked. In that
situation, skip a redundant call to 'cache_tree_update()' in
'unpack_trees()' by enabling the 'skip_cache_tree_update' unpack option.
Removing the redundant cache tree update provides a substantial performance
improvement to 'git read-tree <tree-ish>', as shown by a test added to
'p0006-read-tree-checkout.sh':
Test before after
----------------------------------------------------------------------
read-tree br_ballast_plus_1 3.94(1.80+1.57) 3.00(1.14+1.28) -23.9%
Note that the 'read-tree' in 't1022-read-tree-partial-clone.sh' is updated
to read two trees, rather than one. The test was first introduced in
d3da223f22 (cache-tree: prefetch in partial clone read-tree, 2021-07-23) to
exercise the 'cache_tree_update()' code path, as used in 'git merge'. Since
this patch drops the call to 'cache_tree_update()' in single-tree 'git
read-tree', change the test to use the two-tree variant so that
'cache_tree_update()' is called as intended.
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
A couple of test scripts have actually been adapted to accommodate for a
configurable default branch name, but they still overrode it via the
`GIT_TEST_*` variable. Let's drop that override where possible.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git read-tree" checks the existence of the blobs referenced by the
given tree, but does not bulk prefetch them. Add a bulk prefetch.
The lack of prefetch here was noticed at $DAYJOB during a merge
involving some specific commits, but I couldn't find a minimal merge
that didn't also trigger the prefetch in check_updates() in
unpack-trees.c (and in all these cases, the lack of prefetch in
cache-tree.c didn't matter because all the relevant blobs would have
already been prefetched by then). This is why I used read-tree here to
exercise this code path.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
