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Test the current state of the cache-tree optimization

The cache-tree optimization originally helped speed up write-tree
operation.  However, many commands no longer properly maintain -- or
use an opportunity to cheaply generate -- the cache-tree data.  In
particular, this affects commit, checkout and reset.  The notable
examples that *do* write cache-tree data are read-tree and write-tree.

This sadly means most people no longer benefit from the optimization,
as they would not normally use the plumbing commands.

Document the current state of affairs in a test file, in preparation
for improvements in the area.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Thomas Rast 2011-12-06 18:43:36 +01:00 committed by Junio C Hamano
parent 1aed2fe394
commit 4eb0346fb8

95
t/t0090-cache-tree.sh Executable file
View File

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#!/bin/sh
test_description="Test whether cache-tree is properly updated
Tests whether various commands properly update and/or rewrite the
cache-tree extension.
"
. ./test-lib.sh
cmp_cache_tree () {
test-dump-cache-tree >actual &&
sed "s/$_x40/SHA/" <actual >filtered &&
test_cmp "$1" filtered
}
# We don't bother with actually checking the SHA1:
# test-dump-cache-tree already verifies that all existing data is
# correct.
test_shallow_cache_tree () {
echo "SHA " \
"($(git ls-files|wc -l) entries, 0 subtrees)" >expect &&
cmp_cache_tree expect
}
test_invalid_cache_tree () {
echo "invalid (0 subtrees)" >expect &&
echo "SHA #(ref) " \
"($(git ls-files|wc -l) entries, 0 subtrees)" >>expect &&
cmp_cache_tree expect
}
test_no_cache_tree () {
: >expect &&
cmp_cache_tree expect
}
test_expect_failure 'initial commit has cache-tree' '
test_commit foo &&
test_shallow_cache_tree
'
test_expect_success 'read-tree HEAD establishes cache-tree' '
git read-tree HEAD &&
test_shallow_cache_tree
'
test_expect_success 'git-add invalidates cache-tree' '
test_when_finished "git reset --hard; git read-tree HEAD" &&
echo "I changed this file" > foo &&
git add foo &&
test_invalid_cache_tree
'
test_expect_success 'update-index invalidates cache-tree' '
test_when_finished "git reset --hard; git read-tree HEAD" &&
echo "I changed this file" > foo &&
git update-index --add foo &&
test_invalid_cache_tree
'
test_expect_success 'write-tree establishes cache-tree' '
test-scrap-cache-tree &&
git write-tree &&
test_shallow_cache_tree
'
test_expect_success 'test-scrap-cache-tree works' '
git read-tree HEAD &&
test-scrap-cache-tree &&
test_no_cache_tree
'
test_expect_failure 'second commit has cache-tree' '
test_commit bar &&
test_shallow_cache_tree
'
test_expect_failure 'reset --hard gives cache-tree' '
test-scrap-cache-tree &&
git reset --hard &&
test_shallow_cache_tree
'
test_expect_failure 'reset --hard without index gives cache-tree' '
rm -f .git/index &&
git reset --hard &&
test_shallow_cache_tree
'
test_expect_failure 'checkout gives cache-tree' '
git checkout HEAD^ &&
test_shallow_cache_tree
'
test_done