git/cache-tree.c, branch v2.33.6

Merge branch 'ds/commit-and-checkout-with-sparse-index'

2021-08-04T20:28:53Z

"git checkout" and "git commit" learn to work without unnecessarily expanding sparse indexes. * ds/commit-and-checkout-with-sparse-index: unpack-trees: resolve sparse-directory/file conflicts t1092: document bad 'git checkout' behavior checkout: stop expanding sparse indexes sparse-index: recompute cache-tree commit: integrate with sparse-index p2000: compress repo names p2000: add 'git checkout -' test and decrease depth

cache-tree: prefetch in partial clone read-tree

2021-07-23T21:22:21Z

"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 Signed-off-by: Junio C Hamano

commit: integrate with sparse-index

2021-07-14T22:05:53Z

Update 'git commit' to allow using the sparse-index in memory without expanding to a full one. The only place that had an ensure_full_index() call was in cache_tree_update(). The recursive algorithm for update_one() was already updated in 2de37c536 (cache-tree: integrate with sparse directory entries, 2021-03-03) to handle sparse directory entries in the index. Most of this change involves testing different command-line options that allow specifying which on-disk changes should be included in the commit. This includes no options (only take currently-staged changes), -a (take all tracked changes), and --include (take a list of specific changes). To simplify testing that these options do not expand the index, update the test that previously verified that 'git status' does not expand the index with a helper method, ensure_not_expanded(). This allows 'git commit' to operate much faster when the sparse-checkout cone is much smaller than the full list of files at HEAD. Here are the relevant lines from p2000-sparse-operations.sh: Test HEAD~1 HEAD ---------------------------------------------------------------------------------- 2000.14: git commit -a -m A (full-v3) 0.35(0.26+0.06) 0.36(0.28+0.07) +2.9% 2000.15: git commit -a -m A (full-v4) 0.32(0.26+0.05) 0.34(0.28+0.06) +6.3% 2000.16: git commit -a -m A (sparse-v3) 0.63(0.59+0.06) 0.04(0.05+0.05) -93.7% 2000.17: git commit -a -m A (sparse-v4) 0.64(0.59+0.08) 0.04(0.04+0.04) -93.8% It is important to compare the full-index case to the sparse-index case, so the improvement for index version v4 is actually an 88% improvement in this synthetic example. In a real repository with over two million files at HEAD and 60,000 files in the sparse-checkout definition, the time for 'git commit -a' went from 2.61 seconds to 134ms. I compared this to the result if the index only contained the paths in the sparse-checkout definition and found the theoretical optimum to be 120ms, so the out-of-cone paths only add a 12% overhead. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

Merge branch 'ds/sparse-index-protections'

2021-04-30T04:50:26Z

Builds on top of the sparse-index infrastructure to mark operations that are not ready to mark with the sparse index, causing them to fall back on fully-populated index that they always have worked with. * ds/sparse-index-protections: (47 commits) name-hash: use expand_to_path() sparse-index: expand_to_path() name-hash: don't add directories to name_hash revision: ensure full index resolve-undo: ensure full index read-cache: ensure full index pathspec: ensure full index merge-recursive: ensure full index entry: ensure full index dir: ensure full index update-index: ensure full index stash: ensure full index rm: ensure full index merge-index: ensure full index ls-files: ensure full index grep: ensure full index fsck: ensure full index difftool: ensure full index commit: ensure full index checkout: ensure full index ...

sparse-index: loose integration with cache_tree_verify()

2021-03-30T19:57:48Z

The cache_tree_verify() method is run when GIT_TEST_CHECK_CACHE_TREE is enabled, which it is by default in the test suite. The logic must be adjusted for the presence of these directory entries. For now, leave the test as a simple check for whether the directory entry is sparse. Do not go any further until needed. This allows us to re-enable GIT_TEST_CHECK_CACHE_TREE in t1092-sparse-checkout-compatibility.sh. Further, p2000-sparse-operations.sh uses the test suite and hence this is enabled for all tests. We need to integrate with it before we run our performance tests with a sparse-index. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

cache-tree: integrate with sparse directory entries

2021-03-30T19:57:48Z

The cache-tree extension was previously disabled with sparse indexes. However, the cache-tree is an important performance feature for commands like 'git status' and 'git add'. Integrate it with sparse directory entries. When writing a sparse index, completely clear and recalculate the cache tree. By starting from scratch, the only integration necessary is to check if we hit a sparse directory entry and create a leaf of the cache-tree that has an entry_count of one and no subtrees. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

sparse-index: convert from full to sparse

2021-03-30T19:57:47Z

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 Signed-off-by: Junio C Hamano

use CALLOC_ARRAY

2021-03-14T00:00:09Z

Add and apply a semantic patch for converting code that open-codes CALLOC_ARRAY to use it instead. It shortens the code and infers the element size automatically. Signed-off-by: René Scharfe Signed-off-by: Junio C Hamano

cache-tree: extract subtree_pos()

2021-01-24T01:14:07Z

This method will be helpful to use outside of cache-tree.c in a later feature. The implementation is subtle due to subtree_name_cmp() sorting by length and then lexicographically. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

cache-tree: simplify verify_cache() prototype

2021-01-24T01:14:07Z

The verify_cache() method takes an array of cache entries and a count, but these are always provided directly from a struct index_state. Use a pointer to the full structure instead. There is a subtle point when istate->cache_nr is zero that subtracting one will underflow. This triggers a failure in t0000-basic.sh, among others. Use "i + 1 < istate->cache_nr" to avoid these strange comparisons. Convert i to be unsigned as well, which also removes the potential signed overflow in the unlikely case that cache_nr is over 2.1 billion entries. The 'funny' variable has a maximum value of 11, so making it unsigned does not change anything of importance. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano