git/diffcore.h, branch v2.45.3

hash-ll.h: split out of hash.h to remove dependency on repository.h

2023-04-24T19:47:32Z

hash.h depends upon and includes repository.h, due to the definition and use of the_hash_algo (defined as the_repository->hash_algo). However, most headers trying to include hash.h are only interested in the layout of the structs like object_id. Move the parts of hash.h that do not depend upon repository.h into a new file hash-ll.h (the "low level" parts of hash.h), and adjust other files to use this new header where the convenience inline functions aren't needed. This allows hash.h and object.h to be fairly small, minimal headers. It also exposes a lot of hidden dependencies on both path.h (which was brought in by repository.h) and repository.h (which was previously implicitly brought in by object.h), so also adjust other files to be more explicit about what they depend upon. Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano

hash.h: move some oid-related declarations from cache.h

2023-02-24T01:25:28Z

These defines and enum are all oid-related and as such seem to make more sense being included in hash.h. Further, moving them there allows us to remove some includes of cache.h in other files. The change to line-log.h might look unrelated, but line-log.h includes diffcore.h, which previously included cache.h, which included the kitchen sink. Since this patch makes diffcore.h no longer include cache.h, the compiler complains about the 'struct string_list *' function parameter. Add a forward declaration for struct string_list to address this. Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano

line-log: free diff queue when processing non-merge commits

2022-11-03T00:16:34Z

When processing a non-merge commit, the line-level log first asks the tree-diff machinery whether any of the files in the given line ranges were modified between the current commit and its parent, and if some of them were, then it loads the contents of those files from both commits to see whether their line ranges were modified and/or need to be adjusted. Alas, it doesn't free() the diff queue holding the results of that query and the contents of those files once its done. This can add up to a substantial amount of leaked memory, especially when the file in question is big and is frequently modified: a user reported "Out of memory, malloc failed" errors with a 2MB text file that was modified ~2800 times [1] (I estimate the leak would use up almost 11GB memory in that case). Free that diff queue to plug this memory leak. However, instead of simply open-coding the necessary three lines, add them as a helper function to the diff API, because it will be useful elsewhere as well. [1] https://public-inbox.org/git/CAFOPqVXz2XwzX8vGU7wLuqb2ZuwTuOFAzBLRM_QPk+NJa=eC-g@mail.gmail.com/ Signed-off-by: SZEDER Gábor Signed-off-by: Taylor Blau

merge-ort: store filepairs and filespecs in our mem_pool

2021-07-30T16:01:19Z

For the testcases mentioned in commit 557ac0350d ("merge-ort: begin performance work; instrument with trace2_region_* calls", 2020-10-28), this change improves the performance as follows: Before After no-renames: 198.1 ms ± 2.6 ms 198.5 ms ± 3.4 ms mega-renames: 715.8 ms ± 4.0 ms 679.1 ms ± 5.6 ms just-one-mega: 276.8 ms ± 4.2 ms 271.9 ms ± 2.8 ms Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano

diffcore-rename, merge-ort: add wrapper functions for filepair alloc/dealloc

2021-07-30T16:01:19Z

We want to be able to allocate filespecs and filepairs using a mem_pool. However, filespec data will still remain outside the pool (perhaps in the future we could plumb the pool through the various diff APIs to allocate the filespec data too, but for now we are limiting the scope). Add some extra functions to allocate these appropriately based on the non-NULL-ness of opt->priv->pool, as well as some extra functions to handle correctly deallocating the relevant parts of them. A future commit will make use of these new functions. Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano

Merge branch 'en/ort-perf-batch-11'

2021-06-14T04:33:27Z

Optimize out repeated rename detection in a sequence of mergy operations. * en/ort-perf-batch-11: merge-ort, diffcore-rename: employ cached renames when possible merge-ort: handle interactions of caching and rename/rename(1to1) cases merge-ort: add helper functions for using cached renames merge-ort: preserve cached renames for the appropriate side merge-ort: avoid accidental API mis-use merge-ort: add code to check for whether cached renames can be reused merge-ort: populate caches of rename detection results merge-ort: add data structures for in-memory caching of rename detection t6429: testcases for remembering renames fast-rebase: write conflict state to working tree, index, and HEAD fast-rebase: change assert() to BUG() Documentation/technical: describe remembering renames optimization t6423: rename file within directory that other side renamed

merge-ort, diffcore-rename: employ cached renames when possible

2021-05-20T06:40:39Z

When there are many renames between the old base of a series of commits and the new base, the way sequencer.c, merge-recursive.c, and diffcore-rename.c have traditionally split the work resulted in redetecting the same renames with each and every commit being transplanted. To address this, the last several commits have been creating a cache of rename detection results, determining when it was safe to use such a cache in subsequent merge operations, adding helper functions, and so on. See the previous half dozen commit messages for additional discussion of this optimization, particularly the message a few commits ago entitled "add code to check for whether cached renames can be reused". This commit finally ties all of that work together, modifying the merge algorithm to make use of these cached renames. For the testcases mentioned in commit 557ac0350d ("merge-ort: begin performance work; instrument with trace2_region_* calls", 2020-10-28), this change improves the performance as follows: Before After no-renames: 5.665 s ± 0.129 s 5.622 s ± 0.059 s mega-renames: 11.435 s ± 0.158 s 10.127 s ± 0.073 s just-one-mega: 494.2 ms ± 6.1 ms 500.3 ms ± 3.8 ms That's a fairly small improvement, but mostly because the previous optimizations were so effective for these particular testcases; this optimization only kicks in when the others don't. If we undid the basename-guided rename detection and skip-irrelevant-renames optimizations, then we'd see that this series by itself improved performance as follows: Before Basename Series After Just This Series no-renames: 13.815 s ± 0.062 s 5.697 s ± 0.080 s mega-renames: 1799.937 s ± 0.493 s 205.709 s ± 0.457 s Since this optimization kicks in to help accelerate cases where the previous optimizations do not apply, this last comparison shows that this cached-renames optimization has the potential to help signficantly in cases that don't meet the requirements for the other optimizations to be effective. The changes made in this optimization also lay some important groundwork for a future optimization around having collect_merge_info() avoid recursing into subtrees in more cases. However, for this optimization to be effective, merge_switch_to_result() should only be called when the rebase or cherry-pick operation has either completed or hit a case where the user needs to resolve a conflict or edit the result. If it is called after every commit, as sequencer.c does, then the working tree and index are needlessly updated with every commit and the cached metadata is tossed, defeating this optimization. Refactoring sequencer.c to only call merge_switch_to_result() at the end of the operation is a bigger undertaking, and the practical benefits of this optimization will not be realized until that work is performed. Since `test-tool fast-rebase` only updates at the end of the operation, it was used to obtain the timings above. Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano

Merge branch 'en/ort-perf-batch-10'

2021-04-16T20:53:33Z

Various rename detection optimization to help "ort" merge strategy backend. * en/ort-perf-batch-10: diffcore-rename: determine which relevant_sources are no longer relevant merge-ort: record the reason that we want a rename for a file diffcore-rename: add computation of number of unknown renames diffcore-rename: check if we have enough renames for directories early on diffcore-rename: only compute dir_rename_count for relevant directories merge-ort: record the reason that we want a rename for a directory merge-ort, diffcore-rename: tweak dirs_removed and relevant_source type diffcore-rename: take advantage of "majority rules" to skip more renames

Merge branch 'en/ort-perf-batch-9'

2021-04-08T20:23:26Z

The ort merge backend has been optimized by skipping irrelevant renames. * en/ort-perf-batch-9: diffcore-rename: avoid doing basename comparisons for irrelevant sources merge-ort: skip rename detection entirely if possible merge-ort: use relevant_sources to filter possible rename sources merge-ort: precompute whether directory rename detection is needed merge-ort: introduce wrappers for alternate tree traversal merge-ort: add data structures for an alternate tree traversal merge-ort: precompute subset of sources for which we need rename detection diffcore-rename: enable filtering possible rename sources

Merge branch 'en/ort-perf-batch-8'

2021-03-22T21:00:24Z

Rename detection rework continues. * en/ort-perf-batch-8: diffcore-rename: compute dir_rename_guess from dir_rename_counts diffcore-rename: limit dir_rename_counts computation to relevant dirs diffcore-rename: compute dir_rename_counts in stages diffcore-rename: extend cleanup_dir_rename_info() diffcore-rename: move dir_rename_counts into dir_rename_info struct diffcore-rename: add function for clearing dir_rename_count Move computation of dir_rename_count from merge-ort to diffcore-rename diffcore-rename: add a mapping of destination names to their indices diffcore-rename: provide basic implementation of idx_possible_rename() diffcore-rename: use directory rename guided basename comparisons