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7252d9a036
This patch implements support for reusing existing pseudo-merge commits when writing bitmaps when there is an existing pseudo-merge bitmap which has exactly the same set of parents as one that we are about to write. Note that unstable pseudo-merges are likely to change between consecutive repacks, and so are generally poor candidates for reuse. However, stable pseudo-merges (see the configuration option 'bitmapPseudoMerge.<name>.stableThreshold') are by definition unlikely to change between runs (as they represent long-running branches). Because there is no index from a *set* of pseudo-merge parents to a matching pseudo-merge bitmap, we have to construct the bitmap corresponding to the set of parents for each pending pseudo-merge commit and see if a matching bitmap exists. This is technically quadratic in the number of pseudo-merges, but is OK in practice for a couple of reasons: - non-matching pseudo-merge bitmaps are rejected quickly as soon as they differ in a single bit - already-matched pseudo-merge bitmaps are discarded from subsequent rounds of search - the number of pseudo-merges is generally small, even for large repositories In order to do this, implement (a) a function that finds a matching pseudo-merge given some uncompressed bitset describing its parents, (b) a function that computes the bitset of parents for a given pseudo-merge commit, and (c) call that function before computing the set of reachable objects for some pending pseudo-merge. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
217 lines
6.1 KiB
C
217 lines
6.1 KiB
C
#ifndef PSEUDO_MERGE_H
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#define PSEUDO_MERGE_H
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#include "git-compat-util.h"
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#include "strmap.h"
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#include "khash.h"
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#include "ewah/ewok.h"
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struct commit;
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struct string_list;
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struct bitmap_index;
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struct bitmap_writer;
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/*
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* A pseudo-merge group tracks the set of non-bitmapped reference tips
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* that match the given pattern.
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*
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* Within those matches, they are further segmented by separating
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* consecutive capture groups with '-' dash character capture groups
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* with '-' dash characters.
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*
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* Those groups are then ordered by committer date and partitioned
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* into individual pseudo-merge(s) according to the decay, max_merges,
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* sample_rate, and threshold parameters.
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*/
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struct pseudo_merge_group {
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regex_t *pattern;
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/* capture group(s) -> struct pseudo_merge_matches */
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struct strmap matches;
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/*
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* The individual pseudo-merge(s) that are generated from the
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* above array of matches, partitioned according to the below
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* parameters.
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*/
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struct commit **merges;
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size_t merges_nr;
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size_t merges_alloc;
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/*
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* Pseudo-merge grouping parameters. See git-config(1) for
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* more information.
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*/
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double decay;
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int max_merges;
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double sample_rate;
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int stable_size;
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timestamp_t threshold;
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timestamp_t stable_threshold;
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};
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struct pseudo_merge_matches {
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struct commit **stable;
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struct commit **unstable;
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size_t stable_nr, stable_alloc;
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size_t unstable_nr, unstable_alloc;
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};
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/*
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* Read the repository's configuration:
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*
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* - bitmapPseudoMerge.<name>.pattern
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* - bitmapPseudoMerge.<name>.decay
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* - bitmapPseudoMerge.<name>.sampleRate
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* - bitmapPseudoMerge.<name>.threshold
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* - bitmapPseudoMerge.<name>.maxMerges
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* - bitmapPseudoMerge.<name>.stableThreshold
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* - bitmapPseudoMerge.<name>.stableSize
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*
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* and populates the given `list` with pseudo-merge groups. String
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* entry keys are the pseudo-merge group names, and the values are
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* pointers to the pseudo_merge_group structure itself.
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*/
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void load_pseudo_merges_from_config(struct string_list *list);
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/*
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* A pseudo-merge commit index (pseudo_merge_commit_idx) maps a
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* particular (non-pseudo-merge) commit to the list of pseudo-merge(s)
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* it appears in.
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*/
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struct pseudo_merge_commit_idx {
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uint32_t *pseudo_merge;
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size_t nr, alloc;
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};
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/*
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* Selects pseudo-merges from a list of commits, populating the given
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* string_list of pseudo-merge groups.
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*
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* Populates the pseudo_merge_commits map with a commit_idx
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* corresponding to each commit in the list. Counts the total number
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* of pseudo-merges generated.
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*
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* Optionally shows a progress meter.
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*/
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void select_pseudo_merges(struct bitmap_writer *writer,
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struct commit **commits, size_t commits_nr);
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/*
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* Represents a serialized view of a file containing pseudo-merge(s)
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* (see Documentation/technical/bitmap-format.txt for a specification
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* of the format).
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*/
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struct pseudo_merge_map {
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/*
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* An array of pseudo-merge(s), lazily loaded from the .bitmap
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* file.
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*/
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struct pseudo_merge *v;
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size_t nr;
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size_t commits_nr;
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/*
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* Pointers into a memory-mapped view of the .bitmap file:
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*
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* - map: the beginning of the .bitmap file
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* - commits: the beginning of the pseudo-merge commit index
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* - map_size: the size of the .bitmap file
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*/
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const unsigned char *map;
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const unsigned char *commits;
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size_t map_size;
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};
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/*
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* An individual pseudo-merge, storing a pair of lazily-loaded
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* bitmaps:
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*
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* - commits: the set of commit(s) that are part of the pseudo-merge
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* - bitmap: the set of object(s) reachable from the above set of
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* commits.
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*
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* The `at` and `bitmap_at` fields are used to store the locations of
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* each of the above bitmaps in the .bitmap file.
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*/
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struct pseudo_merge {
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struct ewah_bitmap *commits;
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struct ewah_bitmap *bitmap;
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off_t at;
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off_t bitmap_at;
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/*
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* `satisfied` indicates whether the given pseudo-merge has been
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* used.
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*
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* `loaded_commits` and `loaded_bitmap` indicate whether the
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* respective bitmaps have been loaded and read from the
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* .bitmap file.
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*/
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unsigned satisfied : 1,
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loaded_commits : 1,
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loaded_bitmap : 1;
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};
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/*
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* Frees the given pseudo-merge map, releasing any memory held by (a)
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* parsed EWAH bitmaps, or (b) the array of pseudo-merges itself. Does
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* not free the memory-mapped view of the .bitmap file.
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*/
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void free_pseudo_merge_map(struct pseudo_merge_map *pm);
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/*
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* Loads the bitmap corresponding to the given pseudo-merge from the
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* map, if it has not already been loaded.
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*/
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struct ewah_bitmap *pseudo_merge_bitmap(const struct pseudo_merge_map *pm,
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struct pseudo_merge *merge);
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/*
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* Loads the pseudo-merge and its commits bitmap from the given
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* pseudo-merge map, if it has not already been loaded.
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*/
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struct pseudo_merge *use_pseudo_merge(const struct pseudo_merge_map *pm,
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struct pseudo_merge *merge);
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/*
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* Applies pseudo-merge(s) containing the given commit to the bitmap
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* "result".
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*
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* If any pseudo-merge(s) were satisfied, returns the number
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* satisfied, otherwise returns 0. If any were satisfied, the
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* remaining unsatisfied pseudo-merges are cascaded (see below).
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*/
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int apply_pseudo_merges_for_commit(const struct pseudo_merge_map *pm,
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struct bitmap *result,
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struct commit *commit, uint32_t commit_pos);
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/*
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* Applies pseudo-merge(s) which are satisfied according to the
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* current bitmap in result (or roots, see below). If any
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* pseudo-merges were satisfied, repeat the process over unsatisfied
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* pseudo-merge commits until no more pseudo-merges are satisfied.
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*
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* Result is the bitmap to which the pseudo-merge(s) are applied.
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* Roots (if given) is a bitmap of the traversal tip(s) for either
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* side of a reachability traversal.
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*
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* Roots may given instead of a populated results bitmap at the
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* beginning of a traversal on either side where the reachability
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* closure over tips is not yet known.
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*/
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int cascade_pseudo_merges(const struct pseudo_merge_map *pm,
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struct bitmap *result,
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struct bitmap *roots);
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/*
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* Returns a pseudo-merge which contains the exact set of commits
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* listed in the "parents" bitamp, or NULL if none could be found.
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*/
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struct pseudo_merge *pseudo_merge_for_parents(const struct pseudo_merge_map *pm,
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struct bitmap *parents);
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#endif
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