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pseudo-merge: implement support for reading pseudo-merge commits
Implement the basic API for reading pseudo-merge bitmaps, which consists
of four basic functions:
- pseudo_merge_bitmap()
- use_pseudo_merge()
- apply_pseudo_merges_for_commit()
- cascade_pseudo_merges()
These functions are all documented in pseudo-merge.h, but their rough
descriptions are as follows:
- pseudo_merge_bitmap() reads and inflates the objects EWAH bitmap for
a given pseudo-merge
- use_pseudo_merge() does the same as pseudo_merge_bitmap(), but on
the commits EWAH bitmap, not the objects bitmap
- apply_pseudo_merges_for_commit() applies all satisfied pseudo-merge
commits for a given result set, and cascades any yet-unsatisfied
pseudo-merges if any were applied in the previous step
- cascade_pseudo_merges() applies all pseudo-merges which are
satisfied but have not been previously applied, repeating this
process until no more pseudo-merges can be applied
The core of the API is the latter two functions, which are responsible
for applying pseudo-merges during the object traversal implemented in
the pack-bitmap machinery.
The other two functions (pseudo_merge_bitmap(), and use_pseudo_merge())
are low-level ways to interact with the pseudo-merge machinery, which
will be useful in future commits.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Taylor Blau
Junio C Hamano
parent
7c0fae8844
commit
955747b4da
235
pseudo-merge.c
235
pseudo-merge.c
@ -10,6 +10,7 @@
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#include "commit.h"
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#include "alloc.h"
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#include "progress.h"
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#include "hex.h"
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#define DEFAULT_PSEUDO_MERGE_DECAY 1.0
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#define DEFAULT_PSEUDO_MERGE_MAX_MERGES 64
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@ -464,3 +465,237 @@ void free_pseudo_merge_map(struct pseudo_merge_map *pm)
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}
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free(pm->v);
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}
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struct pseudo_merge_commit_ext {
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uint32_t nr;
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const unsigned char *ptr;
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};
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static int pseudo_merge_ext_at(const struct pseudo_merge_map *pm,
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struct pseudo_merge_commit_ext *ext, size_t at)
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{
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if (at >= pm->map_size)
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return error(_("extended pseudo-merge read out-of-bounds "
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"(%"PRIuMAX" >= %"PRIuMAX")"),
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(uintmax_t)at, (uintmax_t)pm->map_size);
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if (at + 4 >= pm->map_size)
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return error(_("extended pseudo-merge entry is too short "
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"(%"PRIuMAX" >= %"PRIuMAX")"),
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(uintmax_t)(at + 4), (uintmax_t)pm->map_size);
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ext->nr = get_be32(pm->map + at);
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ext->ptr = pm->map + at + sizeof(uint32_t);
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return 0;
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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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if (!merge->loaded_commits)
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BUG("cannot use unloaded pseudo-merge bitmap");
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if (!merge->loaded_bitmap) {
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size_t at = merge->bitmap_at;
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merge->bitmap = read_bitmap(pm->map, pm->map_size, &at);
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merge->loaded_bitmap = 1;
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}
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return merge->bitmap;
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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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if (!merge->loaded_commits) {
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size_t pos = merge->at;
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merge->commits = read_bitmap(pm->map, pm->map_size, &pos);
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merge->bitmap_at = pos;
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merge->loaded_commits = 1;
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}
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return merge;
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}
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static struct pseudo_merge *pseudo_merge_at(const struct pseudo_merge_map *pm,
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struct object_id *oid,
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size_t want)
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{
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size_t lo = 0;
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size_t hi = pm->nr;
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while (lo < hi) {
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size_t mi = lo + (hi - lo) / 2;
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size_t got = pm->v[mi].at;
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if (got == want)
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return use_pseudo_merge(pm, &pm->v[mi]);
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else if (got < want)
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hi = mi;
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else
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lo = mi + 1;
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}
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warning(_("could not find pseudo-merge for commit %s at offset %"PRIuMAX),
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oid_to_hex(oid), (uintmax_t)want);
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return NULL;
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}
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struct pseudo_merge_commit {
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uint32_t commit_pos;
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uint64_t pseudo_merge_ofs;
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};
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#define PSEUDO_MERGE_COMMIT_RAWSZ (sizeof(uint32_t)+sizeof(uint64_t))
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static void read_pseudo_merge_commit_at(struct pseudo_merge_commit *merge,
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const unsigned char *at)
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{
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merge->commit_pos = get_be32(at);
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merge->pseudo_merge_ofs = get_be64(at + sizeof(uint32_t));
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}
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static int nth_pseudo_merge_ext(const struct pseudo_merge_map *pm,
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struct pseudo_merge_commit_ext *ext,
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struct pseudo_merge_commit *merge,
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uint32_t n)
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{
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size_t ofs;
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if (n >= ext->nr)
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return error(_("extended pseudo-merge lookup out-of-bounds "
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"(%"PRIu32" >= %"PRIu32")"), n, ext->nr);
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ofs = get_be64(ext->ptr + st_mult(n, sizeof(uint64_t)));
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if (ofs >= pm->map_size)
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return error(_("out-of-bounds read: (%"PRIuMAX" >= %"PRIuMAX")"),
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(uintmax_t)ofs, (uintmax_t)pm->map_size);
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read_pseudo_merge_commit_at(merge, pm->map + ofs);
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return 0;
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}
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static unsigned apply_pseudo_merge(const struct pseudo_merge_map *pm,
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struct pseudo_merge *merge,
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struct bitmap *result,
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struct bitmap *roots)
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{
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if (merge->satisfied)
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return 0;
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if (!ewah_bitmap_is_subset(merge->commits, roots ? roots : result))
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return 0;
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bitmap_or_ewah(result, pseudo_merge_bitmap(pm, merge));
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if (roots)
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bitmap_or_ewah(roots, pseudo_merge_bitmap(pm, merge));
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merge->satisfied = 1;
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return 1;
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}
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static int pseudo_merge_commit_cmp(const void *va, const void *vb)
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{
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struct pseudo_merge_commit merge;
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uint32_t key = *(uint32_t*)va;
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read_pseudo_merge_commit_at(&merge, vb);
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if (key < merge.commit_pos)
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return -1;
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if (key > merge.commit_pos)
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return 1;
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return 0;
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}
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static struct pseudo_merge_commit *find_pseudo_merge(const struct pseudo_merge_map *pm,
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uint32_t pos)
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{
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if (!pm->commits_nr)
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return NULL;
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return bsearch(&pos, pm->commits, pm->commits_nr,
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PSEUDO_MERGE_COMMIT_RAWSZ, pseudo_merge_commit_cmp);
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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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struct pseudo_merge *merge;
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struct pseudo_merge_commit *merge_commit;
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int ret = 0;
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merge_commit = find_pseudo_merge(pm, commit_pos);
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if (!merge_commit)
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return 0;
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if (merge_commit->pseudo_merge_ofs & ((uint64_t)1<<63)) {
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struct pseudo_merge_commit_ext ext = { 0 };
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off_t ofs = merge_commit->pseudo_merge_ofs & ~((uint64_t)1<<63);
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uint32_t i;
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if (pseudo_merge_ext_at(pm, &ext, ofs) < -1) {
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warning(_("could not read extended pseudo-merge table "
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"for commit %s"),
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oid_to_hex(&commit->object.oid));
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return ret;
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}
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for (i = 0; i < ext.nr; i++) {
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if (nth_pseudo_merge_ext(pm, &ext, merge_commit, i) < 0)
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return ret;
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merge = pseudo_merge_at(pm, &commit->object.oid,
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merge_commit->pseudo_merge_ofs);
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if (!merge)
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return ret;
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if (apply_pseudo_merge(pm, merge, result, NULL))
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ret++;
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}
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} else {
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merge = pseudo_merge_at(pm, &commit->object.oid,
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merge_commit->pseudo_merge_ofs);
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if (!merge)
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return ret;
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if (apply_pseudo_merge(pm, merge, result, NULL))
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ret++;
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}
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if (ret)
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cascade_pseudo_merges(pm, result, NULL);
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return ret;
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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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unsigned any_satisfied;
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int ret = 0;
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do {
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struct pseudo_merge *merge;
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uint32_t i;
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any_satisfied = 0;
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for (i = 0; i < pm->nr; i++) {
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merge = use_pseudo_merge(pm, &pm->v[i]);
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if (apply_pseudo_merge(pm, merge, result, roots)) {
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any_satisfied |= 1;
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ret++;
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}
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}
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} while (any_satisfied);
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return ret;
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}
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@ -162,4 +162,48 @@ struct pseudo_merge {
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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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#endif
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