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@xxxxxxxxxxxx>
---
pseudo-merge.c | 235 +++++++++++++++++++++++++++++++++++++++++++++++++
pseudo-merge.h | 44 +++++++++
2 files changed, 279 insertions(+)
diff --git a/pseudo-merge.c b/pseudo-merge.c
index f0080d53c03..7d131011497 100644
--- a/pseudo-merge.c
+++ b/pseudo-merge.c
@@ -10,6 +10,7 @@
#include "commit.h"
#include "alloc.h"
#include "progress.h"
+#include "hex.h"
#define DEFAULT_PSEUDO_MERGE_DECAY 1.0
#define DEFAULT_PSEUDO_MERGE_MAX_MERGES 64
@@ -464,3 +465,237 @@ void free_pseudo_merge_map(struct pseudo_merge_map *pm)
}
free(pm->v);
}
+
+struct pseudo_merge_commit_ext {
+ uint32_t nr;
+ const unsigned char *ptr;
+};
+
+static int pseudo_merge_ext_at(const struct pseudo_merge_map *pm,
+ struct pseudo_merge_commit_ext *ext, size_t at)
+{
+ if (at >= pm->map_size)
+ return error(_("extended pseudo-merge read out-of-bounds "
+ "(%"PRIuMAX" >= %"PRIuMAX")"),
+ (uintmax_t)at, (uintmax_t)pm->map_size);
+ if (at + 4 >= pm->map_size)
+ return error(_("extended pseudo-merge entry is too short "
+ "(%"PRIuMAX" >= %"PRIuMAX")"),
+ (uintmax_t)(at + 4), (uintmax_t)pm->map_size);
+
+ ext->nr = get_be32(pm->map + at);
+ ext->ptr = pm->map + at + sizeof(uint32_t);
+
+ return 0;
+}
+
+struct ewah_bitmap *pseudo_merge_bitmap(const struct pseudo_merge_map *pm,
+ struct pseudo_merge *merge)
+{
+ if (!merge->loaded_commits)
+ BUG("cannot use unloaded pseudo-merge bitmap");
+
+ if (!merge->loaded_bitmap) {
+ size_t at = merge->bitmap_at;
+
+ merge->bitmap = read_bitmap(pm->map, pm->map_size, &at);
+ merge->loaded_bitmap = 1;
+ }
+
+ return merge->bitmap;
+}
+
+struct pseudo_merge *use_pseudo_merge(const struct pseudo_merge_map *pm,
+ struct pseudo_merge *merge)
+{
+ if (!merge->loaded_commits) {
+ size_t pos = merge->at;
+
+ merge->commits = read_bitmap(pm->map, pm->map_size, &pos);
+ merge->bitmap_at = pos;
+ merge->loaded_commits = 1;
+ }
+ return merge;
+}
+
+static struct pseudo_merge *pseudo_merge_at(const struct pseudo_merge_map *pm,
+ struct object_id *oid,
+ size_t want)
+{
+ size_t lo = 0;
+ size_t hi = pm->nr;
+
+ while (lo < hi) {
+ size_t mi = lo + (hi - lo) / 2;
+ size_t got = pm->v[mi].at;
+
+ if (got == want)
+ return use_pseudo_merge(pm, &pm->v[mi]);
+ else if (got < want)
+ hi = mi;
+ else
+ lo = mi + 1;
+ }
+
+ warning(_("could not find pseudo-merge for commit %s at offset %"PRIuMAX),
+ oid_to_hex(oid), (uintmax_t)want);
+
+ return NULL;
+}
+
+struct pseudo_merge_commit {
+ uint32_t commit_pos;
+ uint64_t pseudo_merge_ofs;
+};
+
+#define PSEUDO_MERGE_COMMIT_RAWSZ (sizeof(uint32_t)+sizeof(uint64_t))
+
+static void read_pseudo_merge_commit_at(struct pseudo_merge_commit *merge,
+ const unsigned char *at)
+{
+ merge->commit_pos = get_be32(at);
+ merge->pseudo_merge_ofs = get_be64(at + sizeof(uint32_t));
+}
+
+static int nth_pseudo_merge_ext(const struct pseudo_merge_map *pm,
+ struct pseudo_merge_commit_ext *ext,
+ struct pseudo_merge_commit *merge,
+ uint32_t n)
+{
+ size_t ofs;
+
+ if (n >= ext->nr)
+ return error(_("extended pseudo-merge lookup out-of-bounds "
+ "(%"PRIu32" >= %"PRIu32")"), n, ext->nr);
+
+ ofs = get_be64(ext->ptr + st_mult(n, sizeof(uint64_t)));
+ if (ofs >= pm->map_size)
+ return error(_("out-of-bounds read: (%"PRIuMAX" >= %"PRIuMAX")"),
+ (uintmax_t)ofs, (uintmax_t)pm->map_size);
+
+ read_pseudo_merge_commit_at(merge, pm->map + ofs);
+
+ return 0;
+}
+
+static unsigned apply_pseudo_merge(const struct pseudo_merge_map *pm,
+ struct pseudo_merge *merge,
+ struct bitmap *result,
+ struct bitmap *roots)
+{
+ if (merge->satisfied)
+ return 0;
+
+ if (!ewah_bitmap_is_subset(merge->commits, roots ? roots : result))
+ return 0;
+
+ bitmap_or_ewah(result, pseudo_merge_bitmap(pm, merge));
+ if (roots)
+ bitmap_or_ewah(roots, pseudo_merge_bitmap(pm, merge));
+ merge->satisfied = 1;
+
+ return 1;
+}
+
+static int pseudo_merge_commit_cmp(const void *va, const void *vb)
+{
+ struct pseudo_merge_commit merge;
+ uint32_t key = *(uint32_t*)va;
+
+ read_pseudo_merge_commit_at(&merge, vb);
+
+ if (key < merge.commit_pos)
+ return -1;
+ if (key > merge.commit_pos)
+ return 1;
+ return 0;
+}
+
+static struct pseudo_merge_commit *find_pseudo_merge(const struct pseudo_merge_map *pm,
+ uint32_t pos)
+{
+ if (!pm->commits_nr)
+ return NULL;
+
+ return bsearch(&pos, pm->commits, pm->commits_nr,
+ PSEUDO_MERGE_COMMIT_RAWSZ, pseudo_merge_commit_cmp);
+}
+
+int apply_pseudo_merges_for_commit(const struct pseudo_merge_map *pm,
+ struct bitmap *result,
+ struct commit *commit, uint32_t commit_pos)
+{
+ struct pseudo_merge *merge;
+ struct pseudo_merge_commit *merge_commit;
+ int ret = 0;
+
+ merge_commit = find_pseudo_merge(pm, commit_pos);
+ if (!merge_commit)
+ return 0;
+
+ if (merge_commit->pseudo_merge_ofs & ((uint64_t)1<<63)) {
+ struct pseudo_merge_commit_ext ext = { 0 };
+ off_t ofs = merge_commit->pseudo_merge_ofs & ~((uint64_t)1<<63);
+ uint32_t i;
+
+ if (pseudo_merge_ext_at(pm, &ext, ofs) < -1) {
+ warning(_("could not read extended pseudo-merge table "
+ "for commit %s"),
+ oid_to_hex(&commit->object.oid));
+ return ret;
+ }
+
+ for (i = 0; i < ext.nr; i++) {
+ if (nth_pseudo_merge_ext(pm, &ext, merge_commit, i) < 0)
+ return ret;
+
+ merge = pseudo_merge_at(pm, &commit->object.oid,
+ merge_commit->pseudo_merge_ofs);
+
+ if (!merge)
+ return ret;
+
+ if (apply_pseudo_merge(pm, merge, result, NULL))
+ ret++;
+ }
+ } else {
+ merge = pseudo_merge_at(pm, &commit->object.oid,
+ merge_commit->pseudo_merge_ofs);
+
+ if (!merge)
+ return ret;
+
+ if (apply_pseudo_merge(pm, merge, result, NULL))
+ ret++;
+ }
+
+ if (ret)
+ cascade_pseudo_merges(pm, result, NULL);
+
+ return ret;
+}
+
+int cascade_pseudo_merges(const struct pseudo_merge_map *pm,
+ struct bitmap *result,
+ struct bitmap *roots)
+{
+ unsigned any_satisfied;
+ int ret = 0;
+
+ do {
+ struct pseudo_merge *merge;
+ uint32_t i;
+
+ any_satisfied = 0;
+
+ for (i = 0; i < pm->nr; i++) {
+ merge = use_pseudo_merge(pm, &pm->v[i]);
+ if (apply_pseudo_merge(pm, merge, result, roots)) {
+ any_satisfied |= 1;
+ ret++;
+ }
+ }
+ } while (any_satisfied);
+
+ return ret;
+}
diff --git a/pseudo-merge.h b/pseudo-merge.h
index e9216baace8..755edc054ae 100644
--- a/pseudo-merge.h
+++ b/pseudo-merge.h
@@ -162,4 +162,48 @@ struct pseudo_merge {
*/
void free_pseudo_merge_map(struct pseudo_merge_map *pm);
+/*
+ * Loads the bitmap corresponding to the given pseudo-merge from the
+ * map, if it has not already been loaded.
+ */
+struct ewah_bitmap *pseudo_merge_bitmap(const struct pseudo_merge_map *pm,
+ struct pseudo_merge *merge);
+
+/*
+ * Loads the pseudo-merge and its commits bitmap from the given
+ * pseudo-merge map, if it has not already been loaded.
+ */
+struct pseudo_merge *use_pseudo_merge(const struct pseudo_merge_map *pm,
+ struct pseudo_merge *merge);
+
+/*
+ * Applies pseudo-merge(s) containing the given commit to the bitmap
+ * "result".
+ *
+ * If any pseudo-merge(s) were satisfied, returns the number
+ * satisfied, otherwise returns 0. If any were satisfied, the
+ * remaining unsatisfied pseudo-merges are cascaded (see below).
+ */
+int apply_pseudo_merges_for_commit(const struct pseudo_merge_map *pm,
+ struct bitmap *result,
+ struct commit *commit, uint32_t commit_pos);
+
+/*
+ * Applies pseudo-merge(s) which are satisfied according to the
+ * current bitmap in result (or roots, see below). If any
+ * pseudo-merges were satisfied, repeat the process over unsatisfied
+ * pseudo-merge commits until no more pseudo-merges are satisfied.
+ *
+ * Result is the bitmap to which the pseudo-merge(s) are applied.
+ * Roots (if given) is a bitmap of the traversal tip(s) for either
+ * side of a reachability traversal.
+ *
+ * Roots may given instead of a populated results bitmap at the
+ * beginning of a traversal on either side where the reachability
+ * closure over tips is not yet known.
+ */
+int cascade_pseudo_merges(const struct pseudo_merge_map *pm,
+ struct bitmap *result,
+ struct bitmap *roots);
+
#endif
--
2.45.1.175.gcf0316ad0e9
