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-rw-r--r--delta-islands.c506
1 files changed, 506 insertions, 0 deletions
diff --git a/delta-islands.c b/delta-islands.c
new file mode 100644
index 0000000..2186bd0
--- /dev/null
+++ b/delta-islands.c
@@ -0,0 +1,506 @@
+#include "cache.h"
+#include "attr.h"
+#include "object.h"
+#include "blob.h"
+#include "commit.h"
+#include "tag.h"
+#include "tree.h"
+#include "delta.h"
+#include "pack.h"
+#include "tree-walk.h"
+#include "diff.h"
+#include "revision.h"
+#include "list-objects.h"
+#include "progress.h"
+#include "refs.h"
+#include "khash.h"
+#include "pack-bitmap.h"
+#include "pack-objects.h"
+#include "delta-islands.h"
+#include "sha1-array.h"
+#include "config.h"
+
+KHASH_INIT(str, const char *, void *, 1, kh_str_hash_func, kh_str_hash_equal)
+
+static khash_sha1 *island_marks;
+static unsigned island_counter;
+static unsigned island_counter_core;
+
+static kh_str_t *remote_islands;
+
+struct remote_island {
+ uint64_t hash;
+ struct oid_array oids;
+};
+
+struct island_bitmap {
+ uint32_t refcount;
+ uint32_t bits[FLEX_ARRAY];
+};
+
+static uint32_t island_bitmap_size;
+
+/*
+ * Allocate a new bitmap; if "old" is not NULL, the new bitmap will be a copy
+ * of "old". Otherwise, the new bitmap is empty.
+ */
+static struct island_bitmap *island_bitmap_new(const struct island_bitmap *old)
+{
+ size_t size = sizeof(struct island_bitmap) + (island_bitmap_size * 4);
+ struct island_bitmap *b = xcalloc(1, size);
+
+ if (old)
+ memcpy(b, old, size);
+
+ b->refcount = 1;
+ return b;
+}
+
+static void island_bitmap_or(struct island_bitmap *a, const struct island_bitmap *b)
+{
+ uint32_t i;
+
+ for (i = 0; i < island_bitmap_size; ++i)
+ a->bits[i] |= b->bits[i];
+}
+
+static int island_bitmap_is_subset(struct island_bitmap *self,
+ struct island_bitmap *super)
+{
+ uint32_t i;
+
+ if (self == super)
+ return 1;
+
+ for (i = 0; i < island_bitmap_size; ++i) {
+ if ((self->bits[i] & super->bits[i]) != self->bits[i])
+ return 0;
+ }
+
+ return 1;
+}
+
+#define ISLAND_BITMAP_BLOCK(x) (x / 32)
+#define ISLAND_BITMAP_MASK(x) (1 << (x % 32))
+
+static void island_bitmap_set(struct island_bitmap *self, uint32_t i)
+{
+ self->bits[ISLAND_BITMAP_BLOCK(i)] |= ISLAND_BITMAP_MASK(i);
+}
+
+static int island_bitmap_get(struct island_bitmap *self, uint32_t i)
+{
+ return (self->bits[ISLAND_BITMAP_BLOCK(i)] & ISLAND_BITMAP_MASK(i)) != 0;
+}
+
+int in_same_island(const struct object_id *trg_oid, const struct object_id *src_oid)
+{
+ khiter_t trg_pos, src_pos;
+
+ /* If we aren't using islands, assume everything goes together. */
+ if (!island_marks)
+ return 1;
+
+ /*
+ * If we don't have a bitmap for the target, we can delta it
+ * against anything -- it's not an important object
+ */
+ trg_pos = kh_get_sha1(island_marks, trg_oid->hash);
+ if (trg_pos >= kh_end(island_marks))
+ return 1;
+
+ /*
+ * if the source (our delta base) doesn't have a bitmap,
+ * we don't want to base any deltas on it!
+ */
+ src_pos = kh_get_sha1(island_marks, src_oid->hash);
+ if (src_pos >= kh_end(island_marks))
+ return 0;
+
+ return island_bitmap_is_subset(kh_value(island_marks, trg_pos),
+ kh_value(island_marks, src_pos));
+}
+
+int island_delta_cmp(const struct object_id *a, const struct object_id *b)
+{
+ khiter_t a_pos, b_pos;
+ struct island_bitmap *a_bitmap = NULL, *b_bitmap = NULL;
+
+ if (!island_marks)
+ return 0;
+
+ a_pos = kh_get_sha1(island_marks, a->hash);
+ if (a_pos < kh_end(island_marks))
+ a_bitmap = kh_value(island_marks, a_pos);
+
+ b_pos = kh_get_sha1(island_marks, b->hash);
+ if (b_pos < kh_end(island_marks))
+ b_bitmap = kh_value(island_marks, b_pos);
+
+ if (a_bitmap) {
+ if (!b_bitmap || !island_bitmap_is_subset(a_bitmap, b_bitmap))
+ return -1;
+ }
+ if (b_bitmap) {
+ if (!a_bitmap || !island_bitmap_is_subset(b_bitmap, a_bitmap))
+ return 1;
+ }
+
+ return 0;
+}
+
+static struct island_bitmap *create_or_get_island_marks(struct object *obj)
+{
+ khiter_t pos;
+ int hash_ret;
+
+ pos = kh_put_sha1(island_marks, obj->oid.hash, &hash_ret);
+ if (hash_ret)
+ kh_value(island_marks, pos) = island_bitmap_new(NULL);
+
+ return kh_value(island_marks, pos);
+}
+
+static void set_island_marks(struct object *obj, struct island_bitmap *marks)
+{
+ struct island_bitmap *b;
+ khiter_t pos;
+ int hash_ret;
+
+ pos = kh_put_sha1(island_marks, obj->oid.hash, &hash_ret);
+ if (hash_ret) {
+ /*
+ * We don't have one yet; make a copy-on-write of the
+ * parent.
+ */
+ marks->refcount++;
+ kh_value(island_marks, pos) = marks;
+ return;
+ }
+
+ /*
+ * We do have it. Make sure we split any copy-on-write before
+ * updating.
+ */
+ b = kh_value(island_marks, pos);
+ if (b->refcount > 1) {
+ b->refcount--;
+ b = kh_value(island_marks, pos) = island_bitmap_new(b);
+ }
+ island_bitmap_or(b, marks);
+}
+
+static void mark_remote_island_1(struct repository *r,
+ struct remote_island *rl,
+ int is_core_island)
+{
+ uint32_t i;
+
+ for (i = 0; i < rl->oids.nr; ++i) {
+ struct island_bitmap *marks;
+ struct object *obj = parse_object(r, &rl->oids.oid[i]);
+
+ if (!obj)
+ continue;
+
+ marks = create_or_get_island_marks(obj);
+ island_bitmap_set(marks, island_counter);
+
+ if (is_core_island && obj->type == OBJ_COMMIT)
+ obj->flags |= NEEDS_BITMAP;
+
+ /* If it was a tag, also make sure we hit the underlying object. */
+ while (obj && obj->type == OBJ_TAG) {
+ obj = ((struct tag *)obj)->tagged;
+ if (obj) {
+ parse_object(r, &obj->oid);
+ marks = create_or_get_island_marks(obj);
+ island_bitmap_set(marks, island_counter);
+ }
+ }
+ }
+
+ if (is_core_island)
+ island_counter_core = island_counter;
+
+ island_counter++;
+}
+
+struct tree_islands_todo {
+ struct object_entry *entry;
+ unsigned int depth;
+};
+
+static int tree_depth_compare(const void *a, const void *b)
+{
+ const struct tree_islands_todo *todo_a = a;
+ const struct tree_islands_todo *todo_b = b;
+
+ return todo_a->depth - todo_b->depth;
+}
+
+void resolve_tree_islands(struct repository *r,
+ int progress,
+ struct packing_data *to_pack)
+{
+ struct progress *progress_state = NULL;
+ struct tree_islands_todo *todo;
+ int nr = 0;
+ int i;
+
+ if (!island_marks)
+ return;
+
+ /*
+ * We process only trees, as commits and tags have already been handled
+ * (and passed their marks on to root trees, as well. We must make sure
+ * to process them in descending tree-depth order so that marks
+ * propagate down the tree properly, even if a sub-tree is found in
+ * multiple parent trees.
+ */
+ ALLOC_ARRAY(todo, to_pack->nr_objects);
+ for (i = 0; i < to_pack->nr_objects; i++) {
+ if (oe_type(&to_pack->objects[i]) == OBJ_TREE) {
+ todo[nr].entry = &to_pack->objects[i];
+ todo[nr].depth = oe_tree_depth(to_pack, &to_pack->objects[i]);
+ nr++;
+ }
+ }
+ QSORT(todo, nr, tree_depth_compare);
+
+ if (progress)
+ progress_state = start_progress(_("Propagating island marks"), nr);
+
+ for (i = 0; i < nr; i++) {
+ struct object_entry *ent = todo[i].entry;
+ struct island_bitmap *root_marks;
+ struct tree *tree;
+ struct tree_desc desc;
+ struct name_entry entry;
+ khiter_t pos;
+
+ pos = kh_get_sha1(island_marks, ent->idx.oid.hash);
+ if (pos >= kh_end(island_marks))
+ continue;
+
+ root_marks = kh_value(island_marks, pos);
+
+ tree = lookup_tree(r, &ent->idx.oid);
+ if (!tree || parse_tree(tree) < 0)
+ die(_("bad tree object %s"), oid_to_hex(&ent->idx.oid));
+
+ init_tree_desc(&desc, tree->buffer, tree->size);
+ while (tree_entry(&desc, &entry)) {
+ struct object *obj;
+
+ if (S_ISGITLINK(entry.mode))
+ continue;
+
+ obj = lookup_object(r, entry.oid.hash);
+ if (!obj)
+ continue;
+
+ set_island_marks(obj, root_marks);
+ }
+
+ free_tree_buffer(tree);
+
+ display_progress(progress_state, i+1);
+ }
+
+ stop_progress(&progress_state);
+ free(todo);
+}
+
+static regex_t *island_regexes;
+static unsigned int island_regexes_alloc, island_regexes_nr;
+static const char *core_island_name;
+
+static int island_config_callback(const char *k, const char *v, void *cb)
+{
+ if (!strcmp(k, "pack.island")) {
+ struct strbuf re = STRBUF_INIT;
+
+ if (!v)
+ return config_error_nonbool(k);
+
+ ALLOC_GROW(island_regexes, island_regexes_nr + 1, island_regexes_alloc);
+
+ if (*v != '^')
+ strbuf_addch(&re, '^');
+ strbuf_addstr(&re, v);
+
+ if (regcomp(&island_regexes[island_regexes_nr], re.buf, REG_EXTENDED))
+ die(_("failed to load island regex for '%s': %s"), k, re.buf);
+
+ strbuf_release(&re);
+ island_regexes_nr++;
+ return 0;
+ }
+
+ if (!strcmp(k, "pack.islandcore"))
+ return git_config_string(&core_island_name, k, v);
+
+ return 0;
+}
+
+static void add_ref_to_island(const char *island_name, const struct object_id *oid)
+{
+ uint64_t sha_core;
+ struct remote_island *rl = NULL;
+
+ int hash_ret;
+ khiter_t pos = kh_put_str(remote_islands, island_name, &hash_ret);
+
+ if (hash_ret) {
+ kh_key(remote_islands, pos) = xstrdup(island_name);
+ kh_value(remote_islands, pos) = xcalloc(1, sizeof(struct remote_island));
+ }
+
+ rl = kh_value(remote_islands, pos);
+ oid_array_append(&rl->oids, oid);
+
+ memcpy(&sha_core, oid->hash, sizeof(uint64_t));
+ rl->hash += sha_core;
+}
+
+static int find_island_for_ref(const char *refname, const struct object_id *oid,
+ int flags, void *data)
+{
+ /*
+ * We should advertise 'ARRAY_SIZE(matches) - 2' as the max,
+ * so we can diagnose below a config with more capture groups
+ * than we support.
+ */
+ regmatch_t matches[16];
+ int i, m;
+ struct strbuf island_name = STRBUF_INIT;
+
+ /* walk backwards to get last-one-wins ordering */
+ for (i = island_regexes_nr - 1; i >= 0; i--) {
+ if (!regexec(&island_regexes[i], refname,
+ ARRAY_SIZE(matches), matches, 0))
+ break;
+ }
+
+ if (i < 0)
+ return 0;
+
+ if (matches[ARRAY_SIZE(matches) - 1].rm_so != -1)
+ warning(_("island regex from config has "
+ "too many capture groups (max=%d)"),
+ (int)ARRAY_SIZE(matches) - 2);
+
+ for (m = 1; m < ARRAY_SIZE(matches); m++) {
+ regmatch_t *match = &matches[m];
+
+ if (match->rm_so == -1)
+ continue;
+
+ if (island_name.len)
+ strbuf_addch(&island_name, '-');
+
+ strbuf_add(&island_name, refname + match->rm_so, match->rm_eo - match->rm_so);
+ }
+
+ add_ref_to_island(island_name.buf, oid);
+ strbuf_release(&island_name);
+ return 0;
+}
+
+static struct remote_island *get_core_island(void)
+{
+ if (core_island_name) {
+ khiter_t pos = kh_get_str(remote_islands, core_island_name);
+ if (pos < kh_end(remote_islands))
+ return kh_value(remote_islands, pos);
+ }
+
+ return NULL;
+}
+
+static void deduplicate_islands(struct repository *r)
+{
+ struct remote_island *island, *core = NULL, **list;
+ unsigned int island_count, dst, src, ref, i = 0;
+
+ island_count = kh_size(remote_islands);
+ ALLOC_ARRAY(list, island_count);
+
+ kh_foreach_value(remote_islands, island, {
+ list[i++] = island;
+ });
+
+ for (ref = 0; ref + 1 < island_count; ref++) {
+ for (src = ref + 1, dst = src; src < island_count; src++) {
+ if (list[ref]->hash == list[src]->hash)
+ continue;
+
+ if (src != dst)
+ list[dst] = list[src];
+
+ dst++;
+ }
+ island_count = dst;
+ }
+
+ island_bitmap_size = (island_count / 32) + 1;
+ core = get_core_island();
+
+ for (i = 0; i < island_count; ++i) {
+ mark_remote_island_1(r, list[i], core && list[i]->hash == core->hash);
+ }
+
+ free(list);
+}
+
+void load_delta_islands(struct repository *r)
+{
+ island_marks = kh_init_sha1();
+ remote_islands = kh_init_str();
+
+ git_config(island_config_callback, NULL);
+ for_each_ref(find_island_for_ref, NULL);
+ deduplicate_islands(r);
+
+ fprintf(stderr, _("Marked %d islands, done.\n"), island_counter);
+}
+
+void propagate_island_marks(struct commit *commit)
+{
+ khiter_t pos = kh_get_sha1(island_marks, commit->object.oid.hash);
+
+ if (pos < kh_end(island_marks)) {
+ struct commit_list *p;
+ struct island_bitmap *root_marks = kh_value(island_marks, pos);
+
+ parse_commit(commit);
+ set_island_marks(&get_commit_tree(commit)->object, root_marks);
+ for (p = commit->parents; p; p = p->next)
+ set_island_marks(&p->item->object, root_marks);
+ }
+}
+
+int compute_pack_layers(struct packing_data *to_pack)
+{
+ uint32_t i;
+
+ if (!core_island_name || !island_marks)
+ return 1;
+
+ for (i = 0; i < to_pack->nr_objects; ++i) {
+ struct object_entry *entry = &to_pack->objects[i];
+ khiter_t pos = kh_get_sha1(island_marks, entry->idx.oid.hash);
+
+ oe_set_layer(to_pack, entry, 1);
+
+ if (pos < kh_end(island_marks)) {
+ struct island_bitmap *bitmap = kh_value(island_marks, pos);
+
+ if (island_bitmap_get(bitmap, island_counter_core))
+ oe_set_layer(to_pack, entry, 0);
+ }
+ }
+
+ return 2;
+}