Sync with 2.18.1
[gitweb.git] / commit.c
index cab8d4455bdbd6e4b87031613300be1112a19df5..449c1f4920cff631f5cf2479772c350c9b8b7325 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -1,17 +1,22 @@
 #include "cache.h"
 #include "tag.h"
 #include "commit.h"
+#include "commit-graph.h"
+#include "repository.h"
+#include "object-store.h"
 #include "pkt-line.h"
 #include "utf8.h"
 #include "diff.h"
 #include "revision.h"
 #include "notes.h"
+#include "alloc.h"
 #include "gpg-interface.h"
 #include "mergesort.h"
 #include "commit-slab.h"
 #include "prio-queue.h"
 #include "sha1-lookup.h"
 #include "wt-status.h"
+#include "advice.h"
 
 static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
 
@@ -19,24 +24,26 @@ int save_commit_buffer = 1;
 
 const char *commit_type = "commit";
 
-struct commit *lookup_commit_reference_gently(const struct object_id *oid,
-                                             int quiet)
+struct commit *lookup_commit_reference_gently(struct repository *r,
+               const struct object_id *oid, int quiet)
 {
-       struct object *obj = deref_tag(parse_object(oid), NULL, 0);
+       struct object *obj = deref_tag(r,
+                                      parse_object(r, oid),
+                                      NULL, 0);
 
        if (!obj)
                return NULL;
-       return object_as_type(obj, OBJ_COMMIT, quiet);
+       return object_as_type(r, obj, OBJ_COMMIT, quiet);
 }
 
-struct commit *lookup_commit_reference(const struct object_id *oid)
+struct commit *lookup_commit_reference(struct repository *r, const struct object_id *oid)
 {
-       return lookup_commit_reference_gently(oid, 0);
+       return lookup_commit_reference_gently(r, oid, 0);
 }
 
 struct commit *lookup_commit_or_die(const struct object_id *oid, const char *ref_name)
 {
-       struct commit *c = lookup_commit_reference(oid);
+       struct commit *c = lookup_commit_reference(the_repository, oid);
        if (!c)
                die(_("could not parse %s"), ref_name);
        if (oidcmp(oid, &c->object.oid)) {
@@ -46,12 +53,13 @@ struct commit *lookup_commit_or_die(const struct object_id *oid, const char *ref
        return c;
 }
 
-struct commit *lookup_commit(const struct object_id *oid)
+struct commit *lookup_commit(struct repository *r, const struct object_id *oid)
 {
-       struct object *obj = lookup_object(oid->hash);
+       struct object *obj = lookup_object(r, oid->hash);
        if (!obj)
-               return create_object(oid->hash, alloc_commit_node());
-       return object_as_type(obj, OBJ_COMMIT, 0);
+               return create_object(r, oid->hash,
+                                    alloc_commit_node(r));
+       return object_as_type(r, obj, OBJ_COMMIT, 0);
 }
 
 struct commit *lookup_commit_reference_by_name(const char *name)
@@ -61,7 +69,7 @@ struct commit *lookup_commit_reference_by_name(const char *name)
 
        if (get_oid_committish(name, &oid))
                return NULL;
-       commit = lookup_commit_reference(&oid);
+       commit = lookup_commit_reference(the_repository, &oid);
        if (parse_commit(commit))
                return NULL;
        return commit;
@@ -94,43 +102,44 @@ static timestamp_t parse_commit_date(const char *buf, const char *tail)
        return parse_timestamp(dateptr, NULL, 10);
 }
 
-static struct commit_graft **commit_graft;
-static int commit_graft_alloc, commit_graft_nr;
-
 static const unsigned char *commit_graft_sha1_access(size_t index, void *table)
 {
        struct commit_graft **commit_graft_table = table;
        return commit_graft_table[index]->oid.hash;
 }
 
-static int commit_graft_pos(const unsigned char *sha1)
+static int commit_graft_pos(struct repository *r, const unsigned char *sha1)
 {
-       return sha1_pos(sha1, commit_graft, commit_graft_nr,
+       return sha1_pos(sha1, r->parsed_objects->grafts,
+                       r->parsed_objects->grafts_nr,
                        commit_graft_sha1_access);
 }
 
-int register_commit_graft(struct commit_graft *graft, int ignore_dups)
+int register_commit_graft(struct repository *r, struct commit_graft *graft,
+                         int ignore_dups)
 {
-       int pos = commit_graft_pos(graft->oid.hash);
+       int pos = commit_graft_pos(r, graft->oid.hash);
 
        if (0 <= pos) {
                if (ignore_dups)
                        free(graft);
                else {
-                       free(commit_graft[pos]);
-                       commit_graft[pos] = graft;
+                       free(r->parsed_objects->grafts[pos]);
+                       r->parsed_objects->grafts[pos] = graft;
                }
                return 1;
        }
        pos = -pos - 1;
-       ALLOC_GROW(commit_graft, commit_graft_nr + 1, commit_graft_alloc);
-       commit_graft_nr++;
-       if (pos < commit_graft_nr)
-               memmove(commit_graft + pos + 1,
-                       commit_graft + pos,
-                       (commit_graft_nr - pos - 1) *
-                       sizeof(*commit_graft));
-       commit_graft[pos] = graft;
+       ALLOC_GROW(r->parsed_objects->grafts,
+                  r->parsed_objects->grafts_nr + 1,
+                  r->parsed_objects->grafts_alloc);
+       r->parsed_objects->grafts_nr++;
+       if (pos < r->parsed_objects->grafts_nr)
+               memmove(r->parsed_objects->grafts + pos + 1,
+                       r->parsed_objects->grafts + pos,
+                       (r->parsed_objects->grafts_nr - pos - 1) *
+                       sizeof(*r->parsed_objects->grafts));
+       r->parsed_objects->grafts[pos] = graft;
        return 0;
 }
 
@@ -172,18 +181,27 @@ struct commit_graft *read_graft_line(struct strbuf *line)
        return NULL;
 }
 
-static int read_graft_file(const char *graft_file)
+static int read_graft_file(struct repository *r, const char *graft_file)
 {
        FILE *fp = fopen_or_warn(graft_file, "r");
        struct strbuf buf = STRBUF_INIT;
        if (!fp)
                return -1;
+       if (advice_graft_file_deprecated)
+               advise(_("Support for <GIT_DIR>/info/grafts is deprecated\n"
+                        "and will be removed in a future Git version.\n"
+                        "\n"
+                        "Please use \"git replace --convert-graft-file\"\n"
+                        "to convert the grafts into replace refs.\n"
+                        "\n"
+                        "Turn this message off by running\n"
+                        "\"git config advice.graftFileDeprecated false\""));
        while (!strbuf_getwholeline(&buf, fp, '\n')) {
                /* The format is just "Commit Parent1 Parent2 ...\n" */
                struct commit_graft *graft = read_graft_line(&buf);
                if (!graft)
                        continue;
-               if (register_commit_graft(graft, 1))
+               if (register_commit_graft(r, graft, 1))
                        error("duplicate graft data: %s", buf.buf);
        }
        fclose(fp);
@@ -191,47 +209,50 @@ static int read_graft_file(const char *graft_file)
        return 0;
 }
 
-static void prepare_commit_graft(void)
+static void prepare_commit_graft(struct repository *r)
 {
-       static int commit_graft_prepared;
        char *graft_file;
 
-       if (commit_graft_prepared)
+       if (r->parsed_objects->commit_graft_prepared)
+               return;
+       if (!startup_info->have_repository)
                return;
-       graft_file = get_graft_file();
-       read_graft_file(graft_file);
+
+       graft_file = get_graft_file(r);
+       read_graft_file(r, graft_file);
        /* make sure shallows are read */
-       is_repository_shallow();
-       commit_graft_prepared = 1;
+       is_repository_shallow(r);
+       r->parsed_objects->commit_graft_prepared = 1;
 }
 
-struct commit_graft *lookup_commit_graft(const struct object_id *oid)
+struct commit_graft *lookup_commit_graft(struct repository *r, const struct object_id *oid)
 {
        int pos;
-       prepare_commit_graft();
-       pos = commit_graft_pos(oid->hash);
+       prepare_commit_graft(r);
+       pos = commit_graft_pos(r, oid->hash);
        if (pos < 0)
                return NULL;
-       return commit_graft[pos];
+       return r->parsed_objects->grafts[pos];
 }
 
 int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 {
        int i, ret;
-       for (i = ret = 0; i < commit_graft_nr && !ret; i++)
-               ret = fn(commit_graft[i], cb_data);
+       for (i = ret = 0; i < the_repository->parsed_objects->grafts_nr && !ret; i++)
+               ret = fn(the_repository->parsed_objects->grafts[i], cb_data);
        return ret;
 }
 
 int unregister_shallow(const struct object_id *oid)
 {
-       int pos = commit_graft_pos(oid->hash);
+       int pos = commit_graft_pos(the_repository, oid->hash);
        if (pos < 0)
                return -1;
-       if (pos + 1 < commit_graft_nr)
-               MOVE_ARRAY(commit_graft + pos, commit_graft + pos + 1,
-                          commit_graft_nr - pos - 1);
-       commit_graft_nr--;
+       if (pos + 1 < the_repository->parsed_objects->grafts_nr)
+               MOVE_ARRAY(the_repository->parsed_objects->grafts + pos,
+                          the_repository->parsed_objects->grafts + pos + 1,
+                          the_repository->parsed_objects->grafts_nr - pos - 1);
+       the_repository->parsed_objects->grafts_nr--;
        return 0;
 }
 
@@ -240,18 +261,32 @@ struct commit_buffer {
        unsigned long size;
 };
 define_commit_slab(buffer_slab, struct commit_buffer);
-static struct buffer_slab buffer_slab = COMMIT_SLAB_INIT(1, buffer_slab);
 
-void set_commit_buffer(struct commit *commit, void *buffer, unsigned long size)
+struct buffer_slab *allocate_commit_buffer_slab(void)
+{
+       struct buffer_slab *bs = xmalloc(sizeof(*bs));
+       init_buffer_slab(bs);
+       return bs;
+}
+
+void free_commit_buffer_slab(struct buffer_slab *bs)
+{
+       clear_buffer_slab(bs);
+       free(bs);
+}
+
+void set_commit_buffer(struct repository *r, struct commit *commit, void *buffer, unsigned long size)
 {
-       struct commit_buffer *v = buffer_slab_at(&buffer_slab, commit);
+       struct commit_buffer *v = buffer_slab_at(
+               r->parsed_objects->buffer_slab, commit);
        v->buffer = buffer;
        v->size = size;
 }
 
-const void *get_cached_commit_buffer(const struct commit *commit, unsigned long *sizep)
+const void *get_cached_commit_buffer(struct repository *r, const struct commit *commit, unsigned long *sizep)
 {
-       struct commit_buffer *v = buffer_slab_peek(&buffer_slab, commit);
+       struct commit_buffer *v = buffer_slab_peek(
+               r->parsed_objects->buffer_slab, commit);
        if (!v) {
                if (sizep)
                        *sizep = 0;
@@ -264,17 +299,17 @@ const void *get_cached_commit_buffer(const struct commit *commit, unsigned long
 
 const void *get_commit_buffer(const struct commit *commit, unsigned long *sizep)
 {
-       const void *ret = get_cached_commit_buffer(commit, sizep);
+       const void *ret = get_cached_commit_buffer(the_repository, commit, sizep);
        if (!ret) {
                enum object_type type;
                unsigned long size;
-               ret = read_sha1_file(commit->object.oid.hash, &type, &size);
+               ret = read_object_file(&commit->object.oid, &type, &size);
                if (!ret)
                        die("cannot read commit object %s",
                            oid_to_hex(&commit->object.oid));
                if (type != OBJ_COMMIT)
                        die("expected commit for %s, got %s",
-                           oid_to_hex(&commit->object.oid), typename(type));
+                           oid_to_hex(&commit->object.oid), type_name(type));
                if (sizep)
                        *sizep = size;
        }
@@ -283,23 +318,53 @@ const void *get_commit_buffer(const struct commit *commit, unsigned long *sizep)
 
 void unuse_commit_buffer(const struct commit *commit, const void *buffer)
 {
-       struct commit_buffer *v = buffer_slab_peek(&buffer_slab, commit);
+       struct commit_buffer *v = buffer_slab_peek(
+               the_repository->parsed_objects->buffer_slab, commit);
        if (!(v && v->buffer == buffer))
                free((void *)buffer);
 }
 
 void free_commit_buffer(struct commit *commit)
 {
-       struct commit_buffer *v = buffer_slab_peek(&buffer_slab, commit);
+       struct commit_buffer *v = buffer_slab_peek(
+               the_repository->parsed_objects->buffer_slab, commit);
        if (v) {
                FREE_AND_NULL(v->buffer);
                v->size = 0;
        }
 }
 
+struct tree *get_commit_tree(const struct commit *commit)
+{
+       if (commit->maybe_tree || !commit->object.parsed)
+               return commit->maybe_tree;
+
+       if (commit->graph_pos == COMMIT_NOT_FROM_GRAPH)
+               BUG("commit has NULL tree, but was not loaded from commit-graph");
+
+       return get_commit_tree_in_graph(the_repository, commit);
+}
+
+struct object_id *get_commit_tree_oid(const struct commit *commit)
+{
+       return &get_commit_tree(commit)->object.oid;
+}
+
+void release_commit_memory(struct commit *c)
+{
+       c->maybe_tree = NULL;
+       c->index = 0;
+       free_commit_buffer(c);
+       free_commit_list(c->parents);
+       /* TODO: what about commit->util? */
+
+       c->object.parsed = 0;
+}
+
 const void *detach_commit_buffer(struct commit *commit, unsigned long *sizep)
 {
-       struct commit_buffer *v = buffer_slab_peek(&buffer_slab, commit);
+       struct commit_buffer *v = buffer_slab_peek(
+               the_repository->parsed_objects->buffer_slab, commit);
        void *ret;
 
        if (!v) {
@@ -316,15 +381,15 @@ const void *detach_commit_buffer(struct commit *commit, unsigned long *sizep)
        return ret;
 }
 
-int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
+int parse_commit_buffer(struct repository *r, struct commit *item, const void *buffer, unsigned long size, int check_graph)
 {
        const char *tail = buffer;
        const char *bufptr = buffer;
        struct object_id parent;
        struct commit_list **pptr;
        struct commit_graft *graft;
-       const int tree_entry_len = GIT_SHA1_HEXSZ + 5;
-       const int parent_entry_len = GIT_SHA1_HEXSZ + 7;
+       const int tree_entry_len = the_hash_algo->hexsz + 5;
+       const int parent_entry_len = the_hash_algo->hexsz + 7;
 
        if (item->object.parsed)
                return 0;
@@ -333,19 +398,19 @@ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long s
        if (tail <= bufptr + tree_entry_len + 1 || memcmp(bufptr, "tree ", 5) ||
                        bufptr[tree_entry_len] != '\n')
                return error("bogus commit object %s", oid_to_hex(&item->object.oid));
-       if (get_sha1_hex(bufptr + 5, parent.hash) < 0)
+       if (get_oid_hex(bufptr + 5, &parent) < 0)
                return error("bad tree pointer in commit %s",
                             oid_to_hex(&item->object.oid));
-       item->tree = lookup_tree(&parent);
+       item->maybe_tree = lookup_tree(r, &parent);
        bufptr += tree_entry_len + 1; /* "tree " + "hex sha1" + "\n" */
        pptr = &item->parents;
 
-       graft = lookup_commit_graft(&item->object.oid);
+       graft = lookup_commit_graft(r, &item->object.oid);
        while (bufptr + parent_entry_len < tail && !memcmp(bufptr, "parent ", 7)) {
                struct commit *new_parent;
 
                if (tail <= bufptr + parent_entry_len + 1 ||
-                   get_sha1_hex(bufptr + 7, parent.hash) ||
+                   get_oid_hex(bufptr + 7, &parent) ||
                    bufptr[parent_entry_len] != '\n')
                        return error("bad parents in commit %s", oid_to_hex(&item->object.oid));
                bufptr += parent_entry_len + 1;
@@ -355,7 +420,7 @@ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long s
                 */
                if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
                        continue;
-               new_parent = lookup_commit(&parent);
+               new_parent = lookup_commit(r, &parent);
                if (new_parent)
                        pptr = &commit_list_insert(new_parent, pptr)->next;
        }
@@ -363,7 +428,8 @@ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long s
                int i;
                struct commit *new_parent;
                for (i = 0; i < graft->nr_parent; i++) {
-                       new_parent = lookup_commit(&graft->parent[i]);
+                       new_parent = lookup_commit(r,
+                                                  &graft->parent[i]);
                        if (!new_parent)
                                continue;
                        pptr = &commit_list_insert(new_parent, pptr)->next;
@@ -371,10 +437,13 @@ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long s
        }
        item->date = parse_commit_date(bufptr, tail);
 
+       if (check_graph)
+               load_commit_graph_info(the_repository, item);
+
        return 0;
 }
 
-int parse_commit_gently(struct commit *item, int quiet_on_missing)
+int parse_commit_internal(struct commit *item, int quiet_on_missing, int use_commit_graph)
 {
        enum object_type type;
        void *buffer;
@@ -385,7 +454,9 @@ int parse_commit_gently(struct commit *item, int quiet_on_missing)
                return -1;
        if (item->object.parsed)
                return 0;
-       buffer = read_sha1_file(item->object.oid.hash, &type, &size);
+       if (use_commit_graph && parse_commit_in_graph(the_repository, item))
+               return 0;
+       buffer = read_object_file(&item->object.oid, &type, &size);
        if (!buffer)
                return quiet_on_missing ? -1 :
                        error("Could not read %s",
@@ -395,15 +466,21 @@ int parse_commit_gently(struct commit *item, int quiet_on_missing)
                return error("Object %s not a commit",
                             oid_to_hex(&item->object.oid));
        }
-       ret = parse_commit_buffer(item, buffer, size);
+
+       ret = parse_commit_buffer(the_repository, item, buffer, size, 0);
        if (save_commit_buffer && !ret) {
-               set_commit_buffer(item, buffer, size);
+               set_commit_buffer(the_repository, item, buffer, size);
                return 0;
        }
        free(buffer);
        return ret;
 }
 
+int parse_commit_gently(struct commit *item, int quiet_on_missing)
+{
+       return parse_commit_internal(item, quiet_on_missing, 1);
+}
+
 void parse_commit_or_die(struct commit *item)
 {
        if (parse_commit(item))
@@ -547,7 +624,7 @@ void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark)
        struct commit_list *list = NULL;
 
        while (nr--) {
-               commit_list_insert(*commit, &list);
+               clear_commit_marks_1(&list, *commit, mark);
                commit++;
        }
        while (list)
@@ -559,20 +636,6 @@ void clear_commit_marks(struct commit *commit, unsigned int mark)
        clear_commit_marks_many(1, &commit, mark);
 }
 
-void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
-{
-       struct object *object;
-       struct commit *commit;
-       unsigned int i;
-
-       for (i = 0; i < a->nr; i++) {
-               object = a->objects[i].item;
-               commit = lookup_commit_reference_gently(&object->oid, 1);
-               if (commit)
-                       clear_commit_marks(commit, mark);
-       }
-}
-
 struct commit *pop_commit(struct commit_list **stack)
 {
        struct commit_list *top = *stack;
@@ -593,7 +656,7 @@ struct commit *pop_commit(struct commit_list **stack)
 define_commit_slab(indegree_slab, int);
 
 /* record author-date for each commit object */
-define_commit_slab(author_date_slab, unsigned long);
+define_commit_slab(author_date_slab, timestamp_t);
 
 static void record_author_date(struct author_date_slab *author_date,
                               struct commit *commit)
@@ -637,6 +700,24 @@ static int compare_commits_by_author_date(const void *a_, const void *b_,
        return 0;
 }
 
+int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_, void *unused)
+{
+       const struct commit *a = a_, *b = b_;
+
+       /* newer commits first */
+       if (a->generation < b->generation)
+               return 1;
+       else if (a->generation > b->generation)
+               return -1;
+
+       /* use date as a heuristic when generations are equal */
+       if (a->date < b->date)
+               return 1;
+       else if (a->date > b->date)
+               return -1;
+       return 0;
+}
+
 int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
 {
        const struct commit *a = a_, *b = b_;
@@ -784,11 +865,17 @@ static int queue_has_nonstale(struct prio_queue *queue)
 }
 
 /* all input commits in one and twos[] must have been parsed! */
-static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
+static struct commit_list *paint_down_to_common(struct commit *one, int n,
+                                               struct commit **twos,
+                                               int min_generation)
 {
-       struct prio_queue queue = { compare_commits_by_commit_date };
+       struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
        struct commit_list *result = NULL;
        int i;
+       uint32_t last_gen = GENERATION_NUMBER_INFINITY;
+
+       if (!min_generation)
+               queue.compare = compare_commits_by_commit_date;
 
        one->object.flags |= PARENT1;
        if (!n) {
@@ -807,6 +894,15 @@ static struct commit_list *paint_down_to_common(struct commit *one, int n, struc
                struct commit_list *parents;
                int flags;
 
+               if (min_generation && commit->generation > last_gen)
+                       BUG("bad generation skip %8x > %8x at %s",
+                           commit->generation, last_gen,
+                           oid_to_hex(&commit->object.oid));
+               last_gen = commit->generation;
+
+               if (commit->generation < min_generation)
+                       break;
+
                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
                if (flags == (PARENT1 | PARENT2)) {
                        if (!(commit->object.flags & RESULT)) {
@@ -855,7 +951,7 @@ static struct commit_list *merge_bases_many(struct commit *one, int n, struct co
                        return NULL;
        }
 
-       list = paint_down_to_common(one, n, twos);
+       list = paint_down_to_common(one, n, twos, 0);
 
        while (list) {
                struct commit *commit = pop_commit(&list);
@@ -875,19 +971,19 @@ struct commit_list *get_octopus_merge_bases(struct commit_list *in)
        commit_list_insert(in->item, &ret);
 
        for (i = in->next; i; i = i->next) {
-               struct commit_list *new = NULL, *end = NULL;
+               struct commit_list *new_commits = NULL, *end = NULL;
 
                for (j = ret; j; j = j->next) {
                        struct commit_list *bases;
                        bases = get_merge_bases(i->item, j->item);
-                       if (!new)
-                               new = bases;
+                       if (!new_commits)
+                               new_commits = bases;
                        else
                                end->next = bases;
                        for (k = bases; k; k = k->next)
                                end = k;
                }
-               ret = new;
+               ret = new_commits;
        }
        return ret;
 }
@@ -913,6 +1009,7 @@ static int remove_redundant(struct commit **array, int cnt)
                parse_commit(array[i]);
        for (i = 0; i < cnt; i++) {
                struct commit_list *common;
+               uint32_t min_generation = array[i]->generation;
 
                if (redundant[i])
                        continue;
@@ -921,16 +1018,19 @@ static int remove_redundant(struct commit **array, int cnt)
                                continue;
                        filled_index[filled] = j;
                        work[filled++] = array[j];
+
+                       if (array[j]->generation < min_generation)
+                               min_generation = array[j]->generation;
                }
-               common = paint_down_to_common(array[i], filled, work);
+               common = paint_down_to_common(array[i], filled, work,
+                                             min_generation);
                if (array[i]->object.flags & PARENT2)
                        redundant[i] = 1;
                for (j = 0; j < filled; j++)
                        if (work[j]->object.flags & PARENT1)
                                redundant[filled_index[j]] = 1;
                clear_commit_marks(array[i], all_flags);
-               for (j = 0; j < filled; j++)
-                       clear_commit_marks(work[j], all_flags);
+               clear_commit_marks_many(filled, work, all_flags);
                free_commit_list(common);
        }
 
@@ -1033,14 +1133,21 @@ int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit *
 {
        struct commit_list *bases;
        int ret = 0, i;
+       uint32_t min_generation = GENERATION_NUMBER_INFINITY;
 
        if (parse_commit(commit))
                return ret;
-       for (i = 0; i < nr_reference; i++)
+       for (i = 0; i < nr_reference; i++) {
                if (parse_commit(reference[i]))
                        return ret;
+               if (reference[i]->generation < min_generation)
+                       min_generation = reference[i]->generation;
+       }
+
+       if (commit->generation > min_generation)
+               return ret;
 
-       bases = paint_down_to_common(commit, nr_reference, reference);
+       bases = paint_down_to_common(commit, nr_reference, reference, commit->generation);
        if (commit->object.flags & PARENT2)
                ret = 1;
        clear_commit_marks(commit, all_flags);
@@ -1223,7 +1330,7 @@ static void handle_signed_tag(struct commit *parent, struct commit_extra_header
        desc = merge_remote_util(parent);
        if (!desc || !desc->obj)
                return;
-       buf = read_sha1_file(desc->obj->oid.hash, &type, &size);
+       buf = read_object_file(&desc->obj->oid, &type, &size);
        if (!buf || type != OBJ_TAG)
                goto free_return;
        len = parse_signature(buf, size);
@@ -1305,17 +1412,19 @@ struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
        return extra;
 }
 
-void for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data)
+int for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data)
 {
        struct commit_extra_header *extra, *to_free;
+       int res = 0;
 
        to_free = read_commit_extra_headers(commit, NULL);
-       for (extra = to_free; extra; extra = extra->next) {
+       for (extra = to_free; !res && extra; extra = extra->next) {
                if (strcmp(extra->key, "mergetag"))
                        continue; /* not a merge tag */
-               fn(commit, extra, data);
+               res = fn(commit, extra, data);
        }
        free_commit_extra_headers(to_free);
+       return res;
 }
 
 static inline int standard_header_field(const char *field, size_t len)
@@ -1395,9 +1504,8 @@ void free_commit_extra_headers(struct commit_extra_header *extra)
        }
 }
 
-int commit_tree(const char *msg, size_t msg_len,
-               const unsigned char *tree,
-               struct commit_list *parents, unsigned char *ret,
+int commit_tree(const char *msg, size_t msg_len, const struct object_id *tree,
+               struct commit_list *parents, struct object_id *ret,
                const char *author, const char *sign_commit)
 {
        struct commit_extra_header *extra = NULL, **tail = &extra;
@@ -1526,8 +1634,8 @@ N_("Warning: commit message did not conform to UTF-8.\n"
    "variable i18n.commitencoding to the encoding your project uses.\n");
 
 int commit_tree_extended(const char *msg, size_t msg_len,
-                        const unsigned char *tree,
-                        struct commit_list *parents, unsigned char *ret,
+                        const struct object_id *tree,
+                        struct commit_list *parents, struct object_id *ret,
                         const char *author, const char *sign_commit,
                         struct commit_extra_header *extra)
 {
@@ -1535,7 +1643,7 @@ int commit_tree_extended(const char *msg, size_t msg_len,
        int encoding_is_utf8;
        struct strbuf buffer;
 
-       assert_sha1_type(tree, OBJ_TREE);
+       assert_oid_type(tree, OBJ_TREE);
 
        if (memchr(msg, '\0', msg_len))
                return error("a NUL byte in commit log message not allowed.");
@@ -1544,7 +1652,7 @@ int commit_tree_extended(const char *msg, size_t msg_len,
        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
 
        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
-       strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
+       strbuf_addf(&buffer, "tree %s\n", oid_to_hex(tree));
 
        /*
         * NOTE! This ordering means that the same exact tree merged with a
@@ -1583,19 +1691,27 @@ int commit_tree_extended(const char *msg, size_t msg_len,
                goto out;
        }
 
-       result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
+       result = write_object_file(buffer.buf, buffer.len, commit_type, ret);
 out:
        strbuf_release(&buffer);
        return result;
 }
 
+define_commit_slab(merge_desc_slab, struct merge_remote_desc *);
+static struct merge_desc_slab merge_desc_slab = COMMIT_SLAB_INIT(1, merge_desc_slab);
+
+struct merge_remote_desc *merge_remote_util(struct commit *commit)
+{
+       return *merge_desc_slab_at(&merge_desc_slab, commit);
+}
+
 void set_merge_remote_desc(struct commit *commit,
                           const char *name, struct object *obj)
 {
        struct merge_remote_desc *desc;
        FLEX_ALLOC_STR(desc, name, name);
        desc->obj = obj;
-       commit->util = desc;
+       *merge_desc_slab_at(&merge_desc_slab, commit) = desc;
 }
 
 struct commit *get_merge_parent(const char *name)
@@ -1605,9 +1721,9 @@ struct commit *get_merge_parent(const char *name)
        struct object_id oid;
        if (get_oid(name, &oid))
                return NULL;
-       obj = parse_object(&oid);
+       obj = parse_object(the_repository, &oid);
        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
-       if (commit && !commit->util)
+       if (commit && !merge_remote_util(commit))
                set_merge_remote_desc(commit, name, obj);
        return commit;
 }
@@ -1632,11 +1748,11 @@ struct commit *get_merge_parent(const char *name)
 struct commit_list **commit_list_append(struct commit *commit,
                                        struct commit_list **next)
 {
-       struct commit_list *new = xmalloc(sizeof(struct commit_list));
-       new->item = commit;
-       *next = new;
-       new->next = NULL;
-       return &new->next;
+       struct commit_list *new_commit = xmalloc(sizeof(struct commit_list));
+       new_commit->item = commit;
+       *next = new_commit;
+       new_commit->next = NULL;
+       return &new_commit->next;
 }
 
 const char *find_commit_header(const char *msg, const char *key, size_t *out_len)