revision: use a prio_queue to hold rewritten parents
[gitweb.git] / revision.c
index e7da2c57abf62dfafdccbc82fd03032982d16e08..9265200b7a0c507da3bd008d3b7195560a44770f 100644 (file)
@@ -25,6 +25,9 @@
 #include "worktree.h"
 #include "argv-array.h"
 #include "commit-reach.h"
+#include "commit-graph.h"
+#include "prio-queue.h"
+#include "hashmap.h"
 
 volatile show_early_output_fn_t show_early_output;
 
@@ -65,10 +68,10 @@ static void mark_tree_contents_uninteresting(struct repository *r,
        while (tree_entry(&desc, &entry)) {
                switch (object_type(entry.mode)) {
                case OBJ_TREE:
-                       mark_tree_uninteresting(r, lookup_tree(r, entry.oid));
+                       mark_tree_uninteresting(r, lookup_tree(r, &entry.oid));
                        break;
                case OBJ_BLOB:
-                       mark_blob_uninteresting(lookup_blob(r, entry.oid));
+                       mark_blob_uninteresting(lookup_blob(r, &entry.oid));
                        break;
                default:
                        /* Subproject commit - not in this repository */
@@ -97,6 +100,148 @@ void mark_tree_uninteresting(struct repository *r, struct tree *tree)
        mark_tree_contents_uninteresting(r, tree);
 }
 
+struct path_and_oids_entry {
+       struct hashmap_entry ent;
+       char *path;
+       struct oidset trees;
+};
+
+static int path_and_oids_cmp(const void *hashmap_cmp_fn_data,
+                            const struct path_and_oids_entry *e1,
+                            const struct path_and_oids_entry *e2,
+                            const void *keydata)
+{
+       return strcmp(e1->path, e2->path);
+}
+
+static void paths_and_oids_init(struct hashmap *map)
+{
+       hashmap_init(map, (hashmap_cmp_fn) path_and_oids_cmp, NULL, 0);
+}
+
+static void paths_and_oids_clear(struct hashmap *map)
+{
+       struct hashmap_iter iter;
+       struct path_and_oids_entry *entry;
+       hashmap_iter_init(map, &iter);
+
+       while ((entry = (struct path_and_oids_entry *)hashmap_iter_next(&iter))) {
+               oidset_clear(&entry->trees);
+               free(entry->path);
+       }
+
+       hashmap_free(map, 1);
+}
+
+static void paths_and_oids_insert(struct hashmap *map,
+                                 const char *path,
+                                 const struct object_id *oid)
+{
+       int hash = strhash(path);
+       struct path_and_oids_entry key;
+       struct path_and_oids_entry *entry;
+
+       hashmap_entry_init(&key, hash);
+
+       /* use a shallow copy for the lookup */
+       key.path = (char *)path;
+       oidset_init(&key.trees, 0);
+
+       if (!(entry = (struct path_and_oids_entry *)hashmap_get(map, &key, NULL))) {
+               entry = xcalloc(1, sizeof(struct path_and_oids_entry));
+               hashmap_entry_init(entry, hash);
+               entry->path = xstrdup(key.path);
+               oidset_init(&entry->trees, 16);
+               hashmap_put(map, entry);
+       }
+
+       oidset_insert(&entry->trees, oid);
+}
+
+static void add_children_by_path(struct repository *r,
+                                struct tree *tree,
+                                struct hashmap *map)
+{
+       struct tree_desc desc;
+       struct name_entry entry;
+
+       if (!tree)
+               return;
+
+       if (parse_tree_gently(tree, 1) < 0)
+               return;
+
+       init_tree_desc(&desc, tree->buffer, tree->size);
+       while (tree_entry(&desc, &entry)) {
+               switch (object_type(entry.mode)) {
+               case OBJ_TREE:
+                       paths_and_oids_insert(map, entry.path, &entry.oid);
+
+                       if (tree->object.flags & UNINTERESTING) {
+                               struct tree *child = lookup_tree(r, &entry.oid);
+                               if (child)
+                                       child->object.flags |= UNINTERESTING;
+                       }
+                       break;
+               case OBJ_BLOB:
+                       if (tree->object.flags & UNINTERESTING) {
+                               struct blob *child = lookup_blob(r, &entry.oid);
+                               if (child)
+                                       child->object.flags |= UNINTERESTING;
+                       }
+                       break;
+               default:
+                       /* Subproject commit - not in this repository */
+                       break;
+               }
+       }
+
+       free_tree_buffer(tree);
+}
+
+void mark_trees_uninteresting_sparse(struct repository *r,
+                                    struct oidset *trees)
+{
+       unsigned has_interesting = 0, has_uninteresting = 0;
+       struct hashmap map;
+       struct hashmap_iter map_iter;
+       struct path_and_oids_entry *entry;
+       struct object_id *oid;
+       struct oidset_iter iter;
+
+       oidset_iter_init(trees, &iter);
+       while ((!has_interesting || !has_uninteresting) &&
+              (oid = oidset_iter_next(&iter))) {
+               struct tree *tree = lookup_tree(r, oid);
+
+               if (!tree)
+                       continue;
+
+               if (tree->object.flags & UNINTERESTING)
+                       has_uninteresting = 1;
+               else
+                       has_interesting = 1;
+       }
+
+       /* Do not walk unless we have both types of trees. */
+       if (!has_uninteresting || !has_interesting)
+               return;
+
+       paths_and_oids_init(&map);
+
+       oidset_iter_init(trees, &iter);
+       while ((oid = oidset_iter_next(&iter))) {
+               struct tree *tree = lookup_tree(r, oid);
+               add_children_by_path(r, tree, &map);
+       }
+
+       hashmap_iter_init(&map, &map_iter);
+       while ((entry = hashmap_iter_next(&map_iter)))
+               mark_trees_uninteresting_sparse(r, &entry->trees);
+
+       paths_and_oids_clear(&map);
+}
+
 struct commit_stack {
        struct commit **items;
        size_t nr, alloc;
@@ -177,7 +322,6 @@ static void add_pending_object_with_path(struct rev_info *revs,
                strbuf_release(&buf);
                return; /* do not add the commit itself */
        }
-       obj->flags |= USER_GIVEN;
        add_object_array_with_path(obj, name, &revs->pending, mode, path);
 }
 
@@ -767,26 +911,11 @@ static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
                commit->object.flags |= TREESAME;
 }
 
-static void commit_list_insert_by_date_cached(struct commit *p, struct commit_list **head,
-                   struct commit_list *cached_base, struct commit_list **cache)
-{
-       struct commit_list *new_entry;
-
-       if (cached_base && p->date < cached_base->item->date)
-               new_entry = commit_list_insert_by_date(p, &cached_base->next);
-       else
-               new_entry = commit_list_insert_by_date(p, head);
-
-       if (cache && (!*cache || p->date < (*cache)->item->date))
-               *cache = new_entry;
-}
-
-static int add_parents_to_list(struct rev_info *revs, struct commit *commit,
-                   struct commit_list **list, struct commit_list **cache_ptr)
+static int process_parents(struct rev_info *revs, struct commit *commit,
+                          struct commit_list **list, struct prio_queue *queue)
 {
        struct commit_list *parent = commit->parents;
        unsigned left_flag;
-       struct commit_list *cached_base = cache_ptr ? *cache_ptr : NULL;
 
        if (commit->object.flags & ADDED)
                return 0;
@@ -821,7 +950,10 @@ static int add_parents_to_list(struct rev_info *revs, struct commit *commit,
                        if (p->object.flags & SEEN)
                                continue;
                        p->object.flags |= SEEN;
-                       commit_list_insert_by_date_cached(p, list, cached_base, cache_ptr);
+                       if (list)
+                               commit_list_insert_by_date(p, list);
+                       if (queue)
+                               prio_queue_put(queue, p);
                }
                return 0;
        }
@@ -860,7 +992,10 @@ static int add_parents_to_list(struct rev_info *revs, struct commit *commit,
                p->object.flags |= left_flag;
                if (!(p->object.flags & SEEN)) {
                        p->object.flags |= SEEN;
-                       commit_list_insert_by_date_cached(p, list, cached_base, cache_ptr);
+                       if (list)
+                               commit_list_insert_by_date(p, list);
+                       if (queue)
+                               prio_queue_put(queue, p);
                }
                if (revs->first_parent_only)
                        break;
@@ -1104,7 +1239,7 @@ static int limit_list(struct rev_info *revs)
 
                if (revs->max_age != -1 && (commit->date < revs->max_age))
                        obj->flags |= UNINTERESTING;
-               if (add_parents_to_list(revs, commit, &list, NULL) < 0)
+               if (process_parents(revs, commit, &list, NULL) < 0)
                        return -1;
                if (obj->flags & UNINTERESTING) {
                        mark_parents_uninteresting(commit);
@@ -1191,7 +1326,7 @@ struct all_refs_cb {
        int warned_bad_reflog;
        struct rev_info *all_revs;
        const char *name_for_errormsg;
-       struct ref_store *refs;
+       struct worktree *wt;
 };
 
 int ref_excluded(struct string_list *ref_excludes, const char *path)
@@ -1228,7 +1363,7 @@ static void init_all_refs_cb(struct all_refs_cb *cb, struct rev_info *revs,
        cb->all_revs = revs;
        cb->all_flags = flags;
        revs->rev_input_given = 1;
-       cb->refs = NULL;
+       cb->wt = NULL;
 }
 
 void clear_ref_exclusion(struct string_list **ref_excludes_p)
@@ -1291,14 +1426,20 @@ static int handle_one_reflog_ent(struct object_id *ooid, struct object_id *noid,
        return 0;
 }
 
-static int handle_one_reflog(const char *path, const struct object_id *oid,
+static int handle_one_reflog(const char *refname_in_wt,
+                            const struct object_id *oid,
                             int flag, void *cb_data)
 {
        struct all_refs_cb *cb = cb_data;
+       struct strbuf refname = STRBUF_INIT;
+
        cb->warned_bad_reflog = 0;
-       cb->name_for_errormsg = path;
-       refs_for_each_reflog_ent(cb->refs, path,
+       strbuf_worktree_ref(cb->wt, &refname, refname_in_wt);
+       cb->name_for_errormsg = refname.buf;
+       refs_for_each_reflog_ent(get_main_ref_store(the_repository),
+                                refname.buf,
                                 handle_one_reflog_ent, cb_data);
+       strbuf_release(&refname);
        return 0;
 }
 
@@ -1313,8 +1454,8 @@ static void add_other_reflogs_to_pending(struct all_refs_cb *cb)
                if (wt->is_current)
                        continue;
 
-               cb->refs = get_worktree_ref_store(wt);
-               refs_for_each_reflog(cb->refs,
+               cb->wt = wt;
+               refs_for_each_reflog(get_worktree_ref_store(wt),
                                     handle_one_reflog,
                                     cb);
        }
@@ -1327,7 +1468,7 @@ void add_reflogs_to_pending(struct rev_info *revs, unsigned flags)
 
        cb.all_revs = revs;
        cb.all_flags = flags;
-       cb.refs = get_main_ref_store(revs->repo);
+       cb.wt = NULL;
        for_each_reflog(handle_one_reflog, &cb);
 
        if (!revs->single_worktree)
@@ -1335,13 +1476,14 @@ void add_reflogs_to_pending(struct rev_info *revs, unsigned flags)
 }
 
 static void add_cache_tree(struct cache_tree *it, struct rev_info *revs,
-                          struct strbuf *path)
+                          struct strbuf *path, unsigned int flags)
 {
        size_t baselen = path->len;
        int i;
 
        if (it->entry_count >= 0) {
                struct tree *tree = lookup_tree(revs->repo, &it->oid);
+               tree->object.flags |= flags;
                add_pending_object_with_path(revs, &tree->object, "",
                                             040000, path->buf);
        }
@@ -1349,14 +1491,15 @@ static void add_cache_tree(struct cache_tree *it, struct rev_info *revs,
        for (i = 0; i < it->subtree_nr; i++) {
                struct cache_tree_sub *sub = it->down[i];
                strbuf_addf(path, "%s%s", baselen ? "/" : "", sub->name);
-               add_cache_tree(sub->cache_tree, revs, path);
+               add_cache_tree(sub->cache_tree, revs, path, flags);
                strbuf_setlen(path, baselen);
        }
 
 }
 
 static void do_add_index_objects_to_pending(struct rev_info *revs,
-                                           struct index_state *istate)
+                                           struct index_state *istate,
+                                           unsigned int flags)
 {
        int i;
 
@@ -1370,13 +1513,14 @@ static void do_add_index_objects_to_pending(struct rev_info *revs,
                blob = lookup_blob(revs->repo, &ce->oid);
                if (!blob)
                        die("unable to add index blob to traversal");
+               blob->object.flags |= flags;
                add_pending_object_with_path(revs, &blob->object, "",
                                             ce->ce_mode, ce->name);
        }
 
        if (istate->cache_tree) {
                struct strbuf path = STRBUF_INIT;
-               add_cache_tree(istate->cache_tree, revs, &path);
+               add_cache_tree(istate->cache_tree, revs, &path, flags);
                strbuf_release(&path);
        }
 }
@@ -1385,8 +1529,8 @@ void add_index_objects_to_pending(struct rev_info *revs, unsigned int flags)
 {
        struct worktree **worktrees, **p;
 
-       read_index(revs->repo->index);
-       do_add_index_objects_to_pending(revs, revs->repo->index);
+       repo_read_index(revs->repo);
+       do_add_index_objects_to_pending(revs, revs->repo->index, flags);
 
        if (revs->single_worktree)
                return;
@@ -1402,7 +1546,7 @@ void add_index_objects_to_pending(struct rev_info *revs, unsigned int flags)
                if (read_index_from(&istate,
                                    worktree_git_path(wt, "index"),
                                    get_worktree_git_dir(wt)) > 0)
-                       do_add_index_objects_to_pending(revs, &istate);
+                       do_add_index_objects_to_pending(revs, &istate, flags);
                discard_index(&istate);
        }
        free_worktrees(worktrees);
@@ -1464,6 +1608,7 @@ void repo_init_revisions(struct repository *r,
        revs->abbrev = DEFAULT_ABBREV;
        revs->ignore_merges = 1;
        revs->simplify_history = 1;
+       revs->pruning.repo = r;
        revs->pruning.flags.recursive = 1;
        revs->pruning.flags.quick = 1;
        revs->pruning.add_remove = file_add_remove;
@@ -1496,8 +1641,8 @@ void repo_init_revisions(struct repository *r,
 }
 
 static void add_pending_commit_list(struct rev_info *revs,
-                                    struct commit_list *commit_list,
-                                    unsigned int flags)
+                                   struct commit_list *commit_list,
+                                   unsigned int flags)
 {
        while (commit_list) {
                struct object *object = &commit_list->item->object;
@@ -1531,7 +1676,7 @@ static void prepare_show_merge(struct rev_info *revs)
        head->object.flags |= SYMMETRIC_LEFT;
 
        if (!istate->cache_nr)
-               read_index(istate);
+               repo_read_index(revs->repo);
        for (i = 0; i < istate->cache_nr; i++) {
                const struct cache_entry *ce = istate->cache[i];
                if (!ce_stage(ce))
@@ -1590,8 +1735,8 @@ static int handle_dotdot_1(const char *arg, char *dotdot,
        if (!*b_name)
                b_name = "HEAD";
 
-       if (get_oid_with_context(a_name, oc_flags, &a_oid, a_oc) ||
-           get_oid_with_context(b_name, oc_flags, &b_oid, b_oc))
+       if (get_oid_with_context(revs->repo, a_name, oc_flags, &a_oid, a_oc) ||
+           get_oid_with_context(revs->repo, b_name, oc_flags, &b_oid, b_oc))
                return -1;
 
        if (!cant_be_filename) {
@@ -1725,11 +1870,13 @@ int handle_revision_arg(const char *arg_, struct rev_info *revs, int flags, unsi
        if (revarg_opt & REVARG_COMMITTISH)
                get_sha1_flags |= GET_OID_COMMITTISH;
 
-       if (get_oid_with_context(arg, get_sha1_flags, &oid, &oc))
+       if (get_oid_with_context(revs->repo, arg, get_sha1_flags, &oid, &oc))
                return revs->ignore_missing ? 0 : -1;
        if (!cant_be_filename)
                verify_non_filename(revs->prefix, arg);
        object = get_reference(revs, arg, &oid, flags ^ local_flags);
+       if (!object)
+               return revs->ignore_missing ? 0 : -1;
        add_rev_cmdline(revs, object, arg_, REV_CMD_REV, flags ^ local_flags);
        add_pending_object_with_path(revs, object, arg, oc.mode, oc.path);
        free(oc.path);
@@ -1792,7 +1939,8 @@ static void add_message_grep(struct rev_info *revs, const char *pattern)
 }
 
 static int handle_revision_opt(struct rev_info *revs, int argc, const char **argv,
-                              int *unkc, const char **unkv)
+                              int *unkc, const char **unkv,
+                              const struct setup_revision_opt* opt)
 {
        const char *arg = argv[0];
        const char *optarg;
@@ -2152,7 +2300,8 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
                revs->limited = 1;
        } else if (!strcmp(arg, "--ignore-missing")) {
                revs->ignore_missing = 1;
-       } else if (!strcmp(arg, "--exclude-promisor-objects")) {
+       } else if (opt && opt->allow_exclude_promisor_objects &&
+                  !strcmp(arg, "--exclude-promisor-objects")) {
                if (fetch_if_missing)
                        BUG("exclude_promisor_objects can only be used when fetch_if_missing is 0");
                revs->exclude_promisor_objects = 1;
@@ -2173,7 +2322,7 @@ void parse_revision_opt(struct rev_info *revs, struct parse_opt_ctx_t *ctx,
                        const char * const usagestr[])
 {
        int n = handle_revision_opt(revs, ctx->argc, ctx->argv,
-                                   &ctx->cpidx, ctx->out);
+                                   &ctx->cpidx, ctx->out, NULL);
        if (n <= 0) {
                error("unknown option `%s'", ctx->argv[0]);
                usage_with_options(usagestr, options);
@@ -2391,7 +2540,8 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
                                continue;
                        }
 
-                       opts = handle_revision_opt(revs, argc - i, argv + i, &left, argv);
+                       opts = handle_revision_opt(revs, argc - i, argv + i,
+                                                  &left, argv, opt);
                        if (opts > 0) {
                                i += opts - 1;
                                continue;
@@ -2453,7 +2603,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
                struct object_id oid;
                struct object *object;
                struct object_context oc;
-               if (get_oid_with_context(revs->def, 0, &oid, &oc))
+               if (get_oid_with_context(revs->repo, revs->def, 0, &oid, &oc))
                        diagnose_missing_default(revs->def);
                object = get_reference(revs, revs->def, &oid, 0);
                add_pending_object_with_mode(revs, object, revs->def, oc.mode);
@@ -2472,7 +2622,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
        if (revs->diffopt.objfind)
                revs->simplify_history = 0;
 
-       if (revs->topo_order)
+       if (revs->topo_order && !generation_numbers_enabled(the_repository))
                revs->limited = 1;
 
        if (revs->prune_data.nr) {
@@ -2911,6 +3061,217 @@ static int mark_uninteresting(const struct object_id *oid,
        return 0;
 }
 
+define_commit_slab(indegree_slab, int);
+define_commit_slab(author_date_slab, timestamp_t);
+
+struct topo_walk_info {
+       uint32_t min_generation;
+       struct prio_queue explore_queue;
+       struct prio_queue indegree_queue;
+       struct prio_queue topo_queue;
+       struct indegree_slab indegree;
+       struct author_date_slab author_date;
+};
+
+static inline void test_flag_and_insert(struct prio_queue *q, struct commit *c, int flag)
+{
+       if (c->object.flags & flag)
+               return;
+
+       c->object.flags |= flag;
+       prio_queue_put(q, c);
+}
+
+static void explore_walk_step(struct rev_info *revs)
+{
+       struct topo_walk_info *info = revs->topo_walk_info;
+       struct commit_list *p;
+       struct commit *c = prio_queue_get(&info->explore_queue);
+
+       if (!c)
+               return;
+
+       if (parse_commit_gently(c, 1) < 0)
+               return;
+
+       if (revs->sort_order == REV_SORT_BY_AUTHOR_DATE)
+               record_author_date(&info->author_date, c);
+
+       if (revs->max_age != -1 && (c->date < revs->max_age))
+               c->object.flags |= UNINTERESTING;
+
+       if (process_parents(revs, c, NULL, NULL) < 0)
+               return;
+
+       if (c->object.flags & UNINTERESTING)
+               mark_parents_uninteresting(c);
+
+       for (p = c->parents; p; p = p->next)
+               test_flag_and_insert(&info->explore_queue, p->item, TOPO_WALK_EXPLORED);
+}
+
+static void explore_to_depth(struct rev_info *revs,
+                            uint32_t gen_cutoff)
+{
+       struct topo_walk_info *info = revs->topo_walk_info;
+       struct commit *c;
+       while ((c = prio_queue_peek(&info->explore_queue)) &&
+              c->generation >= gen_cutoff)
+               explore_walk_step(revs);
+}
+
+static void indegree_walk_step(struct rev_info *revs)
+{
+       struct commit_list *p;
+       struct topo_walk_info *info = revs->topo_walk_info;
+       struct commit *c = prio_queue_get(&info->indegree_queue);
+
+       if (!c)
+               return;
+
+       if (parse_commit_gently(c, 1) < 0)
+               return;
+
+       explore_to_depth(revs, c->generation);
+
+       for (p = c->parents; p; p = p->next) {
+               struct commit *parent = p->item;
+               int *pi = indegree_slab_at(&info->indegree, parent);
+
+               if (*pi)
+                       (*pi)++;
+               else
+                       *pi = 2;
+
+               test_flag_and_insert(&info->indegree_queue, parent, TOPO_WALK_INDEGREE);
+
+               if (revs->first_parent_only)
+                       return;
+       }
+}
+
+static void compute_indegrees_to_depth(struct rev_info *revs,
+                                      uint32_t gen_cutoff)
+{
+       struct topo_walk_info *info = revs->topo_walk_info;
+       struct commit *c;
+       while ((c = prio_queue_peek(&info->indegree_queue)) &&
+              c->generation >= gen_cutoff)
+               indegree_walk_step(revs);
+}
+
+static void init_topo_walk(struct rev_info *revs)
+{
+       struct topo_walk_info *info;
+       struct commit_list *list;
+       revs->topo_walk_info = xmalloc(sizeof(struct topo_walk_info));
+       info = revs->topo_walk_info;
+       memset(info, 0, sizeof(struct topo_walk_info));
+
+       init_indegree_slab(&info->indegree);
+       memset(&info->explore_queue, 0, sizeof(info->explore_queue));
+       memset(&info->indegree_queue, 0, sizeof(info->indegree_queue));
+       memset(&info->topo_queue, 0, sizeof(info->topo_queue));
+
+       switch (revs->sort_order) {
+       default: /* REV_SORT_IN_GRAPH_ORDER */
+               info->topo_queue.compare = NULL;
+               break;
+       case REV_SORT_BY_COMMIT_DATE:
+               info->topo_queue.compare = compare_commits_by_commit_date;
+               break;
+       case REV_SORT_BY_AUTHOR_DATE:
+               init_author_date_slab(&info->author_date);
+               info->topo_queue.compare = compare_commits_by_author_date;
+               info->topo_queue.cb_data = &info->author_date;
+               break;
+       }
+
+       info->explore_queue.compare = compare_commits_by_gen_then_commit_date;
+       info->indegree_queue.compare = compare_commits_by_gen_then_commit_date;
+
+       info->min_generation = GENERATION_NUMBER_INFINITY;
+       for (list = revs->commits; list; list = list->next) {
+               struct commit *c = list->item;
+
+               if (parse_commit_gently(c, 1))
+                       continue;
+
+               test_flag_and_insert(&info->explore_queue, c, TOPO_WALK_EXPLORED);
+               test_flag_and_insert(&info->indegree_queue, c, TOPO_WALK_INDEGREE);
+
+               if (c->generation < info->min_generation)
+                       info->min_generation = c->generation;
+
+               *(indegree_slab_at(&info->indegree, c)) = 1;
+
+               if (revs->sort_order == REV_SORT_BY_AUTHOR_DATE)
+                       record_author_date(&info->author_date, c);
+       }
+       compute_indegrees_to_depth(revs, info->min_generation);
+
+       for (list = revs->commits; list; list = list->next) {
+               struct commit *c = list->item;
+
+               if (*(indegree_slab_at(&info->indegree, c)) == 1)
+                       prio_queue_put(&info->topo_queue, c);
+       }
+
+       /*
+        * This is unfortunate; the initial tips need to be shown
+        * in the order given from the revision traversal machinery.
+        */
+       if (revs->sort_order == REV_SORT_IN_GRAPH_ORDER)
+               prio_queue_reverse(&info->topo_queue);
+}
+
+static struct commit *next_topo_commit(struct rev_info *revs)
+{
+       struct commit *c;
+       struct topo_walk_info *info = revs->topo_walk_info;
+
+       /* pop next off of topo_queue */
+       c = prio_queue_get(&info->topo_queue);
+
+       if (c)
+               *(indegree_slab_at(&info->indegree, c)) = 0;
+
+       return c;
+}
+
+static void expand_topo_walk(struct rev_info *revs, struct commit *commit)
+{
+       struct commit_list *p;
+       struct topo_walk_info *info = revs->topo_walk_info;
+       if (process_parents(revs, commit, NULL, NULL) < 0) {
+               if (!revs->ignore_missing_links)
+                       die("Failed to traverse parents of commit %s",
+                           oid_to_hex(&commit->object.oid));
+       }
+
+       for (p = commit->parents; p; p = p->next) {
+               struct commit *parent = p->item;
+               int *pi;
+
+               if (parse_commit_gently(parent, 1) < 0)
+                       continue;
+
+               if (parent->generation < info->min_generation) {
+                       info->min_generation = parent->generation;
+                       compute_indegrees_to_depth(revs, info->min_generation);
+               }
+
+               pi = indegree_slab_at(&info->indegree, parent);
+
+               (*pi)--;
+               if (*pi == 1)
+                       prio_queue_put(&info->topo_queue, parent);
+
+               if (revs->first_parent_only)
+                       return;
+       }
+}
+
 int prepare_revision_walk(struct rev_info *revs)
 {
        int i;
@@ -2947,11 +3308,13 @@ int prepare_revision_walk(struct rev_info *revs)
                commit_list_sort_by_date(&revs->commits);
        if (revs->no_walk)
                return 0;
-       if (revs->limited)
+       if (revs->limited) {
                if (limit_list(revs) < 0)
                        return -1;
-       if (revs->topo_order)
-               sort_in_topological_order(&revs->commits, revs->sort_order);
+               if (revs->topo_order)
+                       sort_in_topological_order(&revs->commits, revs->sort_order);
+       } else if (revs->topo_order)
+               init_topo_walk(revs);
        if (revs->line_level_traverse)
                line_log_filter(revs);
        if (revs->simplify_merges)
@@ -2961,14 +3324,14 @@ int prepare_revision_walk(struct rev_info *revs)
        return 0;
 }
 
-static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
+static enum rewrite_result rewrite_one_1(struct rev_info *revs,
+                                        struct commit **pp,
+                                        struct prio_queue *queue)
 {
-       struct commit_list *cache = NULL;
-
        for (;;) {
                struct commit *p = *pp;
                if (!revs->limited)
-                       if (add_parents_to_list(revs, p, &revs->commits, &cache) < 0)
+                       if (process_parents(revs, p, NULL, queue) < 0)
                                return rewrite_one_error;
                if (p->object.flags & UNINTERESTING)
                        return rewrite_one_ok;
@@ -2982,6 +3345,31 @@ static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp
        }
 }
 
+static void merge_queue_into_list(struct prio_queue *q, struct commit_list **list)
+{
+       while (q->nr) {
+               struct commit *item = prio_queue_peek(q);
+               struct commit_list *p = *list;
+
+               if (p && p->item->date >= item->date)
+                       list = &p->next;
+               else {
+                       p = commit_list_insert(item, list);
+                       list = &p->next; /* skip newly added item */
+                       prio_queue_get(q); /* pop item */
+               }
+       }
+}
+
+static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
+{
+       struct prio_queue queue = { compare_commits_by_commit_date };
+       enum rewrite_result ret = rewrite_one_1(revs, pp, &queue);
+       merge_queue_into_list(&queue, &revs->commits);
+       clear_prio_queue(&queue);
+       return ret;
+}
+
 int rewrite_parents(struct rev_info *revs, struct commit *commit,
        rewrite_parent_fn_t rewrite_parent)
 {
@@ -3276,6 +3664,8 @@ static struct commit *get_revision_1(struct rev_info *revs)
 
                if (revs->reflog_info)
                        commit = next_reflog_entry(revs->reflog_info);
+               else if (revs->topo_walk_info)
+                       commit = next_topo_commit(revs);
                else
                        commit = pop_commit(&revs->commits);
 
@@ -3297,7 +3687,9 @@ static struct commit *get_revision_1(struct rev_info *revs)
 
                        if (revs->reflog_info)
                                try_to_simplify_commit(revs, commit);
-                       else if (add_parents_to_list(revs, commit, &revs->commits, NULL) < 0) {
+                       else if (revs->topo_walk_info)
+                               expand_topo_walk(revs, commit);
+                       else if (process_parents(revs, commit, &revs->commits, NULL) < 0) {
                                if (!revs->ignore_missing_links)
                                        die("Failed to traverse parents of commit %s",
                                                oid_to_hex(&commit->object.oid));