send-pack.c: move async's #ifdef NO_PTHREADS back to run-command.c
[gitweb.git] / fetch-pack.c
index a320ce9872b5e752aeb592a16cc9108ae87e9d71..b3ed7121bc86805e87e909ff995eb8b439a2f995 100644 (file)
 #include "connect.h"
 #include "transport.h"
 #include "version.h"
-#include "prio-queue.h"
 #include "sha1-array.h"
 #include "oidset.h"
 #include "packfile.h"
+#include "object-store.h"
+#include "connected.h"
+#include "fetch-negotiator.h"
+#include "fsck.h"
 
 static int transfer_unpack_limit = -1;
 static int fetch_unpack_limit = -1;
@@ -33,16 +36,12 @@ static int agent_supported;
 static int server_supports_filtering;
 static struct lock_file shallow_lock;
 static const char *alternate_shallow_file;
+static char *negotiation_algorithm;
+static struct strbuf fsck_msg_types = STRBUF_INIT;
 
 /* Remember to update object flag allocation in object.h */
 #define COMPLETE       (1U << 0)
-#define COMMON         (1U << 1)
-#define COMMON_REF     (1U << 2)
-#define SEEN           (1U << 3)
-#define POPPED         (1U << 4)
-#define ALTERNATE      (1U << 5)
-
-static int marked;
+#define ALTERNATE      (1U << 1)
 
 /*
  * After sending this many "have"s if we do not get any new ACK , we
@@ -50,8 +49,7 @@ static int marked;
  */
 #define MAX_IN_VAIN 256
 
-static struct prio_queue rev_list = { compare_commits_by_commit_date };
-static int non_common_revs, multi_ack, use_sideband;
+static int multi_ack, use_sideband;
 /* Allow specifying sha1 if it is a ref tip. */
 #define ALLOW_TIP_SHA1 01
 /* Allow request of a sha1 if it is reachable from a ref (possibly hidden ref). */
@@ -78,12 +76,11 @@ struct alternate_object_cache {
        size_t nr, alloc;
 };
 
-static void cache_one_alternate(const char *refname,
-                               const struct object_id *oid,
+static void cache_one_alternate(const struct object_id *oid,
                                void *vcache)
 {
        struct alternate_object_cache *cache = vcache;
-       struct object *obj = parse_object(oid);
+       struct object *obj = parse_object(the_repository, oid);
 
        if (!obj || (obj->flags & ALTERNATE))
                return;
@@ -93,7 +90,9 @@ static void cache_one_alternate(const char *refname,
        cache->items[cache->nr++] = obj;
 }
 
-static void for_each_cached_alternate(void (*cb)(struct object *))
+static void for_each_cached_alternate(struct fetch_negotiator *negotiator,
+                                     void (*cb)(struct fetch_negotiator *,
+                                                struct object *))
 {
        static int initialized;
        static struct alternate_object_cache cache;
@@ -105,30 +104,19 @@ static void for_each_cached_alternate(void (*cb)(struct object *))
        }
 
        for (i = 0; i < cache.nr; i++)
-               cb(cache.items[i]);
-}
-
-static void rev_list_push(struct commit *commit, int mark)
-{
-       if (!(commit->object.flags & mark)) {
-               commit->object.flags |= mark;
-
-               if (parse_commit(commit))
-                       return;
-
-               prio_queue_put(&rev_list, commit);
-
-               if (!(commit->object.flags & COMMON))
-                       non_common_revs++;
-       }
+               cb(negotiator, cache.items[i]);
 }
 
-static int rev_list_insert_ref(const char *refname, const struct object_id *oid)
+static int rev_list_insert_ref(struct fetch_negotiator *negotiator,
+                              const char *refname,
+                              const struct object_id *oid)
 {
-       struct object *o = deref_tag(parse_object(oid), refname, 0);
+       struct object *o = deref_tag(the_repository,
+                                    parse_object(the_repository, oid),
+                                    refname, 0);
 
        if (o && o->type == OBJ_COMMIT)
-               rev_list_push((struct commit *)o, SEEN);
+               negotiator->add_tip(negotiator, (struct commit *)o);
 
        return 0;
 }
@@ -136,98 +124,7 @@ static int rev_list_insert_ref(const char *refname, const struct object_id *oid)
 static int rev_list_insert_ref_oid(const char *refname, const struct object_id *oid,
                                   int flag, void *cb_data)
 {
-       return rev_list_insert_ref(refname, oid);
-}
-
-static int clear_marks(const char *refname, const struct object_id *oid,
-                      int flag, void *cb_data)
-{
-       struct object *o = deref_tag(parse_object(oid), refname, 0);
-
-       if (o && o->type == OBJ_COMMIT)
-               clear_commit_marks((struct commit *)o,
-                                  COMMON | COMMON_REF | SEEN | POPPED);
-       return 0;
-}
-
-/*
-   This function marks a rev and its ancestors as common.
-   In some cases, it is desirable to mark only the ancestors (for example
-   when only the server does not yet know that they are common).
-*/
-
-static void mark_common(struct commit *commit,
-               int ancestors_only, int dont_parse)
-{
-       if (commit != NULL && !(commit->object.flags & COMMON)) {
-               struct object *o = (struct object *)commit;
-
-               if (!ancestors_only)
-                       o->flags |= COMMON;
-
-               if (!(o->flags & SEEN))
-                       rev_list_push(commit, SEEN);
-               else {
-                       struct commit_list *parents;
-
-                       if (!ancestors_only && !(o->flags & POPPED))
-                               non_common_revs--;
-                       if (!o->parsed && !dont_parse)
-                               if (parse_commit(commit))
-                                       return;
-
-                       for (parents = commit->parents;
-                                       parents;
-                                       parents = parents->next)
-                               mark_common(parents->item, 0, dont_parse);
-               }
-       }
-}
-
-/*
-  Get the next rev to send, ignoring the common.
-*/
-
-static const struct object_id *get_rev(void)
-{
-       struct commit *commit = NULL;
-
-       while (commit == NULL) {
-               unsigned int mark;
-               struct commit_list *parents;
-
-               if (rev_list.nr == 0 || non_common_revs == 0)
-                       return NULL;
-
-               commit = prio_queue_get(&rev_list);
-               parse_commit(commit);
-               parents = commit->parents;
-
-               commit->object.flags |= POPPED;
-               if (!(commit->object.flags & COMMON))
-                       non_common_revs--;
-
-               if (commit->object.flags & COMMON) {
-                       /* do not send "have", and ignore ancestors */
-                       commit = NULL;
-                       mark = COMMON | SEEN;
-               } else if (commit->object.flags & COMMON_REF)
-                       /* send "have", and ignore ancestors */
-                       mark = COMMON | SEEN;
-               else
-                       /* send "have", also for its ancestors */
-                       mark = SEEN;
-
-               while (parents) {
-                       if (!(parents->item->object.flags & SEEN))
-                               rev_list_push(parents->item, mark);
-                       if (mark & COMMON)
-                               mark_common(parents->item, 1, 0);
-                       parents = parents->next;
-               }
-       }
-
-       return &commit->object.oid;
+       return rev_list_insert_ref(cb_data, refname, oid);
 }
 
 enum ack_type {
@@ -296,9 +193,10 @@ static void send_request(struct fetch_pack_args *args,
                write_or_die(fd, buf->buf, buf->len);
 }
 
-static void insert_one_alternate_object(struct object *obj)
+static void insert_one_alternate_object(struct fetch_negotiator *negotiator,
+                                       struct object *obj)
 {
-       rev_list_insert_ref(NULL, &obj->oid);
+       rev_list_insert_ref(negotiator, NULL, &obj->oid);
 }
 
 #define INITIAL_FLUSH 16
@@ -321,7 +219,24 @@ static int next_flush(int stateless_rpc, int count)
        return count;
 }
 
-static int find_common(struct fetch_pack_args *args,
+static void mark_tips(struct fetch_negotiator *negotiator,
+                     const struct oid_array *negotiation_tips)
+{
+       int i;
+
+       if (!negotiation_tips) {
+               for_each_ref(rev_list_insert_ref_oid, negotiator);
+               return;
+       }
+
+       for (i = 0; i < negotiation_tips->nr; i++)
+               rev_list_insert_ref(negotiator, NULL,
+                                   &negotiation_tips->oid[i]);
+       return;
+}
+
+static int find_common(struct fetch_negotiator *negotiator,
+                      struct fetch_pack_args *args,
                       int fd[2], struct object_id *result_oid,
                       struct ref *refs)
 {
@@ -336,12 +251,11 @@ static int find_common(struct fetch_pack_args *args,
 
        if (args->stateless_rpc && multi_ack == 1)
                die(_("--stateless-rpc requires multi_ack_detailed"));
-       if (marked)
-               for_each_ref(clear_marks, NULL);
-       marked = 1;
 
-       for_each_ref(rev_list_insert_ref_oid, NULL);
-       for_each_cached_alternate(insert_one_alternate_object);
+       if (!args->no_dependents) {
+               mark_tips(negotiator, args->negotiation_tips);
+               for_each_cached_alternate(negotiator, insert_one_alternate_object);
+       }
 
        fetching = 0;
        for ( ; refs ; refs = refs->next) {
@@ -358,8 +272,12 @@ static int find_common(struct fetch_pack_args *args,
                 * We use lookup_object here because we are only
                 * interested in the case we *know* the object is
                 * reachable and we have already scanned it.
+                *
+                * Do this only if args->no_dependents is false (if it is true,
+                * we cannot trust the object flags).
                 */
-               if (((o = lookup_object(remote->hash)) != NULL) &&
+               if (!args->no_dependents &&
+                   ((o = lookup_object(the_repository, remote->hash)) != NULL) &&
                                (o->flags & COMPLETE)) {
                        continue;
                }
@@ -396,7 +314,7 @@ static int find_common(struct fetch_pack_args *args,
                return 1;
        }
 
-       if (is_repository_shallow())
+       if (is_repository_shallow(the_repository))
                write_shallow_commits(&req_buf, 1, NULL);
        if (args->depth > 0)
                packet_buf_write(&req_buf, "deepen %d", args->depth);
@@ -427,16 +345,16 @@ static int find_common(struct fetch_pack_args *args,
                        if (skip_prefix(line, "shallow ", &arg)) {
                                if (get_oid_hex(arg, &oid))
                                        die(_("invalid shallow line: %s"), line);
-                               register_shallow(&oid);
+                               register_shallow(the_repository, &oid);
                                continue;
                        }
                        if (skip_prefix(line, "unshallow ", &arg)) {
                                if (get_oid_hex(arg, &oid))
                                        die(_("invalid unshallow line: %s"), line);
-                               if (!lookup_object(oid.hash))
+                               if (!lookup_object(the_repository, oid.hash))
                                        die(_("object not found: %s"), line);
                                /* make sure that it is parsed as shallow */
-                               if (!parse_object(&oid))
+                               if (!parse_object(the_repository, &oid))
                                        die(_("error in object: %s"), line);
                                if (unregister_shallow(&oid))
                                        die(_("no shallow found: %s"), line);
@@ -459,7 +377,7 @@ static int find_common(struct fetch_pack_args *args,
        retval = -1;
        if (args->no_dependents)
                goto done;
-       while ((oid = get_rev())) {
+       while ((oid = negotiator->next(negotiator))) {
                packet_buf_write(&req_buf, "have %s\n", oid_to_hex(oid));
                print_verbose(args, "have %s", oid_to_hex(oid));
                in_vain++;
@@ -495,12 +413,16 @@ static int find_common(struct fetch_pack_args *args,
                                case ACK_ready:
                                case ACK_continue: {
                                        struct commit *commit =
-                                               lookup_commit(result_oid);
+                                               lookup_commit(the_repository,
+                                                             result_oid);
+                                       int was_common;
+
                                        if (!commit)
                                                die(_("invalid commit %s"), oid_to_hex(result_oid));
+                                       was_common = negotiator->ack(negotiator, commit);
                                        if (args->stateless_rpc
                                         && ack == ACK_common
-                                        && !(commit->object.flags & COMMON)) {
+                                        && !was_common) {
                                                /* We need to replay the have for this object
                                                 * on the next RPC request so the peer knows
                                                 * it is in common with us.
@@ -517,13 +439,10 @@ static int find_common(struct fetch_pack_args *args,
                                        } else if (!args->stateless_rpc
                                                   || ack != ACK_common)
                                                in_vain = 0;
-                                       mark_common(commit, 0, 1);
                                        retval = 0;
                                        got_continue = 1;
-                                       if (ack == ACK_ready) {
-                                               clear_prio_queue(&rev_list);
+                                       if (ack == ACK_ready)
                                                got_ready = 1;
-                                       }
                                        break;
                                        }
                                }
@@ -533,6 +452,8 @@ static int find_common(struct fetch_pack_args *args,
                                print_verbose(args, _("giving up"));
                                break; /* give up */
                        }
+                       if (got_ready)
+                               break;
                }
        }
 done:
@@ -569,14 +490,14 @@ static struct commit_list *complete;
 
 static int mark_complete(const struct object_id *oid)
 {
-       struct object *o = parse_object(oid);
+       struct object *o = parse_object(the_repository, oid);
 
        while (o && o->type == OBJ_TAG) {
                struct tag *t = (struct tag *) o;
                if (!t->tagged)
                        break; /* broken repository */
                o->flags |= COMPLETE;
-               o = parse_object(&t->tagged->oid);
+               o = parse_object(the_repository, &t->tagged->oid);
        }
        if (o && o->type == OBJ_COMMIT) {
                struct commit *commit = (struct commit *)o;
@@ -610,21 +531,14 @@ static void add_refs_to_oidset(struct oidset *oids, struct ref *refs)
                oidset_insert(oids, &refs->old_oid);
 }
 
-static int tip_oids_contain(struct oidset *tip_oids,
-                           struct ref *unmatched, struct ref *newlist,
-                           const struct object_id *id)
+static int is_unmatched_ref(const struct ref *ref)
 {
-       /*
-        * Note that this only looks at the ref lists the first time it's
-        * called. This works out in filter_refs() because even though it may
-        * add to "newlist" between calls, the additions will always be for
-        * oids that are already in the set.
-        */
-       if (!tip_oids->map.map.tablesize) {
-               add_refs_to_oidset(tip_oids, unmatched);
-               add_refs_to_oidset(tip_oids, newlist);
-       }
-       return oidset_contains(tip_oids, id);
+       struct object_id oid;
+       const char *p;
+       return  ref->match_status == REF_NOT_MATCHED &&
+               !parse_oid_hex(ref->name, &oid, &p) &&
+               *p == '\0' &&
+               oideq(&oid, &ref->old_oid);
 }
 
 static void filter_refs(struct fetch_pack_args *args,
@@ -637,6 +551,8 @@ static void filter_refs(struct fetch_pack_args *args,
        struct ref *ref, *next;
        struct oidset tip_oids = OIDSET_INIT;
        int i;
+       int strict = !(allow_unadvertised_object_request &
+                      (ALLOW_TIP_SHA1 | ALLOW_REACHABLE_SHA1));
 
        i = 0;
        for (ref = *refs; ref; ref = next) {
@@ -657,11 +573,11 @@ static void filter_refs(struct fetch_pack_args *args,
                                }
                                i++;
                        }
-               }
 
-               if (!keep && args->fetch_all &&
-                   (!args->deepen || !starts_with(ref->name, "refs/tags/")))
-                       keep = 1;
+                       if (!keep && args->fetch_all &&
+                           (!args->deepen || !starts_with(ref->name, "refs/tags/")))
+                               keep = 1;
+               }
 
                if (keep) {
                        *newtail = ref;
@@ -673,23 +589,25 @@ static void filter_refs(struct fetch_pack_args *args,
                }
        }
 
+       if (strict) {
+               for (i = 0; i < nr_sought; i++) {
+                       ref = sought[i];
+                       if (!is_unmatched_ref(ref))
+                               continue;
+
+                       add_refs_to_oidset(&tip_oids, unmatched);
+                       add_refs_to_oidset(&tip_oids, newlist);
+                       break;
+               }
+       }
+
        /* Append unmatched requests to the list */
        for (i = 0; i < nr_sought; i++) {
-               struct object_id oid;
-               const char *p;
-
                ref = sought[i];
-               if (ref->match_status != REF_NOT_MATCHED)
-                       continue;
-               if (parse_oid_hex(ref->name, &oid, &p) ||
-                   *p != '\0' ||
-                   oidcmp(&oid, &ref->old_oid))
+               if (!is_unmatched_ref(ref))
                        continue;
 
-               if ((allow_unadvertised_object_request &
-                    (ALLOW_TIP_SHA1 | ALLOW_REACHABLE_SHA1)) ||
-                   tip_oids_contain(&tip_oids, unmatched, newlist,
-                                    &ref->old_oid)) {
+               if (!strict || oidset_contains(&tip_oids, &ref->old_oid)) {
                        ref->match_status = REF_MATCHED;
                        *newtail = copy_ref(ref);
                        newtail = &(*newtail)->next;
@@ -707,7 +625,8 @@ static void filter_refs(struct fetch_pack_args *args,
        *refs = newlist;
 }
 
-static void mark_alternate_complete(struct object *obj)
+static void mark_alternate_complete(struct fetch_negotiator *unused,
+                                   struct object *obj)
 {
        mark_complete(&obj->oid);
 }
@@ -734,12 +653,21 @@ static int add_loose_objects_to_set(const struct object_id *oid,
        return 0;
 }
 
-static int everything_local(struct fetch_pack_args *args,
-                           struct ref **refs,
-                           struct ref **sought, int nr_sought)
+/*
+ * Mark recent commits available locally and reachable from a local ref as
+ * COMPLETE. If args->no_dependents is false, also mark COMPLETE remote refs as
+ * COMMON_REF (otherwise, we are not planning to participate in negotiation, and
+ * thus do not need COMMON_REF marks).
+ *
+ * The cutoff time for recency is determined by this heuristic: it is the
+ * earliest commit time of the objects in refs that are commits and that we know
+ * the commit time of.
+ */
+static void mark_complete_and_common_ref(struct fetch_negotiator *negotiator,
+                                        struct fetch_pack_args *args,
+                                        struct ref **refs)
 {
        struct ref *ref;
-       int retval;
        int old_save_commit_buffer = save_commit_buffer;
        timestamp_t cutoff = 0;
        struct oidset loose_oid_set = OIDSET_INIT;
@@ -767,7 +695,7 @@ static int everything_local(struct fetch_pack_args *args,
 
                if (!has_object_file_with_flags(&ref->old_oid, flags))
                        continue;
-               o = parse_object(&ref->old_oid);
+               o = parse_object(the_repository, &ref->old_oid);
                if (!o)
                        continue;
 
@@ -784,41 +712,49 @@ static int everything_local(struct fetch_pack_args *args,
 
        oidset_clear(&loose_oid_set);
 
-       if (!args->no_dependents) {
-               if (!args->deepen) {
-                       for_each_ref(mark_complete_oid, NULL);
-                       for_each_cached_alternate(mark_alternate_complete);
-                       commit_list_sort_by_date(&complete);
-                       if (cutoff)
-                               mark_recent_complete_commits(args, cutoff);
-               }
-
-               /*
-                * Mark all complete remote refs as common refs.
-                * Don't mark them common yet; the server has to be told so first.
-                */
-               for (ref = *refs; ref; ref = ref->next) {
-                       struct object *o = deref_tag(lookup_object(ref->old_oid.hash),
-                                                    NULL, 0);
+       if (!args->deepen) {
+               for_each_ref(mark_complete_oid, NULL);
+               for_each_cached_alternate(NULL, mark_alternate_complete);
+               commit_list_sort_by_date(&complete);
+               if (cutoff)
+                       mark_recent_complete_commits(args, cutoff);
+       }
 
-                       if (!o || o->type != OBJ_COMMIT || !(o->flags & COMPLETE))
-                               continue;
+       /*
+        * Mark all complete remote refs as common refs.
+        * Don't mark them common yet; the server has to be told so first.
+        */
+       for (ref = *refs; ref; ref = ref->next) {
+               struct object *o = deref_tag(the_repository,
+                                            lookup_object(the_repository,
+                                            ref->old_oid.hash),
+                                            NULL, 0);
 
-                       if (!(o->flags & SEEN)) {
-                               rev_list_push((struct commit *)o, COMMON_REF | SEEN);
+               if (!o || o->type != OBJ_COMMIT || !(o->flags & COMPLETE))
+                       continue;
 
-                               mark_common((struct commit *)o, 1, 1);
-                       }
-               }
+               negotiator->known_common(negotiator,
+                                        (struct commit *)o);
        }
 
-       filter_refs(args, refs, sought, nr_sought);
+       save_commit_buffer = old_save_commit_buffer;
+}
+
+/*
+ * Returns 1 if every object pointed to by the given remote refs is available
+ * locally and reachable from a local ref, and 0 otherwise.
+ */
+static int everything_local(struct fetch_pack_args *args,
+                           struct ref **refs)
+{
+       struct ref *ref;
+       int retval;
 
        for (retval = 1, ref = *refs; ref ; ref = ref->next) {
                const struct object_id *remote = &ref->old_oid;
                struct object *o;
 
-               o = lookup_object(remote->hash);
+               o = lookup_object(the_repository, remote->hash);
                if (!o || !(o->flags & COMPLETE)) {
                        retval = 0;
                        print_verbose(args, "want %s (%s)", oid_to_hex(remote),
@@ -829,8 +765,6 @@ static int everything_local(struct fetch_pack_args *args,
                              ref->name);
        }
 
-       save_commit_buffer = old_save_commit_buffer;
-
        return retval;
 }
 
@@ -935,7 +869,8 @@ static int get_pack(struct fetch_pack_args *args,
                         */
                        argv_array_push(&cmd.args, "--fsck-objects");
                else
-                       argv_array_push(&cmd.args, "--strict");
+                       argv_array_pushf(&cmd.args, "--strict%s",
+                                        fsck_msg_types.buf);
        }
 
        cmd.in = demux.out;
@@ -981,11 +916,13 @@ static struct ref *do_fetch_pack(struct fetch_pack_args *args,
        struct object_id oid;
        const char *agent_feature;
        int agent_len;
+       struct fetch_negotiator negotiator;
+       fetch_negotiator_init(&negotiator, negotiation_algorithm);
 
        sort_ref_list(&ref, ref_compare_name);
        QSORT(sought, nr_sought, cmp_ref_by_name);
 
-       if ((args->depth > 0 || is_repository_shallow()) && !server_supports("shallow"))
+       if ((args->depth > 0 || is_repository_shallow(the_repository)) && !server_supports("shallow"))
                die(_("Server does not support shallow clients"));
        if (args->depth > 0 || args->deepen_since || args->deepen_not)
                args->deepen = 1;
@@ -1053,11 +990,17 @@ static struct ref *do_fetch_pack(struct fetch_pack_args *args,
        if (!server_supports("deepen-relative") && args->deepen_relative)
                die(_("Server does not support --deepen"));
 
-       if (everything_local(args, &ref, sought, nr_sought)) {
-               packet_flush(fd[1]);
-               goto all_done;
+       if (!args->no_dependents) {
+               mark_complete_and_common_ref(&negotiator, args, &ref);
+               filter_refs(args, &ref, sought, nr_sought);
+               if (everything_local(args, &ref)) {
+                       packet_flush(fd[1]);
+                       goto all_done;
+               }
+       } else {
+               filter_refs(args, &ref, sought, nr_sought);
        }
-       if (find_common(args, fd, &oid, ref) < 0)
+       if (find_common(&negotiator, args, fd, &oid, ref) < 0)
                if (!args->keep_pack)
                        /* When cloning, it is not unusual to have
                         * no common commit.
@@ -1077,13 +1020,14 @@ static struct ref *do_fetch_pack(struct fetch_pack_args *args,
                die(_("git fetch-pack: fetch failed."));
 
  all_done:
+       negotiator.release(&negotiator);
        return ref;
 }
 
 static void add_shallow_requests(struct strbuf *req_buf,
                                 const struct fetch_pack_args *args)
 {
-       if (is_repository_shallow())
+       if (is_repository_shallow(the_repository))
                write_shallow_commits(req_buf, 1, NULL);
        if (args->depth > 0)
                packet_buf_write(req_buf, "deepen %d", args->depth);
@@ -1100,11 +1044,12 @@ static void add_shallow_requests(struct strbuf *req_buf,
        }
 }
 
-static void add_wants(const struct ref *wants, struct strbuf *req_buf)
+static void add_wants(int no_dependents, const struct ref *wants, struct strbuf *req_buf)
 {
+       int use_ref_in_want = server_supports_feature("fetch", "ref-in-want", 0);
+
        for ( ; wants ; wants = wants->next) {
                const struct object_id *remote = &wants->old_oid;
-               const char *remote_hex;
                struct object *o;
 
                /*
@@ -1116,14 +1061,20 @@ static void add_wants(const struct ref *wants, struct strbuf *req_buf)
                 * We use lookup_object here because we are only
                 * interested in the case we *know* the object is
                 * reachable and we have already scanned it.
+                *
+                * Do this only if args->no_dependents is false (if it is true,
+                * we cannot trust the object flags).
                 */
-               if (((o = lookup_object(remote->hash)) != NULL) &&
+               if (!no_dependents &&
+                   ((o = lookup_object(the_repository, remote->hash)) != NULL) &&
                    (o->flags & COMPLETE)) {
                        continue;
                }
 
-               remote_hex = oid_to_hex(remote);
-               packet_buf_write(req_buf, "want %s\n", remote_hex);
+               if (!use_ref_in_want || wants->exact_oid)
+                       packet_buf_write(req_buf, "want %s\n", oid_to_hex(remote));
+               else
+                       packet_buf_write(req_buf, "want-ref %s\n", wants->name);
        }
 }
 
@@ -1138,13 +1089,15 @@ static void add_common(struct strbuf *req_buf, struct oidset *common)
        }
 }
 
-static int add_haves(struct strbuf *req_buf, int *haves_to_send, int *in_vain)
+static int add_haves(struct fetch_negotiator *negotiator,
+                    struct strbuf *req_buf,
+                    int *haves_to_send, int *in_vain)
 {
        int ret = 0;
        int haves_added = 0;
        const struct object_id *oid;
 
-       while ((oid = get_rev())) {
+       while ((oid = negotiator->next(negotiator))) {
                packet_buf_write(req_buf, "have %s\n", oid_to_hex(oid));
                if (++haves_added >= *haves_to_send)
                        break;
@@ -1163,7 +1116,8 @@ static int add_haves(struct strbuf *req_buf, int *haves_to_send, int *in_vain)
        return ret;
 }
 
-static int send_fetch_request(int fd_out, const struct fetch_pack_args *args,
+static int send_fetch_request(struct fetch_negotiator *negotiator, int fd_out,
+                             const struct fetch_pack_args *args,
                              const struct ref *wants, struct oidset *common,
                              int *haves_to_send, int *in_vain)
 {
@@ -1195,7 +1149,7 @@ static int send_fetch_request(int fd_out, const struct fetch_pack_args *args,
        /* Add shallow-info and deepen request */
        if (server_supports_feature("fetch", "shallow", 0))
                add_shallow_requests(&req_buf, args);
-       else if (is_repository_shallow() || args->deepen)
+       else if (is_repository_shallow(the_repository) || args->deepen)
                die(_("Server does not support shallow requests"));
 
        /* Add filter */
@@ -1209,7 +1163,7 @@ static int send_fetch_request(int fd_out, const struct fetch_pack_args *args,
        }
 
        /* add wants */
-       add_wants(wants, &req_buf);
+       add_wants(args->no_dependents, wants, &req_buf);
 
        if (args->no_dependents) {
                packet_buf_write(&req_buf, "done");
@@ -1219,7 +1173,7 @@ static int send_fetch_request(int fd_out, const struct fetch_pack_args *args,
                add_common(&req_buf, common);
 
                /* Add initial haves */
-               ret = add_haves(&req_buf, haves_to_send, in_vain);
+               ret = add_haves(negotiator, &req_buf, haves_to_send, in_vain);
        }
 
        /* Send request */
@@ -1242,13 +1196,13 @@ static int process_section_header(struct packet_reader *reader,
        int ret;
 
        if (packet_reader_peek(reader) != PACKET_READ_NORMAL)
-               die("error reading section header '%s'", section);
+               die(_("error reading section header '%s'"), section);
 
        ret = !strcmp(reader->line, section);
 
        if (!peek) {
                if (!ret)
-                       die("expected '%s', received '%s'",
+                       die(_("expected '%s', received '%s'"),
                            section, reader->line);
                packet_reader_read(reader);
        }
@@ -1256,7 +1210,9 @@ static int process_section_header(struct packet_reader *reader,
        return ret;
 }
 
-static int process_acks(struct packet_reader *reader, struct oidset *common)
+static int process_acks(struct fetch_negotiator *negotiator,
+                       struct packet_reader *reader,
+                       struct oidset *common)
 {
        /* received */
        int received_ready = 0;
@@ -1274,24 +1230,23 @@ static int process_acks(struct packet_reader *reader, struct oidset *common)
                        if (!get_oid_hex(arg, &oid)) {
                                struct commit *commit;
                                oidset_insert(common, &oid);
-                               commit = lookup_commit(&oid);
-                               mark_common(commit, 0, 1);
+                               commit = lookup_commit(the_repository, &oid);
+                               negotiator->ack(negotiator, commit);
                        }
                        continue;
                }
 
                if (!strcmp(reader->line, "ready")) {
-                       clear_prio_queue(&rev_list);
                        received_ready = 1;
                        continue;
                }
 
-               die("unexpected acknowledgment line: '%s'", reader->line);
+               die(_("unexpected acknowledgment line: '%s'"), reader->line);
        }
 
        if (reader->status != PACKET_READ_FLUSH &&
            reader->status != PACKET_READ_DELIM)
-               die("error processing acks: %d", reader->status);
+               die(_("error processing acks: %d"), reader->status);
 
        /* return 0 if no common, 1 if there are common, or 2 if ready */
        return received_ready ? 2 : (received_ack ? 1 : 0);
@@ -1308,16 +1263,16 @@ static void receive_shallow_info(struct fetch_pack_args *args,
                if (skip_prefix(reader->line, "shallow ", &arg)) {
                        if (get_oid_hex(arg, &oid))
                                die(_("invalid shallow line: %s"), reader->line);
-                       register_shallow(&oid);
+                       register_shallow(the_repository, &oid);
                        continue;
                }
                if (skip_prefix(reader->line, "unshallow ", &arg)) {
                        if (get_oid_hex(arg, &oid))
                                die(_("invalid unshallow line: %s"), reader->line);
-                       if (!lookup_object(oid.hash))
+                       if (!lookup_object(the_repository, oid.hash))
                                die(_("object not found: %s"), reader->line);
                        /* make sure that it is parsed as shallow */
-                       if (!parse_object(&oid))
+                       if (!parse_object(the_repository, &oid))
                                die(_("error in object: %s"), reader->line);
                        if (unregister_shallow(&oid))
                                die(_("no shallow found: %s"), reader->line);
@@ -1328,12 +1283,39 @@ static void receive_shallow_info(struct fetch_pack_args *args,
 
        if (reader->status != PACKET_READ_FLUSH &&
            reader->status != PACKET_READ_DELIM)
-               die("error processing shallow info: %d", reader->status);
+               die(_("error processing shallow info: %d"), reader->status);
 
        setup_alternate_shallow(&shallow_lock, &alternate_shallow_file, NULL);
        args->deepen = 1;
 }
 
+static void receive_wanted_refs(struct packet_reader *reader,
+                               struct ref **sought, int nr_sought)
+{
+       process_section_header(reader, "wanted-refs", 0);
+       while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
+               struct object_id oid;
+               const char *end;
+               int i;
+
+               if (parse_oid_hex(reader->line, &oid, &end) || *end++ != ' ')
+                       die(_("expected wanted-ref, got '%s'"), reader->line);
+
+               for (i = 0; i < nr_sought; i++) {
+                       if (!strcmp(end, sought[i]->name)) {
+                               oidcpy(&sought[i]->old_oid, &oid);
+                               break;
+                       }
+               }
+
+               if (i == nr_sought)
+                       die(_("unexpected wanted-ref: '%s'"), reader->line);
+       }
+
+       if (reader->status != PACKET_READ_DELIM)
+               die(_("error processing wanted refs: %d"), reader->status);
+}
+
 enum fetch_state {
        FETCH_CHECK_LOCAL = 0,
        FETCH_SEND_REQUEST,
@@ -1354,6 +1336,8 @@ static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
        struct packet_reader reader;
        int in_vain = 0;
        int haves_to_send = INITIAL_FLUSH;
+       struct fetch_negotiator negotiator;
+       fetch_negotiator_init(&negotiator, negotiation_algorithm);
        packet_reader_init(&reader, fd[0], NULL, 0,
                           PACKET_READ_CHOMP_NEWLINE);
 
@@ -1369,21 +1353,26 @@ static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
                        if (args->depth > 0 || args->deepen_since || args->deepen_not)
                                args->deepen = 1;
 
-                       if (marked)
-                               for_each_ref(clear_marks, NULL);
-                       marked = 1;
-
-                       for_each_ref(rev_list_insert_ref_oid, NULL);
-                       for_each_cached_alternate(insert_one_alternate_object);
-
                        /* Filter 'ref' by 'sought' and those that aren't local */
-                       if (everything_local(args, &ref, sought, nr_sought))
-                               state = FETCH_DONE;
-                       else
+                       if (!args->no_dependents) {
+                               mark_complete_and_common_ref(&negotiator, args, &ref);
+                               filter_refs(args, &ref, sought, nr_sought);
+                               if (everything_local(args, &ref))
+                                       state = FETCH_DONE;
+                               else
+                                       state = FETCH_SEND_REQUEST;
+
+                               mark_tips(&negotiator, args->negotiation_tips);
+                               for_each_cached_alternate(&negotiator,
+                                                         insert_one_alternate_object);
+                       } else {
+                               filter_refs(args, &ref, sought, nr_sought);
                                state = FETCH_SEND_REQUEST;
+                       }
                        break;
                case FETCH_SEND_REQUEST:
-                       if (send_fetch_request(fd[1], args, ref, &common,
+                       if (send_fetch_request(&negotiator, fd[1], args, ref,
+                                              &common,
                                               &haves_to_send, &in_vain))
                                state = FETCH_GET_PACK;
                        else
@@ -1391,7 +1380,7 @@ static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
                        break;
                case FETCH_PROCESS_ACKS:
                        /* Process ACKs/NAKs */
-                       switch (process_acks(&reader, &common)) {
+                       switch (process_acks(&negotiator, &reader, &common)) {
                        case 2:
                                state = FETCH_GET_PACK;
                                break;
@@ -1408,6 +1397,9 @@ static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
                        if (process_section_header(&reader, "shallow-info", 1))
                                receive_shallow_info(args, &reader);
 
+                       if (process_section_header(&reader, "wanted-refs", 1))
+                               receive_wanted_refs(&reader, sought, nr_sought);
+
                        /* get the pack */
                        process_section_header(&reader, "packfile", 0);
                        if (get_pack(args, fd, pack_lockfile))
@@ -1420,10 +1412,36 @@ static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
                }
        }
 
+       negotiator.release(&negotiator);
        oidset_clear(&common);
        return ref;
 }
 
+static int fetch_pack_config_cb(const char *var, const char *value, void *cb)
+{
+       if (strcmp(var, "fetch.fsck.skiplist") == 0) {
+               const char *path;
+
+               if (git_config_pathname(&path, var, value))
+                       return 1;
+               strbuf_addf(&fsck_msg_types, "%cskiplist=%s",
+                       fsck_msg_types.len ? ',' : '=', path);
+               free((char *)path);
+               return 0;
+       }
+
+       if (skip_prefix(var, "fetch.fsck.", &var)) {
+               if (is_valid_msg_type(var, value))
+                       strbuf_addf(&fsck_msg_types, "%c%s=%s",
+                               fsck_msg_types.len ? ',' : '=', var, value);
+               else
+                       warning("Skipping unknown msg id '%s'", var);
+               return 0;
+       }
+
+       return git_default_config(var, value, cb);
+}
+
 static void fetch_pack_config(void)
 {
        git_config_get_int("fetch.unpacklimit", &fetch_unpack_limit);
@@ -1431,8 +1449,10 @@ static void fetch_pack_config(void)
        git_config_get_bool("repack.usedeltabaseoffset", &prefer_ofs_delta);
        git_config_get_bool("fetch.fsckobjects", &fetch_fsck_objects);
        git_config_get_bool("transfer.fsckobjects", &transfer_fsck_objects);
+       git_config_get_string("fetch.negotiationalgorithm",
+                             &negotiation_algorithm);
 
-       git_config(git_default_config, NULL);
+       git_config(fetch_pack_config_cb, NULL);
 }
 
 static void fetch_pack_setup(void)
@@ -1479,7 +1499,7 @@ static void update_shallow(struct fetch_pack_args *args,
 
        if (args->deepen && alternate_shallow_file) {
                if (*alternate_shallow_file == '\0') { /* --unshallow */
-                       unlink_or_warn(git_path_shallow());
+                       unlink_or_warn(git_path_shallow(the_repository));
                        rollback_lock_file(&shallow_lock);
                } else
                        commit_lock_file(&shallow_lock);
@@ -1563,6 +1583,18 @@ static void update_shallow(struct fetch_pack_args *args,
        oid_array_clear(&ref);
 }
 
+static int iterate_ref_map(void *cb_data, struct object_id *oid)
+{
+       struct ref **rm = cb_data;
+       struct ref *ref = *rm;
+
+       if (!ref)
+               return -1; /* end of the list */
+       *rm = ref->next;
+       oidcpy(oid, &ref->old_oid);
+       return 0;
+}
+
 struct ref *fetch_pack(struct fetch_pack_args *args,
                       int fd[], struct child_process *conn,
                       const struct ref *ref,
@@ -1579,7 +1611,21 @@ struct ref *fetch_pack(struct fetch_pack_args *args,
        if (nr_sought)
                nr_sought = remove_duplicates_in_refs(sought, nr_sought);
 
-       if (!ref) {
+       if (args->no_dependents && !args->filter_options.choice) {
+               /*
+                * The protocol does not support requesting that only the
+                * wanted objects be sent, so approximate this by setting a
+                * "blob:none" filter if no filter is already set. This works
+                * for all object types: note that wanted blobs will still be
+                * sent because they are directly specified as a "want".
+                *
+                * NEEDSWORK: Add an option in the protocol to request that
+                * only the wanted objects be sent, and implement it.
+                */
+               parse_list_objects_filter(&args->filter_options, "blob:none");
+       }
+
+       if (version != protocol_v2 && !ref) {
                packet_flush(fd[1]);
                die(_("no matching remote head"));
        }
@@ -1591,7 +1637,25 @@ struct ref *fetch_pack(struct fetch_pack_args *args,
                ref_cpy = do_fetch_pack(args, fd, ref, sought, nr_sought,
                                        &si, pack_lockfile);
        reprepare_packed_git(the_repository);
+
+       if (!args->cloning && args->deepen) {
+               struct check_connected_options opt = CHECK_CONNECTED_INIT;
+               struct ref *iterator = ref_cpy;
+               opt.shallow_file = alternate_shallow_file;
+               if (args->deepen)
+                       opt.is_deepening_fetch = 1;
+               if (check_connected(iterate_ref_map, &iterator, &opt)) {
+                       error(_("remote did not send all necessary objects"));
+                       free_refs(ref_cpy);
+                       ref_cpy = NULL;
+                       rollback_lock_file(&shallow_lock);
+                       goto cleanup;
+               }
+               args->connectivity_checked = 1;
+       }
+
        update_shallow(args, sought, nr_sought, &si);
+cleanup:
        clear_shallow_info(&si);
        return ref_cpy;
 }