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authorJonathan Tan <jonathantanmy@google.com>2018-06-14 22:54:28 (GMT)
committerJunio C Hamano <gitster@pobox.com>2018-06-15 15:44:24 (GMT)
commitec06283844a90c3e9440286401e9ad7d86daa5ae (patch)
tree57270c7f90133aa44cd9486248168321ab7527d6 /negotiator/default.c
parentd093bc7582fc60b51b42d2edf32b3ce68cd283eb (diff)
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fetch-pack: introduce negotiator API
Introduce the new files fetch-negotiator.{h,c}, which contains an API behind which the details of negotiation are abstracted. Currently, only one algorithm is available: the existing one. This patch is written to be easily reviewed: static functions are moved verbatim from fetch-pack.c to negotiator/default.c, and it can be seen that the lines replaced by negotiator->X() calls are present in the X() functions respectively. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'negotiator/default.c')
-rw-r--r--negotiator/default.c176
1 files changed, 176 insertions, 0 deletions
diff --git a/negotiator/default.c b/negotiator/default.c
new file mode 100644
index 0000000..382fc77
--- /dev/null
+++ b/negotiator/default.c
@@ -0,0 +1,176 @@
+#include "cache.h"
+#include "default.h"
+#include "../commit.h"
+#include "../fetch-negotiator.h"
+#include "../prio-queue.h"
+#include "../refs.h"
+#include "../tag.h"
+
+/* Remember to update object flag allocation in object.h */
+#define COMMON (1U << 2)
+#define COMMON_REF (1U << 3)
+#define SEEN (1U << 4)
+#define POPPED (1U << 5)
+
+static int marked;
+
+struct negotiation_state {
+ struct prio_queue rev_list;
+ int non_common_revs;
+};
+
+static void rev_list_push(struct negotiation_state *ns,
+ struct commit *commit, int mark)
+{
+ if (!(commit->object.flags & mark)) {
+ commit->object.flags |= mark;
+
+ if (parse_commit(commit))
+ return;
+
+ prio_queue_put(&ns->rev_list, commit);
+
+ if (!(commit->object.flags & COMMON))
+ ns->non_common_revs++;
+ }
+}
+
+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 negotiation_state *ns, 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(ns, commit, SEEN);
+ else {
+ struct commit_list *parents;
+
+ if (!ancestors_only && !(o->flags & POPPED))
+ ns->non_common_revs--;
+ if (!o->parsed && !dont_parse)
+ if (parse_commit(commit))
+ return;
+
+ for (parents = commit->parents;
+ parents;
+ parents = parents->next)
+ mark_common(ns, parents->item, 0,
+ dont_parse);
+ }
+ }
+}
+
+/*
+ * Get the next rev to send, ignoring the common.
+ */
+static const struct object_id *get_rev(struct negotiation_state *ns)
+{
+ struct commit *commit = NULL;
+
+ while (commit == NULL) {
+ unsigned int mark;
+ struct commit_list *parents;
+
+ if (ns->rev_list.nr == 0 || ns->non_common_revs == 0)
+ return NULL;
+
+ commit = prio_queue_get(&ns->rev_list);
+ parse_commit(commit);
+ parents = commit->parents;
+
+ commit->object.flags |= POPPED;
+ if (!(commit->object.flags & COMMON))
+ ns->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(ns, parents->item, mark);
+ if (mark & COMMON)
+ mark_common(ns, parents->item, 1, 0);
+ parents = parents->next;
+ }
+ }
+
+ return &commit->object.oid;
+}
+
+static void known_common(struct fetch_negotiator *n, struct commit *c)
+{
+ if (!(c->object.flags & SEEN)) {
+ rev_list_push(n->data, c, COMMON_REF | SEEN);
+ mark_common(n->data, c, 1, 1);
+ }
+}
+
+static void add_tip(struct fetch_negotiator *n, struct commit *c)
+{
+ n->known_common = NULL;
+ rev_list_push(n->data, c, SEEN);
+}
+
+static const struct object_id *next(struct fetch_negotiator *n)
+{
+ n->known_common = NULL;
+ n->add_tip = NULL;
+ return get_rev(n->data);
+}
+
+static int ack(struct fetch_negotiator *n, struct commit *c)
+{
+ int known_to_be_common = !!(c->object.flags & COMMON);
+ mark_common(n->data, c, 0, 1);
+ return known_to_be_common;
+}
+
+static void release(struct fetch_negotiator *n)
+{
+ clear_prio_queue(&((struct negotiation_state *)n->data)->rev_list);
+ FREE_AND_NULL(n->data);
+}
+
+void default_negotiator_init(struct fetch_negotiator *negotiator)
+{
+ struct negotiation_state *ns;
+ negotiator->known_common = known_common;
+ negotiator->add_tip = add_tip;
+ negotiator->next = next;
+ negotiator->ack = ack;
+ negotiator->release = release;
+ negotiator->data = ns = xcalloc(1, sizeof(*ns));
+ ns->rev_list.compare = compare_commits_by_commit_date;
+
+ if (marked)
+ for_each_ref(clear_marks, NULL);
+ marked = 1;
+}