Merge branch 'cc/fetch-error-message-fix'
[git/git.git] / negotiator / skipping.c
1 #include "cache.h"
2 #include "skipping.h"
3 #include "../commit.h"
4 #include "../fetch-negotiator.h"
5 #include "../prio-queue.h"
6 #include "../refs.h"
7 #include "../tag.h"
8
9 /* Remember to update object flag allocation in object.h */
10 /*
11 * Both us and the server know that both parties have this object.
12 */
13 #define COMMON (1U << 2)
14 /*
15 * The server has told us that it has this object. We still need to tell the
16 * server that we have this object (or one of its descendants), but since we are
17 * going to do that, we do not need to tell the server about its ancestors.
18 */
19 #define ADVERTISED (1U << 3)
20 /*
21 * This commit has entered the priority queue.
22 */
23 #define SEEN (1U << 4)
24 /*
25 * This commit has left the priority queue.
26 */
27 #define POPPED (1U << 5)
28
29 static int marked;
30
31 /*
32 * An entry in the priority queue.
33 */
34 struct entry {
35 struct commit *commit;
36
37 /*
38 * Used only if commit is not COMMON.
39 */
40 uint16_t original_ttl;
41 uint16_t ttl;
42 };
43
44 struct data {
45 struct prio_queue rev_list;
46
47 /*
48 * The number of non-COMMON commits in rev_list.
49 */
50 int non_common_revs;
51 };
52
53 static int compare(const void *a_, const void *b_, void *unused)
54 {
55 const struct entry *a = a_;
56 const struct entry *b = b_;
57 return compare_commits_by_commit_date(a->commit, b->commit, NULL);
58 }
59
60 static struct entry *rev_list_push(struct data *data, struct commit *commit, int mark)
61 {
62 struct entry *entry;
63 commit->object.flags |= mark | SEEN;
64
65 entry = xcalloc(1, sizeof(*entry));
66 entry->commit = commit;
67 prio_queue_put(&data->rev_list, entry);
68
69 if (!(mark & COMMON))
70 data->non_common_revs++;
71 return entry;
72 }
73
74 static int clear_marks(const char *refname, const struct object_id *oid,
75 int flag, void *cb_data)
76 {
77 struct object *o = deref_tag(the_repository, parse_object(the_repository, oid), refname, 0);
78
79 if (o && o->type == OBJ_COMMIT)
80 clear_commit_marks((struct commit *)o,
81 COMMON | ADVERTISED | SEEN | POPPED);
82 return 0;
83 }
84
85 /*
86 * Mark this SEEN commit and all its SEEN ancestors as COMMON.
87 */
88 static void mark_common(struct data *data, struct commit *c)
89 {
90 struct commit_list *p;
91
92 if (c->object.flags & COMMON)
93 return;
94 c->object.flags |= COMMON;
95 if (!(c->object.flags & POPPED))
96 data->non_common_revs--;
97
98 if (!c->object.parsed)
99 return;
100 for (p = c->parents; p; p = p->next) {
101 if (p->item->object.flags & SEEN)
102 mark_common(data, p->item);
103 }
104 }
105
106 /*
107 * Ensure that the priority queue has an entry for to_push, and ensure that the
108 * entry has the correct flags and ttl.
109 *
110 * This function returns 1 if an entry was found or created, and 0 otherwise
111 * (because the entry for this commit had already been popped).
112 */
113 static int push_parent(struct data *data, struct entry *entry,
114 struct commit *to_push)
115 {
116 struct entry *parent_entry;
117
118 if (to_push->object.flags & SEEN) {
119 int i;
120 if (to_push->object.flags & POPPED)
121 /*
122 * The entry for this commit has already been popped,
123 * due to clock skew. Pretend that this parent does not
124 * exist.
125 */
126 return 0;
127 /*
128 * Find the existing entry and use it.
129 */
130 for (i = 0; i < data->rev_list.nr; i++) {
131 parent_entry = data->rev_list.array[i].data;
132 if (parent_entry->commit == to_push)
133 goto parent_found;
134 }
135 BUG("missing parent in priority queue");
136 parent_found:
137 ;
138 } else {
139 parent_entry = rev_list_push(data, to_push, 0);
140 }
141
142 if (entry->commit->object.flags & (COMMON | ADVERTISED)) {
143 mark_common(data, to_push);
144 } else {
145 uint16_t new_original_ttl = entry->ttl
146 ? entry->original_ttl : entry->original_ttl * 3 / 2 + 1;
147 uint16_t new_ttl = entry->ttl
148 ? entry->ttl - 1 : new_original_ttl;
149 if (parent_entry->original_ttl < new_original_ttl) {
150 parent_entry->original_ttl = new_original_ttl;
151 parent_entry->ttl = new_ttl;
152 }
153 }
154
155 return 1;
156 }
157
158 static const struct object_id *get_rev(struct data *data)
159 {
160 struct commit *to_send = NULL;
161
162 while (to_send == NULL) {
163 struct entry *entry;
164 struct commit *commit;
165 struct commit_list *p;
166 int parent_pushed = 0;
167
168 if (data->rev_list.nr == 0 || data->non_common_revs == 0)
169 return NULL;
170
171 entry = prio_queue_get(&data->rev_list);
172 commit = entry->commit;
173 commit->object.flags |= POPPED;
174 if (!(commit->object.flags & COMMON))
175 data->non_common_revs--;
176
177 if (!(commit->object.flags & COMMON) && !entry->ttl)
178 to_send = commit;
179
180 parse_commit(commit);
181 for (p = commit->parents; p; p = p->next)
182 parent_pushed |= push_parent(data, entry, p->item);
183
184 if (!(commit->object.flags & COMMON) && !parent_pushed)
185 /*
186 * This commit has no parents, or all of its parents
187 * have already been popped (due to clock skew), so send
188 * it anyway.
189 */
190 to_send = commit;
191
192 free(entry);
193 }
194
195 return &to_send->object.oid;
196 }
197
198 static void known_common(struct fetch_negotiator *n, struct commit *c)
199 {
200 if (c->object.flags & SEEN)
201 return;
202 rev_list_push(n->data, c, ADVERTISED);
203 }
204
205 static void add_tip(struct fetch_negotiator *n, struct commit *c)
206 {
207 n->known_common = NULL;
208 if (c->object.flags & SEEN)
209 return;
210 rev_list_push(n->data, c, 0);
211 }
212
213 static const struct object_id *next(struct fetch_negotiator *n)
214 {
215 n->known_common = NULL;
216 n->add_tip = NULL;
217 return get_rev(n->data);
218 }
219
220 static int ack(struct fetch_negotiator *n, struct commit *c)
221 {
222 int known_to_be_common = !!(c->object.flags & COMMON);
223 if (!(c->object.flags & SEEN))
224 die("received ack for commit %s not sent as 'have'\n",
225 oid_to_hex(&c->object.oid));
226 mark_common(n->data, c);
227 return known_to_be_common;
228 }
229
230 static void release(struct fetch_negotiator *n)
231 {
232 clear_prio_queue(&((struct data *)n->data)->rev_list);
233 FREE_AND_NULL(n->data);
234 }
235
236 void skipping_negotiator_init(struct fetch_negotiator *negotiator)
237 {
238 struct data *data;
239 negotiator->known_common = known_common;
240 negotiator->add_tip = add_tip;
241 negotiator->next = next;
242 negotiator->ack = ack;
243 negotiator->release = release;
244 negotiator->data = data = xcalloc(1, sizeof(*data));
245 data->rev_list.compare = compare;
246
247 if (marked)
248 for_each_ref(clear_marks, NULL);
249 marked = 1;
250 }