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5d23e13 Refactor patch-id filtering out of git-cherry and git-format-patch.
Junio C Hamano authored Apr 9, 2007
1 #include "cache.h"
2 #include "diff.h"
3 #include "commit.h"
4 #include "patch-ids.h"
5
6 static int commit_patch_id(struct commit *commit, struct diff_options *options,
7 unsigned char *sha1)
8 {
9 if (commit->parents)
10 diff_tree_sha1(commit->parents->item->object.sha1,
11 commit->object.sha1, "", options);
12 else
13 diff_root_tree_sha1(commit->object.sha1, "", options);
14 diffcore_std(options);
15 return diff_flush_patch_id(options, sha1);
16 }
17
18 static uint32_t take2(const unsigned char *id)
19 {
20 return ((id[0] << 8) | id[1]);
21 }
22
23 /*
24 * Conventional binary search loop looks like this:
25 *
26 * do {
27 * int mi = (lo + hi) / 2;
28 * int cmp = "entry pointed at by mi" minus "target";
29 * if (!cmp)
30 * return (mi is the wanted one)
31 * if (cmp > 0)
32 * hi = mi; "mi is larger than target"
33 * else
34 * lo = mi+1; "mi is smaller than target"
35 * } while (lo < hi);
36 *
37 * The invariants are:
38 *
39 * - When entering the loop, lo points at a slot that is never
40 * above the target (it could be at the target), hi points at a
41 * slot that is guaranteed to be above the target (it can never
42 * be at the target).
43 *
44 * - We find a point 'mi' between lo and hi (mi could be the same
45 * as lo, but never can be the same as hi), and check if it hits
46 * the target. There are three cases:
47 *
48 * - if it is a hit, we are happy.
49 *
50 * - if it is strictly higher than the target, we update hi with
51 * it.
52 *
53 * - if it is strictly lower than the target, we update lo to be
54 * one slot after it, because we allow lo to be at the target.
55 *
56 * When choosing 'mi', we do not have to take the "middle" but
57 * anywhere in between lo and hi, as long as lo <= mi < hi is
58 * satisfied. When we somehow know that the distance between the
59 * target and lo is much shorter than the target and hi, we could
60 * pick mi that is much closer to lo than the midway.
61 */
62 static int patch_pos(struct patch_id **table, int nr, const unsigned char *id)
63 {
64 int hi = nr;
65 int lo = 0;
66 int mi = 0;
67
68 if (!nr)
69 return -1;
70
71 if (nr != 1) {
72 unsigned lov, hiv, miv, ofs;
73
74 for (ofs = 0; ofs < 18; ofs += 2) {
75 lov = take2(table[0]->patch_id + ofs);
76 hiv = take2(table[nr-1]->patch_id + ofs);
77 miv = take2(id + ofs);
78 if (miv < lov)
79 return -1;
80 if (hiv < miv)
81 return -1 - nr;
82 if (lov != hiv) {
83 /*
84 * At this point miv could be equal
85 * to hiv (but id could still be higher);
86 * the invariant of (mi < hi) should be
87 * kept.
88 */
89 mi = (nr-1) * (miv - lov) / (hiv - lov);
90 if (lo <= mi && mi < hi)
91 break;
92 die("oops");
93 }
94 }
95 if (18 <= ofs)
96 die("cannot happen -- lo and hi are identical");
97 }
98
99 do {
100 int cmp;
101 cmp = hashcmp(table[mi]->patch_id, id);
102 if (!cmp)
103 return mi;
104 if (cmp > 0)
105 hi = mi;
106 else
107 lo = mi + 1;
108 mi = (hi + lo) / 2;
109 } while (lo < hi);
110 return -lo-1;
111 }
112
113 #define BUCKET_SIZE 190 /* 190 * 21 = 3990, with slop close enough to 4K */
114 struct patch_id_bucket {
115 struct patch_id_bucket *next;
116 int nr;
117 struct patch_id bucket[BUCKET_SIZE];
118 };
119
120 int init_patch_ids(struct patch_ids *ids)
121 {
122 memset(ids, 0, sizeof(*ids));
123 diff_setup(&ids->diffopts);
8f67f8a Make the diff_options bitfields be an unsigned with explicit masks.
Pierre Habouzit authored Nov 10, 2007
124 DIFF_OPT_SET(&ids->diffopts, RECURSIVE);
5d23e13 Refactor patch-id filtering out of git-cherry and git-format-patch.
Junio C Hamano authored Apr 10, 2007
125 if (diff_setup_done(&ids->diffopts) < 0)
126 return error("diff_setup_done failed");
127 return 0;
128 }
129
130 int free_patch_ids(struct patch_ids *ids)
131 {
132 struct patch_id_bucket *next, *patches;
133
134 free(ids->table);
135 for (patches = ids->patches; patches; patches = next) {
136 next = patches->next;
137 free(patches);
138 }
139 return 0;
140 }
141
142 static struct patch_id *add_commit(struct commit *commit,
143 struct patch_ids *ids,
144 int no_add)
145 {
146 struct patch_id_bucket *bucket;
147 struct patch_id *ent;
148 unsigned char sha1[20];
149 int pos;
150
151 if (commit_patch_id(commit, &ids->diffopts, sha1))
152 return NULL;
153 pos = patch_pos(ids->table, ids->nr, sha1);
154 if (0 <= pos)
155 return ids->table[pos];
156 if (no_add)
157 return NULL;
158
159 pos = -1 - pos;
160
161 bucket = ids->patches;
162 if (!bucket || (BUCKET_SIZE <= bucket->nr)) {
163 bucket = xcalloc(1, sizeof(*bucket));
164 bucket->next = ids->patches;
165 ids->patches = bucket;
166 }
167 ent = &bucket->bucket[bucket->nr++];
168 hashcpy(ent->patch_id, sha1);
169
170 if (ids->alloc <= ids->nr) {
171 ids->alloc = alloc_nr(ids->nr);
172 ids->table = xrealloc(ids->table, sizeof(ent) * ids->alloc);
173 }
174 if (pos < ids->nr)
175 memmove(ids->table + pos + 1, ids->table + pos,
176 sizeof(ent) * (ids->nr - pos));
177 ids->nr++;
178 ids->table[pos] = ent;
179 return ids->table[pos];
180 }
181
182 struct patch_id *has_commit_patch_id(struct commit *commit,
183 struct patch_ids *ids)
184 {
185 return add_commit(commit, ids, 1);
186 }
187
188 struct patch_id *add_commit_patch_id(struct commit *commit,
189 struct patch_ids *ids)
190 {
191 return add_commit(commit, ids, 0);
192 }
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