Use a hashtable for objects instead of a sorted list
[git] / object.c
1 #include "cache.h"
2 #include "object.h"
3 #include "blob.h"
4 #include "tree.h"
5 #include "commit.h"
6 #include "tag.h"
7
8 struct object **objs;
9 static int nr_objs;
10 int obj_allocs;
11
12 int track_object_refs = 1;
13
14 static int hashtable_index(const unsigned char *sha1)
15 {
16         unsigned int i = *(unsigned int *)sha1;
17         return (int)(i % obj_allocs);
18 }
19
20 static int find_object(const unsigned char *sha1)
21 {
22         int i = hashtable_index(sha1);
23
24         if (!objs)
25                 return -1;
26
27         while (objs[i]) {
28                 if (memcmp(sha1, objs[i]->sha1, 20) == 0)
29                         return i;
30                 i++;
31                 if (i == obj_allocs)
32                         i = 0;
33         }
34         return -1 - i;
35 }
36
37 struct object *lookup_object(const unsigned char *sha1)
38 {
39         int pos = find_object(sha1);
40         if (pos >= 0)
41                 return objs[pos];
42         return NULL;
43 }
44
45 void created_object(const unsigned char *sha1, struct object *obj)
46 {
47         int pos;
48
49         obj->parsed = 0;
50         memcpy(obj->sha1, sha1, 20);
51         obj->type = NULL;
52         obj->refs = NULL;
53         obj->used = 0;
54
55         if (obj_allocs - 1 <= nr_objs * 2) {
56                 int i, count = obj_allocs;
57                 obj_allocs = (obj_allocs < 32 ? 32 : 2 * obj_allocs);
58                 objs = xrealloc(objs, obj_allocs * sizeof(struct object *));
59                 memset(objs + count, 0, (obj_allocs - count)
60                                 * sizeof(struct object *));
61                 for (i = 0; i < count; i++)
62                         if (objs[i]) {
63                                 int j = find_object(objs[i]->sha1);
64                                 if (j != i) {
65                                         j = -1 - j;
66                                         objs[j] = objs[i];
67                                         objs[i] = NULL;
68                                 }
69                         }
70         }
71
72         pos = find_object(sha1);
73         if (pos >= 0)
74                 die("Inserting %s twice\n", sha1_to_hex(sha1));
75         pos = -pos-1;
76
77         objs[pos] = obj;
78         nr_objs++;
79 }
80
81 struct object_refs *alloc_object_refs(unsigned count)
82 {
83         struct object_refs *refs;
84         size_t size = sizeof(*refs) + count*sizeof(struct object *);
85
86         refs = xmalloc(size);
87         memset(refs, 0, size);
88         refs->count = count;
89         return refs;
90 }
91
92 static int compare_object_pointers(const void *a, const void *b)
93 {
94         const struct object * const *pa = a;
95         const struct object * const *pb = b;
96         if (*pa == *pb)
97                 return 0;
98         else if (*pa < *pb)
99                 return -1;
100         else
101                 return 1;
102 }
103
104 void set_object_refs(struct object *obj, struct object_refs *refs)
105 {
106         unsigned int i, j;
107
108         /* Do not install empty list of references */
109         if (refs->count < 1) {
110                 free(refs);
111                 return;
112         }
113
114         /* Sort the list and filter out duplicates */
115         qsort(refs->ref, refs->count, sizeof(refs->ref[0]),
116               compare_object_pointers);
117         for (i = j = 1; i < refs->count; i++) {
118                 if (refs->ref[i] != refs->ref[i - 1])
119                         refs->ref[j++] = refs->ref[i];
120         }
121         if (j < refs->count) {
122                 /* Duplicates were found - reallocate list */
123                 size_t size = sizeof(*refs) + j*sizeof(struct object *);
124                 refs->count = j;
125                 refs = xrealloc(refs, size);
126         }
127
128         for (i = 0; i < refs->count; i++)
129                 refs->ref[i]->used = 1;
130         obj->refs = refs;
131 }
132
133 void mark_reachable(struct object *obj, unsigned int mask)
134 {
135         if (!track_object_refs)
136                 die("cannot do reachability with object refs turned off");
137         /* If we've been here already, don't bother */
138         if (obj->flags & mask)
139                 return;
140         obj->flags |= mask;
141         if (obj->refs) {
142                 const struct object_refs *refs = obj->refs;
143                 unsigned i;
144                 for (i = 0; i < refs->count; i++)
145                         mark_reachable(refs->ref[i], mask);
146         }
147 }
148
149 struct object *lookup_object_type(const unsigned char *sha1, const char *type)
150 {
151         if (!type) {
152                 return lookup_unknown_object(sha1);
153         } else if (!strcmp(type, blob_type)) {
154                 return &lookup_blob(sha1)->object;
155         } else if (!strcmp(type, tree_type)) {
156                 return &lookup_tree(sha1)->object;
157         } else if (!strcmp(type, commit_type)) {
158                 return &lookup_commit(sha1)->object;
159         } else if (!strcmp(type, tag_type)) {
160                 return &lookup_tag(sha1)->object;
161         } else {
162                 error("Unknown type %s", type);
163                 return NULL;
164         }
165 }
166
167 union any_object {
168         struct object object;
169         struct commit commit;
170         struct tree tree;
171         struct blob blob;
172         struct tag tag;
173 };
174
175 struct object *lookup_unknown_object(const unsigned char *sha1)
176 {
177         struct object *obj = lookup_object(sha1);
178         if (!obj) {
179                 union any_object *ret = xmalloc(sizeof(*ret));
180                 memset(ret, 0, sizeof(*ret));
181                 created_object(sha1, &ret->object);
182                 ret->object.type = NULL;
183                 return &ret->object;
184         }
185         return obj;
186 }
187
188 struct object *parse_object(const unsigned char *sha1)
189 {
190         unsigned long size;
191         char type[20];
192         void *buffer = read_sha1_file(sha1, type, &size);
193         if (buffer) {
194                 struct object *obj;
195                 if (check_sha1_signature(sha1, buffer, size, type) < 0)
196                         printf("sha1 mismatch %s\n", sha1_to_hex(sha1));
197                 if (!strcmp(type, "blob")) {
198                         struct blob *blob = lookup_blob(sha1);
199                         parse_blob_buffer(blob, buffer, size);
200                         obj = &blob->object;
201                 } else if (!strcmp(type, "tree")) {
202                         struct tree *tree = lookup_tree(sha1);
203                         parse_tree_buffer(tree, buffer, size);
204                         obj = &tree->object;
205                 } else if (!strcmp(type, "commit")) {
206                         struct commit *commit = lookup_commit(sha1);
207                         parse_commit_buffer(commit, buffer, size);
208                         if (!commit->buffer) {
209                                 commit->buffer = buffer;
210                                 buffer = NULL;
211                         }
212                         obj = &commit->object;
213                 } else if (!strcmp(type, "tag")) {
214                         struct tag *tag = lookup_tag(sha1);
215                         parse_tag_buffer(tag, buffer, size);
216                         obj = &tag->object;
217                 } else {
218                         obj = NULL;
219                 }
220                 free(buffer);
221                 return obj;
222         }
223         return NULL;
224 }
225
226 struct object_list *object_list_insert(struct object *item,
227                                        struct object_list **list_p)
228 {
229         struct object_list *new_list = xmalloc(sizeof(struct object_list));
230         new_list->item = item;
231         new_list->next = *list_p;
232         *list_p = new_list;
233         return new_list;
234 }
235
236 void object_list_append(struct object *item,
237                         struct object_list **list_p)
238 {
239         while (*list_p) {
240                 list_p = &((*list_p)->next);
241         }
242         *list_p = xmalloc(sizeof(struct object_list));
243         (*list_p)->next = NULL;
244         (*list_p)->item = item;
245 }
246
247 unsigned object_list_length(struct object_list *list)
248 {
249         unsigned ret = 0;
250         while (list) {
251                 list = list->next;
252                 ret++;
253         }
254         return ret;
255 }
256
257 int object_list_contains(struct object_list *list, struct object *obj)
258 {
259         while (list) {
260                 if (list->item == obj)
261                         return 1;
262                 list = list->next;
263         }
264         return 0;
265 }