git.oblomov.eu Git - git/blob - 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 static const char *object_type_strings[] = {
   9         NULL,           /* OBJ_NONE = 0 */
  10         "commit",       /* OBJ_COMMIT = 1 */
  11         "tree",         /* OBJ_TREE = 2 */
  12         "blob",         /* OBJ_BLOB = 3 */
  13         "tag",          /* OBJ_TAG = 4 */
  14 };
  15
  16 const char *typename(unsigned int type)
  17 {
  18         if (type >= ARRAY_SIZE(object_type_strings))
  19                 return NULL;
  20         return object_type_strings[type];
  21 }
  22
  23 int type_from_string(const char *str)
  24 {
  25         int i;
  26
  27         for (i = 1; i < ARRAY_SIZE(object_type_strings); i++)
  28                 if (!strcmp(str, object_type_strings[i]))
  29                         return i;
  30         die("invalid object type \"%s\"", str);
  31 }
  32
  33 static struct object **obj_hash;
  34 static int nr_objs, obj_hash_size;
  35
  36 unsigned int get_max_object_index(void)
  37 {
  38         return obj_hash_size;
  39 }
  40
  41 struct object *get_indexed_object(unsigned int idx)
  42 {
  43         return obj_hash[idx];
  44 }
  45
  46
  47 /* Choose from 2, 3, 4 or 5 */
  48 #define CUCKOO_FACTOR 4
  49
  50 #define H(hv,ix) ((hv[ix]) & (obj_hash_size-1))
  51
  52 struct object *lookup_object(const unsigned char *sha1)
  53 {
  54         struct object *obj;
  55         const unsigned int *hashval;
  56
  57         if (!obj_hash)
  58                 return NULL;
  59
  60         hashval = (const unsigned int *)sha1;
  61         if ((obj = obj_hash[H(hashval, 0)]) && !hashcmp(sha1, obj->sha1))
  62                 return obj;
  63         if ((obj = obj_hash[H(hashval, 1)]) && !hashcmp(sha1, obj->sha1))
  64                 return obj;
  65 #if CUCKOO_FACTOR >= 3
  66         if ((obj = obj_hash[H(hashval, 2)]) && !hashcmp(sha1, obj->sha1))
  67                 return obj;
  68 #endif
  69 #if CUCKOO_FACTOR >= 4
  70         if ((obj = obj_hash[H(hashval, 3)]) && !hashcmp(sha1, obj->sha1))
  71                 return obj;
  72 #endif
  73 #if CUCKOO_FACTOR >= 5
  74         if ((obj = obj_hash[H(hashval, 4)]) && !hashcmp(sha1, obj->sha1))
  75                 return obj;
  76 #endif
  77         return NULL;
  78 }
  79
  80 static void grow_object_hash(void); /* forward */
  81
  82 /*
  83  * A naive single-table cuckoo hashing implementation.
  84  * Return NULL when "obj" is successfully inserted. Otherwise
  85  * return a pointer to the object to be inserted (which may
  86  * be different from the original obj). The caller is expected
  87  * to grow the hash table and re-insert the returned object.
  88  */
  89 static struct object *insert_obj_hash(struct object *obj)
  90 {
  91         int loop;
  92
  93         for (loop = obj_hash_size - obj_hash_size / 8; 0 <= loop; loop--) {
  94                 struct object *tmp_obj;
  95                 unsigned int ix, i0;
  96                 const unsigned int *hashval;
  97
  98                 hashval = (const unsigned int *)(obj->sha1);
  99                 i0 = ix = H(hashval, 0);
 100                 tmp_obj = obj_hash[i0];
 101                 if (!tmp_obj) {
 102                         obj_hash[ix] = obj;
 103                         return NULL;
 104                 }
 105                 ix = H(hashval, 1);
 106                 if (!obj_hash[ix]) {
 107                         obj_hash[ix] = obj;
 108                         return NULL;
 109                 }
 110 #if CUCKOO_FACTOR >= 3
 111                 ix = H(hashval, 2);
 112                 if (!obj_hash[ix]) {
 113                         obj_hash[ix] = obj;
 114                         return NULL;
 115                 }
 116 #endif
 117 #if CUCKOO_FACTOR >= 4
 118                 ix = H(hashval, 3);
 119                 if (!obj_hash[ix]) {
 120                         obj_hash[ix] = obj;
 121                         return NULL;
 122                 }
 123 #endif
 124 #if CUCKOO_FACTOR >= 5
 125                 ix = H(hashval, 4);
 126                 if (!obj_hash[ix]) {
 127                         obj_hash[ix] = obj;
 128                         return NULL;
 129                 }
 130 #endif
 131                 obj_hash[i0] = obj;
 132                 obj = tmp_obj;
 133         }
 134         return obj;
 135 }
 136
 137 static int next_size(int sz)
 138 {
 139         return (sz < 32 ? 32 :
 140                 (sz < 1024 * 1024 ? 8 : 2) * sz);
 141 }
 142
 143 static void grow_object_hash(void)
 144 {
 145         struct object **current_hash;
 146         int current_size;
 147
 148         current_hash = obj_hash;
 149         current_size = obj_hash_size;
 150         while (1) {
 151                 int i;
 152                 obj_hash_size = next_size(obj_hash_size);
 153                 obj_hash = xcalloc(obj_hash_size, sizeof(struct object *));
 154
 155                 for (i = 0; i < current_size; i++) {
 156                         if (!current_hash[i])
 157                                 continue;
 158                         if (insert_obj_hash(current_hash[i]))
 159                                 break;
 160                 }
 161                 if (i < current_size) {
 162                         /* too small - grow and retry */
 163                         free(obj_hash);
 164                         continue;
 165                 }
 166                 free(current_hash);
 167                 return;
 168         }
 169 }
 170
 171 void *create_object(const unsigned char *sha1, int type, void *o)
 172 {
 173         struct object *obj = o;
 174         struct object *to_insert;
 175
 176         obj->parsed = 0;
 177         obj->used = 0;
 178         obj->type = type;
 179         obj->flags = 0;
 180         hashcpy(obj->sha1, sha1);
 181
 182         if (!obj_hash_size)
 183                 grow_object_hash();
 184
 185         to_insert = obj;
 186         while (1) {
 187                 to_insert = insert_obj_hash(to_insert);
 188                 if (!to_insert)
 189                         break;
 190                 grow_object_hash();
 191         }
 192         nr_objs++;
 193         return obj;
 194 }
 195
 196 struct object *lookup_unknown_object(const unsigned char *sha1)
 197 {
 198         struct object *obj = lookup_object(sha1);
 199         if (!obj)
 200                 obj = create_object(sha1, OBJ_NONE, alloc_object_node());
 201         return obj;
 202 }
 203
 204 struct object *parse_object_buffer(const unsigned char *sha1, enum object_type type, unsigned long size, void *buffer, int *eaten_p)
 205 {
 206         struct object *obj;
 207         int eaten = 0;
 208
 209         obj = NULL;
 210         if (type == OBJ_BLOB) {
 211                 struct blob *blob = lookup_blob(sha1);
 212                 if (blob) {
 213                         if (parse_blob_buffer(blob, buffer, size))
 214                                 return NULL;
 215                         obj = &blob->object;
 216                 }
 217         } else if (type == OBJ_TREE) {
 218                 struct tree *tree = lookup_tree(sha1);
 219                 if (tree) {
 220                         obj = &tree->object;
 221                         if (!tree->object.parsed) {
 222                                 if (parse_tree_buffer(tree, buffer, size))
 223                                         return NULL;
 224                                 eaten = 1;
 225                         }
 226                 }
 227         } else if (type == OBJ_COMMIT) {
 228                 struct commit *commit = lookup_commit(sha1);
 229                 if (commit) {
 230                         if (parse_commit_buffer(commit, buffer, size))
 231                                 return NULL;
 232                         if (!commit->buffer) {
 233                                 commit->buffer = buffer;
 234                                 eaten = 1;
 235                         }
 236                         obj = &commit->object;
 237                 }
 238         } else if (type == OBJ_TAG) {
 239                 struct tag *tag = lookup_tag(sha1);
 240                 if (tag) {
 241                         if (parse_tag_buffer(tag, buffer, size))
 242                                return NULL;
 243                         obj = &tag->object;
 244                 }
 245         } else {
 246                 warning("object %s has unknown type id %d\n", sha1_to_hex(sha1), type);
 247                 obj = NULL;
 248         }
 249         if (obj && obj->type == OBJ_NONE)
 250                 obj->type = type;
 251         *eaten_p = eaten;
 252         return obj;
 253 }
 254
 255 struct object *parse_object(const unsigned char *sha1)
 256 {
 257         unsigned long size;
 258         enum object_type type;
 259         int eaten;
 260         const unsigned char *repl = lookup_replace_object(sha1);
 261         void *buffer = read_sha1_file(sha1, &type, &size);
 262
 263         if (buffer) {
 264                 struct object *obj;
 265                 if (check_sha1_signature(repl, buffer, size, typename(type)) < 0) {
 266                         free(buffer);
 267                         error("sha1 mismatch %s\n", sha1_to_hex(repl));
 268                         return NULL;
 269                 }
 270
 271                 obj = parse_object_buffer(sha1, type, size, buffer, &eaten);
 272                 if (!eaten)
 273                         free(buffer);
 274                 return obj;
 275         }
 276         return NULL;
 277 }
 278
 279 struct object_list *object_list_insert(struct object *item,
 280                                        struct object_list **list_p)
 281 {
 282         struct object_list *new_list = xmalloc(sizeof(struct object_list));
 283         new_list->item = item;
 284         new_list->next = *list_p;
 285         *list_p = new_list;
 286         return new_list;
 287 }
 288
 289 int object_list_contains(struct object_list *list, struct object *obj)
 290 {
 291         while (list) {
 292                 if (list->item == obj)
 293                         return 1;
 294                 list = list->next;
 295         }
 296         return 0;
 297 }
 298
 299 void add_object_array(struct object *obj, const char *name, struct object_array *array)
 300 {
 301         add_object_array_with_mode(obj, name, array, S_IFINVALID);
 302 }
 303
 304 void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode)
 305 {
 306         unsigned nr = array->nr;
 307         unsigned alloc = array->alloc;
 308         struct object_array_entry *objects = array->objects;
 309
 310         if (nr >= alloc) {
 311                 alloc = (alloc + 32) * 2;
 312                 objects = xrealloc(objects, alloc * sizeof(*objects));
 313                 array->alloc = alloc;
 314                 array->objects = objects;
 315         }
 316         objects[nr].item = obj;
 317         objects[nr].name = name;
 318         objects[nr].mode = mode;
 319         array->nr = ++nr;
 320 }
 321
 322 void object_array_remove_duplicates(struct object_array *array)
 323 {
 324         unsigned int ref, src, dst;
 325         struct object_array_entry *objects = array->objects;
 326
 327         for (ref = 0; ref + 1 < array->nr; ref++) {
 328                 for (src = ref + 1, dst = src;
 329                      src < array->nr;
 330                      src++) {
 331                         if (!strcmp(objects[ref].name, objects[src].name))
 332                                 continue;
 333                         if (src != dst)
 334                                 objects[dst] = objects[src];
 335                         dst++;
 336                 }
 337                 array->nr = dst;
 338         }
 339 }