Git 2.2.3
[git/git.git] / name-hash.c
CommitLineData
96872bc2
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1/*
2 * name-hash.c
3 *
4 * Hashing names in the index state
5 *
6 * Copyright (C) 2008 Linus Torvalds
7 */
8#define NO_THE_INDEX_COMPATIBILITY_MACROS
9#include "cache.h"
10
2092678c 11struct dir_entry {
e05881a4 12 struct hashmap_entry ent;
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13 struct dir_entry *parent;
14 struct cache_entry *ce;
15 int nr;
16 unsigned int namelen;
17};
18
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19static int dir_entry_cmp(const struct dir_entry *e1,
20 const struct dir_entry *e2, const char *name)
21{
22 return e1->namelen != e2->namelen || strncasecmp(e1->ce->name,
23 name ? name : e2->ce->name, e1->namelen);
24}
25
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26static struct dir_entry *find_dir_entry(struct index_state *istate,
27 const char *name, unsigned int namelen)
28{
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29 struct dir_entry key;
30 hashmap_entry_init(&key, memihash(name, namelen));
31 key.namelen = namelen;
32 return hashmap_get(&istate->dir_hash, &key, name);
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33}
34
35static struct dir_entry *hash_dir_entry(struct index_state *istate,
36 struct cache_entry *ce, int namelen)
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37{
38 /*
39 * Throw each directory component in the hash for quick lookup
d28eec26 40 * during a git status. Directory components are stored without their
5102c617 41 * closing slash. Despite submodules being a directory, they never
d28eec26 42 * reach this point, because they are stored
2092678c 43 * in index_state.name_hash (as ordinary cache_entries).
5102c617 44 *
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45 * Note that the cache_entry stored with the dir_entry merely
46 * supplies the name of the directory (up to dir_entry.namelen). We
47 * track the number of 'active' files in a directory in dir_entry.nr,
48 * so we can tell if the directory is still relevant, e.g. for git
49 * status. However, if cache_entries are removed, we cannot pinpoint
50 * an exact cache_entry that's still active. It is very possible that
51 * multiple dir_entries point to the same cache_entry.
5102c617 52 */
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53 struct dir_entry *dir;
54
55 /* get length of parent directory */
56 while (namelen > 0 && !is_dir_sep(ce->name[namelen - 1]))
57 namelen--;
58 if (namelen <= 0)
59 return NULL;
d28eec26 60 namelen--;
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61
62 /* lookup existing entry for that directory */
63 dir = find_dir_entry(istate, ce->name, namelen);
64 if (!dir) {
65 /* not found, create it and add to hash table */
2092678c 66 dir = xcalloc(1, sizeof(struct dir_entry));
e05881a4 67 hashmap_entry_init(dir, memihash(ce->name, namelen));
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68 dir->namelen = namelen;
69 dir->ce = ce;
e05881a4 70 hashmap_add(&istate->dir_hash, dir);
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71
72 /* recursively add missing parent directories */
d28eec26 73 dir->parent = hash_dir_entry(istate, ce, namelen);
5102c617 74 }
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75 return dir;
76}
77
78static void add_dir_entry(struct index_state *istate, struct cache_entry *ce)
79{
80 /* Add reference to the directory entry (and parents if 0). */
81 struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
82 while (dir && !(dir->nr++))
83 dir = dir->parent;
84}
85
86static void remove_dir_entry(struct index_state *istate, struct cache_entry *ce)
87{
88 /*
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89 * Release reference to the directory entry. If 0, remove and continue
90 * with parent directory.
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91 */
92 struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
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93 while (dir && !(--dir->nr)) {
94 struct dir_entry *parent = dir->parent;
95 hashmap_remove(&istate->dir_hash, dir, NULL);
96 free(dir);
97 dir = parent;
98 }
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99}
100
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101static void hash_index_entry(struct index_state *istate, struct cache_entry *ce)
102{
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103 if (ce->ce_flags & CE_HASHED)
104 return;
105 ce->ce_flags |= CE_HASHED;
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106 hashmap_entry_init(ce, memihash(ce->name, ce_namelen(ce)));
107 hashmap_add(&istate->name_hash, ce);
5102c617 108
419a597f 109 if (ignore_case)
2092678c 110 add_dir_entry(istate, ce);
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111}
112
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113static int cache_entry_cmp(const struct cache_entry *ce1,
114 const struct cache_entry *ce2, const void *remove)
115{
116 /*
117 * For remove_name_hash, find the exact entry (pointer equality); for
7b359ea6 118 * index_file_exists, find all entries with matching hash code and
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119 * decide whether the entry matches in same_name.
120 */
121 return remove ? !(ce1 == ce2) : 0;
122}
123
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124static void lazy_init_name_hash(struct index_state *istate)
125{
126 int nr;
127
128 if (istate->name_hash_initialized)
129 return;
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130 hashmap_init(&istate->name_hash, (hashmap_cmp_fn) cache_entry_cmp,
131 istate->cache_nr);
e05881a4 132 hashmap_init(&istate->dir_hash, (hashmap_cmp_fn) dir_entry_cmp, 0);
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133 for (nr = 0; nr < istate->cache_nr; nr++)
134 hash_index_entry(istate, istate->cache[nr]);
135 istate->name_hash_initialized = 1;
136}
137
138void add_name_hash(struct index_state *istate, struct cache_entry *ce)
139{
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140 if (istate->name_hash_initialized)
141 hash_index_entry(istate, ce);
142}
143
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144void remove_name_hash(struct index_state *istate, struct cache_entry *ce)
145{
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146 if (!istate->name_hash_initialized || !(ce->ce_flags & CE_HASHED))
147 return;
148 ce->ce_flags &= ~CE_HASHED;
149 hashmap_remove(&istate->name_hash, ce, ce);
2092678c 150
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151 if (ignore_case)
152 remove_dir_entry(istate, ce);
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153}
154
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155static int slow_same_name(const char *name1, int len1, const char *name2, int len2)
156{
157 if (len1 != len2)
158 return 0;
159
160 while (len1) {
161 unsigned char c1 = *name1++;
162 unsigned char c2 = *name2++;
163 len1--;
164 if (c1 != c2) {
165 c1 = toupper(c1);
166 c2 = toupper(c2);
167 if (c1 != c2)
168 return 0;
169 }
170 }
171 return 1;
172}
173
174static int same_name(const struct cache_entry *ce, const char *name, int namelen, int icase)
175{
176 int len = ce_namelen(ce);
177
178 /*
179 * Always do exact compare, even if we want a case-ignoring comparison;
180 * we do the quick exact one first, because it will be the common case.
181 */
be99ec97 182 if (len == namelen && !memcmp(name, ce->name, len))
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183 return 1;
184
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185 if (!icase)
186 return 0;
187
2092678c 188 return slow_same_name(name, namelen, ce->name, len);
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189}
190
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191struct cache_entry *index_dir_exists(struct index_state *istate, const char *name, int namelen)
192{
193 struct cache_entry *ce;
194 struct dir_entry *dir;
195
196 lazy_init_name_hash(istate);
197 dir = find_dir_entry(istate, name, namelen);
198 if (dir && dir->nr)
199 return dir->ce;
200
201 /*
202 * It might be a submodule. Unlike plain directories, which are stored
203 * in the dir-hash, submodules are stored in the name-hash, so check
204 * there, as well.
205 */
d28eec26 206 ce = index_file_exists(istate, name, namelen, 1);
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207 if (ce && S_ISGITLINK(ce->ce_mode))
208 return ce;
209
210 return NULL;
211}
212
213struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int icase)
96872bc2 214{
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215 struct cache_entry *ce;
216
217 lazy_init_name_hash(istate);
96872bc2 218
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219 ce = hashmap_get_from_hash(&istate->name_hash,
220 memihash(name, namelen), NULL);
96872bc2 221 while (ce) {
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222 if (same_name(ce, name, namelen, icase))
223 return ce;
8b013788 224 ce = hashmap_get_next(&istate->name_hash, ce);
96872bc2 225 }
df292c79 226 return NULL;
96872bc2 227}
2092678c 228
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229void free_name_hash(struct index_state *istate)
230{
231 if (!istate->name_hash_initialized)
232 return;
233 istate->name_hash_initialized = 0;
2092678c 234
8b013788 235 hashmap_free(&istate->name_hash, 0);
e05881a4 236 hashmap_free(&istate->dir_hash, 1);
2092678c 237}