hashmap: add simplified hashmap_get_from_hash() API
Hashmap entries are typically looked up by just a key. The hashmap_get() API expects an initialized entry structure instead, to support compound keys. This flexibility is currently only needed by find_dir_entry() in name-hash.c (and compat/win32/fscache.c in the msysgit fork). All other (currently five) call sites of hashmap_get() have to set up a near emtpy entry structure, resulting in duplicate code like this: struct hashmap_entry keyentry; hashmap_entry_init(&keyentry, hash(key)); return hashmap_get(map, &keyentry, key); Add a hashmap_get_from_hash() API that allows hashmap lookups by just specifying the key and its hash code, i.e.: return hashmap_get_from_hash(map, hash(key), key); Signed-off-by: Karsten Blees <blees@dcon.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Karsten Blees committed
Jul 3, 2014 at 00:22 UTC
ab73a9d119240b0b908ccb9edd19b8e536ce29b9
6 files changed
+31
-18
Documentation/technical/api-hashmap.txt
+14
@@ -118,6 +118,20 @@ hashmap_entry) that has at least been initialized with the proper hash code
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If an entry with matching hash code is found, `key` and `keydata` are passed
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to `hashmap_cmp_fn` to decide whether the entry matches the key.
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+`void *hashmap_get_from_hash(const struct hashmap *map, unsigned int hash, const void *keydata)`::
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+
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+ Returns the hashmap entry for the specified hash code and key data,
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+ or NULL if not found.
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++
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+`map` is the hashmap structure.
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++
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+`hash` is the hash code of the entry to look up.
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++
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+If an entry with matching hash code is found, `keydata` is passed to
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+`hashmap_cmp_fn` to decide whether the entry matches the key. The
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+`entry_or_key` parameter points to a bogus hashmap_entry structure that
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+should not be used in the comparison.
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+
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`void *hashmap_get_next(const struct hashmap *map, const void *entry)`::
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Returns the next equal hashmap entry, or NULL if not found. This can be
builtin/describe.c
+1
-3
@@ -58,9 +58,7 @@ static int commit_name_cmp(const struct commit_name *cn1,
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static inline struct commit_name *find_commit_name(const unsigned char *peeled)
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{
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- struct commit_name key;
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- hashmap_entry_init(&key, sha1hash(peeled));
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- return hashmap_get(&names, &key, peeled);
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+ return hashmap_get_from_hash(&names, sha1hash(peeled), peeled);
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}
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static int replace_name(struct commit_name *e,
diffcore-rename.c
+3
-4
@@ -257,15 +257,14 @@ static int find_identical_files(struct hashmap *srcs,
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int renames = 0;
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struct diff_filespec *target = rename_dst[dst_index].two;
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- struct file_similarity *p, *best, dst;
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+ struct file_similarity *p, *best = NULL;
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int i = 100, best_score = -1;
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/*
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* Find the best source match for specified destination.
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*/
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- best = NULL;
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- hashmap_entry_init(&dst, hash_filespec(target));
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- for (p = hashmap_get(srcs, &dst, NULL); p; p = hashmap_get_next(srcs, p)) {
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+ p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
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+ for (; p; p = hashmap_get_next(srcs, p)) {
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int score;
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struct diff_filespec *source = p->filespec;
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hashmap.h
+8
@@ -68,6 +68,14 @@ extern void *hashmap_put(struct hashmap *map, void *entry);
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extern void *hashmap_remove(struct hashmap *map, const void *key,
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const void *keydata);
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+static inline void *hashmap_get_from_hash(const struct hashmap *map,
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+ unsigned int hash, const void *keydata)
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+{
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+ struct hashmap_entry key;
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+ hashmap_entry_init(&key, hash);
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+ return hashmap_get(map, &key, keydata);
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+}
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+
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/* hashmap_iter functions */
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extern void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter);
name-hash.c
+2
-3
@@ -213,12 +213,11 @@ struct cache_entry *index_dir_exists(struct index_state *istate, const char *nam
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struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int icase)
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{
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struct cache_entry *ce;
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- struct hashmap_entry key;
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lazy_init_name_hash(istate);
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- hashmap_entry_init(&key, memihash(name, namelen));
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- ce = hashmap_get(&istate->name_hash, &key, NULL);
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+ ce = hashmap_get_from_hash(&istate->name_hash,
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+ memihash(name, namelen), NULL);
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while (ce) {
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if (same_name(ce, name, namelen, icase))
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return ce;
test-hashmap.c
+3
-8
@@ -115,9 +115,8 @@ static void perf_hashmap(unsigned int method, unsigned int rounds)
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for (j = 0; j < rounds; j++) {
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for (i = 0; i < TEST_SIZE; i++) {
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- struct hashmap_entry key;
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- hashmap_entry_init(&key, hashes[i]);
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- hashmap_get(&map, &key, entries[i]->key);
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+ hashmap_get_from_hash(&map, hashes[i],
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+ entries[i]->key);
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}
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}
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@@ -199,12 +198,8 @@ int main(int argc, char *argv[])
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} else if (!strcmp("get", cmd) && l1) {
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- /* setup static key */
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- struct hashmap_entry key;
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- hashmap_entry_init(&key, hash);
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-
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/* lookup entry in hashmap */
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- entry = hashmap_get(&map, &key, p1);
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+ entry = hashmap_get_from_hash(&map, hash, p1);
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/* print result */
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if (!entry)