kernel/git - git - PowerEL Git System

Tree: b65c05882f

Author	SHA1	Message	Date
Karsten Blees	7b64d42d22	hashmap: add string interning API Interning short strings with high probability of duplicates can reduce the memory footprint and speed up comparisons. Add strintern() and memintern() APIs that use a hashmap to manage the pool of unique, interned strings. Note: strintern(getenv()) could be used to sanitize git's use of getenv(), in case we ever encounter a platform where a call to getenv() invalidates previous getenv() results (which is allowed by POSIX). Signed-off-by: Karsten Blees <blees@dcon.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Karsten Blees	ab73a9d119	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>	11 years ago
Jonathan Nieder	e8fa59b908	test-hashmap.c: drop unnecessary #includes Per Documentation/CodingGuidelines most C files in git start with a #include of git-compat-util.h or another header file that includes it, such as cache.h or builtin.h. This file doesn't need anything beyond "git-compat-util.h", so use that. Remove a #include of the system header <stdio.h> since it is already included by "git-compat-util.h". Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Karsten Blees	efc684245b	remove old hash.[ch] implementation Signed-off-by: Karsten Blees <blees@dcon.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Karsten Blees	6a364ced49	add a hashtable implementation that supports O(1) removal The existing hashtable implementation (in hash.[ch]) uses open addressing (i.e. resolve hash collisions by distributing entries across the table). Thus, removal is difficult to implement with less than O(n) complexity. Resolving collisions of entries with identical hashes (e.g. via chaining) is left to the client code. Add a hashtable implementation that supports O(1) removal and is slightly easier to use due to builtin entry chaining. Supports all basic operations init, free, get, add, remove and iteration. Also includes ready-to-use hash functions based on the public domain FNV-1 algorithm (http://www.isthe.com/chongo/tech/comp/fnv). The per-entry data structure (hashmap_entry) is piggybacked in front of the client's data structure to save memory. See test-hashmap.c for usage examples. The hashtable is resized by a factor of four when 80% full. With these settings, average memory consumption is about 2/3 of hash.[ch], and insertion is about twice as fast due to less frequent resizing. Lookups are also slightly faster, because entries are strictly confined to their bucket (i.e. no data of other buckets needs to be traversed). Signed-off-by: Karsten Blees <blees@dcon.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago