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| author | Nguyễn Thái Ngọc Duy <pclouds@gmail.com> | 2013-03-17 10:28:06 +0700 |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2013-03-16 22:57:29 -0700 |
| commit | c73592812d36ccc7eccfd0489177970d246fa522 (patch) | |
| tree | 1e92b0c8fb8cb4bf5bbb10f38cf695785457b2e7 | |
| parent | 03a0fb0ccf48c831060c2243f830b6a12cd8fdf3 (diff) | |
| download | git-c73592812d36ccc7eccfd0489177970d246fa522.tar.gz | |
Preallocate hash tables when the number of inserts are known in advance
This avoids unnecessary re-allocations and reinsertions. On webkit.git
(i.e. about 182k inserts to the name hash table), this reduces about
100ms out of 3s user time.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
| -rw-r--r-- | diffcore-rename.c | 1 | ||||
| -rw-r--r-- | hash.h | 7 | ||||
| -rw-r--r-- | name-hash.c | 2 |
3 files changed, 10 insertions, 0 deletions
diff --git a/diffcore-rename.c b/diffcore-rename.c index 512d0ac5fd..6c7a72fbe7 100644 --- a/diffcore-rename.c +++ b/diffcore-rename.c @@ -389,6 +389,7 @@ static int find_exact_renames(struct diff_options *options) struct hash_table file_table; init_hash(&file_table); + preallocate_hash(&file_table, rename_src_nr + rename_dst_nr); for (i = 0; i < rename_src_nr; i++) insert_file_table(&file_table, -1, i, rename_src[i].p->one); @@ -40,4 +40,11 @@ static inline void init_hash(struct hash_table *table) table->array = NULL; } +static inline void preallocate_hash(struct hash_table *table, unsigned int elts) +{ + assert(table->size == 0 && table->nr == 0 && table->array == NULL); + table->size = elts * 2; + table->array = xcalloc(sizeof(struct hash_table_entry), table->size); +} + #endif diff --git a/name-hash.c b/name-hash.c index d8d25c23e9..2a1f108247 100644 --- a/name-hash.c +++ b/name-hash.c @@ -92,6 +92,8 @@ static void lazy_init_name_hash(struct index_state *istate) if (istate->name_hash_initialized) return; + if (istate->cache_nr) + preallocate_hash(&istate->name_hash, istate->cache_nr); for (nr = 0; nr < istate->cache_nr; nr++) hash_index_entry(istate, istate->cache[nr]); istate->name_hash_initialized = 1; |