Subject: [PATCH 1/6] name-hash: specify initial size for istate.dir_hash table

From: [email-masked]
Date: Wed, 22 Mar 2017 17:14:20 +0000

From: Jeff Hostetler <[email-masked]>

Specify an initial size for the istate.dir_hash HashMap matching
the size of the istate.name_hash.

Previously hashmap_init() was given 0, causing a 64 bucket
hashmap to be created.  When working with very large
repositories, this would cause numerous rehash() calls to
realloc and rebalance the hashmap. This is especially true
when the worktree is deep, with many directories containing
a few files.

Signed-off-by: Jeff Hostetler <[email-masked]>
---
 name-hash.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/name-hash.c b/name-hash.c
index 6d9f23e..3f7722a 100644
--- a/name-hash.c
+++ b/name-hash.c
@@ -120,7 +120,8 @@ static void lazy_init_name_hash(struct index_state *istate)
 		return;
 	hashmap_init(&istate->name_hash, (hashmap_cmp_fn) cache_entry_cmp,
 			istate->cache_nr);
-	hashmap_init(&istate->dir_hash, (hashmap_cmp_fn) dir_entry_cmp, 0);
+	hashmap_init(&istate->dir_hash, (hashmap_cmp_fn) dir_entry_cmp,
+			istate->cache_nr);
 	for (nr = 0; nr < istate->cache_nr; nr++)
 		hash_index_entry(istate, istate->cache[nr]);
 	istate->name_hash_initialized = 1;
-- 
2.7.4