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name-hash: precompute hash values during preload-index

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Precompute the istate.name_hash and istate.dir_hash values
for each cache-entry during the preload-index phase.

Move the expensive memihash() calculations from lazy_init_name_hash()
to the multi-threaded preload-index phase.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
This commit is contained in:
Jeff Hostetler
2016-11-17 09:59:59 -05:00
committed by Johannes Schindelin
parent d484faac20
commit d27bd052d2
4 changed files with 85 additions and 2 deletions
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66
name-hash.c
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@@ -50,6 +50,17 @@ static struct dir_entry *hash_dir_entry(struct index_state *istate,
*/
struct dir_entry *dir;
unsigned int hash;
int use_precomputed_dir_hash = 0;
if (ce->precompute_hash_state & CE_PRECOMPUTE_HASH_STATE__SET) {
if (!(ce->precompute_hash_state & CE_PRECOMPUTE_HASH_STATE__DIR))
return NULL; /* item does not have a parent directory */
if (namelen == ce_namelen(ce)) {
/* dir hash only valid for outer-most call (not recursive ones) */
use_precomputed_dir_hash = 1;
hash = ce->precompute_hash_dir;
}
}
/* get length of parent directory */
while (namelen > 0 && !is_dir_sep(ce->name[namelen - 1]))
@@ -59,7 +70,8 @@ static struct dir_entry *hash_dir_entry(struct index_state *istate,
namelen--;
/* lookup existing entry for that directory */
hash = memihash(ce->name, namelen);
if (!use_precomputed_dir_hash)
hash = memihash(ce->name, namelen);
dir = find_dir_entry__hash(istate, ce->name, namelen, hash);
if (!dir) {
/* not found, create it and add to hash table */
@@ -99,10 +111,18 @@ static void remove_dir_entry(struct index_state *istate, struct cache_entry *ce)
static void hash_index_entry(struct index_state *istate, struct cache_entry *ce)
{
unsigned int h;
if (ce->ce_flags & CE_HASHED)
return;
ce->ce_flags |= CE_HASHED;
hashmap_entry_init(ce, memihash(ce->name, ce_namelen(ce)));
if (ce->precompute_hash_state & CE_PRECOMPUTE_HASH_STATE__SET)
h = ce->precompute_hash_name;
else
h = memihash(ce->name, ce_namelen(ce));
hashmap_entry_init(ce, h);
hashmap_add(&istate->name_hash, ce);
if (ignore_case)
@@ -244,3 +264,45 @@ void free_name_hash(struct index_state *istate)
hashmap_free(&istate->name_hash, 0);
hashmap_free(&istate->dir_hash, 1);
}
/*
* Precompute the hash values for this cache_entry
* for use in the istate.name_hash and istate.dir_hash.
*
* If the item is in the root directory, just compute the
* hash value (for istate.name_hash) on the full path.
*
* If the item is in a subdirectory, first compute the
* hash value for the immediate parent directory (for
* istate.dir_hash) and then the hash value for the full
* path by continuing the computation.
*
* Note that these hashes will be used by
* wt_status_collect_untracked() as it scans the worktree
* and maps observed paths back to the index (optionally
* ignoring case). Therefore, we probably only *NEED* to
* precompute this for non-skip-worktree items (since
* status should not observe skipped items), but because
* lazy_init_name_hash() hashes everything, we force it
* here.
*/
void precompute_istate_hashes(struct cache_entry *ce)
{
int namelen = ce_namelen(ce);
while (namelen > 0 && !is_dir_sep(ce->name[namelen - 1]))
namelen--;
if (namelen <= 0) {
ce->precompute_hash_name = memihash(ce->name, ce_namelen(ce));
ce->precompute_hash_state = CE_PRECOMPUTE_HASH_STATE__SET;
} else {
namelen--;
ce->precompute_hash_dir = memihash(ce->name, namelen);
ce->precompute_hash_name = memihash_cont(
ce->precompute_hash_dir, &ce->name[namelen],
ce_namelen(ce) - namelen);
ce->precompute_hash_state =
CE_PRECOMPUTE_HASH_STATE__SET | CE_PRECOMPUTE_HASH_STATE__DIR;
}
}