From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
Teach add_index_entry_with_check() and has_dir_name()
to see if the path of the new item is greater than the
last path in the index array before attempting to search
for it.
During checkout, merge_working_tree() populates the new
index in sorted order, so this change will save at least 2
binary lookups per file. This preserves the original
behavior but simply checks the last element before starting
the search.
This helps performance on very large repositories.
================
Before and after numbers on index with 1M files
./p0004-read-tree.sh
0004.2: read-tree work1 (1003037) 3.21(2.54+0.62)
0004.3: switch base work1 (3038 1003037) 7.49(5.39+1.84)
0004.5: switch work1 work2 (1003037) 11.91(8.38+3.00)
0004.6: switch commit aliases (1003037) 12.22(8.30+3.06)
./p0004-read-tree.sh
0004.2: read-tree work1 (1003040) 2.40(1.65+0.73)
0004.3: switch base work1 (3041 1003040) 6.07(4.12+1.66)
0004.5: switch work1 work2 (1003040) 10.23(6.76+2.92)
0004.6: switch commit aliases (1003040) 10.53(6.97+2.83)
================
Signed-off-by: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
---
read-cache.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 43 insertions(+), 1 deletion(-)
diff --git a/read-cache.c b/read-cache.c
index e8f1900..58f69b2 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -918,6 +918,21 @@ static int has_dir_name(struct index_state *istate,
int stage = ce_stage(ce);
const char *name = ce->name;
const char *slash = name + ce_namelen(ce);
+ int len_eq_last;
+ int cmp_last = 0;
+
+ if (istate->cache_nr > 0) {
+ /*
+ * Compare the entry's full path with the last path in the index.
+ * If it sorts AFTER the last entry in the index and they have no
+ * common prefix, then there cannot be any F/D name conflicts.
+ */
+ cmp_last = strcmp_offset(name,
+ istate->cache[istate->cache_nr-1]->name,
+ &len_eq_last);
+ if (cmp_last > 0 && len_eq_last == 0)
+ return retval;
+ }
for (;;) {
int len;
@@ -930,6 +945,24 @@ static int has_dir_name(struct index_state *istate,
}
len = slash - name;
+ if (cmp_last > 0) {
+ /*
+ * If this part of the directory prefix (including the trailing
+ * slash) already appears in the path of the last entry in the
+ * index, then we cannot also have a file with this prefix (or
+ * any parent directory prefix).
+ */
+ if (len+1 <= len_eq_last)
+ return retval;
+ /*
+ * If this part of the directory prefix (excluding the trailing
+ * slash) is longer than the known equal portions, then this part
+ * of the prefix cannot collide with a file. Go on to the parent.
+ */
+ if (len > len_eq_last)
+ continue;
+ }
+
pos = index_name_stage_pos(istate, name, len, stage);
if (pos >= 0) {
/*
@@ -1021,7 +1054,16 @@ static int add_index_entry_with_check(struct index_state *istate, struct cache_e
if (!(option & ADD_CACHE_KEEP_CACHE_TREE))
cache_tree_invalidate_path(istate, ce->name);
- pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
+
+ /*
+ * If this entry's path sorts after the last entry in the index,
+ * we can avoid searching for it.
+ */
+ if (istate->cache_nr > 0 &&
+ strcmp(ce->name, istate->cache[istate->cache_nr - 1]->name) > 0)
+ pos = -istate->cache_nr - 1;
+ else
+ pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
/* existing match? Just replace it. */
if (pos >= 0) {
--
2.9.3