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tree_entry_interesting: do basedir compare on wildcard patterns when …

…possible

Currently we treat "*.c" and "path/to/*.c" the same way. Which means
we check all possible paths in repo against "path/to/*.c". One could
see that "path/elsewhere/foo.c" obviously cannot match "path/to/*.c"
and we only need to check all paths _inside_ "path/to/" against that
pattern.

This patch checks the leading fixed part of a pathspec against base
directory and exit early if possible. We could even optimize further
in "path/to/something*.c" case (i.e. check the fixed part against
name_entry as well) but that's more complicated and probably does not
gain us much.

-O2 build on linux-2.6, without and with this patch respectively:

$ time git rev-list --quiet HEAD -- 'drivers/*.c'

real    1m9.484s
user    1m9.128s
sys     0m0.181s

$ time ~/w/git/git rev-list --quiet HEAD -- 'drivers/*.c'

real    0m15.710s
user    0m15.564s
sys     0m0.107s

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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1 parent 8c6abbc commit c904cd89e4328c0b5041b6ee0bb2df32459a33a2 @pclouds pclouds committed with gitster
Showing with 64 additions and 1 deletion.
  1. +64 −1 tree-walk.c
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65 tree-walk.c
@@ -573,6 +573,54 @@ static int match_dir_prefix(const char *base,
}
/*
+ * Perform matching on the leading non-wildcard part of
+ * pathspec. item->nowildcard_len must be greater than zero. Return
+ * non-zero if base is matched.
+ */
+static int match_wildcard_base(const struct pathspec_item *item,
+ const char *base, int baselen,
+ int *matched)
+{
+ const char *match = item->match;
+ /* the wildcard part is not considered in this function */
+ int matchlen = item->nowildcard_len;
+
+ if (baselen) {
+ int dirlen;
+ /*
+ * Return early if base is longer than the
+ * non-wildcard part but it does not match.
+ */
+ if (baselen >= matchlen) {
+ *matched = matchlen;
+ return !strncmp(base, match, matchlen);
+ }
+
+ dirlen = matchlen;
+ while (dirlen && match[dirlen - 1] != '/')
+ dirlen--;
+
+ /*
+ * Return early if base is shorter than the
+ * non-wildcard part but it does not match. Note that
+ * base ends with '/' so we are sure it really matches
+ * directory
+ */
+ if (strncmp(base, match, baselen))
+ return 0;
+ *matched = baselen;
+ } else
+ *matched = 0;
+ /*
+ * we could have checked entry against the non-wildcard part
+ * that is not in base and does similar never_interesting
+ * optimization as in match_entry. For now just be happy with
+ * base comparison.
+ */
+ return entry_interesting;
+}
+
+/*
* Is a tree entry interesting given the pathspec we have?
*
* Pre-condition: either baselen == base_offset (i.e. empty path)
@@ -602,7 +650,7 @@ enum interesting tree_entry_interesting(const struct name_entry *entry,
const struct pathspec_item *item = ps->items+i;
const char *match = item->match;
const char *base_str = base->buf + base_offset;
- int matchlen = item->len;
+ int matchlen = item->len, matched = 0;
if (baselen >= matchlen) {
/* If it doesn't match, move along... */
@@ -647,9 +695,24 @@ enum interesting tree_entry_interesting(const struct name_entry *entry,
if (item->nowildcard_len == item->len)
continue;
+ if (item->nowildcard_len &&
+ !match_wildcard_base(item, base_str, baselen, &matched))
+ return entry_not_interesting;
+
/*
* Concatenate base and entry->path into one and do
* fnmatch() on it.
+ *
+ * While we could avoid concatenation in certain cases
+ * [1], which saves a memcpy and potentially a
+ * realloc, it turns out not worth it. Measurement on
+ * linux-2.6 does not show any clear improvements,
+ * partly because of the nowildcard_len optimization
+ * in git_fnmatch(). Avoid micro-optimizations here.
+ *
+ * [1] if match_wildcard_base() says the base
+ * directory is already matched, we only need to match
+ * the rest, which is shorter so _in theory_ faster.
*/
strbuf_add(base, entry->path, pathlen);

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