From: Linus Torvalds Date: Sun, 18 Mar 2007 03:06:24 +0000 (-0700) Subject: Avoid unnecessary strlen() calls X-Git-Tag: v1.5.1-rc1~14 X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=304de2d2d6afc7500fe9b8f2e22dd0a16a902d8b;p=git.git Avoid unnecessary strlen() calls This is a micro-optimization that grew out of the mailing list discussion about "strlen()" showing up in profiles. We used to pass regular C strings around to the low-level tree walking routines, and while this worked fine, it meant that we needed to call strlen() on strings that the caller always actually knew the size of anyway. So pass the length of the string down wih the string, and avoid unnecessary calls to strlen(). Also, when extracting a pathname from a tree entry, use "tree_entry_len()" instead of strlen(), since the length of the pathname is directly calculable from the decoded tree entry itself without having to actually do another strlen(). This shaves off another ~5-10% from some loads that are very tree intensive (notably doing commit filtering by a pathspec). Signed-off-by: Linus Torvalds " Signed-off-by: Junio C Hamano --- diff --git a/tree-diff.c b/tree-diff.c index c8275823d..f89b9d31e 100644 --- a/tree-diff.c +++ b/tree-diff.c @@ -5,9 +5,8 @@ #include "diff.h" #include "tree.h" -static char *malloc_base(const char *base, const char *path, int pathlen) +static char *malloc_base(const char *base, int baselen, const char *path, int pathlen) { - int baselen = strlen(base); char *newbase = xmalloc(baselen + pathlen + 2); memcpy(newbase, base, baselen); memcpy(newbase + baselen, path, pathlen); @@ -16,9 +15,9 @@ static char *malloc_base(const char *base, const char *path, int pathlen) } static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc, - const char *base); + const char *base, int baselen); -static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt) +static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt) { unsigned mode1, mode2; const char *path1, *path2; @@ -28,15 +27,15 @@ static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const sha1 = tree_entry_extract(t1, &path1, &mode1); sha2 = tree_entry_extract(t2, &path2, &mode2); - pathlen1 = strlen(path1); - pathlen2 = strlen(path2); + pathlen1 = tree_entry_len(path1, sha1); + pathlen2 = tree_entry_len(path2, sha2); cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2); if (cmp < 0) { - show_entry(opt, "-", t1, base); + show_entry(opt, "-", t1, base, baselen); return -1; } if (cmp > 0) { - show_entry(opt, "+", t2, base); + show_entry(opt, "+", t2, base, baselen); return 1; } if (!opt->find_copies_harder && !hashcmp(sha1, sha2) && mode1 == mode2) @@ -47,14 +46,14 @@ static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const * file, we need to consider it a remove and an add. */ if (S_ISDIR(mode1) != S_ISDIR(mode2)) { - show_entry(opt, "-", t1, base); - show_entry(opt, "+", t2, base); + show_entry(opt, "-", t1, base, baselen); + show_entry(opt, "+", t2, base, baselen); return 0; } if (opt->recursive && S_ISDIR(mode1)) { int retval; - char *newbase = malloc_base(base, path1, pathlen1); + char *newbase = malloc_base(base, baselen, path1, pathlen1); if (opt->tree_in_recursive) opt->change(opt, mode1, mode2, sha1, sha2, base, path1); @@ -67,20 +66,20 @@ static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const return 0; } -static int interesting(struct tree_desc *desc, const char *base, struct diff_options *opt) +static int interesting(struct tree_desc *desc, const char *base, int baselen, struct diff_options *opt) { const char *path; + const unsigned char *sha1; unsigned mode; int i; - int baselen, pathlen; + int pathlen; if (!opt->nr_paths) return 1; - (void)tree_entry_extract(desc, &path, &mode); + sha1 = tree_entry_extract(desc, &path, &mode); - pathlen = strlen(path); - baselen = strlen(base); + pathlen = tree_entry_len(path, sha1); for (i=0; i < opt->nr_paths; i++) { const char *match = opt->paths[i]; @@ -121,18 +120,18 @@ static int interesting(struct tree_desc *desc, const char *base, struct diff_opt } /* A whole sub-tree went away or appeared */ -static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base) +static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen) { while (desc->size) { - if (interesting(desc, base, opt)) - show_entry(opt, prefix, desc, base); + if (interesting(desc, base, baselen, opt)) + show_entry(opt, prefix, desc, base, baselen); update_tree_entry(desc); } } /* A file entry went away or appeared */ static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc, - const char *base) + const char *base, int baselen) { unsigned mode; const char *path; @@ -140,7 +139,8 @@ static void show_entry(struct diff_options *opt, const char *prefix, struct tree if (opt->recursive && S_ISDIR(mode)) { enum object_type type; - char *newbase = malloc_base(base, path, strlen(path)); + int pathlen = tree_entry_len(path, sha1); + char *newbase = malloc_base(base, baselen, path, pathlen); struct tree_desc inner; void *tree; @@ -149,7 +149,7 @@ static void show_entry(struct diff_options *opt, const char *prefix, struct tree die("corrupt tree sha %s", sha1_to_hex(sha1)); inner.buf = tree; - show_tree(opt, prefix, &inner, newbase); + show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen); free(tree); free(newbase); @@ -160,26 +160,28 @@ static void show_entry(struct diff_options *opt, const char *prefix, struct tree int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt) { + int baselen = strlen(base); + while (t1->size | t2->size) { - if (opt->nr_paths && t1->size && !interesting(t1, base, opt)) { + if (opt->nr_paths && t1->size && !interesting(t1, base, baselen, opt)) { update_tree_entry(t1); continue; } - if (opt->nr_paths && t2->size && !interesting(t2, base, opt)) { + if (opt->nr_paths && t2->size && !interesting(t2, base, baselen, opt)) { update_tree_entry(t2); continue; } if (!t1->size) { - show_entry(opt, "+", t2, base); + show_entry(opt, "+", t2, base, baselen); update_tree_entry(t2); continue; } if (!t2->size) { - show_entry(opt, "-", t1, base); + show_entry(opt, "-", t1, base, baselen); update_tree_entry(t1); continue; } - switch (compare_tree_entry(t1, t2, base, opt)) { + switch (compare_tree_entry(t1, t2, base, baselen, opt)) { case -1: update_tree_entry(t1); continue; diff --git a/tree-walk.c b/tree-walk.c index 70f899957..a4a4e2a98 100644 --- a/tree-walk.c +++ b/tree-walk.c @@ -32,7 +32,7 @@ static void entry_clear(struct name_entry *a) static void entry_extract(struct tree_desc *t, struct name_entry *a) { a->sha1 = tree_entry_extract(t, &a->path, &a->mode); - a->pathlen = strlen(a->path); + a->pathlen = tree_entry_len(a->path, a->sha1); } void update_tree_entry(struct tree_desc *desc) @@ -169,7 +169,7 @@ static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char sha1 = tree_entry_extract(t, &entry, mode); update_tree_entry(t); - entrylen = strlen(entry); + entrylen = tree_entry_len(entry, sha1); if (entrylen > namelen) continue; cmp = memcmp(name, entry, entrylen); diff --git a/tree-walk.h b/tree-walk.h index e57befa4d..a0d7afd89 100644 --- a/tree-walk.h +++ b/tree-walk.h @@ -13,6 +13,11 @@ struct name_entry { int pathlen; }; +static inline int tree_entry_len(const char *name, const unsigned char *sha1) +{ + return (char *)sha1 - (char *)name - 1; +} + void update_tree_entry(struct tree_desc *); const unsigned char *tree_entry_extract(struct tree_desc *, const char **, unsigned int *);