Threaded grep

Make git grep use threads when it is available.

The results below are best of five runs in the Linux repository (on a
box with two cores).

With the patch:

git grep qwerty
1.58user 0.55system 0:01.16elapsed 183%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+800outputs (0major+5774minor)pagefaults 0swaps

Without:

git grep qwerty
1.59user 0.43system 0:02.02elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+800outputs (0major+3716minor)pagefaults 0swaps

And with a pattern with quite a few matches:

With the patch:

$ /usr/bin/time git grep void
5.61user 0.56system 0:03.44elapsed 179%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+800outputs (0major+5587minor)pagefaults 0swaps

Without:

$ /usr/bin/time git grep void
5.36user 0.51system 0:05.87elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+800outputs (0major+3693minor)pagefaults 0swaps

In either case we gain about 40% by the threading.

Signed-off-by: Fredrik Kuivinen <frekui@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 88 insertions, 18 deletions

diff --git a/grep.c b/grep.c
index 8e1f7de77..d281a020e 100644
--- a/grep.c
+++ b/grep.c
@@ -29,6 +29,28 @@ void append_grep_pattern(struct grep_opt *opt, const char *pat,
 	p->next = NULL;
 }
 
+struct grep_opt *grep_opt_dup(const struct grep_opt *opt)
+{
+	struct grep_pat *pat;
+	struct grep_opt *ret = xmalloc(sizeof(struct grep_opt));
+	*ret = *opt;
+
+	ret->pattern_list = NULL;
+	ret->pattern_tail = &ret->pattern_list;
+
+	for(pat = opt->pattern_list; pat != NULL; pat = pat->next)
+	{
+		if(pat->token == GREP_PATTERN_HEAD)
+			append_header_grep_pattern(ret, pat->field,
+						   pat->pattern);
+		else
+			append_grep_pattern(ret, pat->pattern, pat->origin,
+					    pat->no, pat->token);
+	}
+
+	return ret;
+}
+
 static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
 	int err;
@@ -253,7 +275,8 @@ static int word_char(char ch)
 
 static void show_name(struct grep_opt *opt, const char *name)
 {
-	printf("%s%c", name, opt->null_following_name ? '\0' : '\n');
+	opt->output(opt, name, strlen(name));
+	opt->output(opt, opt->null_following_name ? "\0" : "\n", 1);
 }
 
 
@@ -490,24 +513,32 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 		      const char *name, unsigned lno, char sign)
 {
 	int rest = eol - bol;
+	char sign_str[1];
 
+	sign_str[0] = sign;
 	if (opt->pre_context || opt->post_context) {
 		if (opt->last_shown == 0) {
 			if (opt->show_hunk_mark)
-				fputs("--\n", stdout);
+				opt->output(opt, "--\n", 3);
 			else
 				opt->show_hunk_mark = 1;
 		} else if (lno > opt->last_shown + 1)
-			fputs("--\n", stdout);
+			opt->output(opt, "--\n", 3);
 	}
 	opt->last_shown = lno;
 
 	if (opt->null_following_name)
-		sign = '\0';
-	if (opt->pathname)
-		printf("%s%c", name, sign);
-	if (opt->linenum)
-		printf("%d%c", lno, sign);
+		sign_str[0] = '\0';
+	if (opt->pathname) {
+		opt->output(opt, name, strlen(name));
+		opt->output(opt, sign_str, 1);
+	}
+	if (opt->linenum) {
+		char buf[32];
+		snprintf(buf, sizeof(buf), "%d", lno);
+		opt->output(opt, buf, strlen(buf));
+		opt->output(opt, sign_str, 1);
+	}
 	if (opt->color) {
 		regmatch_t match;
 		enum grep_context ctx = GREP_CONTEXT_BODY;
@@ -518,18 +549,22 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 		while (next_match(opt, bol, eol, ctx, &match, eflags)) {
 			if (match.rm_so == match.rm_eo)
 				break;
-			printf("%.*s%s%.*s%s",
-			       (int)match.rm_so, bol,
-			       opt->color_match,
-			       (int)(match.rm_eo - match.rm_so), bol + match.rm_so,
-			       GIT_COLOR_RESET);
+
+			opt->output(opt, bol, match.rm_so);
+			opt->output(opt, opt->color_match,
+				    strlen(opt->color_match));
+			opt->output(opt, bol + match.rm_so,
+				    (int)(match.rm_eo - match.rm_so));
+			opt->output(opt, GIT_COLOR_RESET,
+				    strlen(GIT_COLOR_RESET));
 			bol += match.rm_eo;
 			rest -= match.rm_eo;
 			eflags = REG_NOTBOL;
 		}
 		*eol = ch;
 	}
-	printf("%.*s\n", rest, bol);
+	opt->output(opt, bol, rest);
+	opt->output(opt, "\n", 1);
 }
 
 static int match_funcname(struct grep_opt *opt, char *bol, char *eol)
@@ -667,6 +702,32 @@ static int look_ahead(struct grep_opt *opt,
 	return 0;
 }
 
+int grep_threads_ok(const struct grep_opt *opt)
+{
+	/* If this condition is true, then we may use the attribute
+	 * machinery in grep_buffer_1. The attribute code is not
+	 * thread safe, so we disable the use of threads.
+	 */
+	if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
+	    !opt->name_only)
+		return 0;
+
+	/* If we are showing hunk marks, we should not do it for the
+	 * first match. The synchronization problem we get for this
+	 * constraint is not yet solved, so we disable threading in
+	 * this case.
+	 */
+	if (opt->pre_context || opt->post_context)
+		return 0;
+
+	return 1;
+}
+
+static void std_output(struct grep_opt *opt, const void *buf, size_t size)
+{
+	fwrite(buf, size, 1, stdout);
+}
+
 static int grep_buffer_1(struct grep_opt *opt, const char *name,
 			 char *buf, unsigned long size, int collect_hits)
 {
@@ -682,6 +743,9 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 
 	opt->last_shown = 0;
 
+	if (!opt->output)
+		opt->output = std_output;
+
 	if (buffer_is_binary(buf, size)) {
 		switch (opt->binary) {
 		case GREP_BINARY_DEFAULT:
@@ -754,7 +818,9 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 			if (opt->status_only)
 				return 1;
 			if (binary_match_only) {
-				printf("Binary file %s matches\n", name);
+				opt->output(opt, "Binary file ", 12);
+				opt->output(opt, name, strlen(name));
+				opt->output(opt, " matches\n", 9);
 				return 1;
 			}
 			if (opt->name_only) {
@@ -810,9 +876,13 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 	 * which feels mostly useless but sometimes useful.  Maybe
 	 * make it another option?  For now suppress them.
 	 */
-	if (opt->count && count)
-		printf("%s%c%u\n", name,
-		       opt->null_following_name ? '\0' : ':', count);
+	if (opt->count && count) {
+		char buf[32];
+		opt->output(opt, name, strlen(name));
+		snprintf(buf, sizeof(buf), "%c%u\n",
+			 opt->null_following_name ? '\0' : ':', count);
+		opt->output(opt, buf, strlen(buf));
+	}
 	return !!last_hit;
 }