git-fetch: rewrite another shell loop in C

Move another shell loop that canonicalizes the list of refs for
underlying git-fetch-pack and fetch-native-store into C.

This seems to shave the runtime for the same 1000 branch
repository from 30 seconds down to 15 seconds (it used to be 2
and half minutes with the original version).

Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-fetch--tool.c

@@ -283,6 +283,46 @@ static int fetch_native_store(FILE *fp,
 	return err;
 }
 
+static int parse_reflist(const char *reflist)
+{
+	const char *ref;
+
+	printf("refs='");
+	for (ref = reflist; ref; ) {
+		const char *next;
+		while (*ref && isspace(*ref))
+			ref++;
+		if (!*ref)
+			break;
+		for (next = ref; *next && !isspace(*next); next++)
+			;
+		printf("\n%.*s", (int)(next - ref), ref);
+		ref = next;
+	}
+	printf("'\n");
+
+	printf("rref='");
+	for (ref = reflist; ref; ) {
+		const char *next, *colon;
+		while (*ref && isspace(*ref))
+			ref++;
+		if (!*ref)
+			break;
+		for (next = ref; *next && !isspace(*next); next++)
+			;
+		if (*ref == '.')
+			ref++;
+		if (*ref == '+')
+			ref++;
+		colon = strchr(ref, ':');
+		putchar('\n');
+		printf("%.*s", (int)((colon ? colon : next) - ref), ref);
+		ref = next;
+	}
+	printf("'\n");
+	return 0;
+}
+
 int cmd_fetch__tool(int argc, const char **argv, const char *prefix)
 {
 	int verbose = 0;
@@ -335,5 +375,11 @@ int cmd_fetch__tool(int argc, const char **argv, const char *prefix)
 		fclose(fp);
 		return result;
 	}
+	if (!strcmp("parse-reflist", argv[1])) {
+		if (argc != 3)
+			return error("parse-reflist takes 1 arg");
+		return parse_reflist(argv[2]);
+	}
+
 	return error("Unknown subcommand: %s", argv[1]);
 }

git-fetch.sh

@@ -155,35 +155,9 @@ then
 fi
 
 fetch_native () {
-  reflist="$1"
-  refs=
-  rref=
 
-  for ref in $reflist
+  eval=$(git-fetch--tool parse-reflist "$1")
-  do
+  eval "$eval"
-      refs="$refs$LF$ref"
-
-      # These are relative path from $GIT_DIR, typically starting at refs/
-      # but may be HEAD
-      if expr "z$ref" : 'z\.' >/dev/null
-      then
-	  not_for_merge=t
-	  ref=$(expr "z$ref" : 'z\.\(.*\)')
-      else
-	  not_for_merge=
-      fi
-      if expr "z$ref" : 'z+' >/dev/null
-      then
-	  single_force=t
-	  ref=$(expr "z$ref" : 'z+\(.*\)')
-      else
-	  single_force=
-      fi
-      remote_name=$(expr "z$ref" : 'z\([^:]*\):')
-      local_name=$(expr "z$ref" : 'z[^:]*:\(.*\)')
-
-      rref="$rref$LF$remote_name"
-  done
 
     ( : subshell because we muck with IFS
       IFS=" 	$LF"