[PATCH 6/6] file-watcher: support inotify

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

"git diff" on webkit:

        no file watcher  1st run   subsequent runs
real        0m1.361s    0m1.445s      0m0.691s
user        0m0.889s    0m0.940s      0m0.649s
sys         0m0.469s    0m0.495s      0m0.040s

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 config.mak.uname |   1 +
 file-watcher.c   | 139 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 140 insertions(+)

diff --git a/config.mak.uname b/config.mak.uname
index 82d549e..603890d 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -33,6 +33,7 @@ ifeq ($(uname_S),Linux)
 	HAVE_PATHS_H = YesPlease
 	LIBC_CONTAINS_LIBINTL = YesPlease
 	HAVE_DEV_TTY = YesPlease
+	BASIC_CFLAGS += -DHAVE_INOTIFY
 endif
 ifeq ($(uname_S),GNU/kFreeBSD)
 	NO_STRLCPY = YesPlease
diff --git a/file-watcher.c b/file-watcher.c
index 35781fa..1512b46 100644
--- a/file-watcher.c
+++ b/file-watcher.c
@@ -3,17 +3,140 @@
 #include "string-list.h"
 #include "pkt-line.h"
 
+#ifdef HAVE_INOTIFY
+#include <sys/inotify.h>
+#endif
+
 static char index_signature[41];
 static struct string_list updated = STRING_LIST_INIT_DUP;
 static int updated_sorted;
 
+#ifdef HAVE_INOTIFY
+
+static struct string_list watched_dirs = STRING_LIST_INIT_DUP;
+static int watched_dirs_sorted;
+static int inotify_fd;
+
+struct dir_info {
+	int wd;
+	struct string_list names;
+	int names_sorted;
+};
+
+static int handle_inotify(int fd)
+{
+	char buf[sizeof(struct inotify_event) + NAME_MAX + 1];
+	struct inotify_event *event;
+	struct dir_info *dir;
+	struct string_list_item *item;
+	int i;
+	int len = read(fd, buf, sizeof(buf));
+	if (len < 0)
+		return -1;
+	event = (struct inotify_event *)buf;
+
+	if (len <= sizeof(struct inotify_event))
+		return 0;
+
+	for (i = 0; i < watched_dirs.nr; i++) {
+		struct dir_info *dir = watched_dirs.items[i].util;
+		if (dir->wd == event->wd)
+			break;
+	}
+	if (i == watched_dirs.nr)
+		return 0;
+	dir = watched_dirs.items[i].util;
+
+	if (!dir->names_sorted) {
+		sort_string_list(&dir->names);
+		dir->names_sorted = 1;
+	}
+	item = string_list_lookup(&dir->names, event->name);
+	if (item) {
+		if (!strcmp(watched_dirs.items[i].string, "."))
+			string_list_append(&updated, event->name);
+		else {
+			struct strbuf sb = STRBUF_INIT;
+			strbuf_addf(&sb, "%s/%s", watched_dirs.items[i].string,
+				    item->string);
+			string_list_append(&updated, sb.buf);
+			updated_sorted = 0;
+			strbuf_release(&sb);
+		}
+
+		unsorted_string_list_delete_item(&dir->names,
+						 item - dir->names.items, 0);
+		if (dir->names.nr == 0) {
+			inotify_rm_watch(inotify_fd, dir->wd);
+			unsorted_string_list_delete_item(&watched_dirs, i, 1);
+		}
+	}
+	return 0;
+}
+
+static int watch_path(char *path)
+{
+	struct string_list_item *item;
+	char *sep = strrchr(path, '/');
+	struct dir_info *dir;
+	const char *dirname = ".";
+
+	if (sep) {
+		*sep = '\0';
+		dirname = path;
+	}
+
+	if (!watched_dirs_sorted) {
+		sort_string_list(&watched_dirs);
+		watched_dirs_sorted = 1;
+	}
+	item = string_list_lookup(&watched_dirs, dirname);
+	if (!item) {
+		int ret = inotify_add_watch(inotify_fd, dirname,
+					    IN_ATTRIB | IN_DELETE | IN_MODIFY |
+					    IN_MOVED_FROM | IN_MOVED_TO);
+		if (ret < 0)
+			return -1;
+		dir = xmalloc(sizeof(*dir));
+		memset(dir, 0, sizeof(*dir));
+		dir->wd = ret;
+		dir->names.strdup_strings = 1;
+		item = string_list_append(&watched_dirs, dirname);
+		item->util = dir;
+	}
+	dir = item->util;
+	string_list_append(&dir->names, sep ? sep + 1 : path);
+	dir->names_sorted = 0;
+	return 0;
+}
+
+static void reset_watches(void)
+{
+	int i;
+	for (i = 0; i < watched_dirs.nr; i++) {
+		struct dir_info *dir = watched_dirs.items[i].util;
+		inotify_rm_watch(inotify_fd, dir->wd);
+		string_list_clear(&dir->names, 0);
+	}
+	string_list_clear(&watched_dirs, 1);
+}
+
+#else
+
 static int watch_path(char *path)
 {
 	return -1;
 }
 
+static void reset_watches(void)
+{
+}
+
+#endif
+
 static void reset(const char *sig)
 {
+	reset_watches();
 	string_list_clear(&updated, 0);
 	strlcpy(index_signature, sig, sizeof(index_signature));
 }
@@ -155,6 +278,14 @@ int main(int argc, char **argv)
 	atexit(cleanup);
 	sigchain_push_common(cleanup_on_signal);
 
+#ifdef HAVE_INOTIFY
+	inotify_fd = inotify_init();
+	if (inotify_fd < 0)
+		die_errno("unable to initialize inotify");
+#else
+	die("no file watching mechanism is supported");
+#endif
+
 	if (getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &msgsize, &vallen))
 		die_errno("could not get SO_SNDBUF");
 	msg = xmalloc(msgsize + 1);
@@ -173,6 +304,10 @@ int main(int argc, char **argv)
 	nr = 0;
 	pfd[nr].fd = fd;
 	pfd[nr++].events = POLLIN;
+#ifdef HAVE_INOTIFY
+	pfd[nr].fd = inotify_fd;
+	pfd[nr++].events = POLLIN;
+#endif
 
 	for (;;) {
 		if (poll(pfd, nr, -1) < 0) {
@@ -185,6 +320,10 @@ int main(int argc, char **argv)
 
 		if ((pfd[0].revents & POLLIN) && handle_command(fd, msg, msgsize))
 			break;
+#ifdef HAVE_INOTIFY
+		if ((pfd[1].revents & POLLIN) && handle_inotify(inotify_fd))
+			break;
+#endif
 	}
 	return 0;
 }
-- 
1.8.5.2.240.g8478abd