[PATCH/WIP v2 07/14] read-cache: add config to start file watcher automatically

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

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/config.txt |  5 +++++
 file-watcher-lib.c       | 18 +++++++++++++++---
 file-watcher-lib.h       |  2 +-
 file-watcher.c           |  8 ++++++--
 read-cache.c             | 17 +++++++++++++++--
 5 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index e394399..3316b69 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1038,6 +1038,11 @@ difftool.<tool>.cmd::
 difftool.prompt::
 	Prompt before each invocation of the diff tool.
 
+filewatcher.autorun::
+	Run `git file-watcher` automatically if the number of cached
+	entries is greater than this limit. Zero means no running
+	file-watcher automatically. Default value is zero.
+
 filewatcher.minfiles::
 	Start watching files if the number of watchable files are
 	above this limit. Default value is 65536.
diff --git a/file-watcher-lib.c b/file-watcher-lib.c
index ed14ef9..71c8545 100644
--- a/file-watcher-lib.c
+++ b/file-watcher-lib.c
@@ -1,16 +1,28 @@
 #include "cache.h"
+#include "run-command.h"
 
 #define WAIT_TIME 20		/* in ms */
 #define TRACE_KEY "GIT_TRACE_WATCHER"
 
-int connect_watcher(const char *path)
+int connect_watcher(const char *path, int autorun)
 {
 	struct strbuf sb = STRBUF_INIT;
 	struct stat st;
-	int fd = -1;
+	int fd = -1, ret;
 
 	strbuf_addf(&sb, "%s.watcher", path);
-	if (!stat(sb.buf, &st) && S_ISSOCK(st.st_mode)) {
+	ret = stat(sb.buf, &st);
+	if (autorun && ret && errno == ENOENT) {
+		const char *av[] = { "file-watcher", "--daemon", "--quiet", NULL };
+		struct child_process cp;
+		memset(&cp, 0, sizeof(cp));
+		cp.git_cmd = 1;
+		cp.argv = av;
+		if (run_command(&cp))
+			return -1;
+		ret = stat(sb.buf, &st);
+	}
+	if (!ret && S_ISSOCK(st.st_mode)) {
 		struct sockaddr_un sun;
 		fd = socket(AF_UNIX, SOCK_DGRAM, 0);
 		sun.sun_family = AF_UNIX;
diff --git a/file-watcher-lib.h b/file-watcher-lib.h
index 0fe9399..ef3d196 100644
--- a/file-watcher-lib.h
+++ b/file-watcher-lib.h
@@ -1,7 +1,7 @@
 #ifndef __FILE_WATCHER_LIB__
 #define __FILE_WATCHER_LIB__
 
-int connect_watcher(const char *path);
+int connect_watcher(const char *path, int autorun);
 ssize_t send_watcher(int sockfd, struct sockaddr_un *dest,
 		     const char *fmt, ...)
 	__attribute__((format (printf, 3, 4)));
diff --git a/file-watcher.c b/file-watcher.c
index 369af37..1b4ac0a 100644
--- a/file-watcher.c
+++ b/file-watcher.c
@@ -168,8 +168,9 @@ int main(int argc, const char **argv)
 	struct pollfd pfd[2];
 	int fd, err, nr;
 	const char *prefix;
-	int daemon = 0;
+	int daemon = 0, quiet = 0;
 	struct option options[] = {
+		OPT__QUIET(&quiet, N_("be quiet")),
 		OPT_BOOL(0, "daemon", &daemon,
 			 N_("run in background")),
 		OPT_END()
@@ -189,8 +190,11 @@ int main(int argc, const char **argv)
 	fd = socket(AF_UNIX, SOCK_DGRAM, 0);
 	sun.sun_family = AF_UNIX;
 	strlcpy(sun.sun_path, socket_path, sizeof(sun.sun_path));
-	if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)))
+	if (bind(fd, (struct sockaddr *)&sun, sizeof(sun))) {
+		if (quiet)
+			exit(128);
 		die_errno("unable to bind to %s", socket_path);
+	}
 	atexit(cleanup);
 	sigchain_push_common(cleanup_on_signal);
 
diff --git a/read-cache.c b/read-cache.c
index 3aa541d..5dae9eb 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -40,6 +40,7 @@ static struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int reall
 struct index_state the_index;
 static int watch_lowerlimit = 65536;
 static int recent_limit = 1800;
+static int autorun_watcher = -1;
 
 static void set_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
 {
@@ -1518,6 +1519,10 @@ failed:
 
 static int watcher_config(const char *var, const char *value, void *data)
 {
+	if (!strcmp(var, "filewatcher.autorun")) {
+		autorun_watcher = git_config_int(var, value);
+		return 0;
+	}
 	if (!strcmp(var, "filewatcher.minfiles")) {
 		watch_lowerlimit = git_config_int(var, value);
 		return 0;
@@ -1538,8 +1543,16 @@ static void validate_watcher(struct index_state *istate, const char *path)
 		return;
 	}
 
-	git_config(watcher_config, NULL);
-	istate->watcher = connect_watcher(path);
+	if (autorun_watcher == -1) {
+		git_config(watcher_config, NULL);
+		if (autorun_watcher == -1)
+			autorun_watcher = 0;
+	}
+
+	istate->watcher = connect_watcher(path,
+					  autorun_watcher &&
+					  istate->cache_nr >= autorun_watcher);
+	autorun_watcher = 0;
 	if (istate->watcher != -1) {
 		struct strbuf sb = STRBUF_INIT;
 		char *msg;
-- 
1.8.5.1.208.g05b12ea