added --flock/--flock2/--flock-wait/--flock-wait2

plugins/python/uwsgi_pymodule.c

@@ -2859,12 +2859,15 @@ PyObject *py_uwsgi_grunt(PyObject * self, PyObject * args) {
 		uwsgi_error("fork()");
 		goto clear;
 	}
+	// now i am a grunt, avoid it making mess
 	else if (grunt_pid == 0) {
+		// it will no more accepts requests
 		uwsgi_close_all_sockets();
 		// create a new session
 		setsid();
 		// exit on SIGPIPE
 		signal(SIGPIPE, (void *) &end_me);
+		// here we create a new worker. Each grunt will race on this datas, so do not rely on them
 		uwsgi.mywid = uwsgi.numproc + 1;
 		uwsgi.mypid = getpid();
 		memset(&uwsgi.workers[uwsgi.mywid], 0, sizeof(struct uwsgi_worker));
@@ -2881,7 +2884,7 @@ PyObject *py_uwsgi_grunt(PyObject * self, PyObject * args) {
 		return Py_True;
 	}
 
-	// close connection on the worker
+	// close connection on the original worker
 	if (PyTuple_Size(args) == 0) {
 		if (wsgi_req->socket) {
 			wsgi_req->socket->proto_close(wsgi_req);

uwsgi.c

@@ -179,6 +179,12 @@ static struct uwsgi_option uwsgi_base_options[] = {
 
 	{"disable-logging", no_argument, 'L', "disable request logging", uwsgi_opt_dyn_false, (void *) UWSGI_OPTION_LOGGING, 0},
 
+	{"flock", required_argument, 0, "lock the specified file before starting, exit if locked", uwsgi_opt_flock, NULL, UWSGI_OPT_IMMEDIATE},
+	{"flock-wait", required_argument, 0, "lock the specified file before starting, wait if locked", uwsgi_opt_flock_wait, NULL, UWSGI_OPT_IMMEDIATE},
+
+	{"flock2", required_argument, 0, "lock the specified file after logging/daemon setup, exit if locked", uwsgi_opt_set_str, &uwsgi.flock2, UWSGI_OPT_IMMEDIATE},
+	{"flock-wait2", required_argument, 0, "lock the specified file after logging/daemon setup, wait if locked", uwsgi_opt_set_str, &uwsgi.flock_wait2, UWSGI_OPT_IMMEDIATE},
+
 	{"pidfile", required_argument, 0, "create pidfile (before privileges drop)", uwsgi_opt_set_str, &uwsgi.pidfile,0},
 	{"pidfile2", required_argument, 0, "create pidfile (after privileges drop)", uwsgi_opt_set_str, &uwsgi.pidfile2,0},
 	{"chroot", required_argument, 0, "chroot() to the specified directory", uwsgi_opt_set_str, &uwsgi.chroot,0},
@@ -1537,6 +1543,14 @@ int main(int argc, char *argv[], char *envp[]) {
 		}
 	}
 
+	if (uwsgi.flock2) {
+		uwsgi_opt_flock(NULL, uwsgi.flock2, NULL);
+	}
+
+	if (uwsgi.flock_wait2) {
+		uwsgi_opt_flock(NULL, uwsgi.flock_wait2, NULL);
+	}
+
 	// setup master logging
 	if (uwsgi.log_master) {
 
@@ -3849,3 +3863,32 @@ void uwsgi_opt_load_json(char *opt, char *filename, void *none) {
 	uwsgi_json_config(filename, uwsgi.magic_table);
 }
 #endif
+
+void uwsgi_opt_flock(char *opt, char *filename, void *none) {
+
+	int fd = open(filename, O_RDWR);
+	if (fd < 0) {
+		uwsgi_error_open(filename);
+		exit(1);
+	}
+
+	if (uwsgi_fcntl_is_locked(fd)) {
+		uwsgi_log("uWSGI ERROR: %s is locked by another instance\n", filename);
+		exit(1);
+	}
+	
+}
+
+void uwsgi_opt_flock_wait(char *opt, char *filename, void *none) {
+
+	int fd = open(filename, O_RDWR);
+	if (fd < 0) {
+		uwsgi_error_open(filename);
+		exit(1);
+	}
+
+	if (uwsgi_fcntl_lock(fd)) {
+		exit(1);
+	}
+	
+}

uwsgi.h

@@ -1363,6 +1363,9 @@ struct uwsgi_server {
 	char *pidfile;
 	char *pidfile2;
 
+	char *flock2;
+	char *flock_wait2;
+
 	int backtrace_depth;
 
 	int harakiri_verbose;
@@ -2632,6 +2635,9 @@ void uwsgi_opt_load_plugin(char *, char *, void *);
 void uwsgi_opt_load(char *, char *, void *);
 void uwsgi_opt_cluster_log(char *, char *, void *);
 void uwsgi_opt_cluster_reload(char *, char *, void *);
+
+void uwsgi_opt_flock(char *, char *, void *);
+void uwsgi_opt_flock_wait(char *, char *, void *);
 #ifdef UWSGI_INI
 void uwsgi_opt_load_ini(char *, char *, void *);
 #endif