first prototype of a fork server

core/fork_server.c

@@ -0,0 +1,69 @@
+#include <uwsgi.h>
+
+extern struct uwsgi_server uwsgi;
+
+void uwsgi_fork_server(char *socket) {
+	int fd = bind_to_unix(socket, uwsgi.listen_queue, uwsgi.chmod_socket, uwsgi.abstract_socket);
+	if (fd < 0) exit(1);
+
+	if (uwsgi_socket_passcred(fd)) exit(1);
+
+	for(;;) {
+		struct sockaddr_un client_src;
+        	socklen_t client_src_len = 0;
+        	int client_fd = accept(fd, (struct sockaddr *) &client_src, &client_src_len);
+        	if (client_fd < 0) {
+                	uwsgi_error("uwsgi_fork_server()/accept()");
+			continue;
+        	}
+		char buf[4096];
+		pid_t ppid = -1;
+		uid_t uid = -1;
+		gid_t gid = -1;
+		ssize_t len = uwsgi_recv_cred2(client_fd, buf, 4096, &ppid, &uid, &gid);
+		uwsgi_log("RET = %d %d %d %d\n", len, ppid, uid, gid);
+
+		pid_t pid = fork();
+		if (pid < 0) {
+			uwsgi_error("uwsgi_fork_server()/fork()");
+			goto end;		
+		}
+		else if (pid > 0) {
+			goto end;
+		}
+		else {
+			// reparent the process
+#ifdef __linux__
+			if (prctl(PR_SET_CHILD_SUBREAPER, ppid, 0, 0, 0)) {
+				uwsgi_error("uwsgi_fork_server()/fork()");
+				exit(1);
+			}
+#endif
+			// now fork again and kill
+			pid_t new_pid = fork();
+			if (new_pid < 0) {
+                        	uwsgi_error("uwsgi_fork_server()/fork()");
+				exit(1);
+			}
+			else if (new_pid > 0) {
+				exit(0);
+			}
+			else {
+				uwsgi_log("double fork() and reparenting successfull (new pid: %d)\n", getpid());
+				uwsgi.argc = 3;
+				uwsgi.argv = uwsgi_malloc(sizeof(char *) * (uwsgi.argc+1));
+				uwsgi.argv[0] = uwsgi.binary_path;
+				uwsgi.argv[1] = uwsgi_str("--socket");
+				uwsgi.argv[2] = uwsgi_str(":1717");
+				uwsgi.argv[3] = NULL;
+				// this is the only step required to have a consistent environment
+				uwsgi.fork_socket = NULL;
+				return;
+			}
+		}	
+
+end:
+		close(client_fd);
+		
+	}
+}

core/init.c

@@ -252,6 +252,8 @@ void uwsgi_commandline_config() {
 	int i;
 
 	uwsgi.option_index = -1;
+	// required in case we want to call getopt_long from the beginning
+	optind = 0;
 
 	char *optname;
 	while ((i = getopt_long(uwsgi.argc, uwsgi.argv, uwsgi.short_options, uwsgi.long_options, &uwsgi.option_index)) != -1) {

core/uwsgi.c

@@ -356,6 +356,7 @@ static struct uwsgi_option uwsgi_base_options[] = {
 	{"setns-skip", required_argument, 0, "skip the specified entry when sending setns file descriptors", uwsgi_opt_add_string_list, &uwsgi.setns_socket_skip, 0},
 	{"setns", required_argument, 0, "join a namespace created by an external uWSGI instance", uwsgi_opt_set_str, &uwsgi.setns, 0},
 	{"setns-preopen", no_argument, 0, "open /proc/self/ns as soon as possible and cache fds", uwsgi_opt_true, &uwsgi.setns_preopen, 0},
+	{"fork-socket", required_argument, 0, "suspend the execution after early initialization and fork() at every unix socket connection", uwsgi_opt_set_str, &uwsgi.fork_socket, 0},
 #endif
 	{"jailed", no_argument, 0, "mark the instance as jailed (force the execution of post_jail hooks)", uwsgi_opt_true, &uwsgi.jailed, 0},
 #if defined(__FreeBSD__) || defined(__GNU_kFreeBSD__)
@@ -2131,6 +2132,8 @@ void uwsgi_setup(int argc, char *argv[], char *envp[]) {
 	struct group *gr = getgrgid(getgid());
 	uwsgi.magic_table['G'] = gr ? gr->gr_name : uwsgi.magic_table['g'];
 
+configure:
+
 	// you can embed a ini file in the uWSGi binary with default options
 #ifdef UWSGI_EMBED_CONFIG
 	uwsgi_ini_config("", uwsgi.magic_table);
@@ -2155,6 +2158,14 @@ void uwsgi_setup(int argc, char *argv[], char *envp[]) {
 	// ok, the options dictionary is available, lets manage it
 	uwsgi_configure();
 
+	// stop the execution until a connection arrives on the fork socket
+	if (uwsgi.fork_socket) {
+		uwsgi_log_verbose("waiting for fork-socket connections...\n");
+		uwsgi_fork_server(uwsgi.fork_socket);
+		// if we are here a new process has been spawned
+		goto configure;
+	}
+
 	// fixup cwd
 	if (uwsgi.force_cwd) uwsgi.cwd = uwsgi.force_cwd;
 

plugins/psgi/psgi.h

@@ -67,6 +67,8 @@ struct uwsgi_perl {
 	CV *spooler;
 
 	int no_plack;
+
+	void *early_psgi_callable;
 };
 
 void init_perl_embedded_module(void);

plugins/psgi/psgi_loader.c

@@ -453,6 +453,12 @@ int init_psgi_app(struct wsgi_request *wsgi_req, char *app, uint16_t app_len, Pe
 		PERL_SET_CONTEXT(interpreters[0]);
 	}
 
+	// is it an early loading ?
+	if (!uwsgi.workers) {
+		uperl.early_psgi_callable = callables[0];
+		return 0;
+	}
+
 	if (uwsgi_apps_cnt >= uwsgi.max_apps) {
 		uwsgi_log("ERROR: you cannot load more than %d apps in a worker\n", uwsgi.max_apps);
 		goto clear;

plugins/psgi/psgi_plugin.c

@@ -26,6 +26,12 @@ static void uwsgi_opt_plshell(char *opt, char *value, void *foobar) {
         }
 }
 
+int uwsgi_perl_init(void);
+static void uwsgi_opt_early_psgi(char *opt, char *value, void *foobar) {
+	uwsgi_perl_init();
+	init_psgi_app(NULL, value, strlen(value), uperl.main);
+}
+
 struct uwsgi_option uwsgi_perl_options[] = {
 
         {"psgi", required_argument, 0, "load a psgi app", uwsgi_opt_set_str, &uperl.psgi, 0},
@@ -46,6 +52,7 @@ struct uwsgi_option uwsgi_perl_options[] = {
         {"plshell-oneshot", no_argument, 0, "run a perl interactive shell (one shot)", uwsgi_opt_plshell, NULL, 0},
 
         {"perl-no-plack", no_argument, 0, "force the use of do instead of Plack::Util::load_psgi", uwsgi_opt_true, &uperl.no_plack, 0},
+        {"early-psgi", required_argument, 0, "load a psgi app soon after perl initialization", uwsgi_opt_early_psgi, NULL, UWSGI_OPT_IMMEDIATE},
         {0, 0, 0, 0, 0, 0, 0},
 
 };
@@ -437,6 +444,9 @@ int uwsgi_perl_init(){
 	int argc;
 	int i;
 
+	// the perl interpreter could be already initialized
+	if (uperl.main) return 0;
+
 	uperl.embedding[0] = "";
 	uperl.embedding[1] = "-e";
 	uperl.embedding[2] = "0";

uwsgi.h

@@ -2709,6 +2709,8 @@ struct uwsgi_server {
 
 	int mule_reload_mercy;
 	int alarm_cheap;
+
+	char *fork_socket;
 };
 
 struct uwsgi_rpc {
@@ -4761,6 +4763,8 @@ mode_t uwsgi_mode_t(char *, int *);
 int uwsgi_notify_socket_manage(int);
 int uwsgi_notify_msg(char *, char *, size_t);
 
+void uwsgi_fork_server(char *);
+
 #ifdef __cplusplus
 }
 #endif

uwsgiconfig.py

@@ -602,7 +602,7 @@ class uConf(object):
             'core/setup_utils', 'core/clock', 'core/init', 'core/buffer', 'core/reader', 'core/writer', 'core/alarm', 'core/cron', 'core/hooks',
             'core/plugins', 'core/lock', 'core/cache', 'core/daemons', 'core/errors', 'core/hash', 'core/master_events', 'core/chunked',
             'core/queue', 'core/event', 'core/signal', 'core/strings', 'core/progress', 'core/timebomb', 'core/ini', 'core/fsmon', 'core/mount',
-            'core/metrics', 'core/plugins_builder', 'core/sharedarea',
+            'core/metrics', 'core/plugins_builder', 'core/sharedarea', 'core/fork_server',
             'core/rpc', 'core/gateway', 'core/loop', 'core/cookie', 'core/querystring', 'core/rb_timers', 'core/transformations', 'core/uwsgi']
         # add protocols
         self.gcc_list.append('proto/base')