lighttpd2/src/main/server.c

#include <lighttpd/base.h>
#include <lighttpd/plugin_core.h>

#ifdef HAVE_LUA_H
# include <lighttpd/core_lua.h>
# include <lualib.h>
# include <lauxlib.h>
#endif

#ifdef HAVE_SYS_RESOURCE_H
# include <sys/resource.h>
#endif

static void li_server_listen_cb(struct ev_loop *loop, ev_io *w, int revents);
static void li_server_stop(liServer *srv);
static void state_ready_cb(struct ev_loop *loop, struct ev_async *w, int revents);

static liServerSocket* server_socket_new(int fd) {
	liServerSocket *sock = g_slice_new0(liServerSocket);

	sock->refcount = 1;
	sock->watcher.data = sock;
	li_fd_init(fd);
	ev_init(&sock->watcher, li_server_listen_cb);
	ev_io_set(&sock->watcher, fd, EV_READ);
	return sock;
}

void li_server_socket_release(liServerSocket* sock) {
	if (!sock) return;
	assert(g_atomic_int_get(&sock->refcount) > 0);
	if (g_atomic_int_dec_and_test(&sock->refcount)) {
		if (sock->release_cb) sock->release_cb(sock);

		g_slice_free(liServerSocket, sock);
	}
}

void li_server_socket_acquire(liServerSocket* sock) {
	assert(g_atomic_int_get(&sock->refcount) > 0);
	g_atomic_int_inc(&sock->refcount);
}

static void server_option_free(gpointer _so) {
	g_slice_free(liServerOption, _so);
}

static void server_optionptr_free(gpointer _so) {
	g_slice_free(liServerOptionPtr, _so);
}

static void server_action_free(gpointer _sa) {
	g_slice_free(liServerAction, _sa);
}

static void server_setup_free(gpointer _ss) {
	g_slice_free(liServerSetup, _ss);
}

#define CATCH_SIGNAL(loop, cb, n) do {              \
    ev_init(&srv->sig_w_##n, cb);                   \
    ev_signal_set(&srv->sig_w_##n, SIG##n);         \
    ev_signal_start(loop, &srv->sig_w_##n);         \
    srv->sig_w_##n.data = srv;                      \
    /* Signal watchers shouldn't keep loop alive */ \
    ev_unref(loop);                                 \
} while (0)

#define UNCATCH_SIGNAL(loop, n) li_ev_safe_ref_and_stop(ev_signal_stop, loop, &srv->sig_w_##n)

static void sigint_cb(struct ev_loop *loop, struct ev_signal *w, int revents) {
	liServer *srv = (liServer*) w->data;
	UNUSED(loop);
	UNUSED(revents);

	if (g_atomic_int_get(&srv->dest_state) != LI_SERVER_DOWN) {
		INFO(srv, "%s", "Got signal, shutdown");
		li_server_goto_state(srv, LI_SERVER_DOWN);
	} else {
		INFO(srv, "%s", "Got second signal, force shutdown");
		exit(1);
	}
}

static void sigpipe_cb(struct ev_loop *loop, struct ev_signal *w, int revents) {
	/* ignore */
	UNUSED(loop); UNUSED(w); UNUSED(revents);
}

liServer* li_server_new(const gchar *module_dir, gboolean module_resident) {
	liServer* srv = g_slice_new0(liServer);

	srv->magic = LIGHTTPD_SERVER_MAGIC;
	srv->state = LI_SERVER_INIT;
	srv->dest_state = LI_SERVER_RUNNING;

	srv->statelock = g_mutex_new();
	g_queue_init(&srv->state_wait_queue);
	srv->state_wait_for = srv->state;
	ev_init(&srv->state_ready_watcher, state_ready_cb);
	srv->state_ready_watcher.data = srv;

#ifdef HAVE_LUA_H
	srv->L = luaL_newstate();
	luaL_openlibs(srv->L);
	li_lua_init(srv->L, srv, NULL);

	srv->lualock = g_mutex_new();
#else
	srv->L = NULL;
#endif

	srv->workers = g_array_new(FALSE, TRUE, sizeof(liWorker*));
	srv->worker_count = 0;

	srv->sockets = g_ptr_array_new();

	srv->modules = li_modules_new(srv, module_dir, module_resident);

	srv->plugins = g_hash_table_new(g_str_hash, g_str_equal);
	srv->options = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, server_option_free);
	srv->optionptrs = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, server_optionptr_free);
	srv->actions = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, server_action_free);
	srv->setups  = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, server_setup_free);

	srv->li_plugins_handle_close = g_array_new(FALSE, TRUE, sizeof(liPlugin*));
	srv->li_plugins_handle_vrclose = g_array_new(FALSE, TRUE, sizeof(liPlugin*));
	srv->option_def_values = g_array_new(FALSE, TRUE, sizeof(liOptionValue));
	srv->optionptr_def_values = g_array_new(FALSE, TRUE, sizeof(liOptionPtrValue*));

	srv->mainaction = NULL;

	srv->exiting = FALSE;

	srv->ts_formats = g_array_new(FALSE, TRUE, sizeof(GString*));
	/* error log ts format */
	li_server_ts_format_add(srv, g_string_new("%a, %d %b %Y %H:%M:%S %Z"));
	/* http header ts format */
	li_server_ts_format_add(srv, g_string_new("%a, %d %b %Y %H:%M:%S GMT"));

	srv->throttle_pools = g_array_new(FALSE, TRUE, sizeof(liThrottlePool*));

	li_log_init(srv);

	srv->connection_load = 0;
	srv->max_connections = 256; /* assume max-fds = 1024 */
	srv->connection_limit_hit = FALSE;
#ifdef HAVE_GETRLIMIT
	{
		struct rlimit rlim;
		rlim_t max_fds = 1024;
		if (0 != getrlimit(RLIMIT_NOFILE, &rlim)) {
			ERROR(srv, "couldn't get 'max filedescriptors': %s", g_strerror(errno));
		} else {
			max_fds = rlim.rlim_cur;
			if (rlim.rlim_cur < rlim.rlim_max) {
				/* go for maximum */
				rlim.rlim_cur = rlim.rlim_max;
				if (0 != setrlimit(RLIMIT_NOFILE, &rlim)) {
					ERROR(srv, "couldn't set 'max filedescriptors': %s", g_strerror(errno));
				} else {
					max_fds = rlim.rlim_cur;
				}
			}
		}
		if (max_fds / 4 > G_MAXUINT32) {
			srv->max_connections = G_MAXUINT32;
		} else {
			srv->max_connections = max_fds / 4;
		}
	}
#endif

	srv->io_timeout = 300; /* default I/O timeout */
	srv->keep_alive_queue_timeout = 5;

	return srv;
}

void li_server_free(liServer* srv) {
	if (!srv) return;

	li_server_stop(srv);
	g_atomic_int_set(&srv->exiting, TRUE);

	/* join all workers */
	{
		guint i;
		for (i = 1; i < srv->workers->len; i++) {
			liWorker *wrk;
			wrk = g_array_index(srv->workers, liWorker*, i);
			li_worker_exit(srv->main_worker, wrk);
			g_thread_join(wrk->thread);
		}
	}

	li_action_release(srv, srv->mainaction);

	li_ev_safe_ref_and_stop(ev_async_stop, srv->loop, &srv->state_ready_watcher);
	g_mutex_free(srv->statelock);

#ifdef HAVE_LUA_H
	lua_close(srv->L);
	srv->L = NULL;
	g_mutex_free(srv->lualock);
#endif

	/* free throttle pools */
	{
		guint i;
		for (i = 0; i < srv->throttle_pools->len; i++) {
			li_throttle_pool_free(srv, g_array_index(srv->throttle_pools, liThrottlePool*, i));
		}
		g_array_free(srv->throttle_pools, TRUE);
	}

	if (srv->acon) {
		li_angel_connection_free(srv->acon);
		srv->acon = NULL;
	}

	/* free all workers */
	{
		guint i;
		for (i = 0; i < srv->workers->len; i++) {
			liWorker *wrk;
			struct ev_loop *loop;
			wrk = g_array_index(srv->workers, liWorker*, i);
			loop = wrk->loop;
			li_worker_free(wrk);
			if (i == 0) {
				ev_default_destroy();
			} else {
				ev_loop_destroy(loop);
			}
		}
		g_array_free(srv->workers, TRUE);
	}

	{
		guint i; for (i = 0; i < srv->sockets->len; i++) {
			liServerSocket *sock = g_ptr_array_index(srv->sockets, i);
			close(sock->watcher.fd);
			li_server_socket_release(sock);
		}
		g_ptr_array_free(srv->sockets, TRUE);
	}

	/* release modules */
	li_modules_free(srv->modules);

	li_plugin_free(srv, srv->core_plugin);

	li_log_cleanup(srv);

	{
		guint i;
		for (i = 0; i < srv->ts_formats->len; i++)
			g_string_free(g_array_index(srv->ts_formats, GString*, i), TRUE);
		g_array_free(srv->ts_formats, TRUE);
	}

	g_array_free(srv->option_def_values, TRUE);
	{
		guint i;
		for (i = 0; i < srv->optionptr_def_values->len; i++) {
			li_release_optionptr(srv, g_array_index(srv->optionptr_def_values, liOptionPtrValue*, i));
		}
	}
	g_array_free(srv->optionptr_def_values, TRUE);
	li_server_plugins_free(srv);
	g_array_free(srv->li_plugins_handle_close, TRUE);
	g_array_free(srv->li_plugins_handle_vrclose, TRUE);

	if (srv->started_str)
		g_string_free(srv->started_str, TRUE);

	g_slice_free(liServer, srv);
}

static gpointer server_worker_cb(gpointer data) {
	liWorker *wrk = (liWorker*) data;
	li_plugins_prepare_worker(wrk);
	li_worker_run(wrk);
	return NULL;
}

gboolean li_server_loop_init(liServer *srv) {
	srv->loop = ev_default_loop(srv->loop_flags);

	if (!srv->loop) {
		li_fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		return FALSE;
	}

	ev_async_start(srv->loop, &srv->state_ready_watcher);
	ev_unref(srv->loop); /* don't keep loop alive */

	srv->main_worker = li_worker_new(srv, srv->loop);
	srv->main_worker->ndx = 0;

	return TRUE;
}

static void li_server_1sec_timer(struct ev_loop *loop, ev_timer *w, int revents) {
	liServer *srv = w->data;
	UNUSED(loop);
	UNUSED(revents);

	if (srv->connection_limit_hit) {
		guint srv_cur_load = g_atomic_int_get(&srv->connection_load);
		guint srv_max_load = g_atomic_int_get(&srv->max_connections);
		if (srv_cur_load <= (srv_max_load - srv_max_load/8)) { /* cur_load <= 7/8 * max_load */
			guint i;

			for (i = 0; i < srv->sockets->len; i++) {
				liServerSocket *sock = g_ptr_array_index(srv->sockets, i);
				ev_io_start(srv->main_worker->loop, &sock->watcher);
			}
			srv->connection_limit_hit = FALSE;
		}
	}
}

static gboolean li_server_worker_init(liServer *srv) {
	struct ev_loop *loop = srv->loop;
	guint i;

	CATCH_SIGNAL(loop, sigint_cb, INT);
	CATCH_SIGNAL(loop, sigint_cb, TERM);
	CATCH_SIGNAL(loop, sigpipe_cb, PIPE);

	ev_timer_init(&srv->srv_1sec_timer, li_server_1sec_timer, 1.0, 1.0);
	srv->srv_1sec_timer.data = srv;
	ev_timer_start(loop, &srv->srv_1sec_timer);
	ev_unref(loop); /* don't keep loop alive */

	if (srv->worker_count < 1) srv->worker_count = 1;
	g_array_set_size(srv->workers, srv->worker_count);
	g_array_index(srv->workers, liWorker*, 0) = srv->main_worker;
	for (i = 1; i < srv->worker_count; i++) {
		liWorker *wrk;
		if (NULL == (loop = ev_loop_new(srv->loop_flags))) {
			li_fatal ("could not create extra libev loops");
			return FALSE;
		}
		wrk = g_array_index(srv->workers, liWorker*, i) = li_worker_new(srv, loop);
		wrk->ndx = i;
	}

	return TRUE;
}

static void li_server_worker_run(liServer *srv) {
	guint i;
	li_plugins_prepare_worker(srv->main_worker);

	for (i = 1; i < srv->worker_count; i++) {
		GError *error = NULL;
		liWorker *wrk  = g_array_index(srv->workers, liWorker*, i);
		if (NULL == (wrk->thread = g_thread_create(server_worker_cb, wrk, TRUE, &error))) {
			g_error ( "g_thread_create failed: %s", error->message );
		}
	}
}

static void server_connection_limit_hit(liServer *srv) {
	guint i;

	for (i = 0; i < srv->sockets->len; i++) {
		liServerSocket *sock = g_ptr_array_index(srv->sockets, i);
		ev_io_stop(srv->main_worker->loop, &sock->watcher);
	}

	srv->connection_limit_hit = TRUE;
}

static void li_server_listen_cb(struct ev_loop *loop, ev_io *w, int revents) {
	liServerSocket *sock = (liServerSocket*) w->data;
	liServer *srv = sock->srv;
	int s;
	liSocketAddress remote_addr;
	struct sockaddr sa;
	socklen_t l = sizeof(sa);
	UNUSED(loop);
	UNUSED(revents);

	for ( ;; ) {
		liWorker *wrk;
		guint i, min_load, srv_cur_load, srv_max_load;

		srv_cur_load = g_atomic_int_get(&srv->connection_load);
		srv_max_load = g_atomic_int_get(&srv->max_connections);
		if (srv_cur_load >= srv_max_load) {
			server_connection_limit_hit(srv);
			return;
		}

		if (-1 == (s = accept(w->fd, &sa, &l))) break;

		wrk = srv->main_worker;
		min_load = g_atomic_int_get(&wrk->connection_load);

		if (l <= sizeof(sa)) {
			remote_addr.addr = g_slice_alloc(l);
			remote_addr.len = l;
			memcpy(remote_addr.addr, &sa, l);
		} else {
			remote_addr = li_sockaddr_remote_from_socket(s);
		}
		l = sizeof(sa); /* reset l */

		li_fd_init(s);

		for (i = 1; i < srv->worker_count; i++) {
			liWorker *wt = g_array_index(srv->workers, liWorker*, i);
			guint load = g_atomic_int_get(&wt->connection_load);
			if (load < min_load) {
				wrk = wt;
				min_load = load;
			}
		}

		g_atomic_int_inc((gint*) &wrk->connection_load);
		g_atomic_int_inc((gint*) &srv->connection_load);
		li_server_socket_acquire(sock);
		li_worker_new_con(srv->main_worker, wrk, remote_addr, s, sock);
	}

#ifdef _WIN32
	errno = WSAGetLastError();
#endif

	switch (errno) {
	case EAGAIN:
#if EWOULDBLOCK != EAGAIN
	case EWOULDBLOCK:
#endif
	case EINTR:
		/* we were stopped _before_ we had a connection */
	case ECONNABORTED: /* this is a FreeBSD thingy */
		/* we were stopped _after_ we had a connection */
		break;

	case EMFILE: /* we are out of FDs */
		li_server_out_of_fds(srv);
		/* TODO: disable accept callbacks? */
		break;
	default:
		ERROR(srv, "accept failed on fd=%d with error: %s", w->fd, g_strerror(errno));
		break;
	}
}

/* main worker only */
liServerSocket* li_server_listen(liServer *srv, int fd) {
	liServerSocket *sock = server_socket_new(fd);

	sock->srv = srv;
	g_ptr_array_add(srv->sockets, sock);

	if (LI_SERVER_RUNNING == srv->state || LI_SERVER_WARMUP == srv->state) ev_io_start(srv->main_worker->loop, &sock->watcher);

	return sock;
}

static void li_server_start_listen(liServer *srv) {
	guint i;

	for (i = 0; i < srv->sockets->len; i++) {
		liServerSocket *sock = g_ptr_array_index(srv->sockets, i);
		ev_io_start(srv->main_worker->loop, &sock->watcher);
	}
}

static void li_server_stop_listen(liServer *srv) {
	guint i;

	for (i = 0; i < srv->sockets->len; i++) {
		liServerSocket *sock = g_ptr_array_index(srv->sockets, i);
		ev_io_stop(srv->main_worker->loop, &sock->watcher);
	}
	srv->connection_limit_hit = FALSE; /* reset flag */

	/* suspend all workers (close keep-alive connections) */
	for (i = 0; i < srv->worker_count; i++) {
		liWorker *wrk;
		wrk = g_array_index(srv->workers, liWorker*, i);
		li_worker_suspend(srv->main_worker, wrk);
	}
}

static void li_server_stop(liServer *srv) {
	guint i;

	for (i = 0; i < srv->sockets->len; i++) {
		liServerSocket *sock = g_ptr_array_index(srv->sockets, i);
		ev_io_stop(srv->main_worker->loop, &sock->watcher);
	}
	srv->connection_limit_hit = FALSE; /* reset flag */

	/* stop all workers */
	for (i = 0; i < srv->worker_count; i++) {
		liWorker *wrk;
		wrk = g_array_index(srv->workers, liWorker*, i);
		li_worker_stop(srv->main_worker, wrk);
	}
}

void li_server_exit(liServer *srv) {
	li_server_stop(srv);

	g_atomic_int_set(&srv->exiting, TRUE);
	g_atomic_int_set(&srv->state, LI_SERVER_DOWN);
	g_atomic_int_set(&srv->dest_state, LI_SERVER_DOWN);

	/* exit all workers */
	{
		guint i;
		for (i = 0; i < srv->worker_count; i++) {
			liWorker *wrk;
			wrk = g_array_index(srv->workers, liWorker*, i);
			li_worker_exit(srv->main_worker, wrk);
		}
	}
}

/* cache timestamp */
GString *li_server_current_timestamp() {
	static GStaticPrivate last_ts_key = G_STATIC_PRIVATE_INIT;
	static GStaticPrivate ts_str_key = G_STATIC_PRIVATE_INIT;

	time_t *last_ts = g_static_private_get(&last_ts_key);
	GString *ts_str = g_static_private_get(&ts_str_key);

	time_t cur_ts = time(NULL);

	if (last_ts == NULL) {
		last_ts = g_new0(time_t, 1);
		g_static_private_set(&last_ts_key, last_ts, g_free);
	}
	if (ts_str == NULL) {
		ts_str = g_string_sized_new(255);
		g_static_private_set(&ts_str_key, ts_str, (GDestroyNotify)li_string_destroy_notify);
	}

	if (cur_ts != *last_ts) {
		gsize s;
#ifdef HAVE_GMTIME_R
		struct tm tm;
#endif

		g_string_set_size(ts_str, 255);
#ifdef HAVE_GMTIME_R
		s = strftime(ts_str->str, ts_str->allocated_len,
				"%a, %d %b %Y %H:%M:%S GMT", gmtime_r(&cur_ts, &tm));
#else
		s = strftime(ts_str->str, ts_str->allocated_len,
				"%a, %d %b %Y %H:%M:%S GMT", gmtime(&cur_ts));
#endif
		g_string_set_size(ts_str, s);
		*last_ts = cur_ts;
	}

	return ts_str;
}

void li_server_out_of_fds(liServer *srv) {
	ERROR(srv, "%s", "Too many open files. Either raise your fd limit or use a lower connection limit.");
}

guint li_server_ts_format_add(liServer *srv, GString* format) {
	/* check if not already registered */
	guint i;
	for (i = 0; i < srv->ts_formats->len; i++) {
		if (g_string_equal(g_array_index(srv->ts_formats, GString*, i), format))
			return i;
	}

	g_array_append_val(srv->ts_formats, format);
	return i;
}

/* state machine: call this functions only in the main worker context */
/* Note: main worker doesn't need atomic read for state */

#if 0
	case LI_SERVER_INIT:
	case LI_SERVER_LOADING:
	case LI_SERVER_SUSPENDED:
	case LI_SERVER_WARMUP:
	case LI_SERVER_RUNNING:
	case LI_SERVER_SUSPENDING:
	case LI_SERVER_STOPPING:
	case LI_SERVER_DOWN:
#endif

static const gchar* li_server_state_string(liServerState state) {
	switch (state) {
	case LI_SERVER_INIT: return "init";
	case LI_SERVER_LOADING: return "loading";
	case LI_SERVER_SUSPENDED: return "suspended";
	case LI_SERVER_WARMUP: return "warmup";
	case LI_SERVER_RUNNING: return "running";
	case LI_SERVER_SUSPENDING: return "suspending";
	case LI_SERVER_STOPPING: return "stopping";
	case LI_SERVER_DOWN: return "down";
	}

	return "<unkown>";
}

/* next state in the machine we want to reach to reach */
static liServerState li_server_next_state(liServer *srv) {
	switch (srv->state) {
	case LI_SERVER_INIT:
		return LI_SERVER_LOADING;
	case LI_SERVER_LOADING:
		if (LI_SERVER_DOWN == srv->dest_state) return LI_SERVER_STOPPING;
		return LI_SERVER_SUSPENDED;
	case LI_SERVER_SUSPENDED:
		switch (srv->dest_state) {
		case LI_SERVER_INIT:
		case LI_SERVER_LOADING:
		case LI_SERVER_SUSPENDED:
			return LI_SERVER_SUSPENDED;
		case LI_SERVER_WARMUP:
		case LI_SERVER_RUNNING:
		case LI_SERVER_SUSPENDING:
			return LI_SERVER_WARMUP;
		case LI_SERVER_STOPPING:
		case LI_SERVER_DOWN:
			return LI_SERVER_STOPPING;
		}
		return LI_SERVER_DOWN;
	case LI_SERVER_WARMUP:
		if (LI_SERVER_WARMUP == srv->dest_state) return LI_SERVER_WARMUP;
		return LI_SERVER_RUNNING;
	case LI_SERVER_RUNNING:
		if (LI_SERVER_RUNNING == srv->dest_state) return LI_SERVER_RUNNING;
		return LI_SERVER_SUSPENDING;
	case LI_SERVER_SUSPENDING:
		if (LI_SERVER_RUNNING == srv->dest_state) return LI_SERVER_RUNNING;
		if (LI_SERVER_SUSPENDING == srv->dest_state) return LI_SERVER_SUSPENDING;
		return LI_SERVER_SUSPENDED;
	case LI_SERVER_STOPPING:
	case LI_SERVER_DOWN:
		return LI_SERVER_DOWN;
	}
	return LI_SERVER_DOWN;
}

static void li_server_start_transition(liServer *srv, liServerState state) {
	guint i;
	liServerStateWait sw_dummy;

	DEBUG(srv, "Try reaching state: %s (dest: %s)", li_server_state_string(state), li_server_state_string(srv->dest_state));

	srv->state_wait_for = state;
	memset(&sw_dummy, 0, sizeof(sw_dummy));
	li_server_state_wait(srv, &sw_dummy);

	switch (state) {
	case LI_SERVER_INIT:
	case LI_SERVER_LOADING:
		li_server_reached_state(srv, state);
		break;
	case LI_SERVER_SUSPENDED:
		if (srv->state == LI_SERVER_LOADING) {
			li_plugins_prepare(srv);
		}
		break;
	case LI_SERVER_WARMUP:
		li_server_start_listen(srv);
		li_plugins_start_listen(srv);
		break;
	case LI_SERVER_RUNNING:
		if (LI_SERVER_WARMUP == srv->state) {
			li_plugins_start_log(srv);
		} else if (LI_SERVER_SUSPENDING == srv->state) {
			li_server_start_listen(srv);
			li_plugins_start_listen(srv);
		}
		break;
	case LI_SERVER_SUSPENDING:
		li_server_stop_listen(srv);
		li_plugins_stop_listen(srv);
		/* wait for closed connections and plugins */
		break;
	case LI_SERVER_STOPPING:
		/* stop all workers */
		for (i = 0; i < srv->worker_count; i++) {
			liWorker *wrk;
			wrk = g_array_index(srv->workers, liWorker*, i);
			li_worker_stop(srv->main_worker, wrk);
		}

		li_log_thread_wakeup(srv);
		li_server_reached_state(srv, LI_SERVER_STOPPING);
		break;
	case LI_SERVER_DOWN:
		/* wait */
		break;
	}

	li_server_state_ready(srv, &sw_dummy);
}

void li_server_goto_state(liServer *srv, liServerState state) {
	if (srv->dest_state == LI_SERVER_DOWN || srv->dest_state == state) return; /* cannot undo this */

	switch (state) {
	case LI_SERVER_INIT:
	case LI_SERVER_LOADING:
	case LI_SERVER_SUSPENDING:
	case LI_SERVER_STOPPING:
		return; /* invalid dest states */
	case LI_SERVER_WARMUP:
	case LI_SERVER_RUNNING:
	case LI_SERVER_SUSPENDED:
	case LI_SERVER_DOWN:
		break;
	}

	g_atomic_int_set(&srv->dest_state, state);

	if (srv->dest_state != srv->state) {
		liServerState want_state = li_server_next_state(srv);
		li_server_start_transition(srv, want_state);
	}
}

void li_server_reached_state(liServer *srv, liServerState state) {
	liServerState want_state = li_server_next_state(srv);
	liServerState old_state = srv->state;
	GList *swlink;

	if (state != want_state) return;
	if (state == srv->state) return;

	g_atomic_int_set(&srv->state, state);
	DEBUG(srv, "Reached state: %s (dest: %s)", li_server_state_string(state), li_server_state_string(srv->dest_state));

	/* cleanup state_wait_queue */
	g_mutex_lock(srv->statelock);

	while (NULL != (swlink = g_queue_pop_head_link(&srv->state_wait_queue))) {
		liServerStateWait *sw = swlink->data;
		sw->active = FALSE;
		if (sw->cancel_cb) {
			sw->cancel_cb(srv, sw);
		}
	}
	g_mutex_unlock(srv->statelock);

	switch (srv->state) {
	case LI_SERVER_INIT:
		break;
	case LI_SERVER_LOADING:
		li_plugins_prepare_callbacks(srv);
		li_server_worker_init(srv);

		{
			GString *str = li_worker_current_timestamp(srv->main_worker, LI_LOCALTIME, LI_TS_FORMAT_DEFAULT);
			srv->started = ev_now(srv->main_worker->loop);
			srv->started_str = g_string_new_len(GSTR_LEN(str));
		}

		li_log_thread_start(srv);
		break;
	case LI_SERVER_SUSPENDED:
		if (LI_SERVER_SUSPENDING == old_state) {
			li_plugins_stop_log(srv);
		} else if (LI_SERVER_LOADING == old_state) {
			li_server_worker_run(srv);
		}
		break;
	case LI_SERVER_WARMUP:
	case LI_SERVER_RUNNING:
		break;
	case LI_SERVER_SUSPENDING:
	case LI_SERVER_STOPPING:
		break;
	case LI_SERVER_DOWN:
		/* li_server_exit(srv); */
		return;
	}

	if (srv->acon) {
		GString *data = g_string_new(li_server_state_string(srv->state));
		GError *err = NULL;

		if (!li_angel_send_simple_call(srv->acon, CONST_STR_LEN("core"), CONST_STR_LEN("reached-state"), data, &err)) {
			GERROR(srv, err, "%s", "couldn't send state update to angel");
			g_error_free(err);
		}
	}

	if (srv->dest_state != srv->state) {
		want_state = li_server_next_state(srv);
		li_server_start_transition(srv, want_state);
	}
}

static void state_ready_cb(struct ev_loop *loop, struct ev_async *w, int revents) {
	liServer *srv = w->data;

	UNUSED(loop);
	UNUSED(revents);

	g_mutex_lock(srv->statelock);

	if (srv->state_wait_queue.length > 0) {
		/* not ready - ignore event */
		g_mutex_unlock(srv->statelock);
		return;
	}

	g_mutex_unlock(srv->statelock);

	if (srv->state_wait_for != li_server_next_state(srv)) {
		/* not the state we have been waiting for - ignore */
		return;
	}

	/* IMPORTANT: do not call this while statelock is locked  */
	li_server_reached_state(srv, srv->state_wait_for);
}

/** threadsafe */
void li_server_state_ready(liServer *srv, liServerStateWait *sw) {
	g_mutex_lock(srv->statelock);

	if (sw->active) {
		g_queue_unlink(&srv->state_wait_queue, &sw->queue_link);
		sw->active = FALSE;

		if (srv->state_wait_queue.length == 0) {
			ev_async_send(srv->loop, &srv->state_ready_watcher);
		}
	}

	g_mutex_unlock(srv->statelock);
}

/** only call from server state plugin hooks; push new wait condition to wait queue */
void li_server_state_wait(liServer *srv, liServerStateWait *sw) {
	g_mutex_lock(srv->statelock);

	sw->queue_link.data = sw;
	g_queue_push_tail_link(&srv->state_wait_queue, &sw->queue_link);
	sw->active = TRUE;

	g_mutex_unlock(srv->statelock);
}