Systemd/src/core/dbus.h
Lennart Poettering e0a085811d core: don't process dbus unit and job queue when there are already too many messages pending
We maintain a queue of units and jobs that we are supposed to generate
change/new notifications for because they were either just created or
some of their property has changed. Let's throttle processing of this
queue a bit: as soon as > 1K of bus messages are queued for writing
let's skip processing the queue, and then recheck on the next
iteration again.

Moreover, never process more than 100 units in one go, return to the
event loop after that. Both limits together should put effective limits
on both space and time usage of the function, delaying further
operations until a later moment, when the queue is empty or the the
event loop is sufficiently idle again.

This should keep the number of generated messages much lower than
before on busy systems or where some client is hanging.

Note that this also means a bad client can slow down message dispatching
substantially for up to 90s if it likes to, for all clients. But that
should be acceptable as we only allow trusted bus clients, anyway.

Fixes: #8166
2018-02-27 19:54:29 +01:00

53 lines
1.9 KiB
C

/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include "manager.h"
int bus_send_queued_message(Manager *m);
int bus_init_private(Manager *m);
int bus_init_api(Manager *m);
int bus_init_system(Manager *m);
void bus_done_private(Manager *m);
void bus_done_api(Manager *m);
void bus_done_system(Manager *m);
void bus_done(Manager *m);
int bus_fdset_add_all(Manager *m, FDSet *fds);
void bus_track_serialize(sd_bus_track *t, FILE *f, const char *prefix);
int bus_track_coldplug(Manager *m, sd_bus_track **t, bool recursive, char **l);
int manager_enqueue_sync_bus_names(Manager *m);
int bus_foreach_bus(Manager *m, sd_bus_track *subscribed2, int (*send_message)(sd_bus *bus, void *userdata), void *userdata);
int bus_verify_manage_units_async(Manager *m, sd_bus_message *call, sd_bus_error *error);
int bus_verify_manage_unit_files_async(Manager *m, sd_bus_message *call, sd_bus_error *error);
int bus_verify_reload_daemon_async(Manager *m, sd_bus_message *call, sd_bus_error *error);
int bus_verify_set_environment_async(Manager *m, sd_bus_message *call, sd_bus_error *error);
int bus_forward_agent_released(Manager *m, const char *path);
uint64_t manager_bus_n_queued_write(Manager *m);