b6d5481b3d
Let's a concept of "rate limiting" to event sources: if specific event sources fire too often in some time interval temporarily take them offline, and take them back online once the interval passed. This is a simple scheme of avoiding starvation of event sources if some event source fires too often. This introduces the new conceptual states of "offline" and "online" for event sources: an event source is "online" only when enabled *and* not ratelimited, and offline in all other cases. An event source that is online hence has its fds registered in the epoll, its signals in the signalfd and so on.
177 lines
8.2 KiB
C
177 lines
8.2 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#ifndef foosdeventhfoo
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#define foosdeventhfoo
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/***
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <inttypes.h>
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#include <signal.h>
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#include <sys/epoll.h>
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#include <sys/inotify.h>
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#include <sys/signalfd.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <time.h>
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#include "_sd-common.h"
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/*
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Why is this better than pure epoll?
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- Supports event source prioritization
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- Scales better with a large number of time events because it does not require one timerfd each
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- Automatically tries to coalesce timer events system-wide
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- Handles signals, child PIDs, inotify events
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- Supports systemd-style automatic watchdog event generation
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*/
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_SD_BEGIN_DECLARATIONS;
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#define SD_EVENT_DEFAULT ((sd_event *) 1)
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typedef struct sd_event sd_event;
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typedef struct sd_event_source sd_event_source;
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enum {
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SD_EVENT_OFF = 0,
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SD_EVENT_ON = 1,
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SD_EVENT_ONESHOT = -1
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};
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enum {
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SD_EVENT_INITIAL,
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SD_EVENT_ARMED,
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SD_EVENT_PENDING,
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SD_EVENT_RUNNING,
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SD_EVENT_EXITING,
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SD_EVENT_FINISHED,
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SD_EVENT_PREPARING
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};
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enum {
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/* And everything in-between and outside is good too */
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SD_EVENT_PRIORITY_IMPORTANT = -100,
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SD_EVENT_PRIORITY_NORMAL = 0,
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SD_EVENT_PRIORITY_IDLE = 100
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};
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typedef int (*sd_event_handler_t)(sd_event_source *s, void *userdata);
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typedef int (*sd_event_io_handler_t)(sd_event_source *s, int fd, uint32_t revents, void *userdata);
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typedef int (*sd_event_time_handler_t)(sd_event_source *s, uint64_t usec, void *userdata);
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typedef int (*sd_event_signal_handler_t)(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata);
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#if defined _GNU_SOURCE || (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 199309L)
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typedef int (*sd_event_child_handler_t)(sd_event_source *s, const siginfo_t *si, void *userdata);
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#else
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typedef void* sd_event_child_handler_t;
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#endif
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typedef int (*sd_event_inotify_handler_t)(sd_event_source *s, const struct inotify_event *event, void *userdata);
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typedef _sd_destroy_t sd_event_destroy_t;
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int sd_event_default(sd_event **e);
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int sd_event_new(sd_event **e);
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sd_event* sd_event_ref(sd_event *e);
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sd_event* sd_event_unref(sd_event *e);
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int sd_event_add_io(sd_event *e, sd_event_source **s, int fd, uint32_t events, sd_event_io_handler_t callback, void *userdata);
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int sd_event_add_time(sd_event *e, sd_event_source **s, clockid_t clock, uint64_t usec, uint64_t accuracy, sd_event_time_handler_t callback, void *userdata);
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int sd_event_add_time_relative(sd_event *e, sd_event_source **s, clockid_t clock, uint64_t usec, uint64_t accuracy, sd_event_time_handler_t callback, void *userdata);
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int sd_event_add_signal(sd_event *e, sd_event_source **s, int sig, sd_event_signal_handler_t callback, void *userdata);
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int sd_event_add_child(sd_event *e, sd_event_source **s, pid_t pid, int options, sd_event_child_handler_t callback, void *userdata);
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int sd_event_add_child_pidfd(sd_event *e, sd_event_source **s, int pidfd, int options, sd_event_child_handler_t callback, void *userdata);
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int sd_event_add_inotify(sd_event *e, sd_event_source **s, const char *path, uint32_t mask, sd_event_inotify_handler_t callback, void *userdata);
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int sd_event_add_defer(sd_event *e, sd_event_source **s, sd_event_handler_t callback, void *userdata);
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int sd_event_add_post(sd_event *e, sd_event_source **s, sd_event_handler_t callback, void *userdata);
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int sd_event_add_exit(sd_event *e, sd_event_source **s, sd_event_handler_t callback, void *userdata);
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int sd_event_prepare(sd_event *e);
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int sd_event_wait(sd_event *e, uint64_t usec);
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int sd_event_dispatch(sd_event *e);
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int sd_event_run(sd_event *e, uint64_t usec);
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int sd_event_loop(sd_event *e);
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int sd_event_exit(sd_event *e, int code);
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int sd_event_now(sd_event *e, clockid_t clock, uint64_t *usec);
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int sd_event_get_fd(sd_event *e);
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int sd_event_get_state(sd_event *e);
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int sd_event_get_tid(sd_event *e, pid_t *tid);
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int sd_event_get_exit_code(sd_event *e, int *code);
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int sd_event_set_watchdog(sd_event *e, int b);
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int sd_event_get_watchdog(sd_event *e);
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int sd_event_get_iteration(sd_event *e, uint64_t *ret);
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sd_event_source* sd_event_source_ref(sd_event_source *s);
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sd_event_source* sd_event_source_unref(sd_event_source *s);
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sd_event_source* sd_event_source_disable_unref(sd_event_source *s);
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sd_event *sd_event_source_get_event(sd_event_source *s);
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void* sd_event_source_get_userdata(sd_event_source *s);
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void* sd_event_source_set_userdata(sd_event_source *s, void *userdata);
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int sd_event_source_set_description(sd_event_source *s, const char *description);
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int sd_event_source_get_description(sd_event_source *s, const char **description);
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int sd_event_source_set_prepare(sd_event_source *s, sd_event_handler_t callback);
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int sd_event_source_get_pending(sd_event_source *s);
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int sd_event_source_get_priority(sd_event_source *s, int64_t *priority);
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int sd_event_source_set_priority(sd_event_source *s, int64_t priority);
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int sd_event_source_get_enabled(sd_event_source *s, int *enabled);
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int sd_event_source_set_enabled(sd_event_source *s, int enabled);
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int sd_event_source_get_io_fd(sd_event_source *s);
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int sd_event_source_set_io_fd(sd_event_source *s, int fd);
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int sd_event_source_get_io_fd_own(sd_event_source *s);
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int sd_event_source_set_io_fd_own(sd_event_source *s, int own);
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int sd_event_source_get_io_events(sd_event_source *s, uint32_t* events);
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int sd_event_source_set_io_events(sd_event_source *s, uint32_t events);
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int sd_event_source_get_io_revents(sd_event_source *s, uint32_t* revents);
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int sd_event_source_get_time(sd_event_source *s, uint64_t *usec);
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int sd_event_source_set_time(sd_event_source *s, uint64_t usec);
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int sd_event_source_set_time_relative(sd_event_source *s, uint64_t usec);
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int sd_event_source_get_time_accuracy(sd_event_source *s, uint64_t *usec);
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int sd_event_source_set_time_accuracy(sd_event_source *s, uint64_t usec);
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int sd_event_source_get_time_clock(sd_event_source *s, clockid_t *clock);
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int sd_event_source_get_signal(sd_event_source *s);
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int sd_event_source_get_child_pid(sd_event_source *s, pid_t *pid);
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int sd_event_source_get_child_pidfd(sd_event_source *s);
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int sd_event_source_get_child_pidfd_own(sd_event_source *s);
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int sd_event_source_set_child_pidfd_own(sd_event_source *s, int own);
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int sd_event_source_get_child_process_own(sd_event_source *s);
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int sd_event_source_set_child_process_own(sd_event_source *s, int own);
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#if defined _GNU_SOURCE || (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 199309L)
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int sd_event_source_send_child_signal(sd_event_source *s, int sig, const siginfo_t *si, unsigned flags);
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#else
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int sd_event_source_send_child_signal(sd_event_source *s, int sig, const void *si, unsigned flags);
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#endif
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int sd_event_source_get_inotify_mask(sd_event_source *s, uint32_t *ret);
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int sd_event_source_set_destroy_callback(sd_event_source *s, sd_event_destroy_t callback);
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int sd_event_source_get_destroy_callback(sd_event_source *s, sd_event_destroy_t *ret);
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int sd_event_source_get_floating(sd_event_source *s);
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int sd_event_source_set_floating(sd_event_source *s, int b);
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int sd_event_source_get_exit_on_failure(sd_event_source *s);
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int sd_event_source_set_exit_on_failure(sd_event_source *s, int b);
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int sd_event_source_set_ratelimit(sd_event_source *s, uint64_t interval_usec, unsigned burst);
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int sd_event_source_get_ratelimit(sd_event_source *s, uint64_t *ret_interval_usec, unsigned *ret_burst);
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int sd_event_source_is_ratelimited(sd_event_source *s);
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/* Define helpers so that __attribute__((cleanup(sd_event_unrefp))) and similar may be used. */
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_SD_DEFINE_POINTER_CLEANUP_FUNC(sd_event, sd_event_unref);
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_SD_DEFINE_POINTER_CLEANUP_FUNC(sd_event_source, sd_event_source_unref);
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_SD_DEFINE_POINTER_CLEANUP_FUNC(sd_event_source, sd_event_source_disable_unref);
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_SD_END_DECLARATIONS;
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#endif
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