sd-event: add high-level sd_event_add_memory_pressure() event source

[thirdparty/systemd.git] / src / systemd / sd-event.h

/* SPDX-License-Identifier: LGPL-2.1-or-later */
#ifndef foosdeventhfoo
#define foosdeventhfoo

/***
  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 <https://www.gnu.org/licenses/>.
***/

#include <inttypes.h>
#include <signal.h>
#include <sys/epoll.h>
#include <sys/inotify.h>
#include <sys/signalfd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>

#include "_sd-common.h"

/*
  Why is this better than pure epoll?

  - Supports event source prioritization
  - Scales better with a large number of time events because it does not require one timerfd each
  - Automatically tries to coalesce timer events system-wide
  - Handles signals, child PIDs, inotify events
  - Supports systemd-style automatic watchdog event generation
*/

_SD_BEGIN_DECLARATIONS;

#define SD_EVENT_DEFAULT ((sd_event *) 1)

typedef struct sd_event sd_event;
typedef struct sd_event_source sd_event_source;

enum {
        SD_EVENT_OFF = 0,
        SD_EVENT_ON = 1,
        SD_EVENT_ONESHOT = -1
};

enum {
        SD_EVENT_INITIAL,
        SD_EVENT_ARMED,
        SD_EVENT_PENDING,
        SD_EVENT_RUNNING,
        SD_EVENT_EXITING,
        SD_EVENT_FINISHED,
        SD_EVENT_PREPARING
};

enum {
        /* And everything in-between and outside is good too */
        SD_EVENT_PRIORITY_IMPORTANT = -100,
        SD_EVENT_PRIORITY_NORMAL = 0,
        SD_EVENT_PRIORITY_IDLE = 100
};

#define SD_EVENT_SIGNAL_PROCMASK (1 << 30)

typedef int (*sd_event_handler_t)(sd_event_source *s, void *userdata);
typedef int (*sd_event_io_handler_t)(sd_event_source *s, int fd, uint32_t revents, void *userdata);
typedef int (*sd_event_time_handler_t)(sd_event_source *s, uint64_t usec, void *userdata);
typedef int (*sd_event_signal_handler_t)(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata);
#if defined _GNU_SOURCE || (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 199309L)
typedef int (*sd_event_child_handler_t)(sd_event_source *s, const siginfo_t *si, void *userdata);
#else
typedef void* sd_event_child_handler_t;
#endif
typedef int (*sd_event_inotify_handler_t)(sd_event_source *s, const struct inotify_event *event, void *userdata);
typedef _sd_destroy_t sd_event_destroy_t;

int sd_event_default(sd_event **e);

int sd_event_new(sd_event **e);
sd_event* sd_event_ref(sd_event *e);
sd_event* sd_event_unref(sd_event *e);

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);
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);
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);
int sd_event_add_signal(sd_event *e, sd_event_source **s, int sig, sd_event_signal_handler_t callback, void *userdata);
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);
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);
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);
int sd_event_add_inotify_fd(sd_event *e, sd_event_source **s, int fd, uint32_t mask, sd_event_inotify_handler_t callback, void *userdata);
int sd_event_add_defer(sd_event *e, sd_event_source **s, sd_event_handler_t callback, void *userdata);
int sd_event_add_post(sd_event *e, sd_event_source **s, sd_event_handler_t callback, void *userdata);
int sd_event_add_exit(sd_event *e, sd_event_source **s, sd_event_handler_t callback, void *userdata);
int sd_event_add_memory_pressure(sd_event *e, sd_event_source **s, sd_event_handler_t callback, void *userdata);

int sd_event_prepare(sd_event *e);
int sd_event_wait(sd_event *e, uint64_t usec);
int sd_event_dispatch(sd_event *e);
int sd_event_run(sd_event *e, uint64_t usec);
int sd_event_loop(sd_event *e);
int sd_event_exit(sd_event *e, int code);

int sd_event_now(sd_event *e, clockid_t clock, uint64_t *usec);

int sd_event_get_fd(sd_event *e);
int sd_event_get_state(sd_event *e);
int sd_event_get_tid(sd_event *e, pid_t *tid);
int sd_event_get_exit_code(sd_event *e, int *code);
int sd_event_set_watchdog(sd_event *e, int b);
int sd_event_get_watchdog(sd_event *e);
int sd_event_get_iteration(sd_event *e, uint64_t *ret);
int sd_event_set_signal_exit(sd_event *e, int b);

sd_event_source* sd_event_source_ref(sd_event_source *s);
sd_event_source* sd_event_source_unref(sd_event_source *s);
sd_event_source* sd_event_source_disable_unref(sd_event_source *s);

sd_event *sd_event_source_get_event(sd_event_source *s);
void* sd_event_source_get_userdata(sd_event_source *s);
void* sd_event_source_set_userdata(sd_event_source *s, void *userdata);

int sd_event_source_set_description(sd_event_source *s, const char *description);
int sd_event_source_get_description(sd_event_source *s, const char **description);
int sd_event_source_set_prepare(sd_event_source *s, sd_event_handler_t callback);
int sd_event_source_get_pending(sd_event_source *s);
int sd_event_source_get_priority(sd_event_source *s, int64_t *priority);
int sd_event_source_set_priority(sd_event_source *s, int64_t priority);
int sd_event_source_get_enabled(sd_event_source *s, int *enabled);
int sd_event_source_set_enabled(sd_event_source *s, int enabled);
int sd_event_source_get_io_fd(sd_event_source *s);
int sd_event_source_set_io_fd(sd_event_source *s, int fd);
int sd_event_source_get_io_fd_own(sd_event_source *s);
int sd_event_source_set_io_fd_own(sd_event_source *s, int own);
int sd_event_source_get_io_events(sd_event_source *s, uint32_t* events);
int sd_event_source_set_io_events(sd_event_source *s, uint32_t events);
int sd_event_source_get_io_revents(sd_event_source *s, uint32_t* revents);
int sd_event_source_get_time(sd_event_source *s, uint64_t *usec);
int sd_event_source_set_time(sd_event_source *s, uint64_t usec);
int sd_event_source_set_time_relative(sd_event_source *s, uint64_t usec);
int sd_event_source_get_time_accuracy(sd_event_source *s, uint64_t *usec);
int sd_event_source_set_time_accuracy(sd_event_source *s, uint64_t usec);
int sd_event_source_get_time_clock(sd_event_source *s, clockid_t *clock);
int sd_event_source_get_signal(sd_event_source *s);
int sd_event_source_get_child_pid(sd_event_source *s, pid_t *pid);
int sd_event_source_get_child_pidfd(sd_event_source *s);
int sd_event_source_get_child_pidfd_own(sd_event_source *s);
int sd_event_source_set_child_pidfd_own(sd_event_source *s, int own);
int sd_event_source_get_child_process_own(sd_event_source *s);
int sd_event_source_set_child_process_own(sd_event_source *s, int own);
#if defined _GNU_SOURCE || (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 199309L)
int sd_event_source_send_child_signal(sd_event_source *s, int sig, const siginfo_t *si, unsigned flags);
#else
int sd_event_source_send_child_signal(sd_event_source *s, int sig, const void *si, unsigned flags);
#endif
int sd_event_source_get_inotify_mask(sd_event_source *s, uint32_t *ret);
int sd_event_source_set_memory_pressure_type(sd_event_source *e, const char *ty);
int sd_event_source_set_memory_pressure_period(sd_event_source *s, uint64_t threshold_usec, uint64_t window_usec);
int sd_event_source_set_destroy_callback(sd_event_source *s, sd_event_destroy_t callback);
int sd_event_source_get_destroy_callback(sd_event_source *s, sd_event_destroy_t *ret);
int sd_event_source_get_floating(sd_event_source *s);
int sd_event_source_set_floating(sd_event_source *s, int b);
int sd_event_source_get_exit_on_failure(sd_event_source *s);
int sd_event_source_set_exit_on_failure(sd_event_source *s, int b);
int sd_event_source_set_ratelimit(sd_event_source *s, uint64_t interval_usec, unsigned burst);
int sd_event_source_get_ratelimit(sd_event_source *s, uint64_t *ret_interval_usec, unsigned *ret_burst);
int sd_event_source_is_ratelimited(sd_event_source *s);
int sd_event_source_set_ratelimit_expire_callback(sd_event_source *s, sd_event_handler_t callback);

int sd_event_trim_memory(void);

/* Define helpers so that __attribute__((cleanup(sd_event_unrefp))) and similar may be used. */
_SD_DEFINE_POINTER_CLEANUP_FUNC(sd_event, sd_event_unref);
_SD_DEFINE_POINTER_CLEANUP_FUNC(sd_event_source, sd_event_source_unref);
_SD_DEFINE_POINTER_CLEANUP_FUNC(sd_event_source, sd_event_source_disable_unref);

_SD_END_DECLARATIONS;

#endif