общая реализация цикла событий (A generic event loop implementation)
Имя (Name)
sd-event - A generic event loop implementation
Синопсис (Synopsis)
#include <systemd/sd-event.h>
pkg-config --cflags --libs libsystemd
Описание (Description)
sd-event.h provides a generic event loop implementation, based on
Linux epoll(7).
See sd_event_new(3), sd_event_run(3), sd_event_add_io(3),
sd_event_add_time(3), sd_event_add_signal(3),
sd_event_add_child(3), sd_event_add_inotify(3),
sd_event_add_defer(3), sd_event_source_unref(3),
sd_event_source_set_priority(3), sd_event_source_set_enabled(3),
sd_event_source_set_userdata(3), sd_event_source_get_event(3),
sd_event_source_get_pending(3),
sd_event_source_set_description(3),
sd_event_source_set_prepare(3), sd_event_source_set_ratelimit(3),
sd_event_wait(3), sd_event_get_fd(3), sd_event_set_watchdog(3),
sd_event_exit(3), sd_event_now(3) for more information about the
functions available.
The event loop design is targeted on running a separate instance
of the event loop in each thread; it has no concept of
distributing events from a single event loop instance onto
multiple worker threads. Dispatching events is strictly ordered
and subject to configurable priorities. In each event loop
iteration a single event source is dispatched. Each time an event
source is dispatched the kernel is polled for new events, before
the next event source is dispatched. The event loop is designed
to honor priorities and provide fairness within each priority. It
is not designed to provide optimal throughput, as this
contradicts these goals due the limitations of the underlying
epoll(7) primitives.
The event loop implementation provides the following features:
1. I/O event sources, based on epoll(7)'s file descriptor
watching, including edge triggered events (EPOLLET). See
sd_event_add_io(3).
2. Timer event sources, based on timerfd_create(2), supporting
the CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_BOOTIME clocks, as
well as the CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM
clocks that can resume the system from suspend. When creating
timer events a required accuracy parameter may be specified
which allows coalescing of timer events to minimize power
consumption. See sd_event_add_time(3).
3. UNIX process signal events, based on signalfd(2), including
full support for real-time signals, and queued parameters.
See sd_event_add_signal(3).
4. Child process state change events, based on waitid(2). See
sd_event_add_child(3).
5. Static event sources, of three types: defer, post and exit,
for invoking calls in each event loop, after other event
sources or at event loop termination. See
sd_event_add_defer(3).
6. Event sources may be assigned a 64bit priority value, that
controls the order in which event sources are dispatched if
multiple are pending simultaneously. See
sd_event_source_set_priority(3).
7. The event loop may automatically send watchdog notification
messages to the service manager. See
sd_event_set_watchdog(3).
8. The event loop may be integrated into foreign event loops,
such as the GLib one. See sd_event_get_fd(3) for an example.
Примечание (Note)
These APIs are implemented as a shared library, which can be
compiled and linked to with the libsystemd pkg-config(1) file.
Смотри также (See also)
systemd(1), sd_event_new(3), sd_event_run(3), sd_event_add_io(3),
sd_event_add_time(3), sd_event_add_signal(3),
sd_event_add_child(3), sd_event_add_inotify(3),
sd_event_add_defer(3), sd_event_source_unref(3),
sd_event_source_set_priority(3), sd_event_source_set_enabled(3),
sd_event_source_set_userdata(3), sd_event_source_get_event(3),
sd_event_source_get_pending(3),
sd_event_source_set_description(3),
sd_event_source_set_prepare(3), sd_event_source_set_ratelimit(3),
sd_event_wait(3), sd_event_get_fd(3), sd_event_set_watchdog(3),
sd_event_exit(3), sd_event_now(3), epoll(7), timerfd_create(2),
signalfd(2), waitid(2)
