SD_EVENT_ADD_DEFER(3)         sd_event_add_defer         SD_EVENT_ADD_DEFER(3)

NAME
       sd_event_add_defer, sd_event_add_post, sd_event_add_exit,
       sd_event_handler_t - Add static event sources to an event loop

SYNOPSIS
       #include <systemd/sd-event.h>

       typedef struct sd_event_source sd_event_source;

       typedef int (*sd_event_handler_t)(sd_event_source *s, void *userdata);

       int sd_event_add_defer(sd_event *event, sd_event_source **source,
                              sd_event_handler_t handler, void *userdata);

       int sd_event_add_post(sd_event *event, sd_event_source **source,
                             sd_event_handler_t handler, void *userdata);

       int sd_event_add_exit(sd_event *event, sd_event_source **source,
                             sd_event_handler_t handler, void *userdata);

DESCRIPTION
       These three functions add new static event sources to an event loop.
       The event loop object is specified in the event parameter, the event
       source object is returned in the source parameter. The event sources
       are enabled statically and will "fire" when the event loop is run and
       the conditions described below are met.

       The handler is a function to call or NULL. The handler function will be
       passed the userdata pointer, which may be chosen freely by the caller.
       The handler may return negative to signal an error (see below), other
       return values are ignored. If handler is NULL, a default handler that
       calls sd_event_exit(3) will be used.

       sd_event_add_defer() adds a new event source that will be dispatched
       instantly, before the event loop goes to sleep again and waits for new
       events. By default, the handler will be called once (SD_EVENT_ONESHOT).
       Note that if the event source is set to SD_EVENT_ON the event loop will
       never go to sleep again, but continuously call the handler, possibly
       interleaved with other event sources.

       sd_event_add_post() adds a new event source that is run before the
       event loop will sleep and wait for new events, but only after at least
       one other non-post event source was dispatched. By default, the source
       is enabled permanently (SD_EVENT_ON). Note that this event source type
       will still allow the event loop to go to sleep again, even if set to
       SD_EVENT_ON, as long as no other event source is ever triggered.

       sd_event_add_exit() adds a new event source that will be dispatched
       when the event loop is terminated with sd_event_exit(3).

       The sd_event_source_set_enabled(3) function may be used to enable the
       event source permanently (SD_EVENT_ON) or to make it fire just once
       (SD_EVENT_ONESHOT).

       If the handler function returns a negative error code, it will either
       be disabled after the invocation, even if the SD_EVENT_ON mode was
       requested before, or it will cause the loop to terminate, see
       sd_event_source_set_exit_on_failure(3).

       To destroy an event source object use sd_event_source_unref(3), but
       note that the event source is only removed from the event loop when all
       references to the event source are dropped. To make sure an event
       source does not fire anymore, even when there's still a reference to it
       kept, consider setting the event source to SD_EVENT_OFF with
       sd_event_source_set_enabled(3).

       If the second parameter of these functions is passed as NULL no
       reference to the event source object is returned. In this case the
       event source is considered "floating", and will be destroyed implicitly
       when the event loop itself is destroyed.

       If the handler parameter to sd_event_add_defer() or sd_event_add_post()
       is NULL, and the event source fires, this will be considered a request
       to exit the event loop. In this case, the userdata parameter, cast to
       an integer, is passed as the exit code parameter to sd_event_exit(3).
       Similar functionality is not available for sd_event_add_exit(), as
       these types of event sources are only dispatched when exiting anyway.

RETURN VALUE
       On success, these functions return 0 or a positive integer. On failure,
       they return a negative errno-style error code.

   Errors
       Returned errors may indicate the following problems:

       -ENOMEM
           Not enough memory to allocate an object.

       -EINVAL
           An invalid argument has been passed.

       -ESTALE
           The event loop is already terminated.

       -ECHILD
           The event loop has been created in a different process.

NOTES
       These APIs are implemented as a shared library, which can be compiled
       and linked to with the libsystemd pkg-config(1) file.

SEE ALSO
       systemd(1), sd-event(3), sd_event_new(3), sd_event_now(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_source_set_enabled(3), sd_event_source_set_priority(3),
       sd_event_source_set_userdata(3), sd_event_source_set_description(3),
       sd_event_source_set_floating(3), sd_event_exit(3)

systemd 252                                              SD_EVENT_ADD_DEFER(3)

Czas wygenerowania: 0.00119 sek.

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