настроить ограничение скорости для источников событий (Configure rate limiting on event sources)
Имя (Name)
sd_event_source_set_ratelimit, sd_event_source_get_ratelimit,
sd_event_source_is_ratelimited - Configure rate limiting on event
sources
Синопсис (Synopsis)
#include <systemd/sd-event.h>
int sd_event_source_set_ratelimit(sd_event_source *source,
uint64_t interval_usec,
unsigned burst);
int sd_event_source_get_ratelimit(sd_event_source *source,
uint64_t* ret_interval_usec,
unsigned* ret_burst);
int sd_event_source_is_ratelimited(sd_event_source *source);
Описание (Description)
sd_event_source_set_ratelimit() may be used to enforce rate
limiting on an event source. When used an event source will be
temporarily turned off when it fires more often then a specified
burst number within a specified time interval. This is useful as
simple mechanism to avoid event source starvation if high
priority event sources fire very frequently.
Pass the event source to operate on as first argument, a time
interval in microseconds as second argument and a maximum
dispatch limit ("burst") as third parameter. Whenever the event
source is dispatched more often than the specified burst within
the specified interval it is placed in a mode similar to being
disabled with sd_event_source_set_enabled(3) and the SD_EVENT_OFF
parameter. However it is disabled only temporarily – once the
specified interval is over regular operation resumes. It is again
disabled temporarily once the specified rate limiting is hit the
next time. If either the interval or the burst value are
specified as zero, rate limiting is turned off. By default event
sources do not have rate limiting enabled. Note that rate
limiting and disabling via sd_event_source_set_enabled() are
independent of each other, and an event source will only effect
event loop wake-ups and is dispatched while it both is enabled
and rate limiting is not in effect.
sd_event_source_get_ratelimit() may be used to query the current
rate limiting parameters set on the event source object source.
The previously set interval and burst vales are returned in the
second and third argument.
sd_event_source_is_ratelimited() may be used to query whether the
event source is currently affected by rate limiting, i.e. it has
recently hit the rate limit and is currently temporarily disabled
due to that.
Rate limiting is currently implemented for I/O, timer, signal,
defer and inotify event sources.
Возвращаемое значение (Return value)
On success, sd_event_source_set_ratelimit() and
sd_event_source_get_ratelimit() return a non-negative integer. On
failure, they return a negative errno-style error code.
sd_event_source_is_ratelimited returns zero if rate limiting is
currently not in effect and greater than zero if it is in effect;
it returns a negative errno-style error code on failure.
Errors
Returned errors may indicate the following problems:
-EINVAL
source is not a valid pointer to an sd_event_source object.
-ECHILD
The event loop has been created in a different process.
-EDOM
It was attempted to use the rate limiting feature on an event
source type that does not support rate limiting.
-ENOEXEC
sd_event_source_get_ratelimit() was called on an event source
that doesn't have rate limiting configured.
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)
sd-event(3), sd_event_add_io(3), sd_event_add_time(3),
sd_event_add_signal(3), sd_event_add_inotify(3),
sd_event_add_defer(3), sd_event_source_set_enabled(3)
