From 55944e5e40b1be2afc4855d8d2baf4b73d1876b5 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 10 Apr 2024 22:49:52 +0200 Subject: Adding upstream version 255.4. Signed-off-by: Daniel Baumann --- man/sd_event_source_set_ratelimit.xml | 188 ++++++++++++++++++++++++++++++++++ 1 file changed, 188 insertions(+) create mode 100644 man/sd_event_source_set_ratelimit.xml (limited to 'man/sd_event_source_set_ratelimit.xml') diff --git a/man/sd_event_source_set_ratelimit.xml b/man/sd_event_source_set_ratelimit.xml new file mode 100644 index 0000000..cf45102 --- /dev/null +++ b/man/sd_event_source_set_ratelimit.xml @@ -0,0 +1,188 @@ + + + + + + + + sd_event_source_set_ratelimit + systemd + + + + sd_event_source_set_ratelimit + 3 + + + + sd_event_source_set_ratelimit + sd_event_source_get_ratelimit + sd_event_source_is_ratelimited + sd_event_source_set_ratelimit_expire_callback + sd_event_source_leave_ratelimit + + Configure rate limiting on event sources + + + + + #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 + + + + int sd_event_source_set_ratelimit_expire_callback + sd_event_source *source + sd_event_handler_tcallback + + + + int sd_event_source_leave_ratelimit + sd_event_source *source + + + + + + 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_enabled3 + 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. + + sd_event_source_set_ratelimit_expire_callback() may be used to set a callback + function that is invoked every time the event source leaves rate limited state. Note that function is + called in the same event loop iteration in which state transition occurred. + + sd_event_source_leave_ratelimit() may be used to immediately reenable an event + source that was temporarily disabled due to rate limiting. This will reset the ratelimit counters for the + current time interval. + + Rate limiting is currently implemented for I/O, timer, signal, defer and inotify event + sources. + + + + Return Value + + On success, sd_event_source_set_ratelimit(), + sd_event_source_set_ratelimit_expire_callback 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. sd_event_source_leave_ratelimit() + returns zero if rate limiting wasn't in effect on the specified event source, and positive if it was and + rate limiting is now turned off again; 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, library or module instance. + + + + + + -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. + + + + + + + + + + + + History + sd_event_source_set_ratelimit(), + sd_event_source_get_ratelimit(), and + sd_event_source_is_ratelimited() were added in version 248. + sd_event_source_set_ratelimit_expire_callback() was added in version 250. + sd_event_source_leave_ratelimit() was added in version 254. + + + + See Also + + + sd-event3, + sd_event_add_io3, + sd_event_add_time3, + sd_event_add_signal3, + sd_event_add_inotify3, + sd_event_add_defer3, + sd_event_source_set_enabled3 + + + + -- cgit v1.2.3