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sd-event: introduce callback invoked when event source ratelimit expires

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This commit is contained in:
Michal Sekletar
2021-11-11 17:02:56 +01:00
parent c65417a011
commit fd69f22475
6 changed files with 86 additions and 14 deletions
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src/libsystemd/libsystemd.sym
+1
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@@ -767,4 +767,5 @@ LIBSYSTEMD_250 {
global:
sd_device_get_diskseq;
sd_event_add_inotify_fd;
sd_event_source_set_ratelimit_expire_callback;
} LIBSYSTEMD_249;
src/libsystemd/sd-event/event-source.h
+1
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@@ -71,6 +71,7 @@ struct sd_event_source {
uint64_t prepare_iteration;
sd_event_destroy_t destroy_callback;
sd_event_handler_t ratelimit_expire_callback;
LIST_FIELDS(sd_event_source, sources);
src/libsystemd/sd-event/sd-event.c
+54 -9
View File
@@ -2908,7 +2908,7 @@ fail:
return r;
}
static int event_source_leave_ratelimit(sd_event_source *s) {
static int event_source_leave_ratelimit(sd_event_source *s, bool run_callback) {
int r;
assert(s);
@@ -2940,6 +2940,30 @@ static int event_source_leave_ratelimit(sd_event_source *s) {
ratelimit_reset(&s->rate_limit);
log_debug("Event source %p (%s) left rate limit state.", s, strna(s->description));
if (run_callback && s->ratelimit_expire_callback) {
s->dispatching = true;
r = s->ratelimit_expire_callback(s, s->userdata);
s->dispatching = false;
if (r < 0) {
log_debug_errno(r, "Ratelimit expiry callback of event source %s (type %s) returned error, %s: %m",
strna(s->description),
event_source_type_to_string(s->type),
s->exit_on_failure ? "exiting" : "disabling");
if (s->exit_on_failure)
(void) sd_event_exit(s->event, r);
}
if (s->n_ref == 0)
source_free(s);
else if (r < 0)
sd_event_source_set_enabled(s, SD_EVENT_OFF);
return 1;
}
return 0;
fail:
@@ -3139,6 +3163,7 @@ static int process_timer(
struct clock_data *d) {
sd_event_source *s;
bool callback_invoked = false;
int r;
assert(e);
@@ -3156,9 +3181,11 @@ static int process_timer(
* again. */
assert(s->ratelimited);
r = event_source_leave_ratelimit(s);
r = event_source_leave_ratelimit(s, /* run_callback */ true);
if (r < 0)
return r;
else if (r == 1)
callback_invoked = true;
continue;
}
@@ -3173,7 +3200,7 @@ static int process_timer(
event_source_time_prioq_reshuffle(s);
}
return 0;
return callback_invoked;
}
static int process_child(sd_event *e, int64_t threshold, int64_t *ret_min_priority) {
@@ -4097,6 +4124,10 @@ _public_ int sd_event_wait(sd_event *e, uint64_t timeout) {
if (r < 0)
goto finish;
r = process_inotify(e);
if (r < 0)
goto finish;
r = process_timer(e, e->timestamp.realtime, &e->realtime);
if (r < 0)
goto finish;
@@ -4105,10 +4136,6 @@ _public_ int sd_event_wait(sd_event *e, uint64_t timeout) {
if (r < 0)
goto finish;
r = process_timer(e, e->timestamp.monotonic, &e->monotonic);
if (r < 0)
goto finish;
r = process_timer(e, e->timestamp.realtime, &e->realtime_alarm);
if (r < 0)
goto finish;
@@ -4117,9 +4144,20 @@ _public_ int sd_event_wait(sd_event *e, uint64_t timeout) {
if (r < 0)
goto finish;
r = process_inotify(e);
r = process_timer(e, e->timestamp.monotonic, &e->monotonic);
if (r < 0)
goto finish;
else if (r == 1) {
/* Ratelimit expiry callback was called. Let's postpone processing pending sources and
* put loop in the initial state in order to evaluate (in the next iteration) also sources
* there were potentially re-enabled by the callback.
*
* Wondering why we treat only this invocation of process_timer() differently? Once event
* source is ratelimited we essentially transform it into CLOCK_MONOTONIC timer hence
* ratelimit expiry callback is never called for any other timer type. */
r = 0;
goto finish;
}
if (event_next_pending(e)) {
e->state = SD_EVENT_PENDING;
@@ -4488,7 +4526,7 @@ _public_ int sd_event_source_set_ratelimit(sd_event_source *s, uint64_t interval
/* When ratelimiting is configured we'll always reset the rate limit state first and start fresh,
* non-ratelimited. */
r = event_source_leave_ratelimit(s);
r = event_source_leave_ratelimit(s, /* run_callback */ false);
if (r < 0)
return r;
@@ -4496,6 +4534,13 @@ _public_ int sd_event_source_set_ratelimit(sd_event_source *s, uint64_t interval
return 0;
}
_public_ int sd_event_source_set_ratelimit_expire_callback(sd_event_source *s, sd_event_handler_t callback) {
assert_return(s, -EINVAL);
s->ratelimit_expire_callback = callback;
return 0;
}
_public_ int sd_event_source_get_ratelimit(sd_event_source *s, uint64_t *ret_interval, unsigned *ret_burst) {
assert_return(s, -EINVAL);
src/libsystemd/sd-event/test-event.c
+12
View File
@@ -623,6 +623,11 @@ static int ratelimit_time_handler(sd_event_source *s, uint64_t usec, void *userd
return 0;
}
static int expired = -1;
static int ratelimit_expired(sd_event_source *s, void *userdata) {
return ++expired;
}
static void test_ratelimit(void) {
_cleanup_close_pair_ int p[2] = {-1, -1};
_cleanup_(sd_event_unrefp) sd_event *e = NULL;
@@ -686,12 +691,19 @@ static void test_ratelimit(void) {
assert_se(sd_event_source_set_ratelimit(s, 1 * USEC_PER_SEC, 10) >= 0);
/* Set callback that will be invoked when we leave rate limited state. */
assert_se(sd_event_source_set_ratelimit_expire_callback(s, ratelimit_expired) >= 0);
do {
assert_se(sd_event_run(e, UINT64_MAX) >= 0);
} while (!sd_event_source_is_ratelimited(s));
log_info("ratelimit_time_handler: called 10 more times, event source got ratelimited");
assert_se(count == 20);
/* Dispatch the event loop once more and check that ratelimit expiration callback got called */
assert_se(sd_event_run(e, UINT64_MAX) >= 0);
assert_se(expired == 0);
}
static void test_simple_timeout(void) {
src/systemd/sd-event.h
+1
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@@ -166,6 +166,7 @@ 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);
/* Define helpers so that __attribute__((cleanup(sd_event_unrefp))) and similar may be used. */
_SD_DEFINE_POINTER_CLEANUP_FUNC(sd_event, sd_event_unref);