227 lines
8.4 KiB
Diff
227 lines
8.4 KiB
Diff
From 51210a849ea7f163a1760de989756206c01dd758 Mon Sep 17 00:00:00 2001
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From: Michal Sekletar <msekleta@redhat.com>
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Date: Mon, 4 Oct 2021 19:44:06 +0200
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Subject: [PATCH] sd-event: introduce callback invoked when event source
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ratelimit expires
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(cherry picked from commit fd69f2247520b0be3190ded96d646a415edc97b7)
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Related: #2036608
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---
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src/libsystemd/libsystemd.sym | 5 +++
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src/libsystemd/sd-event/sd-event.c | 61 +++++++++++++++++++++++-----
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src/libsystemd/sd-event/test-event.c | 12 ++++++
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src/systemd/sd-event.h | 1 +
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4 files changed, 68 insertions(+), 11 deletions(-)
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diff --git a/src/libsystemd/libsystemd.sym b/src/libsystemd/libsystemd.sym
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index 149d2e7b82..f4a1426248 100644
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--- a/src/libsystemd/libsystemd.sym
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+++ b/src/libsystemd/libsystemd.sym
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@@ -579,3 +579,8 @@ global:
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sd_event_source_get_ratelimit;
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sd_event_source_is_ratelimited;
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} LIBSYSTEMD_239;
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+
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+LIBSYSTEMD_250 {
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+global:
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+ sd_event_source_set_ratelimit_expire_callback;
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+} LIBSYSTEMD_248;
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diff --git a/src/libsystemd/sd-event/sd-event.c b/src/libsystemd/sd-event/sd-event.c
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index 47cf93b3f4..0adfdd9e1a 100644
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--- a/src/libsystemd/sd-event/sd-event.c
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+++ b/src/libsystemd/sd-event/sd-event.c
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@@ -125,6 +125,7 @@ struct sd_event_source {
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uint64_t prepare_iteration;
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sd_event_destroy_t destroy_callback;
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+ sd_event_handler_t ratelimit_expire_callback;
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LIST_FIELDS(sd_event_source, sources);
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@@ -2734,7 +2735,7 @@ fail:
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return r;
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}
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-static int event_source_leave_ratelimit(sd_event_source *s) {
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+static int event_source_leave_ratelimit(sd_event_source *s, bool run_callback) {
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int r;
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assert(s);
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@@ -2766,6 +2767,23 @@ static int event_source_leave_ratelimit(sd_event_source *s) {
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ratelimit_reset(&s->rate_limit);
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log_debug("Event source %p (%s) left rate limit state.", s, strna(s->description));
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+
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+ if (run_callback && s->ratelimit_expire_callback) {
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+ s->dispatching = true;
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+ r = s->ratelimit_expire_callback(s, s->userdata);
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+ s->dispatching = false;
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+
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+ if (r < 0) {
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+ log_debug_errno(r, "Ratelimit expiry callback of event source %s (type %s) returned error, disabling: %m",
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+ strna(s->description),
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+ event_source_type_to_string(s->type));
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+
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+ sd_event_source_set_enabled(s, SD_EVENT_OFF);
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+ }
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+
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+ return 1;
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+ }
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+
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return 0;
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fail:
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@@ -2966,6 +2984,7 @@ static int process_timer(
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struct clock_data *d) {
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sd_event_source *s;
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+ bool callback_invoked = false;
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int r;
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assert(e);
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@@ -2981,9 +3000,11 @@ static int process_timer(
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* again. */
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assert(s->ratelimited);
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- r = event_source_leave_ratelimit(s);
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+ r = event_source_leave_ratelimit(s, /* run_callback */ true);
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if (r < 0)
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return r;
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+ else if (r == 1)
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+ callback_invoked = true;
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continue;
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}
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@@ -2998,7 +3019,7 @@ static int process_timer(
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event_source_time_prioq_reshuffle(s);
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}
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- return 0;
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+ return callback_invoked;
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}
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static int process_child(sd_event *e) {
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@@ -3698,15 +3719,15 @@ _public_ int sd_event_wait(sd_event *e, uint64_t timeout) {
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if (r < 0)
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goto finish;
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- r = process_timer(e, e->timestamp.realtime, &e->realtime);
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+ r = process_inotify(e);
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if (r < 0)
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goto finish;
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- r = process_timer(e, e->timestamp.boottime, &e->boottime);
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+ r = process_timer(e, e->timestamp.realtime, &e->realtime);
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if (r < 0)
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goto finish;
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- r = process_timer(e, e->timestamp.monotonic, &e->monotonic);
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+ r = process_timer(e, e->timestamp.boottime, &e->boottime);
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if (r < 0)
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goto finish;
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@@ -3718,16 +3739,27 @@ _public_ int sd_event_wait(sd_event *e, uint64_t timeout) {
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if (r < 0)
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goto finish;
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+ r = process_timer(e, e->timestamp.monotonic, &e->monotonic);
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+ if (r < 0)
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+ goto finish;
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+ else if (r == 1) {
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+ /* Ratelimit expiry callback was called. Let's postpone processing pending sources and
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+ * put loop in the initial state in order to evaluate (in the next iteration) also sources
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+ * there were potentially re-enabled by the callback.
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+ *
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+ * Wondering why we treat only this invocation of process_timer() differently? Once event
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+ * source is ratelimited we essentially transform it into CLOCK_MONOTONIC timer hence
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+ * ratelimit expiry callback is never called for any other timer type. */
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+ r = 0;
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+ goto finish;
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+ }
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+
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if (e->need_process_child) {
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r = process_child(e);
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if (r < 0)
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goto finish;
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}
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- r = process_inotify(e);
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- if (r < 0)
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- goto finish;
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-
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if (event_next_pending(e)) {
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e->state = SD_EVENT_PENDING;
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@@ -4054,7 +4086,7 @@ _public_ int sd_event_source_set_ratelimit(sd_event_source *s, uint64_t interval
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/* When ratelimiting is configured we'll always reset the rate limit state first and start fresh,
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* non-ratelimited. */
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- r = event_source_leave_ratelimit(s);
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+ r = event_source_leave_ratelimit(s, /* run_callback */ false);
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if (r < 0)
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return r;
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@@ -4062,6 +4094,13 @@ _public_ int sd_event_source_set_ratelimit(sd_event_source *s, uint64_t interval
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return 0;
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}
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+_public_ int sd_event_source_set_ratelimit_expire_callback(sd_event_source *s, sd_event_handler_t callback) {
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+ assert_return(s, -EINVAL);
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+
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+ s->ratelimit_expire_callback = callback;
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+ return 0;
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+}
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+
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_public_ int sd_event_source_get_ratelimit(sd_event_source *s, uint64_t *ret_interval, unsigned *ret_burst) {
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assert_return(s, -EINVAL);
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diff --git a/src/libsystemd/sd-event/test-event.c b/src/libsystemd/sd-event/test-event.c
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index e3ee4cd5c3..9135b22839 100644
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--- a/src/libsystemd/sd-event/test-event.c
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+++ b/src/libsystemd/sd-event/test-event.c
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@@ -506,6 +506,11 @@ static int ratelimit_time_handler(sd_event_source *s, uint64_t usec, void *userd
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return 0;
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}
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+static int expired = -1;
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+static int ratelimit_expired(sd_event_source *s, void *userdata) {
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+ return ++expired;
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+}
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+
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static void test_ratelimit(void) {
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_cleanup_close_pair_ int p[2] = {-1, -1};
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_cleanup_(sd_event_unrefp) sd_event *e = NULL;
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@@ -568,12 +573,19 @@ static void test_ratelimit(void) {
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assert_se(sd_event_source_set_ratelimit(s, 1 * USEC_PER_SEC, 10) >= 0);
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+ /* Set callback that will be invoked when we leave rate limited state. */
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+ assert_se(sd_event_source_set_ratelimit_expire_callback(s, ratelimit_expired) >= 0);
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+
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do {
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assert_se(sd_event_run(e, UINT64_MAX) >= 0);
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} while (!sd_event_source_is_ratelimited(s));
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log_info("ratelimit_time_handler: called 10 more times, event source got ratelimited");
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assert_se(count == 20);
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+
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+ /* Dispatch the event loop once more and check that ratelimit expiration callback got called */
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+ assert_se(sd_event_run(e, UINT64_MAX) >= 0);
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+ assert_se(expired == 0);
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}
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int main(int argc, char *argv[]) {
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diff --git a/src/systemd/sd-event.h b/src/systemd/sd-event.h
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index a17a9b3488..c2e9c9614d 100644
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--- a/src/systemd/sd-event.h
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+++ b/src/systemd/sd-event.h
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@@ -147,6 +147,7 @@ int sd_event_source_get_destroy_callback(sd_event_source *s, sd_event_destroy_t
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int sd_event_source_set_ratelimit(sd_event_source *s, uint64_t interval_usec, unsigned burst);
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int sd_event_source_get_ratelimit(sd_event_source *s, uint64_t *ret_interval_usec, unsigned *ret_burst);
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int sd_event_source_is_ratelimited(sd_event_source *s);
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+int sd_event_source_set_ratelimit_expire_callback(sd_event_source *s, sd_event_handler_t callback);
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/* Define helpers so that __attribute__((cleanup(sd_event_unrefp))) and similar may be used. */
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_SD_DEFINE_POINTER_CLEANUP_FUNC(sd_event, sd_event_unref);
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