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File _service:tar_scm_kernel_repo:backport-sd-event-introduce-callback-invoked-when-event-sourc.patch of Package systemd
From fd69f2247520b0be3190ded96d646a415edc97b7 Mon Sep 17 00:00:00 2001 From: Michal Sekletar <msekleta@redhat.com> Date: Mon, 4 Oct 2021 19:44:06 +0200 Subject: [PATCH] sd-event: introduce callback invoked when event source ratelimit expires Conflict:code context adaptation Reference:https://github.com/systemd/systemd-stable/commit/fd69f2247520b0be3190ded96d646a415edc97b7 --- man/sd_event_source_set_ratelimit.xml | 22 +++++++--- src/libsystemd/libsystemd.sym | 1 + src/libsystemd/sd-event/event-source.h | 1 + src/libsystemd/sd-event/sd-event.c | 61 ++++++++++++++++++++++---- src/libsystemd/sd-event/test-event.c | 12 +++++ src/systemd/sd-event.h | 1 + 6 files changed, 85 insertions(+), 13 deletions(-) diff --git a/man/sd_event_source_set_ratelimit.xml b/man/sd_event_source_set_ratelimit.xml index ac8529074a..37354a09f6 100644 --- a/man/sd_event_source_set_ratelimit.xml +++ b/man/sd_event_source_set_ratelimit.xml @@ -19,6 +19,7 @@ <refname>sd_event_source_set_ratelimit</refname> <refname>sd_event_source_get_ratelimit</refname> <refname>sd_event_source_is_ratelimited</refname> + <refname>sd_event_source_set_ratelimit_expire_callback</refname> <refpurpose>Configure rate limiting on event sources</refpurpose> </refnamediv> @@ -46,6 +47,12 @@ <paramdef>sd_event_source *<parameter>source</parameter></paramdef> </funcprototype> + <funcprototype> + <funcdef>int <function>sd_event_source_set_ratelimit_expire_callback</function></funcdef> + <paramdef>sd_event_source *<parameter>source</parameter></paramdef> + <paramdef>sd_event_handler_t<parameter>callback</parameter></paramdef> + </funcprototype> + </funcsynopsis> </refsynopsisdiv> @@ -78,6 +85,10 @@ is currently affected by rate limiting, i.e. it has recently hit the rate limit and is currently temporarily disabled due to that.</para> + <para><function>sd_event_source_set_ratelimit_expire_callback</function> 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 occured.</para> + <para>Rate limiting is currently implemented for I/O, timer, signal, defer and inotify event sources.</para> </refsect1> @@ -85,11 +96,12 @@ <refsect1> <title>Return Value</title> - <para>On success, <function>sd_event_source_set_ratelimit()</function> and - <function>sd_event_source_get_ratelimit()</function> return a non-negative integer. On failure, they - return a negative errno-style error code. <function>sd_event_source_is_ratelimited</function> 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.</para> + <para>On success, <function>sd_event_source_set_ratelimit()</function>, + <function>sd_event_source_set_ratelimit_expire_callback</function> and + <function>sd_event_source_get_ratelimit()</function> return a non-negative integer. On failure, they return + a negative errno-style error code. <function>sd_event_source_is_ratelimited</function> 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.</para> <refsect2> <title>Errors</title> diff --git a/src/libsystemd/libsystemd.sym b/src/libsystemd/libsystemd.sym index 5e2fc9e231..2178668d11 100644 --- a/src/libsystemd/libsystemd.sym +++ b/src/libsystemd/libsystemd.sym @@ -767,4 +767,5 @@ LIBSYSTEMD_249 { sd_device_get_trigger_uuid; sd_device_new_from_ifname; sd_device_new_from_ifindex; + sd_event_source_set_ratelimit_expire_callback; } LIBSYSTEMD_248; diff --git a/src/libsystemd/sd-event/event-source.h b/src/libsystemd/sd-event/event-source.h index 41845c0bb5..74cbc26962 100644 --- a/src/libsystemd/sd-event/event-source.h +++ b/src/libsystemd/sd-event/event-source.h @@ -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); diff --git a/src/libsystemd/sd-event/sd-event.c b/src/libsystemd/sd-event/sd-event.c index 0ca0248510..d8f84d9ba7 100644 --- a/src/libsystemd/sd-event/sd-event.c +++ b/src/libsystemd/sd-event/sd-event.c @@ -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) { @@ -4097,15 +4124,15 @@ _public_ int sd_event_wait(sd_event *e, uint64_t timeout) { if (r < 0) goto finish; - r = process_timer(e, e->timestamp.realtime, &e->realtime); + r = process_inotify(e); if (r < 0) goto finish; - r = process_timer(e, e->timestamp.boottime, &e->boottime); + r = process_timer(e, e->timestamp.realtime, &e->realtime); if (r < 0) goto finish; - r = process_timer(e, e->timestamp.monotonic, &e->monotonic); + r = process_timer(e, e->timestamp.boottime, &e->boottime); 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); diff --git a/src/libsystemd/sd-event/test-event.c b/src/libsystemd/sd-event/test-event.c index b637639f26..0ac23c1118 100644 --- a/src/libsystemd/sd-event/test-event.c +++ b/src/libsystemd/sd-event/test-event.c @@ -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) { diff --git a/src/systemd/sd-event.h b/src/systemd/sd-event.h index f4357aa593..63984eef15 100644 --- a/src/systemd/sd-event.h +++ b/src/systemd/sd-event.h @@ -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); -- 2.33.0
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