sd-event: expose the event loop iteration counter via sd_event_get_iteration() (#3631)

This extends the existing event loop iteration counter to 64bit, and exposes it
via a new function sd_event_get_iteration(). This is helpful for cases like
issue #3612. After all, since we maintain the counter anyway, we might as well
expose it.

(This also fixes an unrelated issue in the man page for sd_event_wait() where
micro and milliseconds got mixed up)

3 files changed, 17 insertions, 3 deletions

diff --git a/src/libsystemd/libsystemd.sym b/src/libsystemd/libsystemd.sym
index 0b3a1708dc..542254295c 100644
--- a/src/libsystemd/libsystemd.sym
+++ b/src/libsystemd/libsystemd.sym
@@ -495,3 +495,8 @@ global:
         sd_journal_open_directory_fd;
         sd_journal_open_files_fd;
 } LIBSYSTEMD_229;
+
+LIBSYSTEMD_231 {
+global:
+        sd_event_get_iteration;
+} LIBSYSTEMD_230;
diff --git a/src/libsystemd/sd-event/sd-event.c b/src/libsystemd/sd-event/sd-event.c
index f364b54b50..9857f8b1fc 100644
--- a/src/libsystemd/sd-event/sd-event.c
+++ b/src/libsystemd/sd-event/sd-event.c
@@ -109,8 +109,8 @@ struct sd_event_source {
         int64_t priority;
         unsigned pending_index;
         unsigned prepare_index;
-        unsigned pending_iteration;
-        unsigned prepare_iteration;
+        uint64_t pending_iteration;
+        uint64_t prepare_iteration;
 
         LIST_FIELDS(sd_event_source, sources);
 
@@ -215,7 +215,7 @@ struct sd_event {
 
         pid_t original_pid;
 
-        unsigned iteration;
+        uint64_t iteration;
         triple_timestamp timestamp;
         int state;
 
@@ -2874,3 +2874,11 @@ _public_ int sd_event_get_watchdog(sd_event *e) {
 
         return e->watchdog;
 }
+
+_public_ int sd_event_get_iteration(sd_event *e, uint64_t *ret) {
+        assert_return(e, -EINVAL);
+        assert_return(!event_pid_changed(e), -ECHILD);
+
+        *ret = e->iteration;
+        return 0;
+}
diff --git a/src/systemd/sd-event.h b/src/systemd/sd-event.h
index 531ace1c34..cc26b7df55 100644
--- a/src/systemd/sd-event.h
+++ b/src/systemd/sd-event.h
@@ -104,6 +104,7 @@ int sd_event_get_tid(sd_event *e, pid_t *tid);
 int sd_event_get_exit_code(sd_event *e, int *code);
 int sd_event_set_watchdog(sd_event *e, int b);
 int sd_event_get_watchdog(sd_event *e);
+int sd_event_get_iteration(sd_event *e, uint64_t *ret);
 
 sd_event_source* sd_event_source_ref(sd_event_source *s);
 sd_event_source* sd_event_source_unref(sd_event_source *s);