core: don't log job status message in case job was effectively NOP (#3199)

We currently generate log message about unit being started even when
unit was started already and job didn't do anything. This is because job
was requested explicitly and hence became anchor job of the transaction
thus we could not eliminate it. That is fine but, let's not pollute
journal with useless log messages.

$ systemctl start systemd-resolved
$ systemctl start systemd-resolved
$ systemctl start systemd-resolved

Current state:
$ journalctl -u systemd-resolved | grep Started

May 05 15:31:42 rawhide systemd[1]: Started Network Name Resolution.
May 05 15:31:59 rawhide systemd[1]: Started Network Name Resolution.
May 05 15:32:01 rawhide systemd[1]: Started Network Name Resolution.

After patch applied:
$ journalctl -u systemd-resolved | grep Started

May 05 16:42:12 rawhide systemd[1]: Started Network Name Resolution.

Fixes #1723

1 files changed, 13 insertions, 11 deletions

diff --git a/src/core/job.c b/src/core/job.c
index d9c5669c9f..7557874d4d 100644
--- a/src/core/job.c
+++ b/src/core/job.c
@@ -191,7 +191,7 @@ Job* job_install(Job *j) {
 
         if (uj) {
                 if (job_type_is_conflicting(uj->type, j->type))
-                        job_finish_and_invalidate(uj, JOB_CANCELED, false);
+                        job_finish_and_invalidate(uj, JOB_CANCELED, false, false);
                 else {
                         /* not conflicting, i.e. mergeable */
 
@@ -614,19 +614,19 @@ int job_run_and_invalidate(Job *j) {
 
         if (j) {
                 if (r == -EALREADY)
-                        r = job_finish_and_invalidate(j, JOB_DONE, true);
+                        r = job_finish_and_invalidate(j, JOB_DONE, true, true);
                 else if (r == -EBADR)
-                        r = job_finish_and_invalidate(j, JOB_SKIPPED, true);
+                        r = job_finish_and_invalidate(j, JOB_SKIPPED, true, false);
                 else if (r == -ENOEXEC)
-                        r = job_finish_and_invalidate(j, JOB_INVALID, true);
+                        r = job_finish_and_invalidate(j, JOB_INVALID, true, false);
                 else if (r == -EPROTO)
-                        r = job_finish_and_invalidate(j, JOB_ASSERT, true);
+                        r = job_finish_and_invalidate(j, JOB_ASSERT, true, false);
                 else if (r == -EOPNOTSUPP)
-                        r = job_finish_and_invalidate(j, JOB_UNSUPPORTED, true);
+                        r = job_finish_and_invalidate(j, JOB_UNSUPPORTED, true, false);
                 else if (r == -EAGAIN)
                         job_set_state(j, JOB_WAITING);
                 else if (r < 0)
-                        r = job_finish_and_invalidate(j, JOB_FAILED, true);
+                        r = job_finish_and_invalidate(j, JOB_FAILED, true, false);
         }
 
         return r;
@@ -827,11 +827,11 @@ static void job_fail_dependencies(Unit *u, UnitDependency d) {
                 if (!IN_SET(j->type, JOB_START, JOB_VERIFY_ACTIVE))
                         continue;
 
-                job_finish_and_invalidate(j, JOB_DEPENDENCY, true);
+                job_finish_and_invalidate(j, JOB_DEPENDENCY, true, false);
         }
 }
 
-int job_finish_and_invalidate(Job *j, JobResult result, bool recursive) {
+int job_finish_and_invalidate(Job *j, JobResult result, bool recursive, bool already) {
         Unit *u;
         Unit *other;
         JobType t;
@@ -848,7 +848,9 @@ int job_finish_and_invalidate(Job *j, JobResult result, bool recursive) {
 
         log_unit_debug(u, "Job %s/%s finished, result=%s", u->id, job_type_to_string(t), job_result_to_string(result));
 
-        job_emit_status_message(u, t, result);
+        /* If this job did nothing to respective unit we don't log the status message */
+        if (!already)
+                job_emit_status_message(u, t, result);
 
         job_add_to_dbus_queue(j);
 
@@ -923,7 +925,7 @@ static int job_dispatch_timer(sd_event_source *s, uint64_t monotonic, void *user
         log_unit_warning(j->unit, "Job %s/%s timed out.", j->unit->id, job_type_to_string(j->type));
 
         u = j->unit;
-        job_finish_and_invalidate(j, JOB_TIMEOUT, true);
+        job_finish_and_invalidate(j, JOB_TIMEOUT, true, false);
 
         failure_action(u->manager, u->job_timeout_action, u->job_timeout_reboot_arg);