unit: rework trigger dependency logic

Instead of having explicit type-specific callbacks that inform the
triggering unit when a triggered unit changes state, make this generic
so that state changes are forwarded betwee any triggered and triggering
unit.

Also, get rid of UnitRef references from automount, timer, path units,
to the units they trigger and rely exclsuively on UNIT_TRIGGER type
dendencies.

14 files changed, 166 insertions, 213 deletions

diff --git a/src/core/automount.c b/src/core/automount.c
index 4a98540d82..e6eedda96f 100644
--- a/src/core/automount.c
+++ b/src/core/automount.c
@@ -109,7 +109,6 @@ static void automount_done(Unit *u) {
         assert(a);
 
         unmount_autofs(a);
-        unit_ref_unset(&a->mount);
 
         free(a->where);
         a->where = NULL;
@@ -200,8 +199,8 @@ static int automount_verify(Automount *a) {
 }
 
 static int automount_load(Unit *u) {
-        int r;
         Automount *a = AUTOMOUNT(u);
+        int r;
 
         assert(u);
         assert(u->load_state == UNIT_STUB);
@@ -222,17 +221,15 @@ static int automount_load(Unit *u) {
 
                 path_kill_slashes(a->where);
 
-                r = automount_add_mount_links(a);
+                r = unit_load_related_unit(u, ".mount", &x);
                 if (r < 0)
                         return r;
 
-                r = unit_load_related_unit(u, ".mount", &x);
+                r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS, x, true);
                 if (r < 0)
                         return r;
 
-                unit_ref_set(&a->mount, x);
-
-                r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS, UNIT_DEREF(a->mount), true);
+                r = automount_add_mount_links(a);
                 if (r < 0)
                         return r;
 
@@ -586,12 +583,11 @@ fail:
 }
 
 static void automount_enter_runnning(Automount *a) {
-        int r;
-        struct stat st;
         _cleanup_dbus_error_free_ DBusError error;
+        struct stat st;
+        int r;
 
         assert(a);
-        assert(UNIT_DEREF(a->mount));
 
         dbus_error_init(&error);
 
@@ -616,11 +612,15 @@ static void automount_enter_runnning(Automount *a) {
         if (!S_ISDIR(st.st_mode) || st.st_dev != a->dev_id)
                 log_info_unit(UNIT(a)->id,
                               "%s's automount point already active?", UNIT(a)->id);
-        else if ((r = manager_add_job(UNIT(a)->manager, JOB_START, UNIT_DEREF(a->mount), JOB_REPLACE, true, &error, NULL)) < 0) {
-                log_warning_unit(UNIT(a)->id,
-                                 "%s failed to queue mount startup job: %s",
-                                 UNIT(a)->id, bus_error(&error, r));
-                goto fail;
+        else {
+                r = manager_add_job(UNIT(a)->manager, JOB_START, UNIT_TRIGGER(UNIT(a)),
+                                    JOB_REPLACE, true, &error, NULL);
+                if (r < 0) {
+                        log_warning_unit(UNIT(a)->id,
+                                         "%s failed to queue mount startup job: %s",
+                                         UNIT(a)->id, bus_error(&error, r));
+                        goto fail;
+                }
         }
 
         automount_set_state(a, AUTOMOUNT_RUNNING);
@@ -643,7 +643,7 @@ static int automount_start(Unit *u) {
                 return -EEXIST;
         }
 
-        if (UNIT_DEREF(a->mount)->load_state != UNIT_LOADED)
+        if (UNIT_TRIGGER(u)->load_state != UNIT_LOADED)
                 return -ENOENT;
 
         a->result = AUTOMOUNT_SUCCESS;
@@ -765,14 +765,12 @@ static const char *automount_sub_state_to_string(Unit *u) {
 }
 
 static bool automount_check_gc(Unit *u) {
-        Automount *a = AUTOMOUNT(u);
-
-        assert(a);
+        assert(u);
 
-        if (!UNIT_DEREF(a->mount))
+        if (!UNIT_TRIGGER(u))
                 return false;
 
-        return UNIT_VTABLE(UNIT_DEREF(a->mount))->check_gc(UNIT_DEREF(a->mount));
+        return UNIT_VTABLE(UNIT_TRIGGER(u))->check_gc(UNIT_TRIGGER(u));
 }
 
 static void automount_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
diff --git a/src/core/automount.h b/src/core/automount.h
index 3d5736d1cb..8276051352 100644
--- a/src/core/automount.h
+++ b/src/core/automount.h
@@ -48,8 +48,6 @@ struct Automount {
 
         char *where;
 
-        UnitRef mount;
-
         int pipe_fd;
         mode_t directory_mode;
         Watch pipe_watch;
diff --git a/src/core/dbus-path.c b/src/core/dbus-path.c
index f7fed1754d..1e62083d9b 100644
--- a/src/core/dbus-path.c
+++ b/src/core/dbus-path.c
@@ -84,15 +84,15 @@ static int bus_path_append_paths(DBusMessageIter *i, const char *property, void
 }
 
 static int bus_path_append_unit(DBusMessageIter *i, const char *property, void *data) {
-        Unit *u = data;
-        Path *p = PATH(u);
+        Unit *u = data, *trigger;
         const char *t;
 
         assert(i);
         assert(property);
         assert(u);
 
-        t = UNIT_DEREF(p->unit) ? UNIT_DEREF(p->unit)->id : "";
+        trigger = UNIT_TRIGGER(u);
+        t = trigger ? trigger->id : "";
 
         return dbus_message_iter_append_basic(i, DBUS_TYPE_STRING, &t) ? 0 : -ENOMEM;
 }
diff --git a/src/core/dbus-timer.c b/src/core/dbus-timer.c
index 75add81519..4082f7f9b9 100644
--- a/src/core/dbus-timer.c
+++ b/src/core/dbus-timer.c
@@ -152,15 +152,15 @@ static int bus_timer_append_calendar_timers(DBusMessageIter *i, const char *prop
 }
 
 static int bus_timer_append_unit(DBusMessageIter *i, const char *property, void *data) {
-        Unit *u = data;
-        Timer *timer = TIMER(u);
+        Unit *u = data, *trigger;
         const char *t;
 
         assert(i);
         assert(property);
         assert(u);
 
-        t = UNIT_DEREF(timer->unit) ? UNIT_DEREF(timer->unit)->id : "";
+        trigger = UNIT_TRIGGER(u);
+        t = trigger ? trigger->id : "";
 
         return dbus_message_iter_append_basic(i, DBUS_TYPE_STRING, &t) ? 0 : -ENOMEM;
 }
diff --git a/src/core/job.c b/src/core/job.c
index af5855b71d..9a425a6da1 100644
--- a/src/core/job.c
+++ b/src/core/job.c
@@ -840,9 +840,11 @@ int job_finish_and_invalidate(Job *j, JobResult result, bool recursive) {
                            job_result_to_string(result),
                            NULL);
 
-                unit_trigger_on_failure(u);
+                unit_start_on_failure(u);
         }
 
+        unit_trigger_notify(u);
+
 finish:
         /* Try to start the next jobs that can be started */
         SET_FOREACH(other, u->dependencies[UNIT_AFTER], i)
diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
index d5e579fd7f..4e1454ee6c 100644
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -241,14 +241,14 @@ Timer.OnBootSec,                 config_parse_timer,                 0,
 Timer.OnStartupSec,              config_parse_timer,                 0,                             0
 Timer.OnUnitActiveSec,           config_parse_timer,                 0,                             0
 Timer.OnUnitInactiveSec,         config_parse_timer,                 0,                             0
-Timer.Unit,                      config_parse_timer_unit,            0,                             0
+Timer.Unit,                      config_parse_trigger_unit,          0,                             0
 m4_dnl
 Path.PathExists,                 config_parse_path_spec,             0,                             0
 Path.PathExistsGlob,             config_parse_path_spec,             0,                             0
 Path.PathChanged,                config_parse_path_spec,             0,                             0
 Path.PathModified,               config_parse_path_spec,             0,                             0
 Path.DirectoryNotEmpty,          config_parse_path_spec,             0,                             0
-Path.Unit,                       config_parse_path_unit,             0,                             0
+Path.Unit,                       config_parse_trigger_unit,          0,                             0
 Path.MakeDirectory,              config_parse_bool,                  0,                             offsetof(Path, make_directory)
 Path.DirectoryMode,              config_parse_mode,                  0,                             offsetof(Path, directory_mode)
 m4_dnl The [Install] section is ignored here.
diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index c3f4f92611..0571d517b0 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -1254,50 +1254,57 @@ int config_parse_timer(const char *unit,
         return 0;
 }
 
-int config_parse_timer_unit(const char *unit,
-                            const char *filename,
-                            unsigned line,
-                            const char *section,
-                            const char *lvalue,
-                            int ltype,
-                            const char *rvalue,
-                            void *data,
-                            void *userdata) {
+int config_parse_trigger_unit(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
 
-        Timer *t = data;
-        int r;
-        DBusError error;
-        Unit *u;
         _cleanup_free_ char *p = NULL;
+        Unit *u = data;
+        UnitType type;
+        int r;
 
         assert(filename);
         assert(lvalue);
         assert(rvalue);
         assert(data);
 
-        dbus_error_init(&error);
+        if (!set_isempty(u->dependencies[UNIT_TRIGGERS])) {
+                log_syntax(unit, LOG_ERR, filename, line, EINVAL,
+                           "Multiple units to trigger specified, ignoring: %s", rvalue);
+                return 0;
+        }
 
-        p = unit_name_printf(UNIT(t), rvalue);
+        p = unit_name_printf(u, rvalue);
         if (!p)
                 return log_oom();
 
-        if (endswith(p, ".timer")) {
+        type = unit_name_to_type(p);
+        if (type < 0) {
                 log_syntax(unit, LOG_ERR, filename, line, EINVAL,
-                           "Unit cannot be of type timer, ignoring: %s", rvalue);
+                           "Unit type not valid, ignoring: %s", rvalue);
                 return 0;
         }
 
-        r = manager_load_unit(UNIT(t)->manager, p, NULL, NULL, &u);
+        if (type == u->type) {
+                log_syntax(unit, LOG_ERR, filename, line, EINVAL,
+                           "Trigger cannot be of same type, ignoring: %s", rvalue);
+                return 0;
+        }
+
+        r = unit_add_two_dependencies_by_name(u, UNIT_BEFORE, UNIT_TRIGGERS, p, NULL, true);
         if (r < 0) {
                 log_syntax(unit, LOG_ERR, filename, line, -r,
-                           "Failed to load unit %s, ignoring: %s",
-                           rvalue, bus_error(&error, r));
-                dbus_error_free(&error);
+                           "Failed to add trigger on %s, ignoring: %s", p, strerror(-r));
                 return 0;
         }
 
-        unit_ref_set(&t->unit, u);
-
         return 0;
 }
 
@@ -1365,53 +1372,6 @@ int config_parse_path_spec(const char *unit,
         return 0;
 }
 
-int config_parse_path_unit(const char *unit,
-                           const char *filename,
-                           unsigned line,
-                           const char *section,
-                           const char *lvalue,
-                           int ltype,
-                           const char *rvalue,
-                           void *data,
-                           void *userdata) {
-
-        Path *t = data;
-        int r;
-        DBusError error;
-        Unit *u;
-        _cleanup_free_ char *p = NULL;
-
-        assert(filename);
-        assert(lvalue);
-        assert(rvalue);
-        assert(data);
-
-        dbus_error_init(&error);
-
-        p = unit_name_printf(UNIT(t), rvalue);
-        if (!p)
-                return log_oom();
-
-        if (endswith(p, ".path")) {
-                log_syntax(unit, LOG_ERR, filename, line, EINVAL,
-                           "Unit cannot be of type path, ignoring: %s", p);
-                return 0;
-        }
-
-        r = manager_load_unit(UNIT(t)->manager, p, NULL, &error, &u);
-        if (r < 0) {
-                log_syntax(unit, LOG_ERR, filename, line, EINVAL,
-                           "Failed to load unit %s, ignoring: %s",
-                           p, bus_error(&error, r));
-                dbus_error_free(&error);
-                return 0;
-        }
-
-        unit_ref_set(&t->unit, u);
-
-        return 0;
-}
-
 int config_parse_socket_service(const char *unit,
                                 const char *filename,
                                 unsigned line,
@@ -2480,10 +2440,9 @@ void unit_dump_config_items(FILE *f) {
                 { config_parse_unit_requires_mounts_for, "PATH [...]" },
                 { config_parse_exec_mount_flags,      "MOUNTFLAG [...]" },
                 { config_parse_unit_string_printf,    "STRING" },
+                { config_parse_trigger_unit,          "UNIT" },
                 { config_parse_timer,                 "TIMER" },
-                { config_parse_timer_unit,            "NAME" },
                 { config_parse_path_spec,             "PATH" },
-                { config_parse_path_unit,             "UNIT" },
                 { config_parse_notify_access,         "ACCESS" },
                 { config_parse_ip_tos,                "TOS" },
                 { config_parse_unit_condition_path,   "CONDITION" },
diff --git a/src/core/load-fragment.h b/src/core/load-fragment.h
index 0161ce0938..ff7f22a6f0 100644
--- a/src/core/load-fragment.h
+++ b/src/core/load-fragment.h
@@ -61,9 +61,8 @@ int config_parse_fsck_passno(const char *unit, const char *filename, unsigned li
 int config_parse_kill_signal(const char *unit, const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_exec_mount_flags(const char *unit, const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_timer(const char *unit, const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
-int config_parse_timer_unit(const char *unit, const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
+int config_parse_trigger_unit(const char *unit, const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_path_spec(const char *unit, const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
-int config_parse_path_unit(const char *unit, const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_socket_service(const char *unit, const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_service_sockets(const char *unit, const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_unit_env_file(const char *unit, const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
diff --git a/src/core/path.c b/src/core/path.c
index d5b5eeb4a1..e1330f6c95 100644
--- a/src/core/path.c
+++ b/src/core/path.c
@@ -298,7 +298,6 @@ static void path_done(Unit *u) {
 
         assert(p);
 
-        unit_ref_unset(&p->unit);
         path_free_specs(p);
 }
 
@@ -390,21 +389,18 @@ static int path_load(Unit *u) {
 
         if (u->load_state == UNIT_LOADED) {
 
-                if (!UNIT_DEREF(p->unit)) {
+                if (set_isempty(u->dependencies[UNIT_TRIGGERS])) {
                         Unit *x;
 
                         r = unit_load_related_unit(u, ".service", &x);
                         if (r < 0)
                                 return r;
 
-                        unit_ref_set(&p->unit, x);
+                        r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS, x, true);
+                        if (r < 0)
+                                return r;
                 }
 
-                r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS,
-                                              UNIT_DEREF(p->unit), true);
-                if (r < 0)
-                        return r;
-
                 r = path_add_mount_links(p);
                 if (r < 0)
                         return r;
@@ -421,11 +417,14 @@ static int path_load(Unit *u) {
 
 static void path_dump(Unit *u, FILE *f, const char *prefix) {
         Path *p = PATH(u);
+        Unit *trigger;
         PathSpec *s;
 
         assert(p);
         assert(f);
 
+        trigger = UNIT_TRIGGER(u);
+
         fprintf(f,
                 "%sPath State: %s\n"
                 "%sResult: %s\n"
@@ -434,7 +433,7 @@ static void path_dump(Unit *u, FILE *f, const char *prefix) {
                 "%sDirectoryMode: %04o\n",
                 prefix, path_state_to_string(p->state),
                 prefix, path_result_to_string(p->result),
-                prefix, UNIT_DEREF(p->unit)->id,
+                prefix, trigger ? trigger->id : "n/a",
                 prefix, yes_no(p->make_directory),
                 prefix, p->directory_mode);
 
@@ -516,17 +515,18 @@ static void path_enter_dead(Path *p, PathResult f) {
 }
 
 static void path_enter_running(Path *p) {
+        _cleanup_dbus_error_free_ DBusError error;
         int r;
-        DBusError error;
 
         assert(p);
+
         dbus_error_init(&error);
 
         /* Don't start job if we are supposed to go down */
-        if (UNIT(p)->job && UNIT(p)->job->type == JOB_STOP)
+        if (unit_pending_inactive(UNIT(p)))
                 return;
 
-        r = manager_add_job(UNIT(p)->manager, JOB_START, UNIT_DEREF(p->unit),
+        r = manager_add_job(UNIT(p)->manager, JOB_START, UNIT_TRIGGER(UNIT(p)),
                             JOB_REPLACE, true, &error, NULL);
         if (r < 0)
                 goto fail;
@@ -544,8 +544,6 @@ fail:
         log_warning("%s failed to queue unit startup job: %s",
                     UNIT(p)->id, bus_error(&error, r));
         path_enter_dead(p, PATH_FAILURE_RESOURCES);
-
-        dbus_error_free(&error);
 }
 
 static bool path_check_good(Path *p, bool initial) {
@@ -616,7 +614,7 @@ static int path_start(Unit *u) {
         assert(p);
         assert(p->state == PATH_DEAD || p->state == PATH_FAILED);
 
-        if (UNIT_DEREF(p->unit)->load_state != UNIT_LOADED)
+        if (UNIT_TRIGGER(u)->load_state != UNIT_LOADED)
                 return -ENOENT;
 
         path_mkdir(p);
@@ -737,33 +735,28 @@ fail:
         path_enter_dead(p, PATH_FAILURE_RESOURCES);
 }
 
-void path_unit_notify(Unit *u, UnitActiveState new_state) {
-        Iterator i;
-        Unit *k;
-
-        if (u->type == UNIT_PATH)
-                return;
+static void path_trigger_notify(Unit *u, Unit *other) {
+        Path *p = PATH(u);
 
-        SET_FOREACH(k, u->dependencies[UNIT_TRIGGERED_BY], i) {
-                Path *p;
+        assert(u);
+        assert(other);
 
-                if (k->type != UNIT_PATH)
-                        continue;
+        /* Invoked whenever the unit we trigger changes state or gains
+         * or loses a job */
 
-                if (k->load_state != UNIT_LOADED)
-                        continue;
-
-                p = PATH(k);
+        if (other->load_state != UNIT_LOADED)
+                return;
 
-                if (p->state == PATH_RUNNING && new_state == UNIT_INACTIVE) {
-                        log_debug("%s got notified about unit deactivation.",
-                                  UNIT(p)->id);
+        if (p->state == PATH_RUNNING &&
+            UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(other))) {
+                log_debug_unit(UNIT(p)->id,
+                               "%s got notified about unit deactivation.",
+                               UNIT(p)->id);
 
-                        /* Hmm, so inotify was triggered since the
-                         * last activation, so I guess we need to
-                         * recheck what is going on. */
-                        path_enter_waiting(p, false, p->inotify_triggered);
-                }
+                /* Hmm, so inotify was triggered since the
+                 * last activation, so I guess we need to
+                 * recheck what is going on. */
+                path_enter_waiting(p, false, p->inotify_triggered);
         }
 }
 
@@ -830,6 +823,8 @@ const UnitVTable path_vtable = {
 
         .fd_event = path_fd_event,
 
+        .trigger_notify = path_trigger_notify,
+
         .reset_failed = path_reset_failed,
 
         .bus_interface = "org.freedesktop.systemd1.Path",
diff --git a/src/core/path.h b/src/core/path.h
index 645feef191..974041539b 100644
--- a/src/core/path.h
+++ b/src/core/path.h
@@ -80,8 +80,6 @@ struct Path {
 
         LIST_HEAD(PathSpec, specs);
 
-        UnitRef unit;
-
         PathState state, deserialized_state;
 
         bool inotify_triggered;
@@ -92,8 +90,6 @@ struct Path {
         PathResult result;
 };
 
-void path_unit_notify(Unit *u, UnitActiveState new_state);
-
 /* Called from the mount code figure out if a mount is a dependency of
  * any of the paths of this path object */
 int path_add_one_mount_link(Path *p, Mount *m);
diff --git a/src/core/timer.c b/src/core/timer.c
index 107dbb3f21..b5d895f048 100644
--- a/src/core/timer.c
+++ b/src/core/timer.c
@@ -72,8 +72,6 @@ static void timer_done(Unit *u) {
 
         unit_unwatch_timer(u, &t->monotonic_watch);
         unit_unwatch_timer(u, &t->realtime_watch);
-
-        unit_ref_unset(&t->unit);
 }
 
 static int timer_verify(Timer *t) {
@@ -122,20 +120,18 @@ static int timer_load(Unit *u) {
 
         if (u->load_state == UNIT_LOADED) {
 
-                if (!UNIT_DEREF(t->unit)) {
+                if (set_isempty(u->dependencies[UNIT_TRIGGERS])) {
                         Unit *x;
 
                         r = unit_load_related_unit(u, ".service", &x);
                         if (r < 0)
                                 return r;
 
-                        unit_ref_set(&t->unit, x);
+                        r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS, x, true);
+                        if (r < 0)
+                                return r;
                 }
 
-                r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS, UNIT_DEREF(t->unit), true);
-                if (r < 0)
-                        return r;
-
                 if (UNIT(t)->default_dependencies) {
                         r = timer_add_default_dependencies(t);
                         if (r < 0)
@@ -148,15 +144,18 @@ static int timer_load(Unit *u) {
 
 static void timer_dump(Unit *u, FILE *f, const char *prefix) {
         Timer *t = TIMER(u);
+        Unit *trigger;
         TimerValue *v;
 
+        trigger = UNIT_TRIGGER(u);
+
         fprintf(f,
                 "%sTimer State: %s\n"
                 "%sResult: %s\n"
                 "%sUnit: %s\n",
                 prefix, timer_state_to_string(t->state),
                 prefix, timer_result_to_string(t->result),
-                prefix, UNIT_DEREF(t->unit)->id);
+                prefix, trigger ? trigger->id : "n/a");
 
         LIST_FOREACH(value, v, t->values) {
 
@@ -285,18 +284,18 @@ static void timer_enter_waiting(Timer *t, bool initial) {
 
                         case TIMER_UNIT_ACTIVE:
 
-                                if (UNIT_DEREF(t->unit)->inactive_exit_timestamp.monotonic <= 0)
+                                if (UNIT_TRIGGER(UNIT(t))->inactive_exit_timestamp.monotonic <= 0)
                                         continue;
 
-                                base = UNIT_DEREF(t->unit)->inactive_exit_timestamp.monotonic;
+                                base = UNIT_TRIGGER(UNIT(t))->inactive_exit_timestamp.monotonic;
                                 break;
 
                         case TIMER_UNIT_INACTIVE:
 
-                                if (UNIT_DEREF(t->unit)->inactive_enter_timestamp.monotonic <= 0)
+                                if (UNIT_TRIGGER(UNIT(t))->inactive_enter_timestamp.monotonic <= 0)
                                         continue;
 
-                                base = UNIT_DEREF(t->unit)->inactive_enter_timestamp.monotonic;
+                                base = UNIT_TRIGGER(UNIT(t))->inactive_enter_timestamp.monotonic;
                                 break;
 
                         default:
@@ -369,10 +368,11 @@ static void timer_enter_running(Timer *t) {
         dbus_error_init(&error);
 
         /* Don't start job if we are supposed to go down */
-        if (UNIT(t)->job && UNIT(t)->job->type == JOB_STOP)
+        if (unit_pending_inactive(UNIT(t)))
                 return;
 
-        r = manager_add_job(UNIT(t)->manager, JOB_START, UNIT_DEREF(t->unit), JOB_REPLACE, true, &error, NULL);
+        r = manager_add_job(UNIT(t)->manager, JOB_START, UNIT_TRIGGER(UNIT(t)),
+                            JOB_REPLACE, true, &error, NULL);
         if (r < 0)
                 goto fail;
 
@@ -394,7 +394,7 @@ static int timer_start(Unit *u) {
         assert(t);
         assert(t->state == TIMER_DEAD || t->state == TIMER_FAILED);
 
-        if (UNIT_DEREF(t->unit)->load_state != UNIT_LOADED)
+        if (UNIT_TRIGGER(u)->load_state != UNIT_LOADED)
                 return -ENOENT;
 
         t->result = TIMER_SUCCESS;
@@ -481,58 +481,49 @@ static void timer_timer_event(Unit *u, uint64_t elapsed, Watch *w) {
         timer_enter_running(t);
 }
 
-void timer_unit_notify(Unit *u, UnitActiveState new_state) {
-        Iterator i;
-        Unit *k;
+static void timer_trigger_notify(Unit *u, Unit *other) {
+        Timer *t = TIMER(u);
+        TimerValue *v;
 
-        if (u->type == UNIT_TIMER)
-                return;
+        assert(u);
+        assert(other);
 
-        SET_FOREACH(k, u->dependencies[UNIT_TRIGGERED_BY], i) {
-                Timer *t;
-                TimerValue *v;
+        log_error("NOTIFY!");
 
-                if (k->type != UNIT_TIMER)
-                        continue;
+        if (other->load_state != UNIT_LOADED)
+                return;
 
-                if (k->load_state != UNIT_LOADED)
-                        continue;
+        /* Reenable all timers that depend on unit state */
+        LIST_FOREACH(value, v, t->values)
+                if (v->base == TIMER_UNIT_ACTIVE ||
+                    v->base == TIMER_UNIT_INACTIVE)
+                        v->disabled = false;
 
-                t = TIMER(k);
+        switch (t->state) {
 
-                /* Reenable all timers that depend on unit state */
-                LIST_FOREACH(value, v, t->values)
-                        if (v->base == TIMER_UNIT_ACTIVE ||
-                            v->base == TIMER_UNIT_INACTIVE)
-                                v->disabled = false;
+        case TIMER_WAITING:
+        case TIMER_ELAPSED:
 
-                switch (t->state) {
+                /* Recalculate sleep time */
+                timer_enter_waiting(t, false);
+                break;
 
-                case TIMER_WAITING:
-                case TIMER_ELAPSED:
+        case TIMER_RUNNING:
 
-                        /* Recalculate sleep time */
+                if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(other))) {
+                        log_debug_unit(UNIT(t)->id,
+                                       "%s got notified about unit deactivation.",
+                                       UNIT(t)->id);
                         timer_enter_waiting(t, false);
-                        break;
-
-                case TIMER_RUNNING:
-
-                        if (UNIT_IS_INACTIVE_OR_FAILED(new_state)) {
-                                log_debug_unit(UNIT(t)->id,
-                                               "%s got notified about unit deactivation.",
-                                               UNIT(t)->id);
-                                timer_enter_waiting(t, false);
-                        }
-
-                        break;
+                }
+                break;
 
-                case TIMER_DEAD:
-                case TIMER_FAILED:
-                        break;
+        case TIMER_DEAD:
+        case TIMER_FAILED:
+                break;
 
-                default:
-                        assert_not_reached("Unknown timer state");
-                }
+        default:
+                assert_not_reached("Unknown timer state");
         }
 }
 
@@ -614,6 +605,8 @@ const UnitVTable timer_vtable = {
 
         .timer_event = timer_timer_event,
 
+        .trigger_notify = timer_trigger_notify,
+
         .reset_failed = timer_reset_failed,
         .time_change = timer_time_change,
 
diff --git a/src/core/timer.h b/src/core/timer.h
index c145348c7d..163bd6c3be 100644
--- a/src/core/timer.h
+++ b/src/core/timer.h
@@ -74,7 +74,6 @@ struct Timer {
         usec_t next_elapse_realtime;
 
         TimerState state, deserialized_state;
-        UnitRef unit;
 
         Watch monotonic_watch;
         Watch realtime_watch;
@@ -82,8 +81,6 @@ struct Timer {
         TimerResult result;
 };
 
-void timer_unit_notify(Unit *u, UnitActiveState new_state);
-
 void timer_free_values(Timer *t);
 
 extern const UnitVTable timer_vtable;
diff --git a/src/core/unit.c b/src/core/unit.c
index 5834009445..4b9abf32dc 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -1304,7 +1304,7 @@ static void check_unneeded_dependencies(Unit *u) {
                         unit_check_unneeded(other);
 }
 
-void unit_trigger_on_failure(Unit *u) {
+void unit_start_on_failure(Unit *u) {
         Unit *other;
         Iterator i;
 
@@ -1324,6 +1324,17 @@ void unit_trigger_on_failure(Unit *u) {
         }
 }
 
+void unit_trigger_notify(Unit *u) {
+        Unit *other;
+        Iterator i;
+
+        assert(u);
+
+        SET_FOREACH(other, u->dependencies[UNIT_TRIGGERED_BY], i)
+                if (UNIT_VTABLE(other)->trigger_notify)
+                        UNIT_VTABLE(other)->trigger_notify(other, u);
+}
+
 void unit_notify(Unit *u, UnitActiveState os, UnitActiveState ns, bool reload_success) {
         Manager *m;
         bool unexpected;
@@ -1354,9 +1365,6 @@ void unit_notify(Unit *u, UnitActiveState os, UnitActiveState ns, bool reload_su
                         u->active_enter_timestamp = ts;
                 else if (UNIT_IS_ACTIVE_OR_RELOADING(os) && !UNIT_IS_ACTIVE_OR_RELOADING(ns))
                         u->active_exit_timestamp = ts;
-
-                timer_unit_notify(u, ns);
-                path_unit_notify(u, ns);
         }
 
         if (UNIT_IS_INACTIVE_OR_FAILED(ns))
@@ -1461,7 +1469,7 @@ void unit_notify(Unit *u, UnitActiveState os, UnitActiveState ns, bool reload_su
                 if (ns != os && ns == UNIT_FAILED) {
                         log_notice_unit(u->id,
                                         "MESSAGE=Unit %s entered failed state.", u->id);
-                        unit_trigger_on_failure(u);
+                        unit_start_on_failure(u);
                 }
         }
 
@@ -1512,6 +1520,7 @@ void unit_notify(Unit *u, UnitActiveState os, UnitActiveState ns, bool reload_su
         }
 
         manager_recheck_journal(m);
+        unit_trigger_notify(u);
 
         /* Maybe we finished startup and are now ready for being
          * stopped because unneeded? */
diff --git a/src/core/unit.h b/src/core/unit.h
index a972a31366..51a8364d63 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -352,7 +352,7 @@ struct UnitVTable {
         /* Called whenever a process of this unit sends us a message */
         void (*notify_message)(Unit *u, pid_t pid, char **tags);
 
-        /* Called whenever a name thus Unit registered for comes or
+        /* Called whenever a name this Unit registered for comes or
          * goes away. */
         void (*bus_name_owner_change)(Unit *u, const char *name, const char *old_owner, const char *new_owner);
 
@@ -368,6 +368,10 @@ struct UnitVTable {
         /* Return the set of units that are following each other */
         int (*following_set)(Unit *u, Set **s);
 
+        /* Invoked each time a unit this unit is triggering changes
+         * state or gains/loses a job */
+        void (*trigger_notify)(Unit *u, Unit *trigger);
+
         /* Called whenever CLOCK_REALTIME made a jump */
         void (*time_change)(Unit *u);
 
@@ -417,6 +421,8 @@ extern const UnitVTable * const unit_vtable[_UNIT_TYPE_MAX];
 /* For casting the various unit types into a unit */
 #define UNIT(u) (&(u)->meta)
 
+#define UNIT_TRIGGER(u) ((Unit*) set_first((u)->dependencies[UNIT_TRIGGERS]))
+
 DEFINE_CAST(SOCKET, Socket);
 DEFINE_CAST(TIMER, Timer);
 DEFINE_CAST(SERVICE, Service);
@@ -540,7 +546,8 @@ char *unit_default_cgroup_path(Unit *u);
 
 int unit_following_set(Unit *u, Set **s);
 
-void unit_trigger_on_failure(Unit *u);
+void unit_start_on_failure(Unit *u);
+void unit_trigger_notify(Unit *u);
 
 bool unit_condition_test(Unit *u);