core: whenever we change state of a unit, force out PropertiesChanged bus signal

This allows clients to follow our internal state changes safely.

Previously, quick state changes (for example, when we restart a unit due
to Restart= after it quickly transitioned through DEAD/FAILED states)
would be coalesced into one bus signal event, with this change there's
the guarantee that all state changes after the unit was announced ones
are reflected on th bus.

Note we only do this kind of guaranteed flushing only for unit state
changes, not for other unit property changes, where clients still have
to expect coalescing. This is because the unit state is a very
important, high-level concept.

Fixes: #10185

diff --git a/src/core/automount.c b/src/core/automount.c
index 3d8348e0b7fc0229b90a66ccae87b1b9d5eb4c85..de8010bf2e5d86865cb7fff98033423713959e77 100644 (file)
--- a/src/core/automount.c
+++ b/src/core/automount.c
@@ -16,6 +16,7 @@
 #include "bus-error.h"
 #include "bus-util.h"
 #include "dbus-automount.h"
+#include "dbus-unit.h"
 #include "fd-util.h"
 #include "format-util.h"
 #include "io-util.h"
@@ -237,6 +238,9 @@ static void automount_set_state(Automount *a, AutomountState state) {
         AutomountState old_state;
         assert(a);
 
+        if (a->state != state)
+                bus_unit_send_pending_change_signal(UNIT(a), false);
+
         old_state = a->state;
         a->state = state;
 

diff --git a/src/core/dbus-unit.c b/src/core/dbus-unit.c
index 6d9b559d2c7d522ff63f561edb41b66f9fc007b6..4cf7364c50e33e92c29d6e854321467e3f54a318 100644 (file)
--- a/src/core/dbus-unit.c
+++ b/src/core/dbus-unit.c
@@ -1202,6 +1202,27 @@ void bus_unit_send_change_signal(Unit *u) {
         u->sent_dbus_new_signal = true;
 }
 
+void bus_unit_send_pending_change_signal(Unit *u, bool including_new) {
+
+        /* Sends out any pending change signals, but only if they really are pending. This call is used when we are
+         * about to change state in order to force out a PropertiesChanged signal beforehand if there was one pending
+         * so that clients can follow the full state transition */
+
+        if (!u->in_dbus_queue) /* If not enqueued, don't bother */
+                return;
+
+        if (!u->sent_dbus_new_signal && !including_new) /* If the unit was never announced, don't bother, it's fine if
+                                                         * the unit appears in the new state right-away (except if the
+                                                         * caller explicitly asked us to send it anyway) */
+                return;
+
+        if (MANAGER_IS_RELOADING(u->manager)) /* Don't generate unnecessary PropertiesChanged signals for the same unit
+                                               * when we are reloading. */
+                return;
+
+        bus_unit_send_change_signal(u);
+}
+
 static int send_removed_signal(sd_bus *bus, void *userdata) {
         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
         _cleanup_free_ char *p = NULL;

diff --git a/src/core/dbus-unit.h b/src/core/dbus-unit.h
index 68eb621836b1a77d79e8f46e4d0e2c4f1c44aceb..345345e3ebadea254c0ab0bd1697b40b15fea79c 100644 (file)
--- a/src/core/dbus-unit.h
+++ b/src/core/dbus-unit.h
@@ -11,6 +11,7 @@ extern const sd_bus_vtable bus_unit_vtable[];
 extern const sd_bus_vtable bus_unit_cgroup_vtable[];
 
 void bus_unit_send_change_signal(Unit *u);
+void bus_unit_send_pending_change_signal(Unit *u, bool including_new);
 void bus_unit_send_removed_signal(Unit *u);
 
 int bus_unit_method_start_generic(sd_bus_message *message, Unit *u, JobType job_type, bool reload_if_possible, sd_bus_error *error);

diff --git a/src/core/device.c b/src/core/device.c
index 8b6126c4cfe8e95e9b0e4fb06421d6fc8e177e17..5acd9b7a7036de7652f2255de69e92f6f3eb4109 100644 (file)
--- a/src/core/device.c
+++ b/src/core/device.c
@@ -6,6 +6,7 @@
 #include "alloc-util.h"
 #include "bus-error.h"
 #include "dbus-device.h"
+#include "dbus-unit.h"
 #include "device-private.h"
 #include "device-util.h"
 #include "device.h"
@@ -115,6 +116,9 @@ static void device_set_state(Device *d, DeviceState state) {
         DeviceState old_state;
         assert(d);
 
+        if (d->state != state)
+                bus_unit_send_pending_change_signal(UNIT(d), false);
+
         old_state = d->state;
         d->state = state;
 

diff --git a/src/core/mount.c b/src/core/mount.c
index 99b2aa0904c39a78782b498802ca143cb9f441f3..afdbaa1d9d0389c6f4b299f42e897c8e612eb72c 100644 (file)
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -11,6 +11,7 @@
 
 #include "alloc-util.h"
 #include "dbus-mount.h"
+#include "dbus-unit.h"
 #include "device.h"
 #include "escape.h"
 #include "exit-status.h"
@@ -640,6 +641,9 @@ static void mount_set_state(Mount *m, MountState state) {
         MountState old_state;
         assert(m);
 
+        if (m->state != state)
+                bus_unit_send_pending_change_signal(UNIT(m), false);
+
         old_state = m->state;
         m->state = state;
 

diff --git a/src/core/path.c b/src/core/path.c
index 01019b0cf77f9e7027ab4d4e9ba87baa45598ed9..831e49df29f2623b0f9e0a49ffaeae66fcf198a8 100644 (file)
--- a/src/core/path.c
+++ b/src/core/path.c
@@ -8,6 +8,7 @@
 #include "bus-error.h"
 #include "bus-util.h"
 #include "dbus-path.h"
+#include "dbus-unit.h"
 #include "fd-util.h"
 #include "fs-util.h"
 #include "glob-util.h"
@@ -410,6 +411,9 @@ static void path_set_state(Path *p, PathState state) {
         PathState old_state;
         assert(p);
 
+        if (p->state != state)
+                bus_unit_send_pending_change_signal(UNIT(p), false);
+
         old_state = p->state;
         p->state = state;
 

diff --git a/src/core/scope.c b/src/core/scope.c
index 151b8989a6416bb38bd7aada60a2ffdb6874636c..e478661f9486fb52849da49f4ebe745b27e3ce16 100644 (file)
--- a/src/core/scope.c
+++ b/src/core/scope.c
@@ -5,6 +5,7 @@
 
 #include "alloc-util.h"
 #include "dbus-scope.h"
+#include "dbus-unit.h"
 #include "load-dropin.h"
 #include "log.h"
 #include "scope.h"
@@ -82,6 +83,9 @@ static void scope_set_state(Scope *s, ScopeState state) {
         ScopeState old_state;
         assert(s);
 
+        if (s->state != state)
+                bus_unit_send_pending_change_signal(UNIT(s), false);
+
         old_state = s->state;
         s->state = state;
 

diff --git a/src/core/service.c b/src/core/service.c
index 964a7fd05725d62e057c5c4a1e292d9bb5992be1..76f1e160697f7d22f53c4554c9d4645f67368505 100644 (file)
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -12,6 +12,7 @@
 #include "bus-kernel.h"
 #include "bus-util.h"
 #include "dbus-service.h"
+#include "dbus-unit.h"
 #include "def.h"
 #include "env-util.h"
 #include "escape.h"
@@ -1035,6 +1036,9 @@ static void service_set_state(Service *s, ServiceState state) {
 
         assert(s);
 
+        if (s->state != state)
+                bus_unit_send_pending_change_signal(UNIT(s), false);
+
         table = s->type == SERVICE_IDLE ? state_translation_table_idle : state_translation_table;
 
         old_state = s->state;

diff --git a/src/core/slice.c b/src/core/slice.c
index dc087680e1931dcc74feb701c9b55d7bd9b05e93..15b18bcad3562fb9876a80db1a452e73a1eca0ff 100644 (file)
--- a/src/core/slice.c
+++ b/src/core/slice.c
@@ -4,6 +4,7 @@
 
 #include "alloc-util.h"
 #include "dbus-slice.h"
+#include "dbus-unit.h"
 #include "log.h"
 #include "serialize.h"
 #include "slice.h"
@@ -29,6 +30,9 @@ static void slice_set_state(Slice *t, SliceState state) {
         SliceState old_state;
         assert(t);
 
+        if (t->state != state)
+                bus_unit_send_pending_change_signal(UNIT(t), false);
+
         old_state = t->state;
         t->state = state;
 

diff --git a/src/core/socket.c b/src/core/socket.c
index f725c9eb009cdf7428722c3c6596bf352f086eef..d3dc0a3216855fab27708f6748550d70cb94c1b1 100644 (file)
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -17,6 +17,7 @@
 #include "bus-util.h"
 #include "copy.h"
 #include "dbus-socket.h"
+#include "dbus-unit.h"
 #include "def.h"
 #include "exit-status.h"
 #include "fd-util.h"
@@ -1748,6 +1749,9 @@ static void socket_set_state(Socket *s, SocketState state) {
         SocketState old_state;
         assert(s);
 
+        if (s->state != state)
+                bus_unit_send_pending_change_signal(UNIT(s), false);
+
         old_state = s->state;
         s->state = state;
 

diff --git a/src/core/swap.c b/src/core/swap.c
index db806fe0bb3bc8a2928f7bf1872ab8ce35273adb..90207a48fa6c76f52d506346341b6e495ceabdd4 100644 (file)
--- a/src/core/swap.c
+++ b/src/core/swap.c
@@ -9,6 +9,7 @@
 
 #include "alloc-util.h"
 #include "dbus-swap.h"
+#include "dbus-unit.h"
 #include "device-private.h"
 #include "device-util.h"
 #include "device.h"
@@ -480,6 +481,9 @@ static void swap_set_state(Swap *s, SwapState state) {
 
         assert(s);
 
+        if (s->state != state)
+                bus_unit_send_pending_change_signal(UNIT(s), false);
+
         old_state = s->state;
         s->state = state;
 

diff --git a/src/core/target.c b/src/core/target.c
index b8b8e32805eb0988b4a90150457c93dc2063abe6..421a304c73da421b14a962ab2cb35e962e23a248 100644 (file)
--- a/src/core/target.c
+++ b/src/core/target.c
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
 #include "dbus-target.h"
+#include "dbus-unit.h"
 #include "log.h"
 #include "serialize.h"
 #include "special.h"
@@ -18,6 +19,9 @@ static void target_set_state(Target *t, TargetState state) {
         TargetState old_state;
         assert(t);
 
+        if (t->state != state)
+                bus_unit_send_pending_change_signal(UNIT(t), false);
+
         old_state = t->state;
         t->state = state;
 

diff --git a/src/core/timer.c b/src/core/timer.c
index 1527aab158279b9ce18c9e04658e261e09df15b2..d9ba2f76b3d3984d6745824ee74cc4abdea9185c 100644 (file)
--- a/src/core/timer.c
+++ b/src/core/timer.c
@@ -6,6 +6,7 @@
 #include "bus-error.h"
 #include "bus-util.h"
 #include "dbus-timer.h"
+#include "dbus-unit.h"
 #include "fs-util.h"
 #include "parse-util.h"
 #include "random-util.h"
@@ -247,6 +248,9 @@ static void timer_set_state(Timer *t, TimerState state) {
         TimerState old_state;
         assert(t);
 
+        if (t->state != state)
+                bus_unit_send_pending_change_signal(UNIT(t), false);
+
         old_state = t->state;
         t->state = state;