Merge lp:~afrantzis/powerd/fix-1531158 into lp:powerd

[Alexandros Frantzis]

Keep the dbus proxy to Unity.Screen (implemented by USC) alive for
the lifetime of the process. Otherwise we may block when trying to
create the proxy while servicing a request from USC (LP: #1531158)

Keep the dbus proxy to Unity.Screen (implemented by USC) alive for
the lifetime of the process. Otherwise we may block when trying to
create the proxy while servicing a request from USC (LP: #1531158)

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:181
http://jenkins.qa.ubuntu.com/job/powerd-ci/192/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/powerd-vivid-armhf-ci/20
        deb: http://jenkins.qa.ubuntu.com/job/powerd-vivid-armhf-ci/20/artifact/work/output/*zip*/output.zip

Click here to trigger a rebuild:
http://s-jenkins.ubuntu-ci:8080/job/powerd-ci/192/rebuild

review: Approve (continuous-integration)

=== modified file 'debian/changelog'
--- debian/changelog	2015-09-30 12:29:39 +0000
+++ debian/changelog	2016-01-11 13:36:27 +0000
@@ -1,3 +1,11 @@
+powerd (0.16+16.04.20160111-0ubuntu1) xenial; urgency=medium
+
+  * Keep the dbus proxy to Unity.Screen (implemented by USC) alive for
+    the lifetime of the process. Otherwise we may block when trying to
+    create the proxy while servicing a request from USC (LP: #1531158)
+
+ -- Alexandros Frantzis <[e-mail]>  Mon, 11 Jan 2016 13:12:11 +0000
+
 powerd (0.16+15.10.20150930-0ubuntu1) wily; urgency=medium
 
   [ Alexandros Frantzis ]
 
=== modified file 'src/display.c'
--- src/display.c	2014-06-18 18:06:10 +0000
+++ src/display.c	2016-01-11 13:36:27 +0000
@@ -29,26 +29,39 @@
 #include "powerd-internal.h"
 #include "log.h"
 
-static GDBusProxy* create_uscreen_proxy()
+static GDBusProxy* uscreen_proxy_get()
 {
-    GError *error = NULL;
-    GDBusProxy *uscreen_proxy = NULL;
-    uscreen_proxy = g_dbus_proxy_new_for_bus_sync(G_BUS_TYPE_SYSTEM,
-            G_DBUS_PROXY_FLAGS_NONE,
-            NULL,
-            "com.canonical.Unity.Screen",
-            "/com/canonical/Unity/Screen",
-            "com.canonical.Unity.Screen",
-            NULL,
-            &error);
-
-    if (error != NULL) {
-        powerd_warn("could not connect to Unity.Screen: %s", error->message);
-        g_error_free(error);
-        return NULL;
+    static GMutex mutex;
+    static GDBusProxy *uscreen_proxy = NULL;
+    GDBusProxy *uscreen_proxy_tmp = NULL;
+
+    g_mutex_lock(&mutex);
+
+    if (uscreen_proxy == NULL)
+    {
+        GError *error = NULL;
+
+        uscreen_proxy = g_dbus_proxy_new_for_bus_sync(G_BUS_TYPE_SYSTEM,
+                G_DBUS_PROXY_FLAGS_NONE,
+                NULL,
+                "com.canonical.Unity.Screen",
+                "/com/canonical/Unity/Screen",
+                "com.canonical.Unity.Screen",
+                NULL,
+                &error);
+
+        if (error != NULL) {
+            powerd_warn("could not connect to Unity.Screen: %s", error->message);
+            g_error_free(error);
+            uscreen_proxy = NULL;
+        }
     }
 
-    return uscreen_proxy;
+    uscreen_proxy_tmp = uscreen_proxy;
+
+    g_mutex_unlock(&mutex);
+
+    return uscreen_proxy_tmp;
 }
 
 static void request_keep_display_on(GDBusConnection *connection,
@@ -63,7 +76,7 @@
 
     powerd_debug("request_keep_display_on");
 
-    uscreen_proxy = create_uscreen_proxy();
+    uscreen_proxy = uscreen_proxy_get();
     if (uscreen_proxy == NULL)
     {
         powerd_warn("failed creating unity screen proxy to keep display on");
@@ -88,7 +101,6 @@
     powerd_debug("keepDisplayOn request succeeded - id: %d", request_id);
 
     g_variant_unref(ret);
-    g_object_unref(uscreen_proxy);
 }
 
 gboolean turn_display_on(gboolean on, enum DisplayStateChangeReason reason)
@@ -100,7 +112,7 @@
     if (on)
         powerd_hal_signal_activity();
 
-    uscreen_proxy = create_uscreen_proxy();
+    uscreen_proxy = uscreen_proxy_get();
     if (uscreen_proxy == NULL)
         return FALSE;
 
@@ -113,8 +125,6 @@
             NULL,
             NULL);
 
-    g_object_unref(uscreen_proxy);
-
     return TRUE;
 }