[geary/mjog/mutiple-main-windows: 10/14] Rework how Application.Client manages application holds

[Michael Gratton <mjog src gnome org>]

commit 0eaa3ac25770c1312f91d4b93439f12d13220b87
Author: Michael Gratton <mike vee net>
Date:   Mon Nov 18 11:57:53 2019 +1100

    Rework how Application.Client manages application holds
    
    Always take out a hold on the application and construct a controller
    in ::startup, so that it does not immediately exit when running as a
    background service now that no main windows will be constructed by
    default.
    
    Manually exit the application when there are no windows remaining
    instead of releasing the hold so that it has a chance to cleanly close
    the controller.

 src/client/application/application-client.vala | 33 ++++++++++++--------------
 1 file changed, 15 insertions(+), 18 deletions(-)
---
diff --git a/src/client/application/application-client.vala b/src/client/application/application-client.vala
index ac386e05..a217a9ea 100644
--- a/src/client/application/application-client.vala
+++ b/src/client/application/application-client.vala
@@ -424,12 +424,14 @@ public class Application.Client : Gtk.Application {
         Components.Inspector.add_accelerators(this);
         Dialogs.ProblemDetailsDialog.add_accelerators(this);
 
-        if (this.is_background_service) {
-            // Since command_line won't be called below if running as
-            // a DBus service, disable logging spew and start the
-            // controller running.
-            this.create_controller.begin();
-        }
+        // Manually place a hold on the application otherwise the
+        // application will exit when the async call to
+        // ::create_controller next returns without having yet created
+        // a window.
+        hold();
+
+        // Finally, start the controller.
+        this.create_controller.begin();
     }
 
     public override int command_line(GLib.ApplicationCommandLine command_line) {
@@ -749,11 +751,6 @@ public class Application.Client : Gtk.Application {
 
     // Opens the controller
     private async void create_controller() {
-        // Manually keep the main loop around for the duration of this
-        // call. Without this, the main loop will exit as soon as we
-        // hit the yield below, before we create the main window.
-        hold();
-
         bool first_run = false;
         try {
             int mutex_token = yield this.controller_mutex.claim_async();
@@ -786,15 +783,10 @@ public class Application.Client : Gtk.Application {
                 quit();
             }
         }
-
-        release();
     }
 
     // Closes the controller, if running
     private async void destroy_controller() {
-        // see create_controller() for reasoning hold/release is used
-        hold();
-
         try {
             int mutex_token = yield this.controller_mutex.claim_async();
             if (this.controller != null) {
@@ -805,8 +797,6 @@ public class Application.Client : Gtk.Application {
         } catch (GLib.Error err) {
             debug("Error destroying controller: %s", err.message);
         }
-
-        release();
     }
 
     private int handle_general_options(GLib.ApplicationCommandLine command_line) {
@@ -1034,6 +1024,13 @@ public class Application.Client : Gtk.Application {
                 );
             }
         }
+
+        // Since ::startup above took out a manual hold on the
+        // application, manually work out if the application should
+        // quit here.
+        if (!this.is_background_service && get_windows().length() == 0) {
+            this.quit();
+        }
     }
 
 }