[geary/mjog/493-undo-send: 12/20] Minor Application.Controller shutdown cleanup

[Michael Gratton <mjog src gnome org>]

commit b8f4687d104e878901012351697b1e876b7a9077
Author: Michael Gratton <mike vee net>
Date:   Tue Nov 12 12:31:42 2019 +1100

    Minor Application.Controller shutdown cleanup
    
    Ensure all refs to closed accounts are cleared when closing them.
    Remove a use of the Geary.Engine.instance global.

 src/client/application/application-controller.vala | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)
---
diff --git a/src/client/application/application-controller.vala 
b/src/client/application/application-controller.vala
index 549f83d4..7470adec 100644
--- a/src/client/application/application-controller.vala
+++ b/src/client/application/application-controller.vala
@@ -339,16 +339,16 @@ public class Application.Controller : Geary.BaseObject {
 
         this.cancellable_open_account.cancel();
 
-        // Create an array of known accounts so the loops below do not
+        // Create a copy of known accounts so the loop below does not
         // explode if accounts are removed while iterating.
-        AccountContext[] accounts = this.accounts.values.to_array();
+        var closing_accounts = new Gee.LinkedList<AccountContext>();
+        closing_accounts.add_all(this.accounts.values);
 
         // Close all Accounts. Launch these in parallel to minimise
         // time taken to close, but here use a barrier to wait for all
         // to actually finish closing.
-        Geary.Nonblocking.CountingSemaphore close_barrier =
-            new Geary.Nonblocking.CountingSemaphore(null);
-        foreach (AccountContext context in accounts) {
+        var close_barrier = new Geary.Nonblocking.CountingSemaphore(null);
+        foreach (AccountContext context in closing_accounts) {
             close_barrier.acquire();
             this.close_account.begin(
                 context.account.information,
@@ -365,10 +365,13 @@ public class Application.Controller : Geary.BaseObject {
             debug("Error waiting at shutdown barrier: %s", err.message);
         }
 
+        // Release last refs to the accounts
+        closing_accounts.clear();
+
         // Turn off the lights and lock the door behind you
         try {
             debug("Closing Engine...");
-            yield Geary.Engine.instance.close_async(null);
+            yield this.application.engine.close_async(null);
             debug("Closed Engine");
         } catch (Error err) {
             message("Error closing Geary Engine instance: %s", err.message);