[gnome-shell] screenShield: Don't unnecessarily close or recreate inhibitors

[Marge Bot <marge-bot src gnome org>]

commit fb313033eaf97fe072850f1bda5cb6eaf02c0312
Author: Sebastian Keller <skeller gnome org>
Date:   Fri Jul 23 17:35:00 2021 +0200

    screenShield: Don't unnecessarily close or recreate inhibitors
    
    ScreenShield::_syncInhibitor() was closing (and recreating) the
    inhibitor everytime it was called, even if no change was needed.
    This gets called in various places, including on property changes in
    the login1 dbus object. These happen by the time logind already started
    suspending at which point new inhibitors can no longer be created. It is
    only waiting for existing inhibitors to be closed, so closing the
    inhibitor without a new inhibitor will cause the suspending to proceed
    immediately if no other inhibitors are present. This can also happen
    before the lock screen is shown, which will then complete after resume.
    
    Fix this by keeping track of the expected inhibition state and only
    create or close inhibitors if there was a change to that.
    
    Fixes https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/3736
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1927>

 js/ui/screenShield.js | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)
---
diff --git a/js/ui/screenShield.js b/js/ui/screenShield.js
index 59c13d8b5f..de8b7f409e 100644
--- a/js/ui/screenShield.js
+++ b/js/ui/screenShield.js
@@ -122,6 +122,7 @@ var ScreenShield = class {
         this._isActive = false;
         this._isLocked = false;
         this._inUnlockAnimation = false;
+        this._inhibited = false;
         this._activationTime = 0;
         this._becameActiveId = 0;
         this._lockTimeoutId = 0;
@@ -203,20 +204,29 @@ var ScreenShield = class {
     }
 
     _syncInhibitor() {
-        let lockEnabled = this._settings.get_boolean(LOCK_ENABLED_KEY);
-        let lockLocked = this._lockSettings.get_boolean(DISABLE_LOCK_KEY);
-        let inhibit = this._loginSession && this._loginSession.Active &&
-                       !this._isActive && lockEnabled && !lockLocked && Main.sessionMode.unlockDialog;
+        const lockEnabled = this._settings.get_boolean(LOCK_ENABLED_KEY);
+        const lockLocked = this._lockSettings.get_boolean(DISABLE_LOCK_KEY);
+        const inhibit = !!this._loginSession && this._loginSession.Active &&
+                         !this._isActive && lockEnabled && !lockLocked &&
+                         !!Main.sessionMode.unlockDialog;
+
+        if (inhibit === this._inhibited)
+            return;
+
+        this._inhibited = inhibit;
+
         if (inhibit) {
-            this._loginManager.inhibit(_("GNOME needs to lock the screen"),
+            this._loginManager.inhibit(_('GNOME needs to lock the screen'),
                 inhibitor => {
-                    if (this._inhibitor)
-                        this._inhibitor.close(null);
-                    this._inhibitor = inhibitor;
+                    if (inhibitor) {
+                        if (this._inhibitor)
+                            inhibitor.close(null);
+                        else
+                            this._inhibitor = inhibitor;
+                    }
                 });
         } else {
-            if (this._inhibitor)
-                this._inhibitor.close(null);
+            this._inhibitor?.close(null);
             this._inhibitor = null;
         }
     }