[gnome-shell] extensionSystem: Rebase the extension order list to help prevent conflicts

[Jasper St. Pierre <jstpierre src gnome org>]

commit fd1b3b4fee271108794ca4150c84cce7e56a6243
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Fri Oct 14 18:06:03 2011 -0400

    extensionSystem: Rebase the extension order list to help prevent conflicts
    
    When two extensions monkey-patch the same area, enable() and disable() may
    behave badly and completely wreck things. To solve this, when disabling
    an extension, "rebase" the extension list so that monkey patches should be
    added and removed in order.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=661815

 js/ui/extensionSystem.js |   34 ++++++++++++++++++++++++++++++++++
 1 files changed, 34 insertions(+), 0 deletions(-)
---
diff --git a/js/ui/extensionSystem.js b/js/ui/extensionSystem.js
index c30da01..95c3a29 100644
--- a/js/ui/extensionSystem.js
+++ b/js/ui/extensionSystem.js
@@ -64,6 +64,8 @@ const extensions = {};
 const extensionStateObjs = {};
 // Maps uuid -> [GFile to the extension directory, Extension type]
 const extensionDirs = {};
+// Contains the order that extensions were enabled in.
+const extensionOrder = [];
 
 // Arrays of uuids
 var enabledExtensions;
@@ -215,6 +217,27 @@ function disableExtension(uuid) {
 
     let extensionState = extensionStateObjs[uuid];
 
+    // "Rebase" the extension order by disabling and then enabling extensions
+    // in order to help prevent conflicts.
+
+    // Example:
+    //   order = [A, B, C, D, E]
+    //   user disables C
+    //   this should: disable E, disable D, disable C, enable D, enable E
+
+    let orderIdx = extensionOrder.indexOf(uuid);
+    let order = extensionOrder.slice(orderIdx + 1);
+    let orderReversed = order.slice().reverse();
+
+    for (let i = 0; i < orderReversed.length; i++) {
+        let uuid = orderReversed[i];
+        try {
+            extensionStateObjs[uuid].disable();
+        } catch(e) {
+            logExtensionError(uuid, e.toString());
+        }
+    }
+
     try {
         extensionState.disable();
     } catch(e) {
@@ -222,6 +245,15 @@ function disableExtension(uuid) {
         return;
     }
 
+    for (let i = 0; i < order.length; i++) {
+        let uuid = order[i];
+        try {
+            extensionStateObjs[uuid].enable();
+        } catch(e) {
+            logExtensionError(uuid, e.toString());
+        }
+    }
+
     meta.state = ExtensionState.DISABLED;
     _signals.emit('extension-state-changed', meta);
 }
@@ -241,6 +273,8 @@ function enableExtension(uuid) {
 
     let extensionState = extensionStateObjs[uuid];
 
+    extensionOrder.push(uuid);
+
     try {
         extensionState.enable();
     } catch(e) {