Issue 6050 - Use localStorage for blocked_total preference on Gecko

lib/prefs.js

Index: lib/prefs.js
diff --git a/lib/prefs.js b/lib/prefs.js
index 7686f83f462e7f19f406583e3bea424c144a3f43..0f77b584b4c37e935f2748432746c74233fcd249 100644
--- a/lib/prefs.js
+++ b/lib/prefs.js
@@ -259,32 +259,17 @@ function savePref(pref)
 let customSave = new Map();
 if (require("info").platform == "gecko")
 {
-  // Saving one storage value causes all others to be saved as well on Gecko.
-  // Make sure that updating ad counter doesn't cause the filters data to be
-  // saved frequently as a side-effect.
-  const MIN_UPDATE_INTERVAL = 60 * 1000;
-  let lastUpdate = -MIN_UPDATE_INTERVAL;
-  let updateScheduled = false;
+  // Saving one browser.storage value causes all others to be saved as well on
+  // Gecko. Until that is rectified[1] we need to avoid saving the ad counter
+  // using browser.storage too often, since the filters data is saved as a
+  // side-effect. We do this by using localStorage instead, only updating the
+  // value saved in browser.storage when the extension first initializes.
+  // Note: This workaround is sub-optimal since if the user clears browser data
+  // localStorage is cleared.
+  // [1] - https://bugzilla.mozilla.org/show_bug.cgi?id=1277612
   customSave.set("blocked_total", pref =>
   {
-    if (updateScheduled)
-      return;
-
-    let callback = () =>
-    {
-      lastUpdate = performance.now();
-      updateScheduled = false;
-      savePref(pref);
-    };
-
-    let timeElapsed = performance.now() - lastUpdate;
-    if (timeElapsed < MIN_UPDATE_INTERVAL)
-    {
-      setTimeout(callback, MIN_UPDATE_INTERVAL - timeElapsed);
-      updateScheduled = true;
-    }
-    else
-      callback();
+    window.localStorage.setItem("blocked_total", overrides.blocked_total);
   });
 }
 
@@ -326,6 +311,20 @@ function init()
       for (let key in items)
         overrides[keyToPref(key)] = items[key];
 
+      if (require("info").platform == "gecko")
+      {
+        let blockedTotal = window.localStorage.getItem("blocked_total");
+        if (typeof blockedTotal == "string")
+        {
+          blockedTotal = JSON.parse(blockedTotal);
+          if (blockedTotal > overrides.blocked_total)
+          {
+            overrides.blocked_total = blockedTotal;
+            savePref("blocked_total");
+          }
+        }
+      }
+
       resolve();
     });
   });