Issue 7096 - Make it possible to lazy initialize a filter's subscriptions

lib/filterListener.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 122 matching lines @@
 /**
  * Notifies Matcher instances or ElemHide object about a new filter
  * if necessary.
  * @param {Filter} filter filter that has been added
  */
 function addFilter(filter)
 {
   if (!(filter instanceof ActiveFilter) || filter.disabled)
     return;
 
-  if (!filter.subscriptionsAdded)
-    filterStorage.addSubscriptionsToFilter(filter);
-
   let hasEnabled = false;
   let allowSnippets = false;
-  for (let subscription of filter.subscriptions())
+  for (let subscription of filterStorage.subscriptionsForFilter(filter))
   {
     if (!subscription.disabled)
     {
       hasEnabled = true;
 
       // Allow snippets to be executed only by the circumvention lists or the
       // user's own filters.
       if (subscription.type == "circumvention" ||
           subscription.url == "https://easylist-downloads.adblockplus.org/abp-filters-anti-cv.txt" ||
           subscription instanceof SpecialSubscription)
@@ skipping 26 matching lines @@
  * if necessary.
  * @param {Filter} filter filter that has been removed
  */
 function removeFilter(filter)
 {
   if (!(filter instanceof ActiveFilter))
     return;
 
   if (!filter.disabled)
   {
-    if (!filter.subscriptionsAdded)
-      filterStorage.addSubscriptionsToFilter(filter);
-
     let hasEnabled = false;
-    for (let subscription of filter.subscriptions())
+    for (let subscription of filterStorage.subscriptionsForFilter(filter))
     {
       if (!subscription.disabled)
       {
         hasEnabled = true;
         break;
       }
     }
     if (hasEnabled)
       return;
   }
 
   if (filter instanceof RegExpFilter)
     defaultMatcher.remove(filter);
   else if (filter instanceof ElemHideBase)
   {
     if (filter instanceof ElemHideFilter)
       ElemHide.remove(filter);
     else if (filter instanceof ElemHideEmulationFilter)
       ElemHideEmulation.remove(filter);
     else
       ElemHideExceptions.remove(filter);
   }
   else if (filter instanceof SnippetFilter)
     Snippets.remove(filter);
 }
 
 const primes = [101, 109, 131, 149, 163, 179, 193, 211, 229, 241];
 
-function addFilters(filters)
+function addSubscriptionFilters(subscription)
 {
   // We add filters using pseudo-random ordering. Reason is that ElemHide will
   // assign consecutive filter IDs that might be visible to the website. The
   // randomization makes sure that no conclusion can be made about the actual
   // filters applying there. We have ten prime numbers to use as iteration step,
   // any of those can be chosen as long as the array length isn't divisible by
   // it.
-  let len = filters.length;
+  let len = subscription.filterCount;
   if (!len)
     return;
 
   let current = (Math.random() * len) | 0;
   let step;
   do
   {
     step = primes[(Math.random() * primes.length) | 0];
   } while (len % step == 0);
 
   for (let i = 0; i < len; i++, current = (current + step) % len)
-    addFilter(filters[current]);
+    addFilter(subscription.filterAt(current));
 }
 
 function onSubscriptionAdded(subscription)
 {
   FilterListener.setDirty(1);
 
   if (!subscription.disabled)
-    addFilters(subscription.filters);
+    addSubscriptionFilters(subscription);
 }
 
 function onSubscriptionRemoved(subscription)
 {
   FilterListener.setDirty(1);
 
   if (!subscription.disabled)
-    subscription.filters.forEach(removeFilter);
+  {
+    for (let filter of subscription.filters())
+      removeFilter(filter);
+  }
 }
 
 function onSubscriptionDisabled(subscription, newValue)
 {
   FilterListener.setDirty(1);
 
   if (filterStorage.knownSubscriptions.has(subscription.url))
   {
     if (newValue == false)
-      addFilters(subscription.filters);
+    {
+      addSubscriptionFilters(subscription);
+    }
     else
-      subscription.filters.forEach(removeFilter);
+    {
+      for (let filter of subscription.filters())
+        removeFilter(filter);
+    }
   }
 }
 
 function onSubscriptionUpdated(subscription, oldFilters)
 {
   FilterListener.setDirty(1);
 
   if (!subscription.disabled &&
       filterStorage.knownSubscriptions.has(subscription.url))
   {
-    oldFilters.forEach(removeFilter);
-    addFilters(subscription.filters);
+    for (let filter of oldFilters)
+      removeFilter(filter);
+
+    addSubscriptionFilters(subscription);
   }
 }
 
 function onFilterHitCount(filter, newValue)
 {
   if (newValue == 0)
     FilterListener.setDirty(0);
   else
     FilterListener.setDirty(0.002);
 }
@@ skipping 36 matching lines @@
 
 function onLoad()
 {
   isDirty = 0;
 
   defaultMatcher.clear();
   ElemHide.clear();
   ElemHideEmulation.clear();
   ElemHideExceptions.clear();
   Snippets.clear();
+
   for (let subscription of filterStorage.subscriptions())
   {
     if (!subscription.disabled)
-      addFilters(subscription.filters);
+      addSubscriptionFilters(subscription);
   }
 }
 
 function onSave()
 {
   isDirty = 0;
 }