From 9f825c30595a2689c48353860461a5dc9049a351 Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Sat, 21 Sep 2019 16:42:15 -0400
Subject: [PATCH] Do not flush blocked-elements cache at webNavigation time

While testing for the new `elemhide` option using ABP's
test page[1], I found out that the placeholder of the
blocked image on that page was not properly collapsed
by uBO.

The reason was because the page is very simple and
flushing the blocked-elements cache at
webNavigation.onCommitted time was causing the loss
of information collected between
webRequest.onBeforeRequest and
webNavigation.onCommitted, preventing uBO from
properly collapsing the placeholders.

The blocked-elements cache is now flushed
ONLY at webRequest.onBeforeRequest time.

[1] https://testpages.adblockplus.org/en/exceptions/elemhide
---
 src/js/pagestore.js | 22 +++-------------------
 src/js/tab.js       |  1 +
 2 files changed, 4 insertions(+), 19 deletions(-)

diff --git a/src/js/pagestore.js b/src/js/pagestore.js
index 4ddc73b60..615515a72 100644
--- a/src/js/pagestore.js
+++ b/src/js/pagestore.js
@@ -41,10 +41,6 @@ const µb = µBlock;
 
 /******************************************************************************/
 
-// To mitigate memory churning
-const netFilteringCacheJunkyard = [];
-const netFilteringCacheJunkyardMax = 10;
-
 const NetFilteringResultCache = class {
     constructor() {
         this.init();
@@ -58,14 +54,6 @@ const NetFilteringResultCache = class {
         return this;
     }
 
-    dispose() {
-        this.empty();
-        if ( netFilteringCacheJunkyard.length < netFilteringCacheJunkyardMax ) {
-            netFilteringCacheJunkyard.push(this);
-        }
-        return null;
-    }
-
     rememberResult(fctxt, result) {
         if ( fctxt.tabId <= 0 ) { return; }
         if ( this.results.size === 0 ) {
@@ -155,10 +143,7 @@ const NetFilteringResultCache = class {
     }
 
     static factory() {
-        const entry = netFilteringCacheJunkyard.pop();
-        return entry !== undefined
-            ? entry.init()
-            : new NetFilteringResultCache();
+        return new NetFilteringResultCache();
     }
 };
 
@@ -218,6 +203,7 @@ const PageStore = class {
         this.journalTimer = null;
         this.journalLastCommitted = this.journalLastUncommitted = undefined;
         this.journalLastUncommittedURL = undefined;
+        this.netFilteringCache = NetFilteringResultCache.factory();
         this.init(tabId, context);
     }
 
@@ -261,7 +247,6 @@ const PageStore = class {
         this.popupBlockedCount = 0;
         this.largeMediaCount = 0;
         this.largeMediaTimer = null;
-        this.netFilteringCache = NetFilteringResultCache.factory();
         this.internalRedirectionCount = 0;
         this.extraData.clear();
 
@@ -327,7 +312,6 @@ const PageStore = class {
             this.largeMediaTimer = null;
         }
         this.disposeFrameStores();
-        this.netFilteringCache = this.netFilteringCache.dispose();
         this.init(this.tabId, context);
         return this;
     }
@@ -337,13 +321,13 @@ const PageStore = class {
         this.title = '';
         this.rawURL = '';
         this.hostnameToCountMap = null;
+        this.netFilteringCache.empty();
         this.allowLargeMediaElementsUntil = 0;
         if ( this.largeMediaTimer !== null ) {
             clearTimeout(this.largeMediaTimer);
             this.largeMediaTimer = null;
         }
         this.disposeFrameStores();
-        this.netFilteringCache = this.netFilteringCache.dispose();
         if ( this.journalTimer !== null ) {
             clearTimeout(this.journalTimer);
             this.journalTimer = null;
diff --git a/src/js/tab.js b/src/js/tab.js
index d0e64bcb3..ea7286251 100644
--- a/src/js/tab.js
+++ b/src/js/tab.js
@@ -887,6 +887,7 @@ vAPI.tabs = new vAPI.Tabs();
     // https://github.com/chrisaljoudi/uBlock/issues/516
     //   If context is 'beforeRequest', do not rebind, wait for confirmation.
     if ( context === 'beforeRequest' ) {
+        pageStore.netFilteringCache.empty();
         return pageStore;
     }