From 155abfba182cc38ce90252a50c5af55640804783 Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Thu, 25 Apr 2019 18:36:03 -0400
Subject: [PATCH] Cache and reuse result of HNTrieRef.matches() when possible

Due to how web pages typically load secondary resources and due
to how HNTrieContainer instances are used in uBO, there is a
great likelihood that the result of a previous call to
HNTrieRef.matches() can be reused in a subsequent call.
This has been confirmed by instrumenting HNTrieRef.matches().

Since uBO uses distinct HNTrieContainer instances to either
match against the request or the origin hostnames, this
means a high likelihood of repeated calls to HNTrieRef.matches()
with the same hostname as argument, hence a performance gain
when caching the argument+result -- as despite that
HNTrie.matches() is fast, comparing two short strings is even
faster if this allows to skip HNTrie.matches() altogether.
---
 src/js/hntrie.js | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/js/hntrie.js b/src/js/hntrie.js
index 8b3dd18e09a90..323144a32133f 100644
--- a/src/js/hntrie.js
+++ b/src/js/hntrie.js
@@ -407,6 +407,8 @@ HNTrieContainer.prototype = {
         this.container = container;
         this.iroot = iroot;
         this.size = size;
+        this.last = -1;
+        this.needle = '';
     },
 
     //--------------------------------------------------------------------------
@@ -548,6 +550,8 @@ HNTrieContainer.prototype = {
 HNTrieContainer.prototype.HNTrieRef.prototype = {
     add: function(hn) {
         if ( this.container.setNeedle(hn).add(this.iroot) === 1 ) {
+            this.last = -1;
+            this.needle = '';
             this.size += 1;
             return true;
         }
@@ -555,6 +559,8 @@ HNTrieContainer.prototype.HNTrieRef.prototype = {
     },
     addJS: function(hn) {
         if ( this.container.setNeedle(hn).addJS(this.iroot) === 1 ) {
+            this.last = -1;
+            this.needle = '';
             this.size += 1;
             return true;
         }
@@ -562,19 +568,33 @@ HNTrieContainer.prototype.HNTrieRef.prototype = {
     },
     addWASM: function(hn) {
         if ( this.container.setNeedle(hn).addWASM(this.iroot) === 1 ) {
+            this.last = -1;
+            this.needle = '';
             this.size += 1;
             return true;
         }
         return false;
     },
     matches: function(needle) {
-        return this.container.setNeedle(needle).matches(this.iroot);
+        if ( needle !== this.needle ) {
+            this.needle = needle;
+            this.last = this.container.setNeedle(needle).matches(this.iroot);
+        }
+        return this.last;
     },
     matchesJS: function(needle) {
-        return this.container.setNeedle(needle).matchesJS(this.iroot);
+        if ( needle !== this.needle ) {
+            this.needle = needle;
+            this.last = this.container.setNeedle(needle).matchesJS(this.iroot);
+        }
+        return this.last;
     },
     matchesWASM: function(needle) {
-        return this.container.setNeedle(needle).matchesWASM(this.iroot);
+        if ( needle !== this.needle ) {
+            this.needle = needle;
+            this.last = this.container.setNeedle(needle).matchesWASM(this.iroot);
+        }
+        return this.last;
     },
     [Symbol.iterator]: function() {
         return {