XSSAuditor performance regression in M26

Source/core/html/parser/XSSAuditor.cpp

 /*
  * Copyright (C) 2011 Adam Barth. All Rights Reserved.
  * Copyright (C) 2011 Daniel Bates (dbates@intudata.com).
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 209 matching lines @@
     , m_didSendValidCSPHeader(false)
     , m_didSendValidXSSProtectionHeader(false)
     , m_state(Uninitialized)
     , m_scriptTagNestingLevel(0)
     , m_encoding(UTF8Encoding())
 {
     // Although tempting to call init() at this point, the various objects
     // we want to reference might not all have been constructed yet.
 }
 
+void XSSAuditor::initForFragment()
+{
+    ASSERT(isMainThread());
+    ASSERT(m_state == Uninitialized);
+    m_state = Initialized;
+    // When parsing a fragment, we don't enable the XSS auditor because it's
+    // too much overhead.
+    ASSERT(!m_isEnabled);
+}
+
 void XSSAuditor::init(Document* document, XSSAuditorDelegate* auditorDelegate)
 {
     const size_t miniumLengthForSuffixTree = 512; // FIXME: Tune this parameter.
     const int suffixTreeDepth = 5;
 
     ASSERT(isMainThread());
     if (m_state == Initialized)
         return;
     ASSERT(m_state == Uninitialized);
     m_state = Initialized;
@@ skipping 77 matching lines @@
 
     if (m_decodedURL.isEmpty() && m_decodedHTTPBody.isEmpty()) {
         m_isEnabled = false;
         return;
     }
 }
 
 PassOwnPtr<XSSInfo> XSSAuditor::filterToken(const FilterTokenRequest& request)
 {
     ASSERT(m_state == Initialized);
     if (!m_isEnabled || m_xssProtection == ContentSecurityPolicy::AllowReflectedXSS)

[tonyg, 2013/04/22 16:06:01]

Would it be cleaner to flip the order of the !m_isEnabled and
m_state==Initialized checks here rather than to lie about m_state in
initForFragment()?

[abarth-chromium, 2013/04/22 18:14:55]

Yeah, that makes a lot of sense.

         return nullptr;
 
     bool didBlockScript = false;
     if (request.token.type() == HTMLToken::StartTag)
         didBlockScript = filterStartToken(request);
     else if (m_scriptTagNestingLevel) {
         if (request.token.type() == HTMLToken::Character)
             didBlockScript = filterCharacterToken(request);
         else if (request.token.type() == HTMLToken::EndTag)
             filterEndToken(request);
@@ skipping 389 matching lines @@
 
 bool XSSAuditor::isSafeToSendToAnotherThread() const
 {
     return m_documentURL.isSafeToSendToAnotherThread()
         && m_decodedURL.isSafeToSendToAnotherThread()
         && m_decodedHTTPBody.isSafeToSendToAnotherThread()
         && m_cachedDecodedSnippet.isSafeToSendToAnotherThread();
 }
 
 } // namespace WebCore