From 4bafd30ad710a5776b75c77a3036a9f1ec0bc667 Mon Sep 17 00:00:00 2001
From: "dbaron%dbaron.org"
 <dbaron%dbaron.org@18797224-902f-48f8-a5cc-f745e15eee43>
Date: Wed, 21 Jan 2004 04:39:58 +0000
Subject: [PATCH] Assert when shared buffers are used on multiple threads. 
 b=112547  r=jst  sr=darin

git-svn-id: svn://10.0.0.236/trunk@151620 18797224-902f-48f8-a5cc-f745e15eee43
---
 mozilla/xpcom/string/public/nsBufferHandle.h | 25 +++++++++
 mozilla/xpcom/string/src/Makefile.in         |  1 +
 mozilla/xpcom/string/src/nsBufferHandle.cpp  | 55 ++++++++++++++++++++
 3 files changed, 81 insertions(+)
 create mode 100644 mozilla/xpcom/string/src/nsBufferHandle.cpp

diff --git a/mozilla/xpcom/string/public/nsBufferHandle.h b/mozilla/xpcom/string/public/nsBufferHandle.h
index a7c24c36e48..1674ea60469 100755
--- a/mozilla/xpcom/string/public/nsBufferHandle.h
+++ b/mozilla/xpcom/string/public/nsBufferHandle.h
@@ -179,6 +179,21 @@ struct nsStringAllocatorTraits<PRUnichar>
 
 // end of string allocator stuff that needs to move
 
+#ifdef DEBUG
+
+// A small utility class for verifying that all reference counting of
+// shared buffer handles (which are not threadsafe) occurs on a single
+// thread.
+class nsSingleThreadVerifier
+  {
+    public:
+      nsSingleThreadVerifier();
+      void verify() const;
+    protected:
+      void* mThread;
+  };
+
+#endif
 
 template <class CharT>
 class nsSharedBufferHandle
@@ -261,16 +276,26 @@ class nsSharedBufferHandle
     protected:
       PRUint32  mFlags;
       size_type mStorageLength;
+#ifdef DEBUG
+      nsSingleThreadVerifier mSingleThreadVerifier;
+#endif
 
       PRUint32
       get_refcount() const
         {
+#ifdef DEBUG
+          mSingleThreadVerifier.verify();
+#endif
           return mFlags & kRefCountMask;
         }
 
       PRUint32
       set_refcount( PRUint32 aNewRefCount )
         {
+#ifdef DEBUG
+          mSingleThreadVerifier.verify();
+#endif
+
           NS_ASSERTION(aNewRefCount <= kRefCountMask, "aNewRefCount <= kRefCountMask");
 
           mFlags = (mFlags & kFlagsMask) | aNewRefCount;
diff --git a/mozilla/xpcom/string/src/Makefile.in b/mozilla/xpcom/string/src/Makefile.in
index 128e936e9b6..e4f1dee9518 100644
--- a/mozilla/xpcom/string/src/Makefile.in
+++ b/mozilla/xpcom/string/src/Makefile.in
@@ -37,6 +37,7 @@ REQUIRES	= xpcom \
 CPPSRCS		=				\
 		nsASingleFragmentString.cpp	\
 		nsAString.cpp			\
+		nsBufferHandle.cpp		\
 		nsDependentConcatenation.cpp	\
 		nsDependentSubstring.cpp	\
 		nsFragmentedString.cpp		\
diff --git a/mozilla/xpcom/string/src/nsBufferHandle.cpp b/mozilla/xpcom/string/src/nsBufferHandle.cpp
new file mode 100644
index 00000000000..e4565ab55a1
--- /dev/null
+++ b/mozilla/xpcom/string/src/nsBufferHandle.cpp
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is nsBufferHandle.cpp.
+ *
+ * The Initial Developer of the Original Code is L. David Baron.
+ * Portions created by the Initial Developer are Copyright (C) 2002
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   L. David Baron <dbaron@fas.harvard.edu> (original author)
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "nsBufferHandle.h"
+
+#ifdef DEBUG
+
+#include "prthread.h"
+
+nsSingleThreadVerifier::nsSingleThreadVerifier()
+{
+  mThread = PR_GetCurrentThread();
+}
+
+void nsSingleThreadVerifier::verify() const
+{
+  NS_ASSERTION(mThread == PR_GetCurrentThread(),
+               "sharable string being used on multiple threads");
+}
+
+#endif