From f9036dbaecbff5d7a4eceb018d40e51902febb80 Mon Sep 17 00:00:00 2001
From: Andrzej Kapolka <drzej.k@gmail.com>
Date: Wed, 9 Jul 2014 14:22:33 -0700
Subject: [PATCH] Lock the attribute mapping, since it can be accessed from
 multiple threads.

---
 libraries/metavoxels/src/AttributeRegistry.cpp | 9 +++++++++
 libraries/metavoxels/src/AttributeRegistry.h   | 8 +++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/libraries/metavoxels/src/AttributeRegistry.cpp b/libraries/metavoxels/src/AttributeRegistry.cpp
index 33ce298859..b43759fa4f 100644
--- a/libraries/metavoxels/src/AttributeRegistry.cpp
+++ b/libraries/metavoxels/src/AttributeRegistry.cpp
@@ -9,7 +9,9 @@
 //  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
 //
 
+#include <QReadLocker>
 #include <QScriptEngine>
+#include <QWriteLocker>
 
 #include "AttributeRegistry.h"
 #include "MetavoxelData.h"
@@ -69,6 +71,7 @@ AttributePointer AttributeRegistry::registerAttribute(AttributePointer attribute
     if (!attribute) {
         return attribute;
     }
+    QWriteLocker locker(&_attributesLock);
     AttributePointer& pointer = _attributes[attribute->getName()];
     if (!pointer) {
         pointer = attribute;
@@ -77,9 +80,15 @@ AttributePointer AttributeRegistry::registerAttribute(AttributePointer attribute
 }
 
 void AttributeRegistry::deregisterAttribute(const QString& name) {
+    QWriteLocker locker(&_attributesLock);
     _attributes.remove(name);
 }
 
+AttributePointer AttributeRegistry::getAttribute(const QString& name) {
+    QReadLocker locker(&_attributesLock);
+    return _attributes.value(name);
+}
+
 QScriptValue AttributeRegistry::getAttribute(QScriptContext* context, QScriptEngine* engine) {
     return engine->newQObject(getInstance()->getAttribute(context->argument(0).toString()).data(), QScriptEngine::QtOwnership,
         QScriptEngine::PreferExistingWrapperObject);
diff --git a/libraries/metavoxels/src/AttributeRegistry.h b/libraries/metavoxels/src/AttributeRegistry.h
index 7dc2e110b8..23e3c1fa97 100644
--- a/libraries/metavoxels/src/AttributeRegistry.h
+++ b/libraries/metavoxels/src/AttributeRegistry.h
@@ -14,6 +14,7 @@
 
 #include <QHash>
 #include <QObject>
+#include <QReadWriteLock>
 #include <QSharedPointer>
 #include <QString>
 #include <QWidget>
@@ -61,11 +62,14 @@ public:
     void deregisterAttribute(const QString& name);
     
     /// Retrieves an attribute by name.
-    AttributePointer getAttribute(const QString& name) const { return _attributes.value(name); }
+    AttributePointer getAttribute(const QString& name);
     
     /// Returns a reference to the attribute hash.
     const QHash<QString, AttributePointer>& getAttributes() const { return _attributes; }
     
+    /// Returns a reference to the attributes lock.
+    QReadWriteLock& getAttributesLock() { return _attributesLock; }    
+    
     /// Returns a reference to the standard SharedObjectPointer "guide" attribute.
     const AttributePointer& getGuideAttribute() const { return _guideAttribute; }
     
@@ -92,6 +96,8 @@ private:
     static QScriptValue getAttribute(QScriptContext* context, QScriptEngine* engine);
 
     QHash<QString, AttributePointer> _attributes;
+    QReadWriteLock _attributesLock;
+    
     AttributePointer _guideAttribute;
     AttributePointer _spannersAttribute;
     AttributePointer _colorAttribute;