From 88585592470af655c96b06585b266e1e91c3fe1f Mon Sep 17 00:00:00 2001
From: howard-stearns <howard.stearns@gmail.com>
Date: Mon, 21 Mar 2016 14:02:18 -0700
Subject: [PATCH] Make access to entityToElementMap thread safe.

---
 libraries/entities/src/EntityTree.cpp | 14 +++++++++-----
 libraries/entities/src/EntityTree.h   |  1 +
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/libraries/entities/src/EntityTree.cpp b/libraries/entities/src/EntityTree.cpp
index 3b68725b06..af1c2e71aa 100644
--- a/libraries/entities/src/EntityTree.cpp
+++ b/libraries/entities/src/EntityTree.cpp
@@ -57,10 +57,13 @@ void EntityTree::eraseAllOctreeElements(bool createNewRoot) {
     if (_simulation) {
         _simulation->clearEntities();
     }
-    foreach (EntityTreeElementPointer element, _entityToElementMap) {
-        element->cleanupEntities();
+    {
+        QWriteLocker locker(&_entityToElementLock);
+        foreach(EntityTreeElementPointer element, _entityToElementMap) {
+            element->cleanupEntities();
+        }
+        _entityToElementMap.clear();
     }
-    _entityToElementMap.clear();
     Octree::eraseAllOctreeElements(createNewRoot);
 
     resetClientEditStats();
@@ -1229,13 +1232,13 @@ int EntityTree::processEraseMessageDetails(const QByteArray& dataByteArray, cons
 }
 
 EntityTreeElementPointer EntityTree::getContainingElement(const EntityItemID& entityItemID)  /*const*/ {
-    // TODO: do we need to make this thread safe? Or is it acceptable as is
+    QReadLocker locker(&_entityToElementLock);
     EntityTreeElementPointer element = _entityToElementMap.value(entityItemID);
     return element;
 }
 
 void EntityTree::setContainingElement(const EntityItemID& entityItemID, EntityTreeElementPointer element) {
-    // TODO: do we need to make this thread safe? Or is it acceptable as is
+    QWriteLocker locker(&_entityToElementLock);
     if (element) {
         _entityToElementMap[entityItemID] = element;
     } else {
@@ -1245,6 +1248,7 @@ void EntityTree::setContainingElement(const EntityItemID& entityItemID, EntityTr
 
 void EntityTree::debugDumpMap() {
     qCDebug(entities) << "EntityTree::debugDumpMap() --------------------------";
+    QReadLocker locker(&_entityToElementLock);
     QHashIterator<EntityItemID, EntityTreeElementPointer> i(_entityToElementMap);
     while (i.hasNext()) {
         i.next();
diff --git a/libraries/entities/src/EntityTree.h b/libraries/entities/src/EntityTree.h
index 1c5a696b17..e6507e66a4 100644
--- a/libraries/entities/src/EntityTree.h
+++ b/libraries/entities/src/EntityTree.h
@@ -290,6 +290,7 @@ protected:
 
     EntityItemFBXService* _fbxService;
 
+    mutable QReadWriteLock _entityToElementLock;
     QHash<EntityItemID, EntityTreeElementPointer> _entityToElementMap;
 
     EntitySimulation* _simulation;