From 576eed9941cfae3bc03ee82cff50aa83c7758fde Mon Sep 17 00:00:00 2001
From: Seth Alves <seth@highfidelity.io>
Date: Thu, 10 Nov 2016 17:12:06 -0800
Subject: [PATCH] use a mutex to avoid a smaller race

---
 libraries/script-engine/src/ScriptEngine.cpp | 21 +++++++++++---------
 libraries/script-engine/src/ScriptEngine.h   |  1 +
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/libraries/script-engine/src/ScriptEngine.cpp b/libraries/script-engine/src/ScriptEngine.cpp
index c6a9874c38..1569a1b9f1 100644
--- a/libraries/script-engine/src/ScriptEngine.cpp
+++ b/libraries/script-engine/src/ScriptEngine.cpp
@@ -1214,16 +1214,19 @@ void ScriptEngine::include(const QStringList& includeFiles, QScriptValue callbac
             QString contents = data[url];
             if (contents.isNull()) {
                 qCDebug(scriptengine) << "Error loading file: " << url << "line:" << __LINE__;
-            } else if (!_includedURLs.contains(url)) {
-                _includedURLs << url;
-                // Set the parent url so that path resolution will be relative
-                // to this script's url during its initial evaluation
-                _parentURL = url.toString();
-                auto operation = [&]() {
-                    evaluate(contents, url.toString());
-                };
+            } else {
+                std::lock_guard<std::recursive_mutex> lock(_lock);
+                if (!_includedURLs.contains(url)) {
+                    _includedURLs << url;
+                    // Set the parent url so that path resolution will be relative
+                    // to this script's url during its initial evaluation
+                    _parentURL = url.toString();
+                    auto operation = [&]() {
+                        evaluate(contents, url.toString());
+                    };
 
-                doWithEnvironment(capturedEntityIdentifier, capturedSandboxURL, operation);
+                    doWithEnvironment(capturedEntityIdentifier, capturedSandboxURL, operation);
+                }
             }
         }
         _parentURL = parentURL;
diff --git a/libraries/script-engine/src/ScriptEngine.h b/libraries/script-engine/src/ScriptEngine.h
index 01088660ff..2b2cb3c81a 100644
--- a/libraries/script-engine/src/ScriptEngine.h
+++ b/libraries/script-engine/src/ScriptEngine.h
@@ -245,6 +245,7 @@ protected:
 
     std::function<bool()> _emitScriptUpdates{ [](){ return true; }  };
 
+    std::recursive_mutex _lock;
 };
 
 #endif // hifi_ScriptEngine_h