From a0196f0cde408f20cfd1e6c4e58dc5ac2165d485 Mon Sep 17 00:00:00 2001
From: Brad Davis <bdavis@saintandreas.org>
Date: Thu, 31 Dec 2015 15:23:39 -0800
Subject: [PATCH] Ensure we don't hang if the QML thread doesn't shutdown

---
 libraries/gl/src/gl/OffscreenQmlSurface.cpp | 29 ++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/libraries/gl/src/gl/OffscreenQmlSurface.cpp b/libraries/gl/src/gl/OffscreenQmlSurface.cpp
index 26a564e20b..f89f1f5b72 100644
--- a/libraries/gl/src/gl/OffscreenQmlSurface.cpp
+++ b/libraries/gl/src/gl/OffscreenQmlSurface.cpp
@@ -254,10 +254,33 @@ private:
         _quit = true;
     }
 
+    static const uint64_t MAX_SHUTDOWN_WAIT_SECS = 5;
     void stop() {
-        QMutexLocker lock(&_mutex);
-        post(STOP);
-        _cond.wait(&_mutex);
+        if (_thread.isRunning()) {
+            qDebug() << "Stopping QML render thread " << _thread.currentThreadId();
+            {
+                QMutexLocker lock(&_mutex);
+                post(STOP);
+            }
+            auto start = usecTimestampNow();
+            auto now = usecTimestampNow();
+            bool shutdownClean = false;
+            while (now - start < (MAX_SHUTDOWN_WAIT_SECS * USECS_PER_SECOND)) {
+                QMutexLocker lock(&_mutex);
+                if (_cond.wait(&_mutex, MSECS_PER_SECOND)) {
+                    shutdownClean = true;
+                    break;
+                }
+                now = usecTimestampNow();
+            }
+
+            if (!shutdownClean) {
+                qWarning() << "Failed to shut down the QML render thread";
+            }
+
+        } else {
+            qDebug() << "QML render thread already completed";
+        }
     }
 
     bool allowNewFrame(uint8_t fps) {