Android: Fix another "QApplication not on main() thread" crash

The assets file engine is created before main() is called, thus
prepopulate was called before main(). In this function, we created
a QDataStream which internally created a QBuffer which inherits
from QObject. This caused the main thread pointer to be initialized
early, and the old "QApplication is not on the main() thread" warning
and crash returned. The fix is to prepopulate the first time the
file engine is used instead.

Task-number: QTBUG-37444
Change-Id: I2c6e5f1a8ca88b5dc7d8e145fffeb7587dc0e623
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/src/plugins/platforms/android/qandroidassetsfileenginehandler.cpp b/src/plugins/platforms/android/qandroidassetsfileenginehandler.cpp
index b112e265a5..4968b8f188 100644
--- a/src/plugins/platforms/android/qandroidassetsfileenginehandler.cpp
+++ b/src/plugins/platforms/android/qandroidassetsfileenginehandler.cpp
@@ -262,17 +262,20 @@ private:
 AndroidAssetsFileEngineHandler::AndroidAssetsFileEngineHandler()
     : m_assetsCache(std::max(5, qgetenv("QT_ANDROID_MAX_ASSETS_CACHE_SIZE").toInt()))
     , m_hasPrepopulatedCache(false)
+    , m_hasTriedPrepopulatingCache(false)
 {
     m_assetManager = QtAndroid::assetManager();
-    prepopulateCache();
 }
 
 AndroidAssetsFileEngineHandler::~AndroidAssetsFileEngineHandler()
 {
 }
 
-void AndroidAssetsFileEngineHandler::prepopulateCache()
+void AndroidAssetsFileEngineHandler::prepopulateCache() const
 {
+    Q_ASSERT(!m_hasTriedPrepopulatingCache);
+    m_hasTriedPrepopulatingCache = true;
+
     QMutexLocker locker(&m_assetsCacheMutext);
     Q_ASSERT(m_assetsCache.isEmpty());
 
@@ -364,7 +367,11 @@ QAbstractFileEngine * AndroidAssetsFileEngineHandler::create(const QString &file
     if (!path.size())
          path = fileName.left(fileName.length() - 1).toUtf8();
 
+
     m_assetsCacheMutext.lock();
+    if (!m_hasTriedPrepopulatingCache)
+        prepopulateCache();
+
     QSharedPointer<AndroidAssetDir> *aad = m_assetsCache.object(path);
     m_assetsCacheMutext.unlock();
     if (!aad) {