[RenderEngine] Reorder when ImageManager thread starts

Previously the background thread for managing EglImages was intialized
as a member variable before the constructor completed running. In very
rare circumstances this can potentially stop the running thread if the
thread ran before mRunning was initialized. To be less error-prone,
require that ImageManger::initThread be explicitly called to guarantee
that class member variables are well-defined when the thread begins
executing.

In case the issue resurfaces after this change, added a debug log to add
context.

Bug: 146416748
Test: builds. There is no reliable repro, so this fix is speculative
Test: systrace to verify thread is running and configured correctly.
Change-Id: I141c86240b90c7f87c22b3768c2e188293987b76

3 files changed, 15 insertions, 2 deletions

diff --git a/libs/renderengine/gl/GLESRenderEngine.cpp b/libs/renderengine/gl/GLESRenderEngine.cpp
index e11b59ff24..186aa25014 100644
--- a/libs/renderengine/gl/GLESRenderEngine.cpp
+++ b/libs/renderengine/gl/GLESRenderEngine.cpp
@@ -441,6 +441,7 @@ GLESRenderEngine::GLESRenderEngine(const RenderEngineCreationArgs& args, EGLDisp
     }
 
     mImageManager = std::make_unique<ImageManager>(this);
+    mImageManager->initThread();
     mDrawingBuffer = createFramebuffer();
 }
 
diff --git a/libs/renderengine/gl/ImageManager.cpp b/libs/renderengine/gl/ImageManager.cpp
index 5af0e4f857..62566494f0 100644
--- a/libs/renderengine/gl/ImageManager.cpp
+++ b/libs/renderengine/gl/ImageManager.cpp
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+//#define LOG_NDEBUG 0
+#undef LOG_TAG
+#define LOG_TAG "RenderEngine"
 #define ATRACE_TAG ATRACE_TAG_GRAPHICS
 
 #include <pthread.h>
@@ -27,7 +30,10 @@ namespace android {
 namespace renderengine {
 namespace gl {
 
-ImageManager::ImageManager(GLESRenderEngine* engine) : mEngine(engine) {
+ImageManager::ImageManager(GLESRenderEngine* engine) : mEngine(engine) {}
+
+void ImageManager::initThread() {
+    mThread = std::thread([this]() { threadMain(); });
     pthread_setname_np(mThread.native_handle(), "ImageManager");
     // Use SCHED_FIFO to minimize jitter
     struct sched_param param = {0};
@@ -133,6 +139,8 @@ void ImageManager::threadMain() {
             entry.barrier->condition.notify_one();
         }
     }
+
+    ALOGD("Reached end of threadMain, terminating ImageManager thread!");
 }
 
 } // namespace gl
diff --git a/libs/renderengine/gl/ImageManager.h b/libs/renderengine/gl/ImageManager.h
index b5ba554c4f..be67de8367 100644
--- a/libs/renderengine/gl/ImageManager.h
+++ b/libs/renderengine/gl/ImageManager.h
@@ -39,6 +39,10 @@ public:
     };
     ImageManager(GLESRenderEngine* engine);
     ~ImageManager();
+    // Starts the background thread for the ImageManager
+    // We need this to guarantee that the class is fully-constructed before the
+    // thread begins running.
+    void initThread();
     void cacheAsync(const sp<GraphicBuffer>& buffer, const std::shared_ptr<Barrier>& barrier)
             EXCLUDES(mMutex);
     status_t cache(const sp<GraphicBuffer>& buffer);
@@ -57,7 +61,7 @@ private:
     void queueOperation(const QueueEntry&& entry);
     void threadMain();
     GLESRenderEngine* const mEngine;
-    std::thread mThread = std::thread([this]() { threadMain(); });
+    std::thread mThread;
     std::condition_variable_any mCondition;
     std::mutex mMutex;
     std::queue<QueueEntry> mQueue GUARDED_BY(mMutex);