[libcamera-devel] [RFC PATCH] android: CameraWorker: Cancel pending messages in queue in stop()

[Hirokazu Honda]

CameraWorker::stop() executes Thread::exit() and Thread::wait().
However, intuitively, the two functions doesn't clean up pending
messages in the message queue of the thread. They are rather
cleaned in the destruction of CameraWorker, but CameraWorker's
life time is the same as CameraDevice and thus CameraManager,
which is never destroyed. On the other hand,
Camera3RequestDescriptors are destroyed in CameraDevice::stop().

This causes CameraWorker::Worker::queueRequest() starts to be
executed after CameraWorker::start(), which is after
CameraDevice::stop(). This obviously causes a segmentation fault,
because CameraWorker::Worker::queueRequest() touches
CaptureRequest which is owned by Camera3RequestDescriptor.

This fixes the issue by cancel pending message in thread queue in
CameraWorker::stop() with Thread::dispatchMessages().

Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
---
 src/android/camera_worker.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/android/camera_worker.cpp b/src/android/camera_worker.cpp
index 300ddde0..b68ce9d5 100644
--- a/src/android/camera_worker.cpp
+++ b/src/android/camera_worker.cpp
@@ -62,6 +62,7 @@ void CameraWorker::start()
 
 void CameraWorker::stop()
 {
+	thread_.dispatchMessages(Message::Type::InvokeMessage);
 	thread_.exit();
 	thread_.wait();
 }
-- 
2.31.1.498.g6c1eba8ee3d-goog