Merge "ExternalCamera: Fix a deadlock crash using std::thread" into main

SimpleThread::SimpleThread() : mDone(true), mThread() {}

SimpleThread::~SimpleThread() {

    // Safe to call requestExitAndWait() from the destructor because requestExitAndWait() ensures

    // that the thread is joinable before joining on it. This is different from how

    // android::Thread worked.

    // b/399939768: We need to be careful calling requestExitAndWait() from

    // the destructor due to the possibility of

    // OutputThread::threadLoop->~ExternalCameraDeviceSession->~OutputThread::requestExit()

    // resulting in join() called on the calling thread.

    //

    // Rather than removing `requestExitAndExit`, we guard the `join` call

    // in it by checking the thread id.

    requestExitAndWait();

}

    mDone.store(true, std::memory_order_release);

    // Wait for thread to exit if needed. This should happen in no more than one iteration of

    // threadLoop

    // threadLoop. Only call 'join' if this function is called from a thread

    // different from the thread associated with this object. Otherwise call

    // 'detach' so that the threadLoop can finish and clean up itself.

    if (mThread.joinable()) {

        if (mThread.get_id() != std::this_thread::get_id()) {

            mThread.join();

        } else {

            mThread.detach();

        }

    }

    mThread = std::thread();

}