[libcamera-devel] [PATCH] test: threads: Test thread cleanup upon abnormal termination

[Umang Jain]

Hi Laurent,

On 10/4/22 5:28 AM, Laurent Pinchart via libcamera-devel wrote:
> If a thread ends abnormally (that is, without retuning normally from its
> run() function, for instance with a direct call to pthread_cancel()),
> thread cleanup should still be performed. Add a test to ensure this.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>   test/threads.cpp | 44 ++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 44 insertions(+)
>
> diff --git a/test/threads.cpp b/test/threads.cpp
> index d83b5833998f..7daa76edb00e 100644
> --- a/test/threads.cpp
> +++ b/test/threads.cpp
> @@ -8,7 +8,9 @@
>   #include <chrono>
>   #include <iostream>
>   #include <memory>
> +#include <pthread.h>
>   #include <thread>
> +#include <time.h>
>   
>   #include <libcamera/base/thread.h>
>   
> @@ -35,6 +37,32 @@ private:
>   	chrono::steady_clock::duration duration_;
>   };
>   
> +class CancelThread : public Thread
> +{
> +public:
> +	CancelThread(bool &cancelled)
> +		: cancelled_(cancelled)
> +	{
> +	}
> +
> +protected:
> +	void run()
> +	{
> +		cancelled_ = true;
> +
> +		/* Cancel the thread can call a guaranteed cancellation point. */
> +		pthread_cancel(pthread_self());
> +
> +		struct timespec req{ 0, 100*000*000 };
> +		nanosleep(&req, nullptr);

Took a bit of reading to determine that nanosleep() is a cancellation 
point :)
Maybe it deserves a comment as well, upto you.

Reviewed-by: Umang Jain <umang.jain at ideasonboard.com>
> +
> +		cancelled_ = false;
> +	}
> +
> +private:
> +	bool &cancelled_;
> +};
> +
>   class ThreadTest : public Test
>   {
>   protected:
> @@ -118,6 +146,22 @@ protected:
>   			return TestFail;
>   		}
>   
> +		/* Test thread cleanup upon abnormal termination. */
> +		bool cancelled = false;
> +		bool finished = false;
> +
> +		thread = std::make_unique<CancelThread>(cancelled);
> +		thread->finished.connect(this, [&finished]() { finished = true; });
> +
> +		thread->start();
> +		thread->exit(0);
> +		thread->wait(chrono::milliseconds(1000));
> +
> +		if (!cancelled || !finished) {
> +			cout << "Cleanup failed upon abnormal termination" << endl;
> +			return TestFail;
> +		}
> +
>   		return TestPass;
>   	}
>