test: threads: Test thread cleanup upon abnormal termination

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@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>

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 +37,35 @@ private:
 	chrono::steady_clock::duration duration_;
 };
 
+class CancelThread : public Thread
+{
+public:
+	CancelThread(bool &cancelled)
+		: cancelled_(cancelled)
+	{
+	}
+
+protected:
+	void run()
+	{
+		cancelled_ = true;
+
+		/*
+		 * Cancel the thread and call a guaranteed cancellation point
+		 * (nanosleep).
+		 */
+		pthread_cancel(pthread_self());
+
+		struct timespec req{ 0, 100*000*000 };
+		nanosleep(&req, nullptr);
+
+		cancelled_ = false;
+	}
+
+private:
+	bool &cancelled_;
+};
+
 class ThreadTest : public Test
 {
 protected:
@@ -118,6 +149,22 @@ 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;
 	}