test: Add test case for signal delivery across threads

The test case creates a receiver inheriting from Object, connects a
signal to one of its slot, moves the receiver to a different thread,
emits the signal and verifies that it gets delivered in the correct
thread with the expected value.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

test/meson.build

@@ -22,6 +22,7 @@ public_tests = [
 internal_tests = [
     ['camera-sensor',                   'camera-sensor.cpp'],
     ['message',                         'message.cpp'],
+    ['signal-threads',                  'signal-threads.cpp'],
     ['threads',                         'threads.cpp'],
 ]
 

test/signal-threads.cpp

@@ -0,0 +1,125 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * signal-threads.cpp - Cross-thread signal delivery test
+ */
+
+#include <chrono>
+#include <iostream>
+#include <thread>
+
+#include "message.h"
+#include "thread.h"
+#include "test.h"
+#include "utils.h"
+
+using namespace std;
+using namespace libcamera;
+
+class SignalReceiver : public Object
+{
+public:
+	enum Status {
+		NoSignal,
+		InvalidThread,
+		SignalReceived,
+	};
+
+	SignalReceiver()
+		: status_(NoSignal)
+	{
+	}
+
+	Status status() const { return status_; }
+	int value() const { return value_; }
+	void reset()
+	{
+		status_ = NoSignal;
+		value_ = 0;
+	}
+
+	void slot(int value)
+	{
+		if (Thread::current() != thread())
+			status_ = InvalidThread;
+		else
+			status_ = SignalReceived;
+
+		value_ = value;
+	}
+
+private:
+	Status status_;
+	int value_;
+};
+
+class SignalThreadsTest : public Test
+{
+protected:
+	int run()
+	{
+		SignalReceiver receiver;
+		signal_.connect(&receiver, &SignalReceiver::slot);
+
+		/* Test that a signal is received in the main thread. */
+		signal_.emit(0);
+
+		switch (receiver.status()) {
+		case SignalReceiver::NoSignal:
+			cout << "No signal received for direct connection" << endl;
+			return TestFail;
+		case SignalReceiver::InvalidThread:
+			cout << "Signal received in incorrect thread "
+				"for direct connection" << endl;
+			return TestFail;
+		default:
+			break;
+		}
+
+		/*
+		 * Move the object to a thread and verify that the signal is
+		 * correctly delivered, with the correct data.
+		 */
+		receiver.reset();
+		receiver.moveToThread(&thread_);
+
+		thread_.start();
+
+		signal_.emit(42);
+
+		this_thread::sleep_for(chrono::milliseconds(100));
+
+		switch (receiver.status()) {
+		case SignalReceiver::NoSignal:
+			cout << "No signal received for message connection" << endl;
+			return TestFail;
+		case SignalReceiver::InvalidThread:
+			cout << "Signal received in incorrect thread "
+				"for message connection" << endl;
+			return TestFail;
+		default:
+			break;
+		}
+
+		if (receiver.value() != 42) {
+			cout << "Signal received with incorrect value" << endl;
+			return TestFail;
+		}
+
+		return TestPass;
+	}
+
+	void cleanup()
+	{
+		thread_.exit(0);
+		thread_.wait();
+	}
+
+private:
+	Thread thread_;
+
+	Signal<int> signal_;
+};
+
+TEST_REGISTER(SignalThreadsTest)