[RFC PATCH v3 19/21] apps: lc-compliance: Run request completion handler in "main" thread

[Barnabás Pőcze]

Currently, `Capture::requestCompleted()` runs in the `CameraManager`'s
thread. This makes it a bit more complicated to use googletest and
report errors in those callbacks since lc-compliance sets up
googletest to throw exceptions on fatal errors / test skip, but
those exceptions are only caught on the "main" thread, the one
running the test suite.

To minimize the burden of dealing with synchronization in tests,
execute `Capture::requestCompleted()` in the event loop's thread
by utilizing `EventLoop::callLater()`.

Signed-off-by: Barnabás Pőcze <pobrn at protonmail.com>
---
 src/apps/lc-compliance/helpers/capture.cpp | 24 +++++++++++++---------
 src/apps/lc-compliance/helpers/capture.h   |  2 +-
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/src/apps/lc-compliance/helpers/capture.cpp b/src/apps/lc-compliance/helpers/capture.cpp
index 4a8627662..5032470d9 100644
--- a/src/apps/lc-compliance/helpers/capture.cpp
+++ b/src/apps/lc-compliance/helpers/capture.cpp
@@ -127,17 +127,13 @@ void Capture::prepareRequests()
 	}
 }
 
-int Capture::queueRequest(libcamera::Request *request)
+void Capture::queueRequest(libcamera::Request *request)
 {
 	if (queueLimit_ && queueCount_ >= *queueLimit_)
-		return 0;
-
-	int ret = camera_->queueRequest(request);
-	if (ret < 0)
-		return ret;
+		return;
 
+	ASSERT_EQ(camera_->queueRequest(request), 0);
 	queueCount_ += 1;
-	return 0;
 }
 
 void Capture::requestComplete(Request *request)
@@ -152,8 +148,7 @@ void Capture::requestComplete(Request *request)
 		<< "Request didn't complete successfully";
 
 	request->reuse(Request::ReuseBuffers);
-	if (queueRequest(request))
-		loop_->exit(-EINVAL);
+	queueRequest(request);
 }
 
 void Capture::start()
@@ -172,7 +167,14 @@ void Capture::start()
 
 	ASSERT_TRUE(allocator_.allocated());
 
-	camera_->requestCompleted.connect(this, &Capture::requestComplete);
+	camera_->requestCompleted.connect(this, [this](libcamera::Request *request) {
+		/* Runs in the CameraManager thread. */
+
+		loop_->callLater([this, request] {
+			/* Run handler in the context of the event loop. */
+			requestComplete(request);
+		}, reinterpret_cast<std::uintptr_t>(this));
+	});
 
 	ASSERT_EQ(camera_->start(), 0) << "Failed to start camera";
 }
@@ -188,6 +190,8 @@ void Capture::stop()
 
 	requests_.clear();
 
+	loop_->cancelLater(reinterpret_cast<std::uintptr_t>(this));
+
 	for (const auto &cfg : *config_) {
 		int ret = allocator_.free(cfg.stream());
 		EXPECT_EQ(ret, 0) << "Failed to free buffers associated with stream";
diff --git a/src/apps/lc-compliance/helpers/capture.h b/src/apps/lc-compliance/helpers/capture.h
index 48a8dadcb..dacce1fe2 100644
--- a/src/apps/lc-compliance/helpers/capture.h
+++ b/src/apps/lc-compliance/helpers/capture.h
@@ -30,7 +30,7 @@ private:
 	void stop();
 
 	void prepareRequests();
-	int queueRequest(libcamera::Request *request);
+	void queueRequest(libcamera::Request *request);
 	void requestComplete(libcamera::Request *request);
 
 	std::shared_ptr<libcamera::Camera> camera_;
-- 
2.48.1