[libcamera-devel] [PATCH 07/13] gstreamer: Handle completed requests in the libcamerasrc task

[Laurent Pinchart]

Move the request wrap to a completed queue in the request completion
handler to move more of the request completion processing to the
libcamerasrc task. This lowers the amount of time spent in the
completion handler, and prepares for reworking the usage of locks.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/gstreamer/gstlibcamerasrc.cpp | 82 ++++++++++++++++++-------------
 1 file changed, 48 insertions(+), 34 deletions(-)

diff --git a/src/gstreamer/gstlibcamerasrc.cpp b/src/gstreamer/gstlibcamerasrc.cpp
index 02fc913764f8..ee9c83fde777 100644
--- a/src/gstreamer/gstlibcamerasrc.cpp
+++ b/src/gstreamer/gstlibcamerasrc.cpp
@@ -57,10 +57,13 @@ struct RequestWrap {
 
 	std::unique_ptr<Request> request_;
 	std::map<Stream *, GstBuffer *> buffers_;
+
+	GstClockTime latency_;
+	GstClockTime pts_;
 };
 
 RequestWrap::RequestWrap(std::unique_ptr<Request> request)
-	: request_(std::move(request))
+	: request_(std::move(request)), latency_(0), pts_(0)
 {
 }
 
@@ -109,6 +112,7 @@ struct GstLibcameraSrcState {
 	std::unique_ptr<CameraConfiguration> config_;
 	std::vector<GstPad *> srcpads_;
 	std::queue<std::unique_ptr<RequestWrap>> queuedRequests_;
+	std::queue<std::unique_ptr<RequestWrap>> completedRequests_;
 	guint group_id_;
 
 	void requestCompleted(Request *request);
@@ -165,9 +169,6 @@ GstLibcameraSrcState::requestCompleted(Request *request)
 		return;
 	}
 
-	GstClockTime latency;
-	GstClockTime pts;
-
 	if (GST_ELEMENT_CLOCK(src_)) {
 		int64_t timestamp = request->metadata().get(controls::SensorTimestamp);
 
@@ -178,31 +179,11 @@ GstLibcameraSrcState::requestCompleted(Request *request)
 
 		/* Deduced from: sys_now - sys_base_time == gst_now - gst_base_time */
 		GstClockTime sys_base_time = sys_now - (gst_now - gst_base_time);
-		pts = timestamp - sys_base_time;
-		latency = sys_now - timestamp;
-	} else {
-		latency = 0;
-		pts = 0;
+		wrap->pts_ = timestamp - sys_base_time;
+		wrap->latency_ = sys_now - timestamp;
 	}
 
-	for (GstPad *srcpad : srcpads_) {
-		Stream *stream = gst_libcamera_pad_get_stream(srcpad);
-		GstBuffer *buffer = wrap->detachBuffer(stream);
-
-		FrameBuffer *fb = gst_libcamera_buffer_get_frame_buffer(buffer);
-
-		if (pts) {
-			GST_BUFFER_PTS(buffer) = pts;
-			gst_libcamera_pad_set_latency(srcpad, latency);
-		} else {
-			GST_BUFFER_PTS(buffer) = 0;
-		}
-
-		GST_BUFFER_OFFSET(buffer) = fb->metadata().sequence;
-		GST_BUFFER_OFFSET_END(buffer) = fb->metadata().sequence;
-
-		gst_libcamera_pad_queue_buffer(srcpad, buffer);
-	}
+	completedRequests_.push(std::move(wrap));
 
 	gst_task_resume(src_->task);
 }
@@ -316,6 +297,39 @@ gst_libcamera_src_task_run(gpointer user_data)
 		/* The RequestWrap will be deleted in the completion handler. */
 	}
 
+	{
+		GLibLocker lock(GST_OBJECT(self));
+
+		if (!state->completedRequests_.empty()) {
+			wrap = std::move(state->completedRequests_.front());
+			state->completedRequests_.pop();
+		}
+	}
+
+	if (!wrap) {
+		gst_task_pause(self->task);
+		return;
+	}
+
+	for (GstPad *srcpad : state->srcpads_) {
+		Stream *stream = gst_libcamera_pad_get_stream(srcpad);
+		GstBuffer *buffer = wrap->detachBuffer(stream);
+
+		FrameBuffer *fb = gst_libcamera_buffer_get_frame_buffer(buffer);
+
+		if (wrap->pts_) {
+			GST_BUFFER_PTS(buffer) = wrap->pts_;
+			gst_libcamera_pad_set_latency(srcpad, wrap->latency_);
+		} else {
+			GST_BUFFER_PTS(buffer) = 0;
+		}
+
+		GST_BUFFER_OFFSET(buffer) = fb->metadata().sequence;
+		GST_BUFFER_OFFSET_END(buffer) = fb->metadata().sequence;
+
+		gst_libcamera_pad_queue_buffer(srcpad, buffer);
+	}
+
 	GstFlowReturn ret = GST_FLOW_OK;
 	gst_flow_combiner_reset(self->flow_combiner);
 	for (GstPad *srcpad : state->srcpads_) {
@@ -344,13 +358,11 @@ gst_libcamera_src_task_run(gpointer user_data)
 		 * happen in lock step with the callback thread which may want
 		 * to resume the task and might push pending buffers.
 		 */
-		GLibLocker lock(GST_OBJECT(self));
-		bool do_pause = true;
-		for (GstPad *srcpad : state->srcpads_) {
-			if (gst_libcamera_pad_has_pending(srcpad)) {
-				do_pause = false;
-				break;
-			}
+		bool do_pause;
+
+		{
+			GLibLocker lock(GST_OBJECT(self));
+			do_pause = state->completedRequests_.empty();
 		}
 
 		if (do_pause)
@@ -504,6 +516,8 @@ gst_libcamera_src_task_leave([[maybe_unused]] GstTask *task,
 
 	state->cam_->stop();
 
+	state->completedRequests_ = {};
+
 	for (GstPad *srcpad : state->srcpads_)
 		gst_libcamera_pad_set_pool(srcpad, nullptr);
 
-- 
Regards,

Laurent Pinchart