[libcamera-devel] [PATCH 07/10] libcamera: pipeline_handler: Split request queueing

[Jacopo Mondi]

In order to prepare to handle synchronization fences at Request
queueing time, split the PipelineHandler::queueRequest() function in
two, by creating a list of waiting requests and introducing a new
doQueueDevice() function that queues Requests to the device in the
order the pipeline has received them.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 include/libcamera/internal/pipeline_handler.h |  7 ++++
 src/libcamera/pipeline_handler.cpp            | 35 +++++++++++++++++--
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
index 41cba44d990f..afb7990ea21b 100644
--- a/include/libcamera/internal/pipeline_handler.h
+++ b/include/libcamera/internal/pipeline_handler.h
@@ -7,7 +7,9 @@
 #ifndef __LIBCAMERA_INTERNAL_PIPELINE_HANDLER_H__
 #define __LIBCAMERA_INTERNAL_PIPELINE_HANDLER_H__
 
+#include <list>
 #include <memory>
+#include <mutex>
 #include <set>
 #include <string>
 #include <sys/types.h>
@@ -76,9 +78,14 @@ private:
 	void mediaDeviceDisconnected(MediaDevice *media);
 	virtual void disconnect();
 
+	void doQueueRequest();
+
 	std::vector<std::shared_ptr<MediaDevice>> mediaDevices_;
 	std::vector<std::weak_ptr<Camera>> cameras_;
 
+	std::mutex waitingRequestsMutex_;
+	std::list<Request *> waitingRequests_;
+
 	const char *name_;
 
 	friend class PipelineHandlerFactory;
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index cada864687ff..38edd00cebad 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -10,6 +10,7 @@
 #include <sys/sysmacros.h>
 
 #include <libcamera/base/log.h>
+#include <libcamera/base/thread.h>
 #include <libcamera/base/utils.h>
 
 #include <libcamera/camera.h>
@@ -312,17 +313,45 @@ void PipelineHandler::queueRequest(Request *request)
 {
 	LIBCAMERA_TRACEPOINT(request_queue, request);
 
+	{
+		MutexLocker lock(waitingRequestsMutex_);
+		waitingRequests_.push_back(request);
+	}
+
+	doQueueRequest();
+}
+
+/**
+ * \brief Queue a request to the device
+ */
+void PipelineHandler::doQueueRequest()
+{
+	Request *request = nullptr;
+	{
+		MutexLocker lock(waitingRequestsMutex_);
+
+		if (!waitingRequests_.size())
+			return;
+
+		request = waitingRequests_.front();
+		waitingRequests_.pop_front();
+	}
+
+	/* Queue Request to the pipeline handler. */
 	Camera *camera = request->_d()->camera();
-	Camera::Private *data = camera->_d();
-	data->queuedRequests_.push_back(request);
+	Camera::Private *camData = camera->_d();
 
-	request->sequence_ = data->requestSequence_++;
+	request->sequence_ = camData->requestSequence_++;
+	camData->queuedRequests_.push_back(request);
 
 	int ret = queueRequestDevice(camera, request);
 	if (ret) {
 		request->cancel();
 		completeRequest(request);
 	}
+
+	/* Try to queue the next Request in the queue, if ready. */
+	doQueueRequest();
 }
 
 /**
-- 
2.33.1