libcamera, android, cam, gstreamer, qcam, v4l2: Reuse Request

Allow reuse of the Request object by implementing reuse(). This means
the applications now have the responsibility of freeing the Request
objects, so make all libcamera users (cam, qcam, v4l2-compat, gstreamer,
android) do so.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

2 files changed, 35 insertions, 13 deletions

diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp
index 3565f369..35d3beda 100644
--- a/src/v4l2/v4l2_camera.cpp
+++ b/src/v4l2/v4l2_camera.cpp
@@ -49,6 +49,8 @@ int V4L2Camera::open(StreamConfiguration *streamConfig)
 
 void V4L2Camera::close()
 {
+	requestPool_.clear();
+
 	delete bufferAllocator_;
 	bufferAllocator_ = nullptr;
 
@@ -96,6 +98,7 @@ void V4L2Camera::requestComplete(Request *request)
 	if (ret != sizeof(data))
 		LOG(V4L2Compat, Error) << "Failed to signal eventfd POLLIN";
 
+	request->reuse();
 	{
 		MutexLocker locker(bufferMutex_);
 		bufferAvailableCount_++;
@@ -154,16 +157,30 @@ int V4L2Camera::validateConfiguration(const PixelFormat &pixelFormat,
 	return 0;
 }
 
-int V4L2Camera::allocBuffers([[maybe_unused]] unsigned int count)
+int V4L2Camera::allocBuffers(unsigned int count)
 {
 	Stream *stream = config_->at(0).stream();
 
-	return bufferAllocator_->allocate(stream);
+	int ret = bufferAllocator_->allocate(stream);
+	if (ret < 0)
+		return ret;
+
+	for (unsigned int i = 0; i < count; i++) {
+		std::unique_ptr<Request> request = camera_->createRequest(i);
+		if (!request) {
+			requestPool_.clear();
+			return -ENOMEM;
+		}
+		requestPool_.push_back(std::move(request));
+	}
+
+	return ret;
 }
 
 void V4L2Camera::freeBuffers()
 {
 	pendingRequests_.clear();
+	requestPool_.clear();
 
 	Stream *stream = config_->at(0).stream();
 	bufferAllocator_->free(stream);
@@ -192,9 +209,9 @@ int V4L2Camera::streamOn()
 
 	isRunning_ = true;
 
-	for (std::unique_ptr<Request> &req : pendingRequests_) {
+	for (Request *req : pendingRequests_) {
 		/* \todo What should we do if this returns -EINVAL? */
-		ret = camera_->queueRequest(req.release());
+		ret = camera_->queueRequest(req);
 		if (ret < 0)
 			return ret == -EACCES ? -EBUSY : ret;
 	}
@@ -206,8 +223,12 @@ int V4L2Camera::streamOn()
 
 int V4L2Camera::streamOff()
 {
-	if (!isRunning_)
+	if (!isRunning_) {
+		for (std::unique_ptr<Request> &req : requestPool_)
+			req->reuse();
+
 		return 0;
+	}
 
 	pendingRequests_.clear();
 
@@ -226,12 +247,11 @@ int V4L2Camera::streamOff()
 
 int V4L2Camera::qbuf(unsigned int index)
 {
-	std::unique_ptr<Request> request =
-		std::unique_ptr<Request>(camera_->createRequest(index));
-	if (!request) {
-		LOG(V4L2Compat, Error) << "Can't create request";
-		return -ENOMEM;
+	if (index >= requestPool_.size()) {
+		LOG(V4L2Compat, Error) << "Invalid index";
+		return -EINVAL;
 	}
+	Request *request = requestPool_[index].get();
 
 	Stream *stream = config_->at(0).stream();
 	FrameBuffer *buffer = bufferAllocator_->buffers(stream)[index].get();
@@ -242,11 +262,11 @@ int V4L2Camera::qbuf(unsigned int index)
 	}
 
 	if (!isRunning_) {
-		pendingRequests_.push_back(std::move(request));
+		pendingRequests_.push_back(request);
 		return 0;
 	}
 
-	ret = camera_->queueRequest(request.release());
+	ret = camera_->queueRequest(request);
 	if (ret < 0) {
 		LOG(V4L2Compat, Error) << "Can't queue request";
 		return ret == -EACCES ? -EBUSY : ret;
diff --git a/src/v4l2/v4l2_camera.h b/src/v4l2/v4l2_camera.h
index 1fc5ebef..a6c35a2e 100644
--- a/src/v4l2/v4l2_camera.h
+++ b/src/v4l2/v4l2_camera.h
@@ -76,7 +76,9 @@ private:
 	std::mutex bufferLock_;
 	FrameBufferAllocator *bufferAllocator_;
 
-	std::deque<std::unique_ptr<Request>> pendingRequests_;
+	std::vector<std::unique_ptr<Request>> requestPool_;
+
+	std::deque<Request *> pendingRequests_;
 	std::deque<std::unique_ptr<Buffer>> completedBuffers_;
 
 	int efd_;