[libcamera-devel] [PATCH v2 2/3] libcamera: use const reference for range loops

[Christian Rauch]

Hi Laurent,

I am not sure how to update the commit message via email :-) So I will
just paste the new commit message here:

    libcamera: use const reference for range loops



    A const reference prevents unnecessary copies of the loop elements.
Also,

    this changes looping over controls in
PipelineHandlerUVC::processControls

    to structured bindings.



    Signed-off-by: Christian Rauch <Rauch.Christian at gmx.de>

    Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>


Best,
Christian


Am 16.08.22 um 21:26 schrieb Laurent Pinchart:
> Hi Christian,
>
> Thank you for the patch.
>
> On Tue, Aug 16, 2022 at 08:38:25PM +0200, Christian Rauch via libcamera-devel wrote:
>> A const reference prevents unnecessary copies of the loop elements.
>
> This should also mention that PipelineHandlerUVC::processControls()
> switches to structured bindings. With that,
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>
> You can propose an updated commit message in a reply to this e-mail,
> there's no need to resubmit the series.
>
>> Signed-off-by: Christian Rauch <Rauch.Christian at gmx.de>
>> ---
>>  src/libcamera/camera_manager.cpp             | 2 +-
>>  src/libcamera/device_enumerator.cpp          | 2 +-
>>  src/libcamera/pipeline/uvcvideo/uvcvideo.cpp | 6 +-----
>>  src/libcamera/pipeline/vimc/vimc.cpp         | 2 +-
>>  src/libcamera/pipeline_handler.cpp           | 2 +-
>>  5 files changed, 5 insertions(+), 9 deletions(-)
>>
>> diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp
>> index 70d73822..7ff4bc6f 100644
>> --- a/src/libcamera/camera_manager.cpp
>> +++ b/src/libcamera/camera_manager.cpp
>> @@ -189,7 +189,7 @@ void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
>>  {
>>  	MutexLocker locker(mutex_);
>>
>> -	for (std::shared_ptr<Camera> c : cameras_) {
>> +	for (const std::shared_ptr<Camera> &c : cameras_) {
>>  		if (c->id() == camera->id()) {
>>  			LOG(Camera, Fatal)
>>  				<< "Trying to register a camera with a duplicated ID '"
>> diff --git a/src/libcamera/device_enumerator.cpp b/src/libcamera/device_enumerator.cpp
>> index d1258050..f2e055de 100644
>> --- a/src/libcamera/device_enumerator.cpp
>> +++ b/src/libcamera/device_enumerator.cpp
>> @@ -161,7 +161,7 @@ std::unique_ptr<DeviceEnumerator> DeviceEnumerator::create()
>>
>>  DeviceEnumerator::~DeviceEnumerator()
>>  {
>> -	for (std::shared_ptr<MediaDevice> media : devices_) {
>> +	for (const std::shared_ptr<MediaDevice> &media : devices_) {
>>  		if (media->busy())
>>  			LOG(DeviceEnumerator, Error)
>>  				<< "Removing media device " << media->deviceNode()
>> diff --git a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
>> index fbe02cdc..9cbf126a 100644
>> --- a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
>> +++ b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
>> @@ -340,12 +340,8 @@ int PipelineHandlerUVC::processControls(UVCCameraData *data, Request *request)
>>  {
>>  	ControlList controls(data->video_->controls());
>>
>> -	for (auto it : request->controls()) {
>> -		unsigned int id = it.first;
>> -		ControlValue &value = it.second;
>> -
>> +	for (const auto &[id, value] : request->controls())
>>  		processControl(&controls, id, value);
>> -	}
>>
>>  	for (const auto &ctrl : controls)
>>  		LOG(UVC, Debug)
>> diff --git a/src/libcamera/pipeline/vimc/vimc.cpp b/src/libcamera/pipeline/vimc/vimc.cpp
>> index 153cf849..d2f2e460 100644
>> --- a/src/libcamera/pipeline/vimc/vimc.cpp
>> +++ b/src/libcamera/pipeline/vimc/vimc.cpp
>> @@ -378,7 +378,7 @@ int PipelineHandlerVimc::processControls(VimcCameraData *data, Request *request)
>>  {
>>  	ControlList controls(data->sensor_->controls());
>>
>> -	for (auto it : request->controls()) {
>> +	for (const auto &it : request->controls()) {
>>  		unsigned int id = it.first;
>>  		unsigned int offset;
>>  		uint32_t cid;
>> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
>> index 7d2d00ef..e5cb751c 100644
>> --- a/src/libcamera/pipeline_handler.cpp
>> +++ b/src/libcamera/pipeline_handler.cpp
>> @@ -616,7 +616,7 @@ void PipelineHandler::disconnect()
>>  	 */
>>  	std::vector<std::weak_ptr<Camera>> cameras{ std::move(cameras_) };
>>
>> -	for (std::weak_ptr<Camera> ptr : cameras) {
>> +	for (const std::weak_ptr<Camera> &ptr : cameras) {
>>  		std::shared_ptr<Camera> camera = ptr.lock();
>>  		if (!camera)
>>  			continue;
>