[libcamera-devel] [PATCH 26/30] cam: Reorganize run() function and merge the two event loops

[Kieran Bingham]

On 07/07/2021 03:19, Laurent Pinchart wrote:
> Reorganize the run() function to make it more readable, and merge the
> two event loops into one as capture and hotplug monitoring don't have to
> be mutually exclusive.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/cam/main.cpp | 60 ++++++++++++++++++++++++------------------------
>  1 file changed, 30 insertions(+), 30 deletions(-)
> 
> diff --git a/src/cam/main.cpp b/src/cam/main.cpp
> index 380c14e02cf0..a3f19d0fa61b 100644
> --- a/src/cam/main.cpp
> +++ b/src/cam/main.cpp
> @@ -5,6 +5,7 @@
>   * main.cpp - cam - The libcamera swiss army knife
>   */
>  
> +#include <atomic>
>  #include <iomanip>
>  #include <iostream>
>  #include <signal.h>
> @@ -48,6 +49,7 @@ private:
>  
>  	std::unique_ptr<CameraManager> cm_;
>  
> +	std::atomic_uint loopUsers_;
>  	EventLoop loop_;
>  };
>  
> @@ -164,14 +166,15 @@ void CamApp::cameraRemoved(std::shared_ptr<Camera> cam)
>  
>  void CamApp::captureDone()
>  {
> -	EventLoop::instance()->exit(0);
> +	if (--loopUsers_ == 0)

Aha, now I see how we're getting multi-session too.

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

> +		EventLoop::instance()->exit(0);
>  }
>  
>  int CamApp::run()
>  {
> -	std::unique_ptr<CameraSession> session;
>  	int ret;
>  
> +	/* 1. List all cameras. */
>  	if (options_.isSet(OptList)) {
>  		std::cout << "Available cameras:" << std::endl;
>  
> @@ -182,6 +185,9 @@ int CamApp::run()
>  		}
>  	}
>  
> +	/* 2. Create the camera session. */
> +	std::unique_ptr<CameraSession> session;
> +
>  	if (options_.isSet(OptCamera)) {
>  		session = std::make_unique<CameraSession>(cm_.get(), options_);
>  		if (!session->isValid()) {
> @@ -195,36 +201,25 @@ int CamApp::run()
>  		session->captureDone.connect(this, &CamApp::captureDone);
>  	}
>  
> -	if (options_.isSet(OptListControls)) {
> +	/* 3. Print camera information. */
> +	if (options_.isSet(OptListControls) ||
> +	    options_.isSet(OptListProperties) ||
> +	    options_.isSet(OptInfo)) {
>  		if (!session) {
> -			std::cout << "Cannot list controls without a camera"
> +			std::cout << "Cannot print camera information without a camera"
>  				  << std::endl;
>  			return -EINVAL;
>  		}
>  
> -		session->listControls();
> -	}
> -
> -	if (options_.isSet(OptListProperties)) {
> -		if (!session) {
> -			std::cout << "Cannot list properties without a camera"
> -				  << std::endl;
> -			return -EINVAL;
> -		}
> -
> -		session->listProperties();
> -	}
> -
> -	if (options_.isSet(OptInfo)) {
> -		if (!session) {
> -			std::cout << "Cannot print stream information without a camera"
> -				  << std::endl;
> -			return -EINVAL;
> -		}
> -
> -		session->infoConfiguration();
> +		if (options_.isSet(OptListControls))
> +			session->listControls();
> +		if (options_.isSet(OptListProperties))
> +			session->listProperties();
> +		if (options_.isSet(OptInfo))
> +			session->infoConfiguration();
>  	}
>  
> +	/* 4. Start capture. */
>  	if (options_.isSet(OptCapture)) {
>  		if (!session) {
>  			std::cout << "Can't capture without a camera" << std::endl;
> @@ -237,12 +232,10 @@ int CamApp::run()
>  			return ret;
>  		}
>  
> -		loop_.exec();
> -
> -		session->stop();
> -		return 0;
> +		loopUsers_++;
>  	}
>  
> +	/* 5. Enable hotplug monitoring. */
>  	if (options_.isSet(OptMonitor)) {
>  		std::cout << "Monitoring new hotplug and unplug events" << std::endl;
>  		std::cout << "Press Ctrl-C to interrupt" << std::endl;
> @@ -250,9 +243,16 @@ int CamApp::run()
>  		cm_->cameraAdded.connect(this, &CamApp::cameraAdded);
>  		cm_->cameraRemoved.connect(this, &CamApp::cameraRemoved);
>  
> -		loop_.exec();
> +		loopUsers_++;
>  	}
>  
> +	if (loopUsers_)
> +		loop_.exec();
> +
> +	/* 6. Stop capture. */
> +	if (options_.isSet(OptCapture))
> +		session->stop();
> +
>  	return 0;
>  }
>  
>