Does errno matter?

[AndyCash1]

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I've been using aravis for a while with GigEVision cameras using Go, starting with https://github.com/thinkski/go-aravis as the cgo wrapper, and its working great.

I'm now starting to use a USB3 camera, and have built aravis with USB3 support. Since this, regardless of if I use a USB3 camera or not, arv_camera_new always gives errno(11), resource temporarily unavailable. This is coming from cgo, which will return the errno for any C function call.

It doesn't look like anything in aravis is setting the errno. And when I simply ignore the errno, it seems to work fine. I wanted to ask if the errno is something that should be looked at, or can be safely ignored. Thanks!

[EmmanuelP]

Hi Andy,

I did not care about errno until then. Since it only happens since you have compiled usb support, and even if you don't use a USB device, I guess errno is set somewhere in arvuvinterface.

You may for now ignore errno. But it would be a good idea to try to locate which function call is setting errno to 11.

[deadprogram]

Not sure if related to this specific issue, but I also get errno(11) "resource temporarily unavailable" sometimes

I am also using the go-aravis wrapper to call Aravis from Go using CGo, however I am not using USB3 support.

This happens on many of the calls to arv_stream_try_pop_buffer() by way of the go-aravis wrapper function TryPopBuffer() https://github.com/thinkski/go-aravis/blob/master/stream.go#L29 probably when the buffer in question is not yet ready. Not sure if this is the expected behaviour here or not.

[AndyCash1]

Yeah that was causing my errors as well. I ended up ignoring errno and doing a nil check, using IS_ARV_BUFFER, and also arv_buffer_get_status to validate the buffer. From looking at many of the C examples, arv_buffer_get_status is primarily used to error check, so that seemed reasonable to me.