Best way for a task to read from two channels

General Usage
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21

Sure. I think I’m already doing that. I’m sending time stamps in both channels:

Video frames channel: (video_frame, source_camera, time_stamp)

Detection channel: (detection_status, source_camera, time_stamp)

Right now I’m merging these two tuples into a single one and sending it along the merged channel:

((video_frame, source_camera, time_stamp), (detection_status, source_camera, time_stamp))

The time stamps accompanying each frame are acting as serial numbers.

22

Now, that’s really interesting, @tkf.

Maybe I could use multiple dispatch to define two inner methods in the buffer_frames() function to process the data taken from the merged channel?

function buffer_frames()

	function do_work(data::PushFrame)
	
		# Add 'data' (a video frame) to the circular buffer
		
		...
	
	end

	function do_work(data::DetectionNotification)
	
		# Use the frame buffer to create a video on disk
	
	
	end

	for data in incoming_channel

		do_work(data)

	end

end
23

Yes, multiple dispatch works pretty well for this. You can also do simple if _ isa _ dispatch:

for data in incoming_channel
    if data isa PushFrame
        ...
    else
        @assert data isa DetectionNotification
        ...
    end
end

Both approaches are supported by the compiler very well.

24

I thought of using if isa ... as well, but I thought that was considered bad programming practice. It certainly reminds me from my old Python days…

25

Hi @tkf,

Just out of curiosity: could FLoops.jl help me with any of this or is it meant specifically for data parallelism problems?

Thanks a lot for all your help with this.

26

Yes, FLoops.jl is for data parallelism (plus sequential loops). FLoops.jl doesn’t help much if you are juggling channels.