The pageview counter designed for this site, i.e., the one at the footer. I estimate that 99% of people nowadays use Python when dealing with MNIST. But this site promises not to use Python, thus chooses C++ for this gadget. The overall experience is not much complicated than Python, while it is expected to save a lot of carbons😁.

Implementation

Download MNIST testset and uncompress by gzip. LeCun said that the first 5k images are easier, so the program only use the first 5k images. Counter is saved into a file fcounter.db. Digits are randomly chosen from test images, assembled into one PNG image, (with Magick++ which is easier), then returned to the webserver via FastCGI.

Code

The code is put in public domain now.

Compilation

  • Install APT packages libmagick++-dev libfcgi-dev.
  • For FastCGI++, compiler flags -lfcgi++ -lfcgi are required.
  • CMake can found Magick++ automatically. Otherwise, append compiler flags from magick++-config.

Deployment

I use spawn-fcgi to spawn the compiled binary (set as a service in systemd). Most webservers support FastCGI, a reverse proxy to the port set by spawn-fcgi completes the deployment. I use Caddy:

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reverse_proxy /counter.png localhost:21930 {
  transport fastcgi
}

Add /counter.png to the footer HTML, then you see digits bump on refresh. Go through internal links will not bump if the explorer cached the image.