* * * * *

             The case of the regression test regression, part IV

Like all bugs, it was a simple fix once identified—it was just identifying
the bug that was difficult. The bug [1] was due to a semantic change in an
API (Application Programming Interface). Lua [2] has a file interface that
includes a read() function, and the parameter it's given dictates how much to
read. One of the parameters is “a” (or “*a” if you are using Lua 5.1) that
indicates you want to read all possible data until the end-of-file is
reached.

I ended up writing my own read() function to deal with network activity. I
couldn't just open up a normal Lua file object with a network connection
because that doesn't work nicely with event driven programs. An earlier
version of my read() function had a different semantic meaning with “a”—it
just returned any buffered data. It was in a later change where I aligned the
semantics to match Lua's semantics, but forgot to change that bit of code in
the one component. And those semantic changes explain the behavior I was
seeing yesterday [3]. It only took what? A week? To find the culprit.

Now the regression test with the updated code runs as fast as the previous
version.

[1] gopher://gopher.conman.org/0Phlog:2021/08/19.1
[2] https://www.lua.org/
[3] gopher://gopher.conman.org/0Phlog:2021/08/25.1

Email author at [email protected]

You are viewing proxied material from gopher.conman.org. The copyright of proxied material belongs to its original authors. Any comments or complaints in relation to proxied material should be directed to the original authors of the content concerned. Please see the disclaimer for more details.