Junk Drawer

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Reading, Refactoring, and RPatterns

22 Jun 2018 in Work

I couldn’t leave the alliteration hanging in a title containing the word ‘patterns’…

Today I Learned

  1. I was not alone in the IXIA troubles
  2. Reading build logs hurts
  3. Refactoring without changing the functional result is fun
  4. I use the right patterns

Icky Ixia

I pinged a colleague in our Mountain View office about the Ixia, and he let our team know that we had done well so far. He had tech support help him when he was where we are now, and he got us rolling with them.

Progress is being made.

On that note, I’d like to add that my colleague Merit McMannis was very pleased with my contributions to the Ixia.

But then, I was pulled off of that and put on…

Build Times

Let me just say one thing about builds, their scripts, and their logs. I expect to be able to jump into a build and know what’s going on at a high level, even if I don’t know the gory details.

This means that

  1. A build should be composed of understandable steps on a high level, like a recipe
  2. Build scripts should reflect on a high level those steps
  3. Logs should output what step is being performed, what actions compose that step, and failures/failure points if any

We can solve 2 with well-refactored scripts, using function names as high- (and low-) level components. We can actually solve 3 with this as well: all of my bash scripts start with something like this–

log() {
  printf '%s\n' "$@" # >&2 # stderr variant
  # variant with script name:
  printf "$0: "'%s\n' "$@"
}

It helps me output simple information when I need it. But we also have to be choosy about what information that is! (If I have to scan through the output of another ./configure --whatever --feature=foobar, I might go mad).

Reflecting 1 in all of this means documentation and a clear understanding of what the process is–in fact, this necessitates 2 and 3 be solved already.

I’m dissecting this today because I have been reassigned to work on improving a build time. Apparently, someone’s feature merge caused a 3x increase in time-to-build. We suspect there’s a duplicate compilation going on, and we’d like to turn that into a make target to do it in parallel, but we can’t find it.

Or, well, I can’t find it. I sifted through a bajillion line error log, knowing already at least what script was the primary builder and what portions of that were possibly causing the problem. I couldn’t find it, between the configure output, make output, errors that get thrown away, and just general lack of informative detail.

I’m sure the information is useful to someone, somewhere. For me, though, not so much. Part of the output was a bash script being run in debug mode (set -x)!

Fortunately, I have free reign to refactor in an effort to diagnose and solve the issue. It might kill the git blame a little bit, but dang does that code look cleaner.

Functional Refactoring

My definition of functional refactoring is

Refactoring which doesn’t alter the function

That is, changing

if [ $var -eq true ]
then
# do a thing
sed 's/func/function' /really/long/file/name
cp /really/long/file/name /other/name
fi

to the equivalent

do_a_thing() {
  local source=/really/long/file/name
  local dest=/other/name
  local sub='s/func/function'
  sed "$sub" "$source"
  cp "$source" "$dest"

main() {
  if [[ "$var" = true ]]; then
    do_a_thing
  fi
}

main

is a valid refactoring. I do this all the time because it helps me pull blocks of code into functions. I even turn developer comments into function names when I don’t know what the code does or why. Theoretically, this is all purely mechanical, it shouldn’t change the net result.

So, I did that all day today. It’s funny how much better things read that way.

Patterns Patterns Patterns

Not much to say here, just a quote from the colleague who assigned me this task:

there’s a lot of ‘crufty’ code here, and based on your coding exercise, you have proper patterns ingrained already

(and reducing build times by 3x is a super awesome project, imo)

well, maybe not quite 3x reduction…but we can round up :wink:

So I’d say my first week finished strong.


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Categories: Work

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