A thin wrapper for actions/checkout

Why?

A few reasons:

• Separate control for submodules' depth
• The submodules' checkout time drastically decreased from 5 minutes to 1:20 for ClickHouse/ClickHouse CI
• Added a very common step to clean out the old code
• --jobs for fetching submodules surprisingly does much less parallel work under the hood than possible, see comparison of different time for different methods.

Submodules checkout difference

Here's the difference between native git submodules' checkout difference and a custom one:

# Prepare repo, launched before each measurment
$ rm -rf ClickHouse/ && time git clone git@github.com:ClickHouse/ClickHouse.git --no-tags --progress --no-recurse-submodules --depth=1 --branch=v23.1.1.3077-stable
...
real	0m9.553s
user	0m4.253s
sys	0m1.359s

$ time (
  git -C ClickHouse submodule sync && \
  git -C ClickHouse submodule init && \
  git config --file ClickHouse/.gitmodules --null --get-regexp path | \
    sed -z 's|.*\n||' | \
    xargs --max-procs=100 --null --no-run-if-empty --max-args=1 \
      git -C ClickHouse submodule update --depth=1 --single-branch
)
...
real	1m48.657s
user	1m34.088s
sys	0m31.364s

$ time (
  git -C ClickHouse submodule sync && \
  git -C ClickHouse submodule init && \
  git -C ClickHouse submodule update --depth=1 --single-branch --jobs=100
)
...
real	2m48.604s
user	1m29.671s
sys	0m30.433s

$ time (
  git -C ClickHouse submodule sync && \
  git -C ClickHouse submodule init && \
  git -C ClickHouse submodule update --depth=1 --single-branch
)
...
real	6m16.782s
user	1m29.483s
sys	0m29.985s

$ time (
  git -C ClickHouse submodule sync && \
  git -C ClickHouse submodule init && \
  git -C ClickHouse submodule update --jobs=100
)
...
real	11m10.315s
user	16m56.844s
sys	1m43.773s

$ time (
  git -C ClickHouse submodule sync && \
  git -C ClickHouse submodule init && \
  git -C ClickHouse submodule update
)
...
real	12m57.784s
user	16m37.995s
sys	1m30.242s

Parameters

• clear-repository: if the repository's directory should be deleted before cloning
• submodules-depth: a separate setting for submodule's checkout

The parameters for the upstream actions/checkout

• fetch-depth
• ref
• submodules
• token