Re: [PATCH 1/7] gitlab-ci: speed up installation of Git for Windows SDK

[Junio C Hamano <gitster@pobox.com>]

Patrick Steinhardt <ps@pks.im> writes:

> The "build:mingw64" job on GitLab CI downloads the minimal Git for
> Windows SDK on every run and then extracts it via `Expand-Archive`,
> which is expensive.
>
> Improve this by caching the SDK and by using tar(1) instead of
> `Expand-Archive`.
> Note that caching actually only gives us a win of a
> couple seconds. The bigger win here is using tar(1), which speeds up
> extracting the archive from 3 minutes to about 10 seconds. Regardless of

Wow, is a tool to move the bits from one part of a rusted iron
surface to another part really so much more expensive compared to
another tool to move the same bits, to make a difference that is
worth doing this?

> that though, caching the SDK feels like a sensible thing to do as it
> removes one step that may spuriously fail.

One thing that may make readers curious is if we need to worry about
this cached copy going stale.

> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  .gitlab-ci.yml     |  9 ++++++++-
>  ci/install-sdk.ps1 | 26 ++++++++++++++++++++------
>  2 files changed, 28 insertions(+), 7 deletions(-)
>
> diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
> index 9b7698a0037..15419a954b3 100644
> --- a/.gitlab-ci.yml
> +++ b/.gitlab-ci.yml
> @@ -127,9 +127,16 @@ build:mingw64:
>      - saas-windows-medium-amd64
>    variables:
>      NO_PERL: 1
> +  cache:
> +    key:
> +      files:
> +        - ci/install-sdk.ps1
> +        - ci/install-dependencies.ps1
> +    paths:
> +      - .dependencies
>    before_script:
>      - *windows_before_script
> -    - ./ci/install-sdk.ps1 -directory "git-sdk"
> +    - ./ci/install-sdk.ps1 -Directory "git-sdk"

Is this change essential to understand this patch, or is it an
unrelated general clean-up to follow some style rules?  I notice
that ...

>      - ./ci/install-dependencies.ps1 -Mingw
>    script:
>      # The minimal SDK's profile resets PATH.
> diff --git a/ci/install-sdk.ps1 b/ci/install-sdk.ps1
> index 66f24838a40..1dbcef04a18 100755
> --- a/ci/install-sdk.ps1
> +++ b/ci/install-sdk.ps1
> @@ -1,12 +1,26 @@
>  param(
> -    [string]$directory='git-sdk',
> -    [string]$url='https://github.com/git-for-windows/git-sdk-64/releases/download/ci-artifacts/git-sdk-x86_64-minimal.zip'
> +    [string]$Directory='git-sdk',
> +    [string]$URL='https://github.com/git-for-windows/git-sdk-64/releases/download/ci-artifacts/git-sdk-x86_64-minimal.zip',
> +    [string]$DownloadDirectory='.dependencies'

... we are making a matching change here to upcase the parameter
names here.