Re: [PATCH v1 2/2] travis-ci: skip a branch build if equal tag is present

[Lars Schneider <larsxschneider@gmail.com>]

> On 11 Sep 2017, at 16:52, SZEDER Gábor <szeder.dev@gmail.com> wrote:
> 
>> If we push a branch and a tag pointing to the HEAD of this branch,
> 
> s/the HEAD of//, perhaps?
> There is no such thing as "HEAD" (all capital!) of a branch, is it?

Agreed, maybe:
"If we push a branch and a tag pointing to the tip of this branch..."

Would that be OK for you?


>> then Travis CI would run the build twice. This wastes resources and
> 
> Nit: s/run the build/build and test the same tree/, to further stress
> that the two builds are redundant.

OK, will fix.


>> slows the testing.
>> 
>> Add a function to detect this situation and skip the build the branch
> 
> s/skip the build/skip building/ ?

OK, will fix.


>> if appropriate. Invoke this function on every build.
>> 
>> Helped-by: Junio C Hamano <gitster@pobox.com>
>> Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
>> ---
>> ci/lib-travisci.sh | 23 +++++++++++++++++++++++
>> 1 file changed, 23 insertions(+)
>> 
>> diff --git a/ci/lib-travisci.sh b/ci/lib-travisci.sh
>> index 44d6ba2dd2..9c4ae9bdd0 100755
>> --- a/ci/lib-travisci.sh
>> +++ b/ci/lib-travisci.sh
>> @@ -1,5 +1,28 @@
>> # Library of functions shared by all CI scripts
>> 
>> +skip_branch_tip_with_tag () {
>> +	# Sometimes, a branch is pushed at the same time the tag that points
>> +	# at the same commit as the tip of the branch is pushed, and building
>> +	# both at the same time is a waste.
>> +	#
>> +	# Travis gives a tagname e.g. v2.14.0 in $TRAVIS_BRANCH when
>> +	# the build is triggered by a push to a tag.  Let's see if
>> +	# $TRAVIS_BRANCH is exactly at a tag, and if so, if it is
>> +	# different from $TRAVIS_BRANCH.  That way, we can tell if
>> +	# we are building the tip of a branch that is tagged and
>> +	# we can skip the build because we won't be skipping a build
>> +	# of a tag.
>> +
>> +	if TAG=$(git describe --exact-match "$TRAVIS_BRANCH" 2>/dev/null) &&
>> +		$TAG != $TRAVIS_BRANCH
> 
> This must be
> 
>    [ $TAG != $TRAVIS_BRANCH ]
> 
> otherwise the shell will rightfully complain:
> 
>  $ TRAVIS_BRANCH=v2.14.0 ./ci/lib-travisci.sh 
>  ./ci/lib-travisci.sh: line 17: v2.14.0: command not found
> 
> Furthermore, I would prefer quotes around $TAG and $TRAVIS_BRANCH.  If
> either one of those two variables were empty (or contain multiple
> words) at that point, the shell would complain.  Now, I don't think
> that either can end up being empty, so quotes are not necessary, but
> having quotes around them would save future readers from spending
> brain cycles on this unnecessarily.

Agreed. I will fix both things!


Thanks for the review,
Lars