TEP-0090 Matrix: Refactor Matrix FanOut() to use the Matrix Struct

[EmmaMunley]

[TEP-0090: Matrix] introduced Matrix to the PipelineTask specification such that the PipelineTask executes a list of TaskRuns or Runs in parallel with the specified list of inputs for a Parameter or with different combinations of the inputs for a set of Parameters.

This PR refactors the FanOut() function to use the Matrix struct instead of the old []Params.

/kind cleanup

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[pritidesai]

Can we please declare this function as a member function:

func (m Matrix) FanOut() Combinations {
	var combinations Combinations
	for _, parameter := range m.Params {
		combinations = combinations.fanOut(parameter)
	}
	return combinations
}

just like:

func (combinations Combinations) fanOut(param v1beta1.Param) Combinations {

[EmmaMunley]

/hold for now until we clarify how this works since the existing logic has matrix.FanOut()

matrixCombinations := matrix.FanOut(rpt.PipelineTask.Matrix.Params).ToMap()

[EmmaMunley]

Chatted with Priti and decided for now we will leave as is. The way that Matrix pkg is right now does not make it is easy to simply refactor FanOut() as a member function.
/hold cancel
/assign @pritidesai

[jerop]

@EmmaMunley is it because of import cycle?

[EmmaMunley]

Yes. We would have to move FanOut() to where the type Matrix is defined in Pipeline_types.go, however Combinations is defined within Matrix and it doesn't make sense to have Combinations defined in the API.

[pritidesai]

thanks @EmmaMunley!

Yup, it results in cyclic imports 🙃 and bringing combinations in pkg/apis/ might not be desirable based on recent discussions of avoiding copy/paste in multiple APIs.

@jerop I am happy to merge this for now but wanted to understand this package github.com/tektoncd/pipeline/pkg/matrix. Also, the package name matrix being same as the type Matrix caused confusion in https://github.com/tektoncd/pipeline/blob/main/pkg/reconciler/pipelinerun/pipelinerun.go#L837

matrix.FanOut(rpt.PipelineTask.Matrix.Params).ToMap()

[pritidesai]

Matrix type is defined in pkg/apis/pipeline/v1beta1/ with a couple of member functions. Matrix type has two fields: Params []Param and Include []MatrixInclude

https://github.com/tektoncd/pipeline/blob/main/pkg/apis/pipeline/v1beta1/pipeline_types.go#L165

pipeline/pkg/apis/pipeline/v1beta1/pipeline_types.go

Line 329 in 90f33a6

func (matrix *Matrix) MatrixHasInclude() bool {

pipeline/pkg/apis/pipeline/v1beta1/pipeline_types.go

Line 334 in 90f33a6

func (matrix *Matrix) MatrixHasParams() bool {

There is a matrix package with matrix.go and matrix_types.go with a combinations defined. Combination type has two fields: MatrixID string and Params []v1beta1.Param.

Can we replace combination type with matrix struct and add MatrixID to matrix struct? This way we do not have maintain a separate struct and a package.

[jerop]

@pritidesai thanks for the suggestions, refactored the implementation - #6282

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[lbernick]

/lgtm

[pritidesai]

thank you @lbernick for merging this PR, was hoping to hear back from @jerop on the comments ⬆️ so that they are not lost (spent quite a bit of typing last night 🤣). Have opened an issue for it to facilitate further discussion. Thanks!

[lbernick]

Sorry Priti, I didn't realize you had unresolved comments! Thanks for opening an issue to track.

[QuanZhang-William]

I'm curious about what is the motivation for this change? 🤔