Improve speed of finding dependency cycles

[mpsnp]

Significantly improve speed of finding cycles in dependency tree

Motivation:

At the moment, if dependencies are composed to layers, depending on graph size, it can take minutes and even hours to validate that there are no cycles. Take a look at this issue and a PR in swift-tools-support-core.

Modifications:

Cache already checked graph nodes and reuse results in subsequent visits.

Result:

This modification improved complexity to O(n) instead of O(n!). So package graph of 100 layers with 100 nodes in each layer is checked in 0.2 seconds instead of hours.

[tomerd]

is the verbosity change intentional?

[mpsnp]

@tomerd excuse me, don’t get what you mean. Which verbosity?

[mpsnp]

Okay, you mean to use validManifests instead of validPackages?

[mpsnp]

Actually I think I’ll replace this func by the one from swift-tools-support-core.

[tomerd]

@mpsnp i mean the changes to the plugin runner. they seem accidental / merge issue?

[tomerd]

wrt to using tools-support-core, our goal is to deprecate that library, so leaning on the SwiftPM version is preferred

[tomerd]

@mpsnp interestingly, GitHub showed different diff before (on my phone, so maybe the GitHub iOS App was caching something). this looks fine, just needs a unit test. wrt to using tools-support-core, our goal is to deprecate that library, so leaning on the SwiftPM version is preferred

[mpsnp]

Yeah, that's why i was confused :)

Will update PR today, with unit tests, small naming fixes and checks that nothing else uses function from tools-support-core

[tomerd]

looks like this was done via #5839

[tomerd]

thanks @mpsnp