wooga / github-changelog-lib / 25

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jenkins

Improve fiter commit algorithm (#4)

## Description

Implements #3 

The commit filter algorithm in the `DefaultChangeDetector` had an exponential complexity (it was searching multiple times the same paths from nodes to same nodes). This was sufficient for most normal wdk repos or other repos that heavily used only PR's.  But unfortunately it was taking too long on a busy repo like for example a game repo like @wooga/switchcraft .

This  PR changes the algorithm a bit in order to memoize the already computed paths.  It also adds a performance test on a worst-case scenario with 30 merges. (2^30 -> 1 billion OPS)

This reduced the complexity from O( E(branching factor)^V(nodes) ) to O( V^2+E) ). Also to be able to re-use multiple paths to the same head with various iterating base's, I reversed the traversal order. (from base->head), reducing the complexity even more to O(V+E)

## Changes
* ![IMPROVE] Adds memoization to commit filter algorithm to reduce complexity to O(V+E)

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