What if we looked at the dependency tree as a more broader graph instead of a tree?

[shubhbapna]

Currently, given a dependency file we produce a project tree to map relations between projects.
We use this mapping to:

• Generate the list of upstream projects for a given project
• Generate the list of full downstream projects for a given project

Now consider the following dependency file: droolsjbmp-build-bootstrap

Notice some issues that make the tree implementation difficult:

• duplicate edges:
  • appformer depends on lienzo-core, droolsjbpm-build-bootstrap, lienzo-tests, kiegroup/kie-soup even though to build lienzo-tests and kie-soup we would have had to build lienzo-core and droolsjbpm-build-bootstrap anyways. So we can simplify appformer dependencies to lienzo-tests and kie-soup.
  • Since we maintain a list of parents and children node in our tree implementation these duplicates increase the number of parents for appformer and number of children for lienzo-core, droolsjbpm-build-bootstrap
• Cycle: it has a cycle (appformer -> lienzo-tests -> lienzo-core -> appformer). But trees shouldn't have cycles
• Our current tree structure needs to store parent and children. This produces a circular json which comes with it's own set of problems
• To produce the list, we traverse the tree, find the leaves first then again traverse the tree etc etc

Proposed new graph structure:

• For each project we will create a node where we store the project name, array of outgoing edges, array of incoming edges
  • Array of outgoing edges:
    • It is just an array of project names that are required to build the given node
  • Array of incoming edges:
    • It is just an array of project names that depend on the given node

How can graph help?

• No circular json! Just need to store the project names.
• Duplicate edges won't matter
• Cycles are okay in graphs
• We just have to run DFS :)
• Maintenance becomes easier

[Ginxo]

I agree, I'm understanding project name will be treated as the node identifier, right?
Thanks for the proposal, I think this would be a great achievement

[shubhbapna]

Yep!

[Ginxo]

solved by #88