Does Riverpod do Topological Sorting?

[kartal-ocell]

So providers can use other providers, and this forms a dag of dependencies. Does Riverpod take care of topologically sorting the resulting graph? As an example, if there are three providers, A, B and C, where B uses A and C uses the other two, and A rebuilds, is it possible that C might rebuild before B, leading to an efficiency where it rebuilds again after B rebuilds?

[rrousselGit]

Technically, the fact that providers can use other providers doesn't form a dag on its own. The graph could be cyclic.
Riverpod goes out of its way to make it an error if you make a cycle though, to ensure we do have a unidirected graph.

This enables Riverpod to guaranteee that providers will update in the optimal order. There's a bunch of tests for it
Your scenario is covered here

riverpod/packages/riverpod/test/framework/visit_states_test.dart

Line 41 in 8e1098c

test('diamond graph', () {

Given:

     A
   /   \
  B     C
    \  /
     D

The only legal orders are:

[a, b, c, d],
[a, c, b, d],

We can't have a chain of rebuild like a > b > d + c > d, and d provider will always rebuild last.

Riverpod doesn't maintain a "sorted graph" though (because the graph's shape tends to change often).
It just does a breadth-first traversal.