Add scheduling, machine info, caching strategies and devices (#9)

Reviewed-on: Rubydragon/MetagraphOptimization.jl#9
Co-authored-by: Anton Reinhard <anton.reinhard@proton.me>
Co-committed-by: Anton Reinhard <anton.reinhard@proton.me>

src/diff/print.jl

@@ -6,6 +6,6 @@ Pretty-print a [`Diff`](@ref). Called via print, println and co.
 function show(io::IO, diff::Diff)
     print(io, "Nodes: ")
     print(io, length(diff.addedNodes) + length(diff.removedNodes))
-    print(io, " Edges: ")
+    print(io, ", Edges: ")
     return print(io, length(diff.addedEdges) + length(diff.removedEdges))
 end

src/diff/type.jl

@@ -4,8 +4,8 @@
 A named tuple representing a difference of added and removed nodes and edges on a [`DAG`](@ref).
 """
 const Diff = NamedTuple{
-    (:addedNodes, :removedNodes, :addedEdges, :removedEdges),
-    Tuple{Vector{Node}, Vector{Node}, Vector{Edge}, Vector{Edge}},
+    (:addedNodes, :removedNodes, :addedEdges, :removedEdges, :updatedChildren),
+    Tuple{Vector{Node}, Vector{Node}, Vector{Edge}, Vector{Edge}, Vector{Tuple{Node, AbstractTask}}},
 }
 
 function Diff()
@@ -14,5 +14,8 @@ function Diff()
         removedNodes = Vector{Node}(),
         addedEdges = Vector{Edge}(),
         removedEdges = Vector{Edge}(),
+
+        # children were updated in the task, updatedChildren[x][2] is the task before the update
+        updatedChildren = Vector{Tuple{Node, AbstractTask}}(),
     )::Diff
 end