Move broken Parallel.gdistances function to Experimental submodule

Author: simonschoelly

src/Experimental/Experimental.jl

@@ -15,6 +15,7 @@ description() = "This module contains experimental graph functions."
 
 include("isomorphism.jl")
 include("vf2.jl") # Julian implementation of VF2 algorithm
+include("Parallel/Parallel.jl")
 include("Traversals/Traversals.jl")
 include("ShortestPaths/ShortestPaths.jl")
 

src/Experimental/Parallel/Parallel.jl

@@ -0,0 +1,8 @@
+module Parallel
+
+using Graphs
+using Base.Threads: @threads, nthreads
+
+include("traversals/gdistances.jl")
+
+end

src/Parallel/traversals/gdistances.jl renamed to src/Experimental/Parallel/traversals/gdistances.jl

@@ -1,3 +1,8 @@
+
+# TODO the algorithms in this file probably relay on incorrect assumptions
+# about the memory handling of Julia.
+# See: https://github.com/JuliaGraphs/Graphs.jl/issues/10
+
 """
     partition_sources!(queue_list, sources)
 
@@ -40,6 +45,8 @@ function gdistances!(
     queue_segment_size::Integer=20
     ) where T <:Integer
 
+    @warn "Graphs.Experimental.Parallel.gdistances is very likely broken at the moment and can return unreliable results."
+
     nvg = nv(g)
     n_t = nthreads()
     segment_size = convert(T, queue_segment_size) # Type stability

src/Parallel/Parallel.jl

@@ -21,7 +21,6 @@ include("centrality/radiality.jl")
 include("centrality/stress.jl")
 include("distance.jl")
 include("traversals/bfs.jl")
-include("traversals/gdistances.jl")
 include("traversals/greedy_color.jl")
 include("utils.jl")
 include("dominatingset/minimal_dom_set.jl")

test/experimental/experimental.jl

@@ -1,5 +1,5 @@
 const exptestdir = dirname(@__FILE__)
-tests = ["isomorphism", "shortestpaths", "traversals"]
+tests = ["isomorphism", "parallel/runtests", "shortestpaths", "traversals"]
 
 @testset "Experimental" begin
     @test length(description()) > 1

test/experimental/parallel/runtests.jl

@@ -0,0 +1,14 @@
+#using Graphs
+#using Graphs.Parallel
+#using Base.Threads: @threads, Atomic
+
+tests = [
+     # "traversals/gdistances",  # TODO currently disabled as the code in gdistances seems to be broken
+]
+
+@testset "Graphs.Experimental.Parallel" begin
+    for t in tests
+        tp = joinpath(dirname(@__FILE__), "$(t).jl")
+        include(tp)
+    end
+end

test/experimental/parallel/traversals/gdistances.jl

@@ -0,0 +1,19 @@
+@testset "Experimental.Parallel.BFS" begin
+
+
+    g5 = SimpleDiGraph(4)
+    add_edge!(g5, 1, 2); add_edge!(g5, 2, 3); add_edge!(g5, 1, 3); add_edge!(g5, 3, 4)
+    
+    for g in testdigraphs(g5)
+        @test @inferred(Experimental.Parallel.gdistances(g, 1))  == gdistances(g, 1)
+        @test @inferred(Experimental.Parallel.gdistances(g, [1, 3]))  == gdistances(g, [1, 3])
+    end
+
+    g6 = smallgraph(:house)
+
+    for g in testgraphs(g6)
+        @test @inferred(Experimental.Parallel.gdistances(g, 2))  == gdistances(g, 2)
+        @test @inferred(Experimental.Parallel.gdistances(g, [1, 2])) == gdistances(g, [1, 2])
+    end
+
+end

test/parallel/runtests.jl

@@ -15,7 +15,6 @@ tests = [
     "shortestpaths/floyd-warshall",
     "shortestpaths/johnson",
     "traversals/bfs",
-    "traversals/gdistances",
     "traversals/greedy_color",
     "dominatingset/minimal_dom_set",
     "independentset/maximal_ind_set",