cosmetics

Project.toml

@@ -7,6 +7,7 @@ version = "0.3.1"
 Downloads = "f43a241f-c20a-4ad4-852c-f6b1247861c6"
 Graphs = "86223c79-3864-5bf0-83f7-82e725a168b6"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
+SHA = "ea8e919c-243c-51af-8825-aaa63cd721ce"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 nauty_jll = "55c6dc9b-343a-50ca-8ff2-b71adb3733d5"
 

src/NautyGraphs.jl

@@ -1,6 +1,7 @@
 module NautyGraphs
 
 import nauty_jll
+using SHA
 const libnauty = nauty_jll.libnautyTL
 const WORDSIZE = 64
 const WordType = Culong

src/bitutils.jl

@@ -115,6 +115,16 @@
     return nidx
 end
 
+function _concatbytes(bytes::AbstractVector{<:UInt8})
+    @assert length(bytes) == sizeof(HashType)
+    w = HashType(0)
+    for b in bytes
+        w |= b
+        w <<= 8
+    end
+    return w
+end
+
 function _to_matrixidx(idx::Integer, m::Integer)
     return 1 + (idx - 1) ÷ m, mod1(idx, m)
 end

src/densenautygraphs.jl

@@ -36,6 +36,7 @@ mutable struct DenseNautyGraph{D} <: AbstractNautyGraph
 end
 
 function DenseNautyGraph{D}(n::Integer, vertex_labels::Union{Vector{<:Integer},Nothing}=nothing) where {D}
+    !isnothing(vertex_labels) && @assert n == length(vertex_labels)
     m = ceil(Cint, n / WORDSIZE)
     graphset = zeros(WordType, Int(n * m))
     labels = _initialize_vertexlabels(n, vertex_labels)

src/nauty.jl

@@ -114,9 +114,16 @@ function nauty(g::DenseNautyGraph, canonical_form=true; ignore_vertex_labels=fal
     return grpsize, canong, canon_perm
 end
 
-function _nautyhash(g::AbstractNautyGraph, h::UInt=zero(UInt))
+function _nautyhash(g::DenseNautyGraph)
     grpsize, canong, canon_perm = nauty(g, true)
-    hashval = hash(view(g.labels, canon_perm), hash(canong, h))
+
+    # Base.hash skips elements in arrays of length >= 8192
+    # Use SHA in these cases
+    canong_hash = length(canong) >= 8192 ? hash_sha(canong) : hash(canong)
+    labels_hash = @views length(g.labels) >= 8192 ? hash_sha(g.labels[canon_perm]) : hash(g.labels[canon_perm])
+
+    hashval = hash(labels_hash, canong_hash)
+    g.hashval = hashval
     return grpsize, canong, canon_perm, hashval
 end
 
@@ -128,10 +135,8 @@ Reorder g's vertices to be in canonical order. Returns the permutation used to c
 """
 function canonize!(g::AbstractNautyGraph)
     grpsize, canong, canon_perm, hashval = _nautyhash(g)
-
-    g.graphset .= canong
-    g.labels .= g.labels[canon_perm]
-    g.hashval = hashval
+    copyto!(g.graphset, canong)
+    permute!(g.labels, canon_perm)
     return canon_perm, grpsize
 end
 
@@ -150,16 +155,17 @@ end
 
 
 """
-    ghash(g::AbstractNautyGraph, h::UInt=zero(UInt))
+    ghash(g::AbstractNautyGraph)
 
 Hash the canonical version of g, so that (up to hash collisions) `ghash(g1) == ghash(g2)` implies `is_isomorphic(g1, g2) == true`.
+Hashes are computed using `Base.hash` for small graphs (nv < 8192), or using the first 64 bits of `sha256` for larger graphs.
 """
-function ghash(g::AbstractNautyGraph, h::UInt=zero(UInt))
+function ghash(g::AbstractNautyGraph)
     if !isnothing(g.hashval)
         return g.hashval
     end
 
-    _, _, _, hashval = _nautyhash(g, h)
+    _, _, _, hashval = _nautyhash(g)
     g.hashval = hashval
     return g.hashval
 end

src/utils.jl

@@ -84,4 +84,10 @@
     end
 
     return g.graphset[set_idx] != word_old
+end
+
+function hash_sha(x)
+    io = IOBuffer()
+    write(io, x)
+    return _concatbytes(sha256(take!(io))[1:8])
 end