make Distributed independent of indices starting at 1 (JuliaLang/julia#34886)

Author: oheil

src/macros.jl

@@ -241,13 +241,12 @@ function remotecall_eval(m::Module, pid::Int, ex)
 end
 
 
-# Statically split range [1,N] into equal sized chunks for np processors
-function splitrange(N::Int, np::Int)
-    each = div(N,np)
-    extras = rem(N,np)
+# Statically split range [firstIndex,lastIndex] into equal sized chunks for np processors
+function splitrange(firstIndex::Int, lastIndex::Int, np::Int)
+    each, extras = divrem(lastIndex-firstIndex+1, np)
     nchunks = each > 0 ? np : extras
     chunks = Vector{UnitRange{Int}}(undef, nchunks)
-    lo = 1
+    lo = firstIndex
     for i in 1:nchunks
         hi = lo + each - 1
         if extras > 0
@@ -261,8 +260,7 @@ function splitrange(N::Int, np::Int)
 end
 
 function preduce(reducer, f, R)
-    N = length(R)
-    chunks = splitrange(Int(N), nworkers())
+    chunks = splitrange(Int(firstindex(R)), Int(lastindex(R)), nworkers())
     all_w = workers()[1:length(chunks)]
 
     w_exec = Task[]
@@ -275,7 +273,7 @@ function preduce(reducer, f, R)
 end
 
 function pfor(f, R)
-    @async @sync for c in splitrange(length(R), nworkers())
+    @async @sync for c in splitrange(Int(firstindex(R)), Int(lastindex(R)), nworkers())
         @spawnat :any f(R, first(c), last(c))
     end
 end

test/macros.jl

@@ -0,0 +1,36 @@
+using Test
+using Distributed
+using Distributed: splitrange
+
+# testing function macros.jl:splitrange
+@test splitrange(1, 11, 1) == Array{UnitRange{Int64},1}([1:11])
+@test splitrange(0, 10, 1) == Array{UnitRange{Int64},1}([0:10])
+@test splitrange(-1, 9, 1) == Array{UnitRange{Int64},1}([-1:9])
+
+@test splitrange(1, 11, 2) == Array{UnitRange{Int64},1}([1:6,7:11])
+@test splitrange(0, 10, 2) == Array{UnitRange{Int64},1}([0:5,6:10])
+@test splitrange(-1, 9, 2) == Array{UnitRange{Int64},1}([-1:4,5:9])
+
+@test splitrange(1, 11, 3) == Array{UnitRange{Int64},1}([1:4,5:8,9:11])
+@test splitrange(0, 10, 3) == Array{UnitRange{Int64},1}([0:3,4:7,8:10])
+@test splitrange(-1, 9, 3) == Array{UnitRange{Int64},1}([-1:2,3:6,7:9])
+
+@test splitrange(1, 3, 3) == Array{UnitRange{Int64},1}([1:1,2:2,3:3])
+@test splitrange(1, 3, 4) == Array{UnitRange{Int64},1}([1:1,2:2,3:3])
+@test splitrange(0, 2, 3) == Array{UnitRange{Int64},1}([0:0,1:1,2:2])
+@test splitrange(0, 2, 4) == Array{UnitRange{Int64},1}([0:0,1:1,2:2])
+@test splitrange(-1, 1, 3) == Array{UnitRange{Int64},1}([-1:-1,0:0,1:1])
+@test splitrange(-1, 1, 4) == Array{UnitRange{Int64},1}([-1:-1,0:0,1:1])
+
+const BASE_TEST_PATH = joinpath(Sys.BINDIR, "..", "share", "julia", "test")
+isdefined(Main, :OffsetArrays) || @eval Main include(joinpath($(BASE_TEST_PATH), "testhelpers", "OffsetArrays.jl"))
+using .Main.OffsetArrays
+
+oa=OffsetArray([-1,0], (-2,))
+@distributed for i in eachindex(oa)
+	@test i <= 0
+end
+
+# testing macros.jl:...
+# ... yet to be implemented
+

test/runtests.jl

@@ -11,4 +11,5 @@ if !success(pipeline(cmd; stdout=stdout, stderr=stderr)) && ccall(:jl_running_on
     error("Distributed test failed, cmd : $cmd")
 end
 
+include("macros.jl")
 include("managers.jl")