Clean up I/O tests to only use MPI I/O (#393)

* Clean up I/O tests to only use MPI I/O

Hopefully fixes #383.

* add MPI.File.sync

Author: simonbyrne

docs/src/io.md

@@ -12,6 +12,12 @@ MPI.File.open
 MPI.File.set_view!
 ```
 
+## Consistency
+
+```@docs
+MPI.File.sync
+```
+
 ## Data access
 
 ### Explicit offsets

src/io.jl

@@ -97,7 +97,22 @@ function set_view!(file::FileHandle, disp::Integer, etype::Datatype, filetype::D
     set_view!(file, disp, etype, filetype, datarep, Info(infokwargs...))
 end
 
+"""
+    MPI.File.sync(fh::FileHandle)
+
+A collective operation causing all previous writes to `fh` by the calling process to be
+transferred to the storage device. If other processes have made updates to the storage
+device, then all such updates become visible to subsequent reads of `fh` by the calling
+process.
 
+# External links
+$(_doc_external("MPI_File_sync"))
+"""
+function sync(file::FileHandle)
+    # int MPI_File_sync(MPI_File fh)
+    @mpichk ccall((:MPI_File_sync, libmpi), Cint, (MPI_File,), file)
+    return nothing
+end
 
 
 # Explicit offsets

test/test_io.jl

@@ -15,52 +15,33 @@ rank = MPI.Comm_rank(comm)
 sz = MPI.Comm_size(comm)
 filename = MPI.bcast(tempname(), 0, comm)
 
-# Write
 MPI.Barrier(comm)
 
-f = MPI.File.open(comm, filename, write=true)
-MPI.File.set_view!(f, 0, MPI.Datatype(Int64), MPI.Datatype(Int64))
-MPI.File.write_at(f, rank*2, ArrayType([Int64(rank+1) for i = 1:2]))
-close(f)
+# Collective write
+fh = MPI.File.open(comm, filename, read=true, write=true, create=true)
+MPI.File.set_view!(fh, 0, MPI.Datatype(Int64), MPI.Datatype(Int64))
+MPI.File.write_at_all(fh, rank*2, ArrayType([Int64(rank+1) for i = 1:2]))
 
-MPI.Barrier(comm)
-
-if rank == 0
-    @test read!(filename, zeros(Int64, (2,sz))) == [j for i = 1:2, j=1:sz]
-end
-
-MPI.Barrier(comm)
-
-f = MPI.File.open(comm, filename, write=true)
-MPI.File.set_view!(f, 0, MPI.Datatype(Int64), MPI.Datatype(Int64))
-MPI.File.write_at_all(f, rank*2, ArrayType([Int64(rank+1) for i = 1:2]))
-close(f)
-
-MPI.Barrier(comm)
+MPI.File.sync(fh)
 
+# Noncollective read
 if rank == 0
-    @test read!(filename, zeros(Int64, (2,sz))) == [j for i = 1:2, j=1:sz]
+    data = zeros(Int64, (2,sz))
+    MPI.File.read_at!(fh, 0, data)
+    @test data == [j for i = 1:2, j=1:sz]
 end
 
+MPI.File.sync(fh)
 MPI.Barrier(comm)
 
-# Read
-if rank == 0
-    write(filename, [Float64(j) for i = 1:3, j = 1:sz])
+if rank == sz-1
+    MPI.File.write_at(fh, 0, ArrayType([Int64(-1) for i = 1:2]))
 end
 
-MPI.Barrier(comm)
-
-
-f = MPI.File.open(comm, filename, read=true)
-MPI.File.set_view!(f, 0, MPI.Datatype(Float64), MPI.Datatype(Float64))
-
-data = ArrayType(zeros(Float64, 3))
-MPI.File.read_at!(f, rank*3, data)
-@test data == Float64[rank+1 for i = 1:3]
-
-MPI.Barrier(comm)
+MPI.File.sync(fh)
 
-data = ArrayType(zeros(Float64, 3))
-MPI.File.read_at_all!(f, rank*3, data)
-@test data == Float64[rank+1 for i = 1:3]
+# Collective read
+data = zeros(Int64, 1)
+MPI.File.read_at_all!(fh, rank*2, data)
+@test data == [rank == 0 ? -1 : rank+1]
+close(fh)