From db70b226292af1953731054a684df19791508c9b Mon Sep 17 00:00:00 2001
From: Anthony Scemama <scemama@irsamc.ups-tlse.fr>
Date: Fri, 29 Mar 2019 23:39:47 +0100
Subject: [PATCH] Prepared inter-node

---
 Parallel_mpi/Parallel.ml  | 14 ++++++++++++--
 Parallel_mpi/Parallel.mli | 35 +++++++++++++++++++++++++++++++++++
 run_parallel.ml           | 10 +++++++++-
 3 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/Parallel_mpi/Parallel.ml b/Parallel_mpi/Parallel.ml
index 3c4ab70..5641272 100644
--- a/Parallel_mpi/Parallel.ml
+++ b/Parallel_mpi/Parallel.ml
@@ -59,7 +59,7 @@ module Node = struct
 
   let name = Unix.gethostname ()
 
-  let comm_node = 
+  let comm = 
     Mpi.allgather (name, rank) Mpi.comm_world
     |> Array.to_list
     |> List.filter (fun (n, r) -> name = n)
@@ -69,10 +69,20 @@ module Node = struct
     |> Mpi.(comm_create comm_world)
 
   let rank = 
-    Mpi.comm_rank comm_node
+    Mpi.comm_rank comm
 
   let master = rank = 0
   
+  let broadcast_generic broadcast x =
+    let x = 
+      if master then Some (Lazy.force x)
+      else None
+    in
+    match broadcast x 0 comm with
+    | Some x -> x
+    | None -> assert false
+
+  let broadcast x = broadcast_generic Mpi.broadcast x
 end
 
 
diff --git a/Parallel_mpi/Parallel.mli b/Parallel_mpi/Parallel.mli
index 4d76cc0..19d1f23 100644
--- a/Parallel_mpi/Parallel.mli
+++ b/Parallel_mpi/Parallel.mli
@@ -30,6 +30,41 @@ val broadcast_float_array : float array -> float array
 val broadcast_vec : Lacaml.D.vec -> Lacaml.D.vec
 (** Broadcasts a Lacaml vector to all processes. *)
 
+(** {5 Intra-node  operations} *)
+module Node : sig
+  val name : string
+  (** Name of the current host *)
+
+  val comm : Mpi.communicator
+  (** MPI Communicator on the current node *)
+
+  val rank : Mpi.rank
+  (** Rank of the current process in the node *)
+
+  val master : bool
+  (** If true, master process of the node *)
+
+  val broadcast : 'a lazy_t -> 'a
+  (** Broadcasts data to all the processes of the current node. *)
+end
+
+(*
+(** {5 Intra-node  operations} *)
+module InterNode : sig
+
+  val comm : Mpi.communicator
+  (** MPI Communicator among the master processes of the each node *)
+
+  val rank : Mpi.rank
+  (** Rank of the current process in the inter-node communicator *)
+
+  val master : bool
+  (** If true, master process of the inter-node communicator *)
+
+  val broadcast : 'a lazy_t -> 'a
+  (** Broadcasts data to all the processes of the inter-node communicator. *)
+end
+*)
 
 (** {5 Vector operations} *)
 module Vec : sig
diff --git a/run_parallel.ml b/run_parallel.ml
index da89fb2..9231e7c 100644
--- a/run_parallel.ml
+++ b/run_parallel.ml
@@ -21,7 +21,7 @@ let v = Parallel.Vec.init 47 (fun i -> float_of_int i) in
   print_newline ()
 
 
-let () =
+let pouet2 () =
   let f (a,b) = (Parallel.rank, a+b) in
   let input  = Stream.of_list
     [ (1,2) ; (3,4) ; (5,6) ; (7,8) ; (9,10)  
@@ -34,3 +34,11 @@ let () =
   in
   Stream.iter (fun (x,y) -> Printf.printf "%d  %d\n%!" x y) stream
 
+
+open Printf
+let () = 
+  printf "%d : %s\n" Parallel.rank Parallel.Node.name;
+  let value = Parallel.broadcast (lazy Parallel.rank) in
+  printf "%d : %d\n" Parallel.rank value;
+  let value = Parallel.Node.broadcast (lazy Parallel.rank) in
+  printf "%d : %d\n" Parallel.rank value