From deb40f5c576f72119cf77e575d4cc068c12e66cf Mon Sep 17 00:00:00 2001
From: Augustin Degomme <degomme@idpann.imag.fr>
Date: Mon, 8 Jul 2013 16:51:55 +0200
Subject: [PATCH] handle non commutative case for scan/exscan

---
 src/smpi/smpi_base.c | 61 ++++++++++++++++++++++++++++++++------------
 1 file changed, 44 insertions(+), 17 deletions(-)

diff --git a/src/smpi/smpi_base.c b/src/smpi/smpi_base.c
index 8afbcae3cb..ec16dbe55f 100644
--- a/src/smpi/smpi_base.c
+++ b/src/smpi/smpi_base.c
@@ -1247,7 +1247,7 @@ void smpi_mpi_allreduce(void *sendbuf, void *recvbuf, int count,
 void smpi_mpi_scan(void *sendbuf, void *recvbuf, int count,
                    MPI_Datatype datatype, MPI_Op op, MPI_Comm comm)
 {
-  int system_tag = 888;
+  int system_tag = -888;
   int rank, size, other, index;
   MPI_Aint lb = 0, dataext = 0;
   MPI_Request *requests;
@@ -1282,14 +1282,25 @@ void smpi_mpi_scan(void *sendbuf, void *recvbuf, int count,
   }
   // Wait for completion of all comms.
   smpi_mpi_startall(size - 1, requests);
-  for(other = 0; other < size - 1; other++) {
-    index = smpi_mpi_waitany(size - 1, requests, MPI_STATUS_IGNORE);
-    if(index == MPI_UNDEFINED) {
-      break;
+
+  if(smpi_op_is_commute(op)){
+    for(other = 0; other < size - 1; other++) {
+      index = smpi_mpi_waitany(size - 1, requests, MPI_STATUS_IGNORE);
+      if(index == MPI_UNDEFINED) {
+        break;
+      }
+      if(index < rank) {
+        // #Request is below rank: it's a irecv
+        smpi_op_apply(op, tmpbufs[index], recvbuf, &count, &datatype);
+      }
     }
-    if(index < rank) {
-      // #Request is below rank: it's a irecv
-      smpi_op_apply(op, tmpbufs[index], recvbuf, &count, &datatype);
+  }else{
+    //non commutative case, wait in order
+    for(other = 0; other < size - 1; other++) {
+      smpi_mpi_wait(&(requests[other]), MPI_STATUS_IGNORE);
+      if(index < rank) {
+        smpi_op_apply(op, tmpbufs[other], recvbuf, &count, &datatype);
+      }
     }
   }
   for(index = 0; index < rank; index++) {
@@ -1302,7 +1313,7 @@ void smpi_mpi_scan(void *sendbuf, void *recvbuf, int count,
 void smpi_mpi_exscan(void *sendbuf, void *recvbuf, int count,
                    MPI_Datatype datatype, MPI_Op op, MPI_Comm comm)
 {
-  int system_tag = 888;
+  int system_tag = -888;
   int rank, size, other, index;
   MPI_Aint lb = 0, dataext = 0;
   MPI_Request *requests;
@@ -1334,15 +1345,31 @@ void smpi_mpi_exscan(void *sendbuf, void *recvbuf, int count,
   }
   // Wait for completion of all comms.
   smpi_mpi_startall(size - 1, requests);
-  for(other = 0; other < size - 1; other++) {
-    index = smpi_mpi_waitany(size - 1, requests, MPI_STATUS_IGNORE);
-    if(index == MPI_UNDEFINED) {
-      break;
+  if(smpi_op_is_commute(op)){
+    for(other = 0; other < size - 1; other++) {
+      index = smpi_mpi_waitany(size - 1, requests, MPI_STATUS_IGNORE);
+      if(index == MPI_UNDEFINED) {
+        break;
+      }
+      if(index < rank) {
+        if(recvbuf_is_empty){
+          smpi_datatype_copy(tmpbufs[index], count, datatype, recvbuf, count, datatype);
+          recvbuf_is_empty=0;
+        }else
+        // #Request is below rank: it's a irecv
+        smpi_op_apply(op, tmpbufs[index], recvbuf, &count, &datatype);
+      }
     }
-    if(index < rank) {
-      if(recvbuf_is_empty)  smpi_datatype_copy(tmpbufs[index], count, datatype, recvbuf, count, datatype);
-      // #Request is below rank: it's a irecv
-      else smpi_op_apply(op, tmpbufs[index], recvbuf, &count, &datatype);
+  }else{
+    //non commutative case, wait in order
+    for(other = 0; other < size - 1; other++) {
+      smpi_mpi_wait(&(requests[other]), MPI_STATUS_IGNORE);
+      if(index < rank) {
+          if(recvbuf_is_empty){
+            smpi_datatype_copy(tmpbufs[index], count, datatype, recvbuf, count, datatype);
+            recvbuf_is_empty=0;
+          }else smpi_op_apply(op, tmpbufs[other], recvbuf, &count, &datatype);
+      }
     }
   }
   for(index = 0; index < rank; index++) {
-- 
2.20.1