+/* Copyright (c) 2009-2019. The SimGrid Team.
+ * All rights reserved. */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+/* This example should be instructive to learn about SMPI_SHARED_CALL */
+
+#include <stdio.h>
+#include <mpi.h>
+#include <stdint.h>
+#include <inttypes.h>
+
+static void* hash(const char *str, uint64_t* ans)
+{
+ const char *tohash = str;
+ *ans=5381;
+ printf("hashing !\n");
+ int c = *tohash;
+ while (c != 0) {
+ *ans = ((*ans << 5) + *ans) + c; /* hash * 33 + c */
+ tohash++;
+ c = *tohash;
+ }
+ return NULL;
+}
+
+int main(int argc, char *argv[])
+{
+ MPI_Init(&argc, &argv);
+ int rank;
+ int size;
+ MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+ MPI_Comm_size(MPI_COMM_WORLD, &size);
+ //Let's Allocate a memory buffer
+ uint64_t* buf = malloc(sizeof(uint64_t));
+ //one writes data in it
+ if(rank==0){
+ *buf=size;
+ }
+
+ MPI_Barrier(MPI_COMM_WORLD);
+ //everyone reads from it.
+ printf("[%d] The value in the shared buffer is: %" PRIu64"\n", rank, *buf);
+
+ MPI_Barrier(MPI_COMM_WORLD);
+ //Try SMPI_SHARED_CALL function, which should call hash only once and for all.
+ static const char str[] = "onceandforall";
+ if(rank==size-1){
+ SMPI_SHARED_CALL(hash,str,str,buf);
+ }
+
+ MPI_Barrier(MPI_COMM_WORLD);
+
+ printf("[%d] After change, the value in the shared buffer is: %" PRIu64"\n", rank, *buf);
+
+ free(buf);
+
+ MPI_Finalize();
+ return 0;
+}