opal/datatype: add opal_datatype_is_monotonic()

return true if the datatype has non-negative displacements and
monotonically nondecreasing, and false otherwise.

Thanks George for the guidance.

Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>

opal/datatype/Makefile.am

@@ -15,6 +15,8 @@
 # Copyright (c) 2009      Oak Ridge National Labs.  All rights reserved.
 # Copyright (c) 2010      Cisco Systems, Inc.  All rights reserved.
 # Copyright (c) 2011-2013 NVIDIA Corporation.  All rights reserved.
+# Copyright (c) 2018      Research Organization for Information Science
+#                         and Technology (RIST). All rights reserved.
 # $COPYRIGHT$
 #
 # Additional copyrights may follow
@@ -59,6 +61,7 @@ libdatatype_la_SOURCES = \
         opal_datatype_fake_stack.c \
         opal_datatype_get_count.c \
         opal_datatype_module.c \
+        opal_datatype_monotonic.c \
         opal_datatype_optimize.c \
         opal_datatype_pack.c \
         opal_datatype_position.c \

opal/datatype/opal_datatype.h

@@ -14,7 +14,7 @@
  *                         reserved.
  * Copyright (c) 2009      Sun Microsystems, Inc.  All rights reserved.
  * Copyright (c) 2009      Oak Ridge National Labs.  All rights reserved.
- * Copyright (c) 2017      Research Organization for Information Science
+ * Copyright (c) 2017-2018 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * $COPYRIGHT$
  *
@@ -186,6 +186,7 @@ OPAL_DECLSPEC opal_datatype_t* opal_datatype_create( int32_t expectedSize );
 OPAL_DECLSPEC int32_t opal_datatype_create_desc( opal_datatype_t * datatype, int32_t expectedSize );
 OPAL_DECLSPEC int32_t opal_datatype_commit( opal_datatype_t * pData );
 OPAL_DECLSPEC int32_t opal_datatype_destroy( opal_datatype_t** );
+OPAL_DECLSPEC int32_t opal_datatype_is_monotonic( opal_datatype_t* type);
 
 static inline int32_t
 opal_datatype_is_committed( const opal_datatype_t* type )

opal/datatype/opal_datatype_monotonic.c

@@ -0,0 +1,57 @@
+/* -*- Mode: C; c-basic-offset:4 ; -*- */
+/*
+ * Copyright (c) 2018      Research Organization for Information Science
+ *                         and Technology (RIST). All rights reserved.
+ * $COPYRIGHT$
+ *
+ * Additional copyrights may follow
+ *
+ * $HEADER$
+ */
+
+#include "opal_config.h"
+
+#include <stddef.h>
+
+#include "opal/constants.h"
+#include "opal/datatype/opal_datatype.h"
+#include "opal/datatype/opal_datatype_internal.h"
+#include "opal/datatype/opal_convertor.h"
+
+int32_t opal_datatype_is_monotonic(opal_datatype_t* type )
+{
+    opal_convertor_t *pConv;
+    uint32_t iov_count;
+    struct iovec iov[5];
+    size_t max_data = 0;
+    long prev = -1;
+    int rc;
+    bool monotonic = true;
+
+    pConv  = opal_convertor_create( opal_local_arch, 0 );
+    if (OPAL_UNLIKELY(NULL == pConv)) {
+        return 0;
+    }
+    rc = opal_convertor_prepare_for_send( pConv, type, 1, NULL );
+    if( OPAL_UNLIKELY(OPAL_SUCCESS != rc)) {
+        OBJ_RELEASE(pConv);
+        return 0;
+    }
+
+    do {
+        iov_count = 5;
+        rc = opal_convertor_raw( pConv, iov, &iov_count, &max_data);
+        for (uint32_t i=0; i<iov_count; i++) {
+            if ((long)iov[i].iov_base < prev) {
+                monotonic = false;
+                goto cleanup;
+            }
+            prev = (long)iov[i].iov_base;
+        }
+    } while (rc != 1);
+
+  cleanup:
+    OBJ_RELEASE( pConv );
+
+    return monotonic;
+}