Ensure scratch operations happen on master core.

Change-Id: I970d645108de041d410599847edce877cb794015
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/275
Tested-by: Jenkins Server
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>
Reviewed-by: A. Patrick Williams III <iawillia@us.ibm.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/src/include/util/lockfree/atomic_construct.H b/src/include/util/lockfree/atomic_construct.H
new file mode 100644
index 000000000..6946a1c60
--- /dev/null
+++ b/src/include/util/lockfree/atomic_construct.H
@@ -0,0 +1,62 @@
+//  IBM_PROLOG_BEGIN_TAG
+//  This is an automatically generated prolog.
+//
+//  $Source: src/include/util/lockfree/atomic_construct.H $
+//
+//  IBM CONFIDENTIAL
+//
+//  COPYRIGHT International Business Machines Corp. 2011
+//
+//  p1
+//
+//  Object Code Only (OCO) source materials
+//  Licensed Internal Code Source Materials
+//  IBM HostBoot Licensed Internal Code
+//
+//  The source code for this program is not published or other-
+//  wise divested of its trade secrets, irrespective of what has
+//  been deposited with the U.S. Copyright Office.
+//
+//  Origin: 30
+//
+//  IBM_PROLOG_END
+#ifndef __UTIL_LOCKFREE_ATOMIC_CONSTRUCT_H
+#define __UTIL_LOCKFREE_ATOMIC_CONSTRUCT_H
+
+namespace Util
+{
+    namespace Lockfree
+    {
+
+        /** @brief Atomically construct an object and assign it to a pointer.
+         *
+         *  This function will check if a pointer is still NULL and
+         *  construct an object, atomically, if needed.  If the pointer is
+         *  not NULL, the current instance will be left alone.
+         *
+         *  @param[in] ptr - Pointer-pointer to the object.
+         *
+         *  Example:
+         *      Foo* iv_foo;  //<--- instance variable in class.
+         *      atomic_construct(&iv_foo);
+         *
+         *  @note It is possible for multiple instances to temporarily exist,
+         *        if this code is called from multiple CPUs, but only the one
+         *        instance will exist outside the lifetime of this function.
+         */
+        template<typename _T>
+            void atomic_construct(_T** ptr)
+            {
+                if (__sync_bool_compare_and_swap(ptr, NULL, NULL))
+                {
+                    _T* instance = new _T();
+                    if (!__sync_bool_compare_and_swap(ptr, NULL, instance))
+                    {
+                        delete instance;
+                    }
+                }
+            }
+    };
+};
+
+#endif