initial code repo

[stor4nfv.git] / src / ceph / src / msg / async / dpdk / transfer.h

diff --git a/src/ceph/src/msg/async/dpdk/transfer.h b/src/ceph/src/msg/async/dpdk/transfer.h
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+++ b/src/ceph/src/msg/async/dpdk/transfer.h
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+/*
+ * This file is open source software, licensed to you under the terms
+ * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership.  You may not use this file except in compliance with the License.
+ *
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+/*
+ * Copyright (C) 2014 Cloudius Systems, Ltd.
+ */
+
+#ifndef CEPH_TRANSFER_H_
+#define CEPH_TRANSFER_H_
+
+// Helper functions for copying or moving multiple objects in an exception
+// safe manner, then destroying the sources.
+//
+// To transfer, call transfer_pass1(allocator, &from, &to) on all object pairs,
+// (this copies the object from @from to @to).  If no exceptions are encountered,
+// call transfer_pass2(allocator, &from, &to).  This destroys the object at the
+// origin.  If exceptions were encountered, simply destroy all copied objects.
+//
+// As an optimization, if the objects are moveable without throwing (noexcept)
+// transfer_pass1() simply moves the objects and destroys the source, and
+// transfer_pass2() does nothing.
+
+#include <type_traits>
+#include <utility>
+
+template <typename T, typename Alloc>
+inline void transfer_pass1(Alloc& a, T* from, T* to,
+                           typename std::enable_if<std::is_nothrow_move_constructible<T>::value>::type* = nullptr) {
+    a.construct(to, std::move(*from));
+    a.destroy(from);
+}
+
+template <typename T, typename Alloc>
+inline void transfer_pass2(Alloc& a, T* from, T* to,
+                           typename std::enable_if<std::is_nothrow_move_constructible<T>::value>::type* = nullptr) {
+}
+
+template <typename T, typename Alloc>
+inline void transfer_pass1(Alloc& a, T* from, T* to,
+               typename std::enable_if<!std::is_nothrow_move_constructible<T>::value>::type* = nullptr) {
+    a.construct(to, *from);
+}
+
+template <typename T, typename Alloc>
+inline void transfer_pass2(Alloc& a, T* from, T* to,
+               typename std::enable_if<!std::is_nothrow_move_constructible<T>::value>::type* = nullptr) {
+    a.destroy(from);
+}
+
+#endif /* CEPH_TRANSFER_H_ */