2 * This file is open source software, licensed to you under the terms
3 * of the Apache License, Version 2.0 (the "License"). See the NOTICE file
4 * distributed with this work for additional information regarding copyright
5 * ownership. You may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
9 * http://www.apache.org/licenses/LICENSE-2.0
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13 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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19 * Copyright (C) 2014 Cloudius Systems, Ltd.
22 #ifndef CEPH_TRANSFER_H_
23 #define CEPH_TRANSFER_H_
25 // Helper functions for copying or moving multiple objects in an exception
26 // safe manner, then destroying the sources.
28 // To transfer, call transfer_pass1(allocator, &from, &to) on all object pairs,
29 // (this copies the object from @from to @to). If no exceptions are encountered,
30 // call transfer_pass2(allocator, &from, &to). This destroys the object at the
31 // origin. If exceptions were encountered, simply destroy all copied objects.
33 // As an optimization, if the objects are moveable without throwing (noexcept)
34 // transfer_pass1() simply moves the objects and destroys the source, and
35 // transfer_pass2() does nothing.
37 #include <type_traits>
40 template <typename T, typename Alloc>
41 inline void transfer_pass1(Alloc& a, T* from, T* to,
42 typename std::enable_if<std::is_nothrow_move_constructible<T>::value>::type* = nullptr) {
43 a.construct(to, std::move(*from));
47 template <typename T, typename Alloc>
48 inline void transfer_pass2(Alloc& a, T* from, T* to,
49 typename std::enable_if<std::is_nothrow_move_constructible<T>::value>::type* = nullptr) {
52 template <typename T, typename Alloc>
53 inline void transfer_pass1(Alloc& a, T* from, T* to,
54 typename std::enable_if<!std::is_nothrow_move_constructible<T>::value>::type* = nullptr) {
55 a.construct(to, *from);
58 template <typename T, typename Alloc>
59 inline void transfer_pass2(Alloc& a, T* from, T* to,
60 typename std::enable_if<!std::is_nothrow_move_constructible<T>::value>::type* = nullptr) {
64 #endif /* CEPH_TRANSFER_H_ */