1/*
2 * Copyright (C) 2017 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#include <atomic>
29#include <wtf/NeverDestroyed.h>
30
31namespace WTF {
32
33template <typename IdentifierType, typename ClassType>
34class IdentifiedBase {
35public:
36 IdentifierType identifier() const
37 {
38 return m_identifier;
39 }
40
41protected:
42 IdentifiedBase(const IdentifiedBase& other)
43 : m_identifier(other.m_identifier)
44 {
45 }
46
47 explicit IdentifiedBase(IdentifierType identifier)
48 : m_identifier(identifier)
49 {
50 }
51
52private:
53 IdentifierType m_identifier;
54};
55
56template <typename T>
57class Identified : public IdentifiedBase<uint64_t, T> {
58protected:
59 Identified()
60 : IdentifiedBase<uint64_t, T>(generateIdentifier())
61 {
62 }
63
64 Identified(const Identified&) = default;
65
66 explicit Identified(uint64_t identifier)
67 : IdentifiedBase<uint64_t, T>(identifier)
68 {
69 }
70
71private:
72 static uint64_t generateIdentifier()
73 {
74 static uint64_t currentIdentifier;
75 return ++currentIdentifier;
76 }
77};
78
79template <typename T>
80class ThreadSafeIdentified : public IdentifiedBase<uint64_t, T> {
81protected:
82 ThreadSafeIdentified()
83 : IdentifiedBase<uint64_t, T>(generateIdentifier())
84 {
85 }
86
87 ThreadSafeIdentified(const ThreadSafeIdentified&) = default;
88
89 explicit ThreadSafeIdentified(uint64_t identifier)
90 : IdentifiedBase<uint64_t, T>(identifier)
91 {
92 }
93
94private:
95 static uint64_t generateIdentifier()
96 {
97 static LazyNeverDestroyed<std::atomic<uint64_t>> currentIdentifier;
98 static std::once_flag initializeCurrentIdentifier;
99 std::call_once(initializeCurrentIdentifier, [] {
100 currentIdentifier.construct(0);
101 });
102 return ++currentIdentifier.get();
103 }
104};
105
106} // namespace WTF
107
108using WTF::Identified;
109using WTF::ThreadSafeIdentified;
110