1/*
2 * Copyright (C) 2009 Google 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 are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#ifndef ThreadIdentifierDataPthreads_h
32#define ThreadIdentifierDataPthreads_h
33
34#include <wtf/Threading.h>
35
36namespace WTF {
37
38// Holds ThreadIdentifier in the thread-specific storage and employs pthreads-specific 2-pass destruction to reliably remove
39// ThreadIdentifier from threadMap. It assumes regular ThreadSpecific types don't use multiple-pass destruction.
40class ThreadIdentifierData {
41    WTF_MAKE_NONCOPYABLE(ThreadIdentifierData);
42public:
43    ~ThreadIdentifierData();
44
45    // One time initialization for this class as a whole.
46    // This method must be called before initialize() and it is not thread-safe.
47    static void initializeOnce();
48
49    // Creates and puts an instance of ThreadIdentifierData into thread-specific storage.
50    static void initialize(ThreadIdentifier identifier);
51
52    // Returns 0 if thread-specific storage was not initialized.
53    static ThreadIdentifier identifier();
54
55private:
56    ThreadIdentifierData(ThreadIdentifier identifier)
57        : m_identifier(identifier)
58        , m_isDestroyedOnce(false)
59    {
60    }
61
62    // This thread-specific destructor is called 2 times when thread terminates:
63    // - first, when all the other thread-specific destructors are called, it simply remembers it was 'destroyed once'
64    // and re-sets itself into the thread-specific slot to make Pthreads to call it again later.
65    // - second, after all thread-specific destructors were invoked, it gets called again - this time, we remove the
66    // ThreadIdentifier from the threadMap, completing the cleanup.
67    static void destruct(void* data);
68
69    ThreadIdentifier m_identifier;
70    bool m_isDestroyedOnce;
71    static pthread_key_t m_key;
72};
73
74} // namespace WTF
75
76#endif // ThreadIdentifierDataPthreads_h
77
78
79