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      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 
     36 namespace 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.
     40 class ThreadIdentifierData {
     41     WTF_MAKE_NONCOPYABLE(ThreadIdentifierData);
     42 public:
     43     ~ThreadIdentifierData();
     44 
     45     // Creates and puts an instance of ThreadIdentifierData into thread-specific storage.
     46     static void initialize(ThreadIdentifier identifier);
     47 
     48     // Returns 0 if thread-specific storage was not initialized.
     49     static ThreadIdentifier identifier();
     50 
     51 private:
     52     ThreadIdentifierData(ThreadIdentifier identifier)
     53         : m_identifier(identifier)
     54         , m_isDestroyedOnce(false)
     55     {
     56     }
     57 
     58     // This thread-specific destructor is called 2 times when thread terminates:
     59     // - first, when all the other thread-specific destructors are called, it simply remembers it was 'destroyed once'
     60     // and re-sets itself into the thread-specific slot to make Pthreads to call it again later.
     61     // - second, after all thread-specific destructors were invoked, it gets called again - this time, we remove the
     62     // ThreadIdentifier from the threadMap, completing the cleanup.
     63     static void destruct(void* data);
     64 
     65     static void initializeKeyOnceHelper();
     66     static void initializeKeyOnce();
     67 
     68     ThreadIdentifier m_identifier;
     69     bool m_isDestroyedOnce;
     70     static pthread_key_t m_key;
     71 };
     72 
     73 } // namespace WTF
     74 
     75 #endif // ThreadIdentifierDataPthreads_h
     76 
     77 
     78