wtf/ThreadIdentifierDataPthreads.h

   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/Noncopyable.h>
  35 #include <wtf/Threading.h>
  36
  37 namespace WTF {
  38
  39 // Holds ThreadIdentifier in the thread-specific storage and employs pthreads-specific 2-pass destruction to reliably remove
  40 // ThreadIdentifier from threadMap. It assumes regular ThreadSpecific types don't use multiple-pass destruction.
  41 class ThreadIdentifierData : public Noncopyable {
  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