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      1 /*
      2  * Copyright (C) 2013 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 #include "config.h"
     32 #include "heap/ThreadState.h"
     33 
     34 #include "wtf/ThreadingPrimitives.h"
     35 
     36 namespace WebCore {
     37 
     38 WTF::ThreadSpecific<ThreadState*>* ThreadState::s_threadSpecific = 0;
     39 uint8_t ThreadState::s_mainThreadStateStorage[sizeof(ThreadState)];
     40 
     41 static Mutex& threadAttachMutex()
     42 {
     43     AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);
     44     return mutex;
     45 }
     46 
     47 void ThreadState::init(intptr_t* startOfStack)
     48 {
     49     s_threadSpecific = new WTF::ThreadSpecific<ThreadState*>();
     50     new(s_mainThreadStateStorage) ThreadState(startOfStack);
     51     attachedThreads().add(mainThreadState());
     52 }
     53 
     54 void ThreadState::shutdown()
     55 {
     56     mainThreadState()->~ThreadState();
     57 }
     58 
     59 void ThreadState::attach(intptr_t* startOfStack)
     60 {
     61     MutexLocker locker(threadAttachMutex());
     62     ThreadState* state = new ThreadState(startOfStack);
     63     attachedThreads().add(state);
     64 }
     65 
     66 void ThreadState::detach()
     67 {
     68     ThreadState* state = current();
     69     MutexLocker locker(threadAttachMutex());
     70     attachedThreads().remove(state);
     71     delete state;
     72 }
     73 
     74 ThreadState::ThreadState(intptr_t* startOfStack)
     75     : m_thread(currentThread())
     76     , m_startOfStack(startOfStack)
     77 {
     78     ASSERT(!**s_threadSpecific);
     79     **s_threadSpecific = this;
     80 
     81     // FIXME: This is to silence clang that complains about unused private
     82     // member. Remove once we implement stack scanning that uses it.
     83     (void) m_startOfStack;
     84 }
     85 
     86 ThreadState::~ThreadState()
     87 {
     88     checkThread();
     89     **s_threadSpecific = 0;
     90 }
     91 
     92 ThreadState::AttachedThreadStateSet& ThreadState::attachedThreads()
     93 {
     94     DEFINE_STATIC_LOCAL(AttachedThreadStateSet, threads, ());
     95     return threads;
     96 }
     97 
     98 }
     99