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#ifndef ThreadState_h
32#define ThreadState_h
33
34#include "wtf/HashSet.h"
35#include "wtf/ThreadSpecific.h"
36#include "wtf/Threading.h"
37
38namespace WebCore {
39
40class ThreadState {
41public:
42    // Initialize threading infrastructure. Should be called from the main
43    // thread.
44    static void init(intptr_t* startOfStack);
45    static void shutdown();
46
47    // Associate ThreadState object with the current thread. After this
48    // call thread can start using the garbage collected heap infrastructure.
49    // It also has to periodically check for safepoints.
50    static void attach(intptr_t* startOfStack);
51
52    // Disassociate attached ThreadState from the current thread. The thread
53    // can no longer use the garbage collected heap after this call.
54    static void detach();
55
56    static ThreadState* current() { return **s_threadSpecific; }
57    static ThreadState* mainThreadState()
58    {
59        return reinterpret_cast<ThreadState*>(s_mainThreadStateStorage);
60    }
61
62    static bool isMainThread() { return current() == mainThreadState(); }
63
64    inline void checkThread() const
65    {
66        ASSERT(m_thread == currentThread());
67    }
68
69private:
70    explicit ThreadState(intptr_t* startOfStack);
71    ~ThreadState();
72
73    typedef HashSet<ThreadState*> AttachedThreadStateSet;
74    static AttachedThreadStateSet& attachedThreads();
75
76    static WTF::ThreadSpecific<ThreadState*>* s_threadSpecific;
77
78    // We can't create a static member of type ThreadState here
79    // because it will introduce global constructor and destructor.
80    // We would like to manage lifetime of the ThreadState attached
81    // to the main thread explicitly instead and still use normal
82    // constructor and destructor for the ThreadState class.
83    // For this we reserve static storage for the main ThreadState
84    // and lazily construct ThreadState in it using placement new.
85    static uint8_t s_mainThreadStateStorage[];
86
87    ThreadIdentifier m_thread;
88    intptr_t* m_startOfStack;
89};
90
91}
92
93#endif // ThreadState_h
94