1 | // -*- mode: c++; c-basic-offset: 4 -*- |
2 | /* |
3 | * This file is part of the KDE libraries |
4 | * Copyright (C) 2005 Apple Computer, Inc. |
5 | * |
6 | * This library is free software; you can redistribute it and/or |
7 | * modify it under the terms of the GNU Library General Public |
8 | * License as published by the Free Software Foundation; either |
9 | * version 2 of the License, or (at your option) any later version. |
10 | * |
11 | * This library is distributed in the hope that it will be useful, |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
14 | * Library General Public License for more details. |
15 | * |
16 | * You should have received a copy of the GNU Library General Public License |
17 | * along with this library; see the file COPYING.LIB. If not, write to |
18 | * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
19 | * Boston, MA 02110-1301, USA. |
20 | * |
21 | */ |
22 | |
23 | #ifndef JSLOCK_H |
24 | #define JSLOCK_H |
25 | |
26 | #include "global.h" |
27 | |
28 | namespace KJS { |
29 | |
30 | // to make it safe to use JavaScript on multiple threads, it is |
31 | // important to lock before doing anything that allocates a |
32 | // garbage-collected object or which may affect other shared state |
33 | // such as the protect count hash table. The simplest way to do |
34 | // this is by having a local JSLock object for the scope |
35 | // where the lock must be held. The lock is recursive so nesting |
36 | // is ok. |
37 | |
38 | // Sometimes it is necessary to temporarily release the lock - |
39 | // since it is recursive you have to actually release all locks |
40 | // held by your thread. This is safe to do if you are executing |
41 | // code that doesn't require the lock, and reacquire the right |
42 | // number of locks at the end. You can do this by constructing a |
43 | // locally scoped JSLock::DropAllLocks object. |
44 | |
45 | class KJS_EXPORT JSLock |
46 | { |
47 | public: |
48 | JSLock() |
49 | { |
50 | lock(); |
51 | } |
52 | ~JSLock() { |
53 | unlock(); |
54 | } |
55 | |
56 | static void lock(); |
57 | static void unlock(); |
58 | static int lockCount(); |
59 | |
60 | class DropAllLocks { |
61 | public: |
62 | DropAllLocks(); |
63 | ~DropAllLocks(); |
64 | private: |
65 | int m_lockCount; |
66 | |
67 | DropAllLocks(const DropAllLocks&); |
68 | DropAllLocks& operator=(const DropAllLocks&); |
69 | }; |
70 | |
71 | private: |
72 | JSLock(const JSLock&); |
73 | JSLock& operator=(const JSLock&); |
74 | }; |
75 | |
76 | #if !USE(MULTIPLE_THREADS) |
77 | inline void JSLock::lock() {} |
78 | inline void JSLock::unlock() {} |
79 | // Fix the lock count at 1 so assertions that the lock is held don't fail |
80 | inline int JSLock::lockCount() { return 1; } |
81 | #endif |
82 | |
83 | } // namespace |
84 | |
85 | #endif // JSLOCK_H |
86 | |