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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef BASE_GLOBAL_DESCRIPTORS_POSIX_H_ | 5 #ifndef BASE_GLOBAL_DESCRIPTORS_POSIX_H_ |
6 #define BASE_GLOBAL_DESCRIPTORS_POSIX_H_ | 6 #define BASE_GLOBAL_DESCRIPTORS_POSIX_H_ |
7 #pragma once | 7 #pragma once |
8 | 8 |
9 #include "build/build_config.h" | 9 #include "build/build_config.h" |
10 | 10 |
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27 // overwriting the slot isn't a viable solution. | 27 // overwriting the slot isn't a viable solution. |
28 // | 28 // |
29 // We could try to fill the reserved slots as soon as possible, but this is a | 29 // We could try to fill the reserved slots as soon as possible, but this is a |
30 // fragile solution since global constructors etc are able to open files. | 30 // fragile solution since global constructors etc are able to open files. |
31 // | 31 // |
32 // Instead, we retreat from the idea of installing descriptors in specific | 32 // Instead, we retreat from the idea of installing descriptors in specific |
33 // slots and add a layer of indirection in the form of this singleton object. | 33 // slots and add a layer of indirection in the form of this singleton object. |
34 // It maps from an abstract key to a descriptor. If independent modules each | 34 // It maps from an abstract key to a descriptor. If independent modules each |
35 // need to define keys, then values should be chosen randomly so as not to | 35 // need to define keys, then values should be chosen randomly so as not to |
36 // collide. | 36 // collide. |
37 class BASE_API GlobalDescriptors { | 37 class BASE_EXPORT GlobalDescriptors { |
38 public: | 38 public: |
39 typedef uint32_t Key; | 39 typedef uint32_t Key; |
40 typedef std::vector<std::pair<Key, int> > Mapping; | 40 typedef std::vector<std::pair<Key, int> > Mapping; |
41 | 41 |
42 // Often we want a canonical descriptor for a given Key. In this case, we add | 42 // Often we want a canonical descriptor for a given Key. In this case, we add |
43 // the following constant to the key value: | 43 // the following constant to the key value: |
44 static const int kBaseDescriptor = 3; // 0, 1, 2 are already taken. | 44 static const int kBaseDescriptor = 3; // 0, 1, 2 are already taken. |
45 | 45 |
46 // Return the singleton instance of GlobalDescriptors. | 46 // Return the singleton instance of GlobalDescriptors. |
47 static GlobalDescriptors* GetInstance(); | 47 static GlobalDescriptors* GetInstance(); |
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61 friend struct DefaultSingletonTraits<GlobalDescriptors>; | 61 friend struct DefaultSingletonTraits<GlobalDescriptors>; |
62 GlobalDescriptors(); | 62 GlobalDescriptors(); |
63 ~GlobalDescriptors(); | 63 ~GlobalDescriptors(); |
64 | 64 |
65 Mapping descriptors_; | 65 Mapping descriptors_; |
66 }; | 66 }; |
67 | 67 |
68 } // namespace base | 68 } // namespace base |
69 | 69 |
70 #endif // BASE_GLOBAL_DESCRIPTORS_POSIX_H_ | 70 #endif // BASE_GLOBAL_DESCRIPTORS_POSIX_H_ |
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