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1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef BASE_THREAD_LOCAL_STORAGE_H_ | |
6 #define BASE_THREAD_LOCAL_STORAGE_H_ | |
7 #pragma once | |
8 | |
9 #include "base/basictypes.h" | |
10 | |
11 #if defined(OS_POSIX) | |
12 #include <pthread.h> | |
13 #endif | |
14 | |
15 // Wrapper for thread local storage. This class doesn't do much except provide | |
16 // an API for portability. | |
17 class ThreadLocalStorage { | |
18 public: | |
19 | |
20 // Prototype for the TLS destructor function, which can be optionally used to | |
21 // cleanup thread local storage on thread exit. 'value' is the data that is | |
22 // stored in thread local storage. | |
23 typedef void (*TLSDestructorFunc)(void* value); | |
24 | |
25 // A key representing one value stored in TLS. | |
26 class Slot { | |
27 public: | |
28 explicit Slot(TLSDestructorFunc destructor = NULL); | |
29 | |
30 // This constructor should be used for statics. | |
31 // It returns an uninitialized Slot. | |
32 explicit Slot(base::LinkerInitialized x) {} | |
33 | |
34 // Set up the TLS slot. Called by the constructor. | |
35 // 'destructor' is a pointer to a function to perform per-thread cleanup of | |
36 // this object. If set to NULL, no cleanup is done for this TLS slot. | |
37 // Returns false on error. | |
38 bool Initialize(TLSDestructorFunc destructor); | |
39 | |
40 // Free a previously allocated TLS 'slot'. | |
41 // If a destructor was set for this slot, removes | |
42 // the destructor so that remaining threads exiting | |
43 // will not free data. | |
44 void Free(); | |
45 | |
46 // Get the thread-local value stored in slot 'slot'. | |
47 // Values are guaranteed to initially be zero. | |
48 void* Get() const; | |
49 | |
50 // Set the thread-local value stored in slot 'slot' to | |
51 // value 'value'. | |
52 void Set(void* value); | |
53 | |
54 bool initialized() const { return initialized_; } | |
55 | |
56 private: | |
57 // The internals of this struct should be considered private. | |
58 bool initialized_; | |
59 #if defined(OS_WIN) | |
60 int slot_; | |
61 #elif defined(OS_POSIX) | |
62 pthread_key_t key_; | |
63 #endif | |
64 | |
65 DISALLOW_COPY_AND_ASSIGN(Slot); | |
66 }; | |
67 | |
68 #if defined(OS_WIN) | |
69 // Function called when on thread exit to call TLS | |
70 // destructor functions. This function is used internally. | |
71 static void ThreadExit(); | |
72 | |
73 private: | |
74 // Function to lazily initialize our thread local storage. | |
75 static void **Initialize(); | |
76 | |
77 private: | |
78 // The maximum number of 'slots' in our thread local storage stack. | |
79 // For now, this is fixed. We could either increase statically, or | |
80 // we could make it dynamic in the future. | |
81 static const int kThreadLocalStorageSize = 64; | |
82 | |
83 static long tls_key_; | |
84 static long tls_max_; | |
85 static TLSDestructorFunc tls_destructors_[kThreadLocalStorageSize]; | |
86 #endif // OS_WIN | |
87 | |
88 DISALLOW_COPY_AND_ASSIGN(ThreadLocalStorage); | |
89 }; | |
90 | |
91 // Temporary backwards-compatible name. | |
92 // TODO(evanm): replace all usage of TLSSlot. | |
93 typedef ThreadLocalStorage::Slot TLSSlot; | |
94 | |
95 #endif // BASE_THREAD_LOCAL_STORAGE_H_ | |
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