ipc/chromium/src/base/thread_local_storage.h@ca08bd8f51b2 (annotated)
ipc/chromium/src/base/thread_local_storage.h
Wed, 31 Dec 2014 06:55:46 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:55:46 +0100
- changeset 1
- ca08bd8f51b2
- permissions
- -rw-r--r--
Added tag TORBROWSER_REPLICA for changeset 6474c204b198
| michael@0 | 1 | // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. |
| michael@0 | 2 | // Use of this source code is governed by a BSD-style license that can be |
| michael@0 | 3 | // found in the LICENSE file. |
| michael@0 | 4 | |
| michael@0 | 5 | #ifndef BASE_THREAD_LOCAL_STORAGE_H_ |
| michael@0 | 6 | #define BASE_THREAD_LOCAL_STORAGE_H_ |
| michael@0 | 7 | |
| michael@0 | 8 | #include "base/basictypes.h" |
| michael@0 | 9 | |
| michael@0 | 10 | #if defined(OS_POSIX) |
| michael@0 | 11 | #include <pthread.h> |
| michael@0 | 12 | #endif |
| michael@0 | 13 | |
| michael@0 | 14 | // Wrapper for thread local storage. This class doesn't do much except provide |
| michael@0 | 15 | // an API for portability. |
| michael@0 | 16 | class ThreadLocalStorage { |
| michael@0 | 17 | public: |
| michael@0 | 18 | |
| michael@0 | 19 | // Prototype for the TLS destructor function, which can be optionally used to |
| michael@0 | 20 | // cleanup thread local storage on thread exit. 'value' is the data that is |
| michael@0 | 21 | // stored in thread local storage. |
| michael@0 | 22 | typedef void (*TLSDestructorFunc)(void* value); |
| michael@0 | 23 | |
| michael@0 | 24 | // A key representing one value stored in TLS. |
| michael@0 | 25 | class Slot { |
| michael@0 | 26 | public: |
| michael@0 | 27 | Slot(TLSDestructorFunc destructor = NULL); |
| michael@0 | 28 | |
| michael@0 | 29 | // This constructor should be used for statics. |
| michael@0 | 30 | // It returns an uninitialized Slot. |
| michael@0 | 31 | explicit Slot(base::LinkerInitialized x) {} |
| michael@0 | 32 | |
| michael@0 | 33 | // Set up the TLS slot. Called by the constructor. |
| michael@0 | 34 | // 'destructor' is a pointer to a function to perform per-thread cleanup of |
| michael@0 | 35 | // this object. If set to NULL, no cleanup is done for this TLS slot. |
| michael@0 | 36 | // Returns false on error. |
| michael@0 | 37 | bool Initialize(TLSDestructorFunc destructor); |
| michael@0 | 38 | |
| michael@0 | 39 | // Free a previously allocated TLS 'slot'. |
| michael@0 | 40 | // If a destructor was set for this slot, removes |
| michael@0 | 41 | // the destructor so that remaining threads exiting |
| michael@0 | 42 | // will not free data. |
| michael@0 | 43 | void Free(); |
| michael@0 | 44 | |
| michael@0 | 45 | // Get the thread-local value stored in slot 'slot'. |
| michael@0 | 46 | // Values are guaranteed to initially be zero. |
| michael@0 | 47 | void* Get() const; |
| michael@0 | 48 | |
| michael@0 | 49 | // Set the thread-local value stored in slot 'slot' to |
| michael@0 | 50 | // value 'value'. |
| michael@0 | 51 | void Set(void* value); |
| michael@0 | 52 | |
| michael@0 | 53 | bool initialized() const { return initialized_; } |
| michael@0 | 54 | |
| michael@0 | 55 | private: |
| michael@0 | 56 | // The internals of this struct should be considered private. |
| michael@0 | 57 | bool initialized_; |
| michael@0 | 58 | #if defined(OS_WIN) |
| michael@0 | 59 | int slot_; |
| michael@0 | 60 | #elif defined(OS_POSIX) |
| michael@0 | 61 | pthread_key_t key_; |
| michael@0 | 62 | #endif |
| michael@0 | 63 | |
| michael@0 | 64 | DISALLOW_COPY_AND_ASSIGN(Slot); |
| michael@0 | 65 | }; |
| michael@0 | 66 | |
| michael@0 | 67 | #if defined(OS_WIN) |
| michael@0 | 68 | // Function called when on thread exit to call TLS |
| michael@0 | 69 | // destructor functions. This function is used internally. |
| michael@0 | 70 | static void ThreadExit(); |
| michael@0 | 71 | |
| michael@0 | 72 | private: |
| michael@0 | 73 | // Function to lazily initialize our thread local storage. |
| michael@0 | 74 | static void **Initialize(); |
| michael@0 | 75 | |
| michael@0 | 76 | private: |
| michael@0 | 77 | // The maximum number of 'slots' in our thread local storage stack. |
| michael@0 | 78 | // For now, this is fixed. We could either increase statically, or |
| michael@0 | 79 | // we could make it dynamic in the future. |
| michael@0 | 80 | static const int kThreadLocalStorageSize = 64; |
| michael@0 | 81 | |
| michael@0 | 82 | static long tls_key_; |
| michael@0 | 83 | static long tls_max_; |
| michael@0 | 84 | static TLSDestructorFunc tls_destructors_[kThreadLocalStorageSize]; |
| michael@0 | 85 | #endif // OS_WIN |
| michael@0 | 86 | |
| michael@0 | 87 | DISALLOW_COPY_AND_ASSIGN(ThreadLocalStorage); |
| michael@0 | 88 | }; |
| michael@0 | 89 | |
| michael@0 | 90 | // Temporary backwards-compatible name. |
| michael@0 | 91 | // TODO(evanm): replace all usage of TLSSlot. |
| michael@0 | 92 | typedef ThreadLocalStorage::Slot TLSSlot; |
| michael@0 | 93 | |
| michael@0 | 94 | #endif // BASE_THREAD_LOCAL_STORAGE_H_ |
