| // Copyright 2008, Google Inc. |
| // All rights reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following disclaimer |
| // in the documentation and/or other materials provided with the |
| // distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef BASE_THREAD_LOCAL_STORAGE_H_ |
| #define BASE_THREAD_LOCAL_STORAGE_H_ |
| |
| #include "base/basictypes.h" |
| |
| #if defined(OS_POSIX) |
| #include <pthread.h> |
| #endif |
| |
| // Wrapper for thread local storage. This class doesn't do much except provide |
| // an API for portability. |
| class ThreadLocalStorage { |
| public: |
| |
| // Prototype for the TLS destructor function, which can be optionally used to |
| // cleanup thread local storage on thread exit. 'value' is the data that is |
| // stored in thread local storage. |
| typedef void (*TLSDestructorFunc)(void* value); |
| |
| // A key representing one value stored in TLS. |
| class Slot { |
| public: |
| Slot(TLSDestructorFunc destructor = NULL); |
| |
| // This constructor should be used for statics. |
| // It returns an uninitialized Slot. |
| explicit Slot(base::LinkerInitialized x) {} |
| |
| // Set up the TLS slot. Called by the constructor. |
| // 'destructor' is a pointer to a function to perform per-thread cleanup of |
| // this object. If set to NULL, no cleanup is done for this TLS slot. |
| // Returns false on error. |
| bool Initialize(TLSDestructorFunc destructor); |
| |
| // Free a previously allocated TLS 'slot'. |
| // If a destructor was set for this slot, removes |
| // the destructor so that remaining threads exiting |
| // will not free data. |
| void Free(); |
| |
| // Get the thread-local value stored in slot 'slot'. |
| // Values are guaranteed to initially be zero. |
| void* Get() const; |
| |
| // Set the thread-local value stored in slot 'slot' to |
| // value 'value'. |
| void Set(void* value); |
| |
| bool initialized() const { return initialized_; } |
| |
| private: |
| // The internals of this struct should be considered private. |
| bool initialized_; |
| #if defined(OS_WIN) |
| int slot_; |
| #elif defined(OS_POSIX) |
| pthread_key_t key_; |
| #endif |
| |
| DISALLOW_COPY_AND_ASSIGN(Slot); |
| }; |
| |
| #if defined(OS_WIN) |
| // Function called when on thread exit to call TLS |
| // destructor functions. This function is used internally. |
| static void ThreadExit(); |
| |
| private: |
| // Function to lazily initialize our thread local storage. |
| static void **Initialize(); |
| |
| private: |
| // The maximum number of 'slots' in our thread local storage stack. |
| // For now, this is fixed. We could either increase statically, or |
| // we could make it dynamic in the future. |
| static const int kThreadLocalStorageSize = 64; |
| |
| static long tls_key_; |
| static long tls_max_; |
| static TLSDestructorFunc tls_destructors_[kThreadLocalStorageSize]; |
| #endif // OS_WIN |
| |
| DISALLOW_COPY_AND_ASSIGN(ThreadLocalStorage); |
| }; |
| |
| // Temporary backwards-compatible name. |
| // TODO(evanm): replace all usage of TLSSlot. |
| typedef ThreadLocalStorage::Slot TLSSlot; |
| |
| #endif // BASE_THREAD_LOCAL_STORAGE_H_ |