diff options
Diffstat (limited to 'chromium/base/threading/thread_local_storage.h')
-rw-r--r-- | chromium/base/threading/thread_local_storage.h | 71 |
1 files changed, 61 insertions, 10 deletions
diff --git a/chromium/base/threading/thread_local_storage.h b/chromium/base/threading/thread_local_storage.h index eb5648f76c9..53ebe55e51c 100644 --- a/chromium/base/threading/thread_local_storage.h +++ b/chromium/base/threading/thread_local_storage.h @@ -8,12 +8,71 @@ #include "base/base_export.h" #include "base/basictypes.h" -#if defined(OS_POSIX) +#if defined(OS_WIN) +#include <windows.h> +#elif defined(OS_POSIX) #include <pthread.h> #endif namespace base { +namespace internal { + +// WARNING: You should *NOT* be using this class directly. +// PlatformThreadLocalStorage is low-level abstraction to the OS's TLS +// interface, you should instead be using ThreadLocalStorage::StaticSlot/Slot. +class BASE_EXPORT PlatformThreadLocalStorage { + public: + +#if defined(OS_WIN) + typedef unsigned long TLSKey; + enum { TLS_KEY_OUT_OF_INDEXES = TLS_OUT_OF_INDEXES }; +#elif defined(OS_POSIX) + typedef pthread_key_t TLSKey; + // The following is a "reserved key" which is used in our generic Chromium + // ThreadLocalStorage implementation. We expect that an OS will not return + // such a key, but if it is returned (i.e., the OS tries to allocate it) we + // will just request another key. + enum { TLS_KEY_OUT_OF_INDEXES = 0x7FFFFFFF }; +#endif + + // The following methods need to be supported on each OS platform, so that + // the Chromium ThreadLocalStore functionality can be constructed. + // Chromium will use these methods to acquire a single OS slot, and then use + // that to support a much larger number of Chromium slots (independent of the + // OS restrictions). + // The following returns true if it successfully is able to return an OS + // key in |key|. + static bool AllocTLS(TLSKey* key); + // Note: FreeTLS() doesn't have to be called, it is fine with this leak, OS + // might not reuse released slot, you might just reset the TLS value with + // SetTLSValue(). + static void FreeTLS(TLSKey key); + static void SetTLSValue(TLSKey key, void* value); + static void* GetTLSValue(TLSKey key); + + // Each platform (OS implementation) is required to call this method on each + // terminating thread when the thread is about to terminate. This method + // will then call all registered destructors for slots in Chromium + // ThreadLocalStorage, until there are no slot values remaining as having + // been set on this thread. + // Destructors may end up being called multiple times on a terminating + // thread, as other destructors may re-set slots that were previously + // destroyed. +#if defined(OS_WIN) + // Since Windows which doesn't support TLS destructor, the implementation + // should use GetTLSValue() to retrieve the value of TLS slot. + static void OnThreadExit(); +#elif defined(OS_POSIX) + // |Value| is the data stored in TLS slot, The implementation can't use + // GetTLSValue() to retrieve the value of slot as it has already been reset + // in Posix. + static void OnThreadExit(void* value); +#endif +}; + +} // namespace internal + // Wrapper for thread local storage. This class doesn't do much except provide // an API for portability. class BASE_EXPORT ThreadLocalStorage { @@ -60,12 +119,7 @@ class BASE_EXPORT ThreadLocalStorage { // 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 - }; // A convenience wrapper around StaticSlot with a constructor. Can be used @@ -77,11 +131,8 @@ class BASE_EXPORT ThreadLocalStorage { private: using StaticSlot::initialized_; -#if defined(OS_WIN) using StaticSlot::slot_; -#elif defined(OS_POSIX) - using StaticSlot::key_; -#endif + DISALLOW_COPY_AND_ASSIGN(Slot); }; |