/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this file, * You can obtain one at http://mozilla.org/MPL/2.0/. */ /* Cross-platform lightweight thread local data wrappers. */ #ifndef mozilla_ThreadLocal_h_ #define mozilla_ThreadLocal_h_ #if defined(XP_WIN) // This file will get included in any file that wants to add a profiler mark. // In order to not bring <windows.h> together we could include windef.h and // winbase.h which are sufficient to get the prototypes for the Tls* functions. // # include <windef.h> // # include <winbase.h> // Unfortunately, even including these headers causes us to add a bunch of ugly // stuff to our namespace e.g #define CreateEvent CreateEventW extern "C" { __declspec(dllimport) void* __stdcall TlsGetValue(unsigned long); __declspec(dllimport) int __stdcall TlsSetValue(unsigned long, void*); __declspec(dllimport) unsigned long __stdcall TlsAlloc(); } #else # include <pthread.h> # include <signal.h> #endif #include "mozilla/Assertions.h" #include "mozilla/Attributes.h" namespace mozilla { // sig_safe_t denotes an atomic type which can be read or stored in a single // instruction. This means that data of this type is safe to be manipulated // from a signal handler, or other similar asynchronous execution contexts. #if defined(XP_WIN) typedef unsigned long sig_safe_t; #else typedef sig_atomic_t sig_safe_t; #endif /* * Thread Local Storage helpers. * * Usage: * * Only static-storage-duration (e.g. global variables, or static class members) * objects of this class should be instantiated. This class relies on * zero-initialization, which is implicit for static-storage-duration objects. * It doesn't have a custom default constructor, to avoid static initializers. * * API usage: * * // Create a TLS item * mozilla::ThreadLocal<int> tlsKey; * if (!tlsKey.init()) { * // deal with the error * } * * // Set the TLS value * tlsKey.set(123); * * // Get the TLS value * int value = tlsKey.get(); */ template<typename T> class ThreadLocal { #if defined(XP_WIN) typedef unsigned long key_t; #else typedef pthread_key_t key_t; #endif union Helper { void* ptr; T value; }; public: MOZ_WARN_UNUSED_RESULT inline bool init(); inline T get() const; inline void set(const T value); bool initialized() const { return inited; } private: key_t key; bool inited; }; template<typename T> inline bool ThreadLocal<T>::init() { MOZ_STATIC_ASSERT(sizeof(T) <= sizeof(void*), "mozilla::ThreadLocal can't be used for types larger than " "a pointer"); MOZ_ASSERT(!initialized()); #ifdef XP_WIN key = TlsAlloc(); inited = key != 0xFFFFFFFFUL; // TLS_OUT_OF_INDEXES #else inited = !pthread_key_create(&key, NULL); #endif return inited; } template<typename T> inline T ThreadLocal<T>::get() const { MOZ_ASSERT(initialized()); Helper h; #ifdef XP_WIN h.ptr = TlsGetValue(key); #else h.ptr = pthread_getspecific(key); #endif return h.value; } template<typename T> inline void ThreadLocal<T>::set(const T value) { MOZ_ASSERT(initialized()); Helper h; h.value = value; bool succeeded; #ifdef XP_WIN succeeded = TlsSetValue(key, h.ptr); #else succeeded = !pthread_setspecific(key, h.ptr); #endif if (!succeeded) MOZ_CRASH(); } } // namespace mozilla #endif // mozilla_ThreadLocal_h_