diff options
Diffstat (limited to 'zen/globals.h')
-rw-r--r-- | zen/globals.h | 37 |
1 files changed, 22 insertions, 15 deletions
diff --git a/zen/globals.h b/zen/globals.h index 5f3dd64a..ff8c890d 100644 --- a/zen/globals.h +++ b/zen/globals.h @@ -13,21 +13,21 @@ namespace zen { -//solve static destruction order fiasco by providing scoped ownership and serialized access to global variables +//solve static destruction order fiasco by providing shared ownership and serialized access to global variables template <class T> class Global { public: - Global() {} + Global() { static_assert(std::is_trivially_destructible<Pod>::value, "this memory needs to live forever"); } explicit Global(std::unique_ptr<T>&& newInst) { set(std::move(newInst)); } ~Global() { set(nullptr); } std::shared_ptr<T> get() //=> return std::shared_ptr to let instance life time be handled by caller (MT usage!) { - while (spinLock.exchange(true)) ; - ZEN_ON_SCOPE_EXIT(spinLock = false); - if (inst) - return *inst; + while (pod.spinLock.exchange(true)) ; + ZEN_ON_SCOPE_EXIT(pod.spinLock = false); + if (pod.inst) + return *pod.inst; return nullptr; } @@ -37,21 +37,28 @@ public: if (newInst) tmpInst = new std::shared_ptr<T>(std::move(newInst)); { - while (spinLock.exchange(true)) ; - ZEN_ON_SCOPE_EXIT(spinLock = false); - std::swap(inst, tmpInst); + while (pod.spinLock.exchange(true)) ; + ZEN_ON_SCOPE_EXIT(pod.spinLock = false); + std::swap(pod.inst, tmpInst); } delete tmpInst; } private: - //avoid static destruction order fiasco: there may be accesses to "Global<T>::get()" during process shutdown - //e.g. show message in debug_minidump.cpp or some detached thread assembling an error message! - //=> use trivially-destructible POD only!!! - std::shared_ptr<T>* inst = nullptr; - //serialize access: can't use std::mutex because of non-trival destructor - std::atomic<bool> spinLock { false }; + //avoid static destruction order fiasco: there may be accesses to "Global<T>::get()" during process shutdown + //e.g. _("") used by message in debug_minidump.cpp or by some detached thread assembling an error message! + //=> use trivially-destructible POD only!!! + struct Pod + { + std::shared_ptr<T>* inst = nullptr; + //serialize access; can't use std::mutex: has non-trival destructor + std::atomic<bool> spinLock { false }; + } pod; }; + +#if defined _MSC_VER && _MSC_VER < 1900 +#error function scope static initialization is not yet thread-safe! +#endif } #endif //GLOBALS_H_8013740213748021573485 |