diff options
Diffstat (limited to 'indra/llcommon/llsingleton.h')
| -rw-r--r-- | indra/llcommon/llsingleton.h | 123 |
1 files changed, 68 insertions, 55 deletions
diff --git a/indra/llcommon/llsingleton.h b/indra/llcommon/llsingleton.h index 91c05bd5ed..d3417a233e 100644 --- a/indra/llcommon/llsingleton.h +++ b/indra/llcommon/llsingleton.h @@ -25,16 +25,24 @@ #ifndef LLSINGLETON_H #define LLSINGLETON_H +#include <boost/call_traits.hpp> #include <boost/noncopyable.hpp> #include <boost/unordered_set.hpp> +#include <functional> #include <initializer_list> #include <list> #include <typeinfo> #include <vector> #include "mutex.h" #include "lockstatic.h" +#include "apply.h" +#include "llprofiler.h" #include "llthread.h" // on_main_thread() -#include "llmainthreadtask.h" + +#ifdef LL_WINDOWS +#pragma warning(push) +#pragma warning(disable : 4506) // no definition for inline function +#endif class LLSingletonBase: private boost::noncopyable { @@ -110,6 +118,8 @@ protected: // If a given call to B::getInstance() happens during either A::A() or // A::initSingleton(), record that A directly depends on B. void capture_dependency(); + // trampoline to non-static member function + static void capture_dependency(LLSingletonBase*); // delegate logging calls to llsingleton.cpp public: @@ -134,6 +144,17 @@ protected: // internal wrapper around calls to cleanupSingleton() void cleanup_(); + // This method is where we dispatch to LLMainThreadTask to acquire the + // subclass LLSingleton instance when the first getInstance() call is from + // a secondary thread. We delegate to the .cpp file to untangle header + // circularity. It accepts a std::function referencing the subclass + // getInstance() method -- which can't be virtual because it's static; we + // don't yet have an instance! For messaging, it also accepts the name of + // the subclass and the subclass method. + static LLSingletonBase* getInstanceForSecondaryThread( + const std::string& name, const std::string& method, + const std::function<LLSingletonBase*()>& getInstance); + // deleteSingleton() isn't -- and shouldn't be -- a virtual method. It's a // class static. However, given only Foo*, deleteAll() does need to be // able to reach Foo::deleteSingleton(). Make LLSingleton (which declares @@ -189,7 +210,7 @@ struct LLSingleton_manage_master } void capture_dependency(LLSingletonBase* sb) { - sb->capture_dependency(); + LLSingletonBase::capture_dependency(sb); } }; @@ -293,7 +314,7 @@ private: // Use a recursive_mutex in case of constructor circularity. With a // non-recursive mutex, that would result in deadlock. typedef std::recursive_mutex mutex_t; - mutex_t mMutex; // LockStatic looks for mMutex + LL_PROFILE_MUTEX_NAMED(mutex_t, mMutex, "Singleton Data"); // LockStatic looks for mMutex EInitState mInitState{UNINITIALIZED}; DERIVED_TYPE* mInstance{nullptr}; @@ -415,12 +436,17 @@ protected: // deleteSingleton() to defend against manual deletion. When we moved // cleanup to deleteSingleton(), we hit crashes due to dangling // pointers in the MasterList. - LockStatic lk; + LockStatic lk; LL_PROFILE_MUTEX_LOCK(lk->mMutex); lk->mInstance = nullptr; lk->mInitState = DELETED; // Remove this instance from the master list. LLSingleton_manage_master<DERIVED_TYPE>().remove(this); + // We should no longer need our LockStatic -- but the fact that we can + // query or even resurrect a deleted LLSingleton means we basically + // have to shrug and leak our SingletonData. It's not large, and this + // only happens at shutdown anyway. +// lk.cleanup(); } public: @@ -443,7 +469,7 @@ public: // Hold the lock while we call cleanupSingleton() and the destructor. // Our destructor also instantiates LockStatic, requiring a recursive // mutex. - LockStatic lk; + LockStatic lk; LL_PROFILE_MUTEX_LOCK(lk->mMutex); // of course, only cleanup and delete if there's something there if (lk->mInstance) { @@ -500,7 +526,7 @@ public: { // nested scope for 'lk' // In case racing threads call getInstance() at the same moment, // serialize the calls. - LockStatic lk; + LockStatic lk; LL_PROFILE_MUTEX_LOCK(lk->mMutex); switch (lk->mInitState) { @@ -528,6 +554,7 @@ public: classname<DERIVED_TYPE>(), " -- creating new instance"}); // fall through + [[fallthrough]]; case UNINITIALIZED: case QUEUED: // QUEUED means some secondary thread has already requested an @@ -555,19 +582,11 @@ public: // Per the comment block above, dispatch to the main thread. loginfos({classname<DERIVED_TYPE>(), "::getInstance() dispatching to main thread"}); - auto instance = LLMainThreadTask::dispatch( - [](){ - // VERY IMPORTANT to call getInstance() on the main thread, - // rather than going straight to constructSingleton()! - // During the time window before mInitState is INITIALIZED, - // multiple requests might be queued. It's essential that, as - // the main thread processes them, only the FIRST such request - // actually constructs the instance -- every subsequent one - // simply returns the existing instance. - loginfos({classname<DERIVED_TYPE>(), - "::getInstance() on main thread"}); - return getInstance(); - }); + auto instance = static_cast<DERIVED_TYPE*>( + getInstanceForSecondaryThread( + classname<DERIVED_TYPE>(), + "getInstance()", + getInstance)); // record the dependency chain tracked on THIS thread, not the main // thread (consider a getInstance() overload with a tag param that // suppresses dep tracking when dispatched to the main thread) @@ -589,7 +608,7 @@ public: static bool instanceExists() { // defend any access to sData from racing threads - LockStatic lk; + LockStatic lk; LL_PROFILE_MUTEX_LOCK(lk->mMutex); return lk->mInitState == INITIALIZED; } @@ -599,7 +618,7 @@ public: static bool wasDeleted() { // defend any access to sData from racing threads - LockStatic lk; + LockStatic lk; LL_PROFILE_MUTEX_LOCK(lk->mMutex); return lk->mInitState == DELETED; } }; @@ -632,13 +651,19 @@ private: // Passes arguments to DERIVED_TYPE's constructor and sets appropriate // states, returning a pointer to the new instance. + // If we just let initParamSingleton_() infer its argument types, the + // compiler has trouble passing int and string literals. Use + // boost::call_traits::param_type to smooth parameter passing. This + // construction requires, though, that each invocation of this method + // explicitly specify template arguments, instead of inferring them. template <typename... Args> - static DERIVED_TYPE* initParamSingleton_(Args&&... args) + static LLSingletonBase* initParamSingleton_( + typename boost::call_traits<Args>::param_type... args) { // In case racing threads both call initParamSingleton() at the same // time, serialize them. One should initialize; the other should see // mInitState already set. - LockStatic lk; + LockStatic lk; LL_PROFILE_MUTEX_LOCK(lk->mMutex); // For organizational purposes this function shouldn't be called twice if (lk->mInitState != super::UNINITIALIZED) { @@ -652,7 +677,7 @@ private: // on the main thread, simply construct instance while holding lock super::logdebugs({super::template classname<DERIVED_TYPE>(), "::initParamSingleton()"}); - super::constructSingleton(lk, std::forward<Args>(args)...); + super::constructSingleton(lk, args...); return lk->mInstance; } else @@ -665,20 +690,19 @@ private: lk.unlock(); super::loginfos({super::template classname<DERIVED_TYPE>(), "::initParamSingleton() dispatching to main thread"}); - // Normally it would be the height of folly to reference-bind - // 'args' into a lambda to be executed on some other thread! By - // the time that thread executed the lambda, the references would - // all be dangling, and Bad Things would result. But - // LLMainThreadTask::dispatch() promises to block until the passed - // task has completed. So in this case we know the references will - // remain valid until the lambda has run, so we dare to bind - // references. - auto instance = LLMainThreadTask::dispatch( - [&](){ - super::loginfos({super::template classname<DERIVED_TYPE>(), - "::initParamSingleton() on main thread"}); - return initParamSingleton_(std::forward<Args>(args)...); - }); + auto instance = static_cast<DERIVED_TYPE*>( + super::getInstanceForSecondaryThread( + super::template classname<DERIVED_TYPE>(), + "initParamSingleton()", + // This lambda does what std::bind() is supposed to do -- + // but when the actual parameter is (e.g.) a string + // literal, type inference makes it fail. Apply param_type + // to each incoming type to make it work. + [args=std::tuple<typename boost::call_traits<Args>::param_type...>(args...)] + () + { + return LL::apply(initParamSingleton_<Args...>, args); + })); super::loginfos({super::template classname<DERIVED_TYPE>(), "::initParamSingleton() returning on requesting thread"}); return instance; @@ -695,14 +719,14 @@ public: template <typename... Args> static DERIVED_TYPE& initParamSingleton(Args&&... args) { - return *initParamSingleton_(std::forward<Args>(args)...); + return *static_cast<DERIVED_TYPE*>(initParamSingleton_<Args...>(args...)); } static DERIVED_TYPE* getInstance() { // In case racing threads call getInstance() at the same moment as // initParamSingleton(), serialize the calls. - LockStatic lk; + LockStatic lk; LL_PROFILE_MUTEX_LOCK(lk->mMutex); switch (lk->mInitState) { @@ -807,17 +831,6 @@ private: \ DERIVED_CLASS(__VA_ARGS__) /** - * A slight variance from the above, but includes the "override" keyword - */ -#define LLSINGLETON_C11(DERIVED_CLASS) \ -private: \ - /* implement LLSingleton pure virtual method whose sole purpose */ \ - /* is to remind people to use this macro */ \ - virtual void you_must_use_LLSINGLETON_macro() override {} \ - friend class LLSingleton<DERIVED_CLASS>; \ - DERIVED_CLASS() - -/** * Use LLSINGLETON_EMPTY_CTOR(Foo); at the start of an LLSingleton<Foo> * subclass body when the constructor is trivial: * @@ -835,10 +848,6 @@ private: \ /* LLSINGLETON() is carefully implemented to permit exactly this */ \ LLSINGLETON(DERIVED_CLASS) {} -#define LLSINGLETON_EMPTY_CTOR_C11(DERIVED_CLASS) \ - /* LLSINGLETON() is carefully implemented to permit exactly this */ \ - LLSINGLETON_C11(DERIVED_CLASS) {} - // Relatively unsafe singleton implementation that is much faster // and simpler than LLSingleton, but has no dependency tracking // or inherent thread safety and requires manual invocation of @@ -871,4 +880,8 @@ private: template <class T> T* LLSimpleton<T>::sInstance{ nullptr }; +#ifdef LL_WINDOWS +#pragma warning(pop) +#endif + #endif |