From ca1d051a158a110d4e3e43efccfcacbd2e9e5c06 Mon Sep 17 00:00:00 2001 From: Nat Goodspeed Date: Thu, 30 May 2019 08:23:32 -0400 Subject: [PATCH] SL-11216: Remove LLSingletonBase::cleanupAll(). Remove call from LLAppViewer::cleanup(). Instead, make each LLSingleton::deleteSingleton() call cleanupSingleton() just before destroying the instance. Since deleteSingleton() is not a destructor, it's fine to call cleanupSingleton() from there; and since deleteAll() calls deleteSingleton() on every remaining instance, the former cleanupAll() functionality has been subsumed into deleteAll(). Since cleanupSingleton() is now called at exactly one point in the instance's lifetime, we no longer need a bool indicating whether it has been called. The previous protocol of calling cleanupAll() before deleteAll() implemented a two-phase cleanup strategy for the application. That is no longer needed. Moreover, the cleanupAll() / deleteAll() sequence created a time window during which individual LLSingleton instances weren't usable (to the extent that their cleanupSingleton() methods released essential resources) but still existed -- so a getInstance() call would return the crippled instance rather than recreating it. Remove cleanupAll() calls from tests; adjust to new order of expected side effects: instead of A::cleanupSingleton(), B::cleanupSingleton(), ~A(), ~B(), now we get A::cleanupSingleton(), ~A(), B::cleanupSingleton(), ~B(). --- indra/llcommon/llsingleton.cpp | 45 +++----- indra/llcommon/llsingleton.h | 120 ++++++++++------------ indra/llcommon/tests/llsingleton_test.cpp | 14 +-- indra/newview/llappviewer.cpp | 16 +-- 4 files changed, 76 insertions(+), 119 deletions(-) diff --git a/indra/llcommon/llsingleton.cpp b/indra/llcommon/llsingleton.cpp index 9fbd78a000..a9ab219051 100644 --- a/indra/llcommon/llsingleton.cpp +++ b/indra/llcommon/llsingleton.cpp @@ -290,8 +290,7 @@ LLSingletonBase::vec_t LLSingletonBase::dep_sort() // SingletonDeps through the life of the program, dynamically adding and // removing LLSingletons as they are created and destroyed, in practice // it's less messy to construct it on demand. The overhead of doing so - // should happen basically twice: once for cleanupAll(), once for - // deleteAll(). + // should happen basically once: for deleteAll(). typedef LLDependencies SingletonDeps; SingletonDeps sdeps; list_t& master(get_master()); @@ -323,35 +322,23 @@ LLSingletonBase::vec_t LLSingletonBase::dep_sort() return ret; } -//static -void LLSingletonBase::cleanupAll() +void LLSingletonBase::cleanup_() { - // It's essential to traverse these in dependency order. - BOOST_FOREACH(LLSingletonBase* sp, dep_sort()) + logdebugs("calling ", + demangle(typeid(*this).name()).c_str(), "::cleanupSingleton()"); + try { - // Call cleanupSingleton() only if we haven't already done so for this - // instance. - if (! sp->mCleaned) - { - sp->mCleaned = true; - - logdebugs("calling ", - demangle(typeid(*sp).name()).c_str(), "::cleanupSingleton()"); - try - { - sp->cleanupSingleton(); - } - catch (const std::exception& e) - { - logwarns("Exception in ", demangle(typeid(*sp).name()).c_str(), - "::cleanupSingleton(): ", e.what()); - } - catch (...) - { - logwarns("Unknown exception in ", demangle(typeid(*sp).name()).c_str(), - "::cleanupSingleton()"); - } - } + cleanupSingleton(); + } + catch (const std::exception& e) + { + logwarns("Exception in ", demangle(typeid(*this).name()).c_str(), + "::cleanupSingleton(): ", e.what()); + } + catch (...) + { + logwarns("Unknown exception in ", demangle(typeid(*this).name()).c_str(), + "::cleanupSingleton()"); } } diff --git a/indra/llcommon/llsingleton.h b/indra/llcommon/llsingleton.h index 859e271e26..2b4e3e8895 100644 --- a/indra/llcommon/llsingleton.h +++ b/indra/llcommon/llsingleton.h @@ -48,7 +48,6 @@ private: typedef std::vector vec_t; static vec_t dep_sort(); - bool mCleaned; // cleanupSingleton() has been called // we directly depend on these other LLSingletons typedef boost::unordered_set set_t; set_t mDepends; @@ -120,6 +119,9 @@ protected: virtual void initSingleton() {} virtual void cleanupSingleton() {} + // internal wrapper around calls to cleanupSingleton() + void cleanup_(); + // 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 @@ -129,32 +131,15 @@ protected: public: /** - * Call this to call the cleanupSingleton() method for every LLSingleton - * constructed since the start of the last cleanupAll() call. (Any - * LLSingleton constructed DURING a cleanupAll() call won't be cleaned up - * until the next cleanupAll() call.) cleanupSingleton() neither deletes - * nor destroys its LLSingleton; therefore it's safe to include logic that - * might take significant realtime or even throw an exception. - * - * The most important property of cleanupAll() is that cleanupSingleton() - * methods are called in dependency order, leaf classes last. Thus, given - * two LLSingleton subclasses A and B, if A's dependency on B is properly - * expressed as a B::getInstance() or B::instance() call during either - * A::A() or A::initSingleton(), B will be cleaned up after A. - * - * If a cleanupSingleton() method throws an exception, the exception is - * logged, but cleanupAll() attempts to continue calling the rest of the - * cleanupSingleton() methods. - */ - static void cleanupAll(); - /** - * Call this to call the deleteSingleton() method for every LLSingleton - * constructed since the start of the last deleteAll() call. (Any - * LLSingleton constructed DURING a deleteAll() call won't be cleaned up - * until the next deleteAll() call.) deleteSingleton() deletes and - * destroys its LLSingleton. Any cleanup logic that might take significant - * realtime -- or throw an exception -- must not be placed in your - * LLSingleton's destructor, but rather in its cleanupSingleton() method. + * deleteAll() calls the cleanupSingleton() and deleteSingleton() methods + * for every LLSingleton constructed since the start of the last + * deleteAll() call. (Any LLSingleton constructed DURING a deleteAll() + * call won't be cleaned up until the next deleteAll() call.) + * deleteSingleton() deletes and destroys its LLSingleton. Any cleanup + * logic that might take significant realtime -- or throw an exception -- + * must not be placed in your LLSingleton's destructor, but rather in its + * cleanupSingleton() method, which is called implicitly by + * deleteSingleton(). * * The most important property of deleteAll() is that deleteSingleton() * methods are called in dependency order, leaf classes last. Thus, given @@ -162,9 +147,9 @@ public: * expressed as a B::getInstance() or B::instance() call during either * A::A() or A::initSingleton(), B will be cleaned up after A. * - * If a deleteSingleton() method throws an exception, the exception is - * logged, but deleteAll() attempts to continue calling the rest of the - * deleteSingleton() methods. + * If a cleanupSingleton() or deleteSingleton() method throws an + * exception, the exception is logged, but deleteAll() attempts to + * continue calling the rest of the deleteSingleton() methods. */ static void deleteAll(); }; @@ -198,7 +183,6 @@ struct LLSingleton_manage_master // Now we can implement LLSingletonBase's template constructor. template LLSingletonBase::LLSingletonBase(tag): - mCleaned(false), mDeleteSingleton(NULL) { // Make this the currently-initializing LLSingleton. @@ -232,10 +216,19 @@ LLSingletonBase::LLSingletonBase(tag): * leading back to yours, move the instance reference from your constructor to * your initSingleton() method. * - * If you override LLSingleton::cleanupSingleton(), your method will be - * called if someone calls LLSingletonBase::cleanupAll(). The significant part - * of this promise is that cleanupAll() will call individual - * cleanupSingleton() methods in reverse dependency order. + * If you override LLSingleton::cleanupSingleton(), your method will + * implicitly be called by LLSingleton::deleteSingleton() just before the + * instance is destroyed. We introduce a special cleanupSingleton() method + * because cleanupSingleton() operations can involve nontrivial realtime, or + * throw an exception. A destructor should do neither! + * + * If your cleanupSingleton() method throws an exception, we log that + * exception but carry on. + * + * If at some point you call LLSingletonBase::deleteAll(), all remaining + * LLSingleton instances will be destroyed in reverse dependency order. (Or + * call MySubclass::deleteSingleton() to specifically destroy the canonical + * MySubclass instance.) * * That is, consider LLSingleton subclasses C, B and A. A depends on B, which * in turn depends on C. These dependencies are expressed as calls to @@ -243,27 +236,15 @@ LLSingletonBase::LLSingletonBase(tag): * It shouldn't matter whether these calls appear in A::A() or * A::initSingleton(), likewise B::B() or B::initSingleton(). * - * We promise that if you later call LLSingletonBase::cleanupAll(): - * 1. A::cleanupSingleton() will be called before - * 2. B::cleanupSingleton(), which will be called before - * 3. C::cleanupSingleton(). + * We promise that if you later call LLSingletonBase::deleteAll(): + * 1. A::deleteSingleton() will be called before + * 2. B::deleteSingleton(), which will be called before + * 3. C::deleteSingleton(). * Put differently, if your LLSingleton subclass constructor or * initSingleton() method explicitly depends on some other LLSingleton * subclass, you may continue to rely on that other subclass in your * cleanupSingleton() method. * - * We introduce a special cleanupSingleton() method because cleanupSingleton() - * operations can involve nontrivial realtime, or might throw an exception. A - * destructor should do neither! - * - * If your cleanupSingleton() method throws an exception, we log that - * exception but proceed with the remaining cleanupSingleton() calls. - * - * Similarly, if at some point you call LLSingletonBase::deleteAll(), all - * remaining LLSingleton instances will be destroyed in dependency order. (Or - * call MySubclass::deleteSingleton() to specifically destroy the canonical - * MySubclass instance.) - * * As currently written, LLSingleton is not thread-safe. */ template @@ -340,31 +321,34 @@ public: } /** - * @brief Immediately delete the singleton. + * @brief Cleanup and destroy the singleton instance. * - * A subsequent call to LLProxy::getInstance() will construct a new + * deleteSingleton() calls this instance's cleanupSingleton() method and + * then destroys the instance. + * + * A subsequent call to LLSingleton::getInstance() will construct a new * instance of the class. * - * Without an explicit call to LLSingletonBase::deleteAll(), LLSingletons - * are implicitly destroyed after main() has exited and the C++ runtime is - * cleaning up statically-constructed objects. Some classes derived from - * LLSingleton have objects that are part of a runtime system that is - * terminated before main() exits. Calling the destructor of those objects - * after the termination of their respective systems can cause crashes and - * other problems during termination of the project. Using this method to - * destroy the singleton early can prevent these crashes. - * - * An example where this is needed is for a LLSingleton that has an APR - * object as a member that makes APR calls on destruction. The APR system is - * shut down explicitly before main() exits. This causes a crash on exit. - * Using this method before the call to apr_terminate() and NOT calling - * getInstance() again will prevent the crash. + * Without an explicit call to LLSingletonBase::deleteAll(), or + * LLSingleton::deleteSingleton(), LLSingleton instances are simply + * leaked. (Allowing implicit destruction at shutdown caused too many + * problems.) */ static void deleteSingleton() { - delete sData.mInstance; + // first call cleanupSingleton() + if (sData.mInstance) + { + sData.mInstance->cleanup_(); + } + // capture the instance and clear SingletonData + auto lameduck = sData.mInstance; sData.mInstance = NULL; sData.mInitState = DELETED; + // Now delete the instance. This sequence guards against the chance + // that the destructor throws, somebody catches it and there's a + // subsequent call to getInstance(). + delete lameduck; } static DERIVED_TYPE* getInstance() diff --git a/indra/llcommon/tests/llsingleton_test.cpp b/indra/llcommon/tests/llsingleton_test.cpp index 56886bc73f..865541be61 100644 --- a/indra/llcommon/tests/llsingleton_test.cpp +++ b/indra/llcommon/tests/llsingleton_test.cpp @@ -142,8 +142,6 @@ namespace tut \ (void)CLS::instance(); \ ensure_equals(sLog, #CLS "i" #CLS); \ - LLSingletonBase::cleanupAll(); \ - ensure_equals(sLog, #CLS "i" #CLS "x" #CLS); \ LLSingletonBase::deleteAll(); \ ensure_equals(sLog, #CLS "i" #CLS "x" #CLS "~" #CLS); \ } \ @@ -158,10 +156,8 @@ namespace tut \ (void)CLS::instance(); \ ensure_equals(sLog, #CLS #OTHER "i" #OTHER "i" #CLS); \ - LLSingletonBase::cleanupAll(); \ - ensure_equals(sLog, #CLS #OTHER "i" #OTHER "i" #CLS "x" #CLS "x" #OTHER); \ LLSingletonBase::deleteAll(); \ - ensure_equals(sLog, #CLS #OTHER "i" #OTHER "i" #CLS "x" #CLS "x" #OTHER "~" #CLS "~" #OTHER); \ + ensure_equals(sLog, #CLS #OTHER "i" #OTHER "i" #CLS "x" #CLS "~" #CLS "x" #OTHER "~" #OTHER); \ } \ \ template<> template<> \ @@ -174,10 +170,8 @@ namespace tut \ (void)CLS::instance(); \ ensure_equals(sLog, #CLS "i" #CLS #OTHER "i" #OTHER); \ - LLSingletonBase::cleanupAll(); \ - ensure_equals(sLog, #CLS "i" #CLS #OTHER "i" #OTHER "x" #CLS "x" #OTHER); \ LLSingletonBase::deleteAll(); \ - ensure_equals(sLog, #CLS "i" #CLS #OTHER "i" #OTHER "x" #CLS "x" #OTHER "~" #CLS "~" #OTHER); \ + ensure_equals(sLog, #CLS "i" #CLS #OTHER "i" #OTHER "x" #CLS "~" #CLS "x" #OTHER "~" #OTHER); \ } \ \ template<> template<> \ @@ -190,10 +184,8 @@ namespace tut \ (void)CLS::instance(); \ ensure_equals(sLog, #CLS "i" #CLS #OTHER "i" #OTHER); \ - LLSingletonBase::cleanupAll(); \ - ensure_equals(sLog, #CLS "i" #CLS #OTHER "i" #OTHER "x" #CLS "x" #OTHER); \ LLSingletonBase::deleteAll(); \ - ensure_equals(sLog, #CLS "i" #CLS #OTHER "i" #OTHER "x" #CLS "x" #OTHER "~" #CLS "~" #OTHER); \ + ensure_equals(sLog, #CLS "i" #CLS #OTHER "i" #OTHER "x" #CLS "~" #CLS "x" #OTHER "~" #OTHER); \ } TESTS(A, B, 4, 5, 6, 7) diff --git a/indra/newview/llappviewer.cpp b/indra/newview/llappviewer.cpp index 56e8cc8ff4..398c5eff65 100644 --- a/indra/newview/llappviewer.cpp +++ b/indra/newview/llappviewer.cpp @@ -2113,25 +2113,19 @@ bool LLAppViewer::cleanup() removeMarkerFiles(); - // It's not at first obvious where, in this long sequence, generic cleanup - // calls OUGHT to go. So let's say this: as we migrate cleanup from + // It's not at first obvious where, in this long sequence, a generic cleanup + // call OUGHT to go. So let's say this: as we migrate cleanup from // explicit hand-placed calls into the generic mechanism, eventually - // all cleanup will get subsumed into the generic calls. So the calls you + // all cleanup will get subsumed into the generic call. So the calls you // still see above are calls that MUST happen before the generic cleanup // kicks in. - // This calls every remaining LLSingleton's cleanupSingleton() method. - // This method should perform any cleanup that might take significant - // realtime, or might throw an exception. - LLSingletonBase::cleanupAll(); - // The logging subsystem depends on an LLSingleton. Any logging after // LLSingletonBase::deleteAll() won't be recorded. LL_INFOS() << "Goodbye!" << LL_ENDL; - // This calls every remaining LLSingleton's deleteSingleton() method. - // No class destructor should perform any cleanup that might take - // significant realtime, or throw an exception. + // This calls every remaining LLSingleton's cleanupSingleton() and + // deleteSingleton() methods. LLSingletonBase::deleteAll(); removeDumpDir();