diff options
Diffstat (limited to 'indra/llcommon/llsingleton.cpp')
| -rw-r--r-- | indra/llcommon/llsingleton.cpp | 356 |
1 files changed, 355 insertions, 1 deletions
diff --git a/indra/llcommon/llsingleton.cpp b/indra/llcommon/llsingleton.cpp index 9b49e52377..4212014e1b 100644 --- a/indra/llcommon/llsingleton.cpp +++ b/indra/llcommon/llsingleton.cpp @@ -25,7 +25,361 @@ */ #include "linden_common.h" - #include "llsingleton.h" +#include "llerror.h" +#include "llerrorcontrol.h" // LLError::is_available() +#include "lldependencies.h" +#include <boost/foreach.hpp> +#include <algorithm> +#include <iostream> // std::cerr in dire emergency +#include <sstream> +#include <stdexcept> + +namespace { +void log(LLError::ELevel level, + const char* p1="", const char* p2="", const char* p3="", const char* p4=""); +} // anonymous namespace + +// Our master list of all LLSingletons is itself an LLSingleton. We used to +// store it in a function-local static, but that could get destroyed before +// the last of the LLSingletons -- and ~LLSingletonBase() definitely wants to +// remove itself from the master list. Since the whole point of this master +// list is to help track inter-LLSingleton dependencies, and since we have +// this implicit dependency from every LLSingleton to the master list, make it +// an LLSingleton. +class LLSingletonBase::MasterList: + public LLSingleton<LLSingletonBase::MasterList> +{ +private: + friend class LLSingleton<LLSingletonBase::MasterList>; + +public: + // No need to make this private with accessors; nobody outside this source + // file can see it. + LLSingletonBase::list_t mList; +}; + +//static +LLSingletonBase::list_t& LLSingletonBase::get_master() +{ + return LLSingletonBase::MasterList::instance().mList; +} + +void LLSingletonBase::add_master() +{ + // As each new LLSingleton is constructed, add to the master list. + get_master().push_back(this); +} + +void LLSingletonBase::remove_master() +{ + // When an LLSingleton is destroyed, remove from master list. + // add_master() used to capture the iterator to the newly-added list item + // so we could directly erase() it from the master list. Unfortunately + // that runs afoul of destruction-dependency order problems. So search the + // master list, and remove this item IF FOUND. We have few enough + // LLSingletons, and they are so rarely destroyed (once per run), that the + // cost of a linear search should not be an issue. + get_master().remove(this); +} + +// Wrapping our initializing list in a static method ensures that it will be +// constructed on demand. This list doesn't also need to be in an LLSingleton +// because (a) it should be empty by program shutdown and (b) none of our +// destructors reference it. +//static +LLSingletonBase::list_t& LLSingletonBase::get_initializing() +{ + static list_t sList; + return sList; +} + +LLSingletonBase::LLSingletonBase(): + mCleaned(false), + mDeleteSingleton(NULL) +{ + // Make this the currently-initializing LLSingleton. + push_initializing(); +} + +LLSingletonBase::~LLSingletonBase() {} + +void LLSingletonBase::push_initializing() +{ + get_initializing().push_back(this); +} + +void LLSingletonBase::pop_initializing() +{ + list_t& list(get_initializing()); + if (list.empty()) + { + logerrs("Underflow in stack of currently-initializing LLSingletons at ", + demangle(typeid(*this).name()).c_str(), "::getInstance()"); + } + if (list.back() != this) + { + LLSingletonBase* back(list.back()); + logerrs("Push/pop mismatch in stack of currently-initializing LLSingletons: ", + demangle(typeid(*this).name()).c_str(), "::getInstance() trying to pop ", + demangle(typeid(*back).name()).c_str()); + } + // Here we're sure that list.back() == this. Whew, pop it. + list.pop_back(); +} + +void LLSingletonBase::capture_dependency(EInitState initState) +{ + // Did this getInstance() call come from another LLSingleton, or from + // vanilla application code? Note that although this is a nontrivial + // method, the vast majority of its calls arrive here with initializing + // empty(). + list_t& initializing(get_initializing()); + if (! initializing.empty()) + { + // getInstance() is being called by some other LLSingleton. But -- is + // this a circularity? That is, does 'this' already appear in the + // initializing stack? + // For what it's worth, normally 'initializing' should contain very + // few elements. + list_t::const_iterator found = + std::find(initializing.begin(), initializing.end(), this); + if (found != initializing.end()) + { + // Report the circularity. Requiring the coder to dig through the + // logic to diagnose exactly how we got here is less than helpful. + std::ostringstream out; + for ( ; found != initializing.end(); ++found) + { + // 'found' is an iterator; *found is an LLSingletonBase*; **found + // is the actual LLSingletonBase instance. + LLSingletonBase* foundp(*found); + out << demangle(typeid(*foundp).name()) << " -> "; + } + // We promise to capture dependencies from both the constructor + // and the initSingleton() method, so an LLSingleton's instance + // pointer is on the initializing list during both. Now that we've + // detected circularity, though, we must distinguish the two. If + // the recursive call is from the constructor, we CAN'T honor it: + // otherwise we'd be returning a pointer to a partially- + // constructed object! But from initSingleton() is okay: that + // method exists specifically to support circularity. + // Decide which log helper to call based on initState. They have + // identical signatures. + ((initState == CONSTRUCTING)? logerrs : logwarns) + ("LLSingleton circularity: ", out.str().c_str(), + demangle(typeid(*this).name()).c_str(), ""); + } + else + { + // Here 'this' is NOT already in the 'initializing' stack. Great! + // Record the dependency. + // initializing.back() is the LLSingletonBase* currently being + // initialized. Store 'this' in its mDepends set. + LLSingletonBase* current(initializing.back()); + if (current->mDepends.insert(this).second) + { + // only log the FIRST time we hit this dependency! + log(LLError::LEVEL_DEBUG, demangle(typeid(*current).name()).c_str(), + " depends on ", demangle(typeid(*this).name()).c_str()); + } + } + } +} + +//static +LLSingletonBase::vec_t LLSingletonBase::dep_sort() +{ + // While it would theoretically be possible to maintain a static + // 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(). + typedef LLDependencies<LLSingletonBase*> SingletonDeps; + SingletonDeps sdeps; + list_t& master(get_master()); + BOOST_FOREACH(LLSingletonBase* sp, master) + { + // Build the SingletonDeps structure by adding, for each + // LLSingletonBase* sp in the master list, sp itself. It has no + // associated value type in our SingletonDeps, hence the 0. We don't + // record the LLSingletons it must follow; rather, we record the ones + // it must precede. Copy its mDepends to a KeyList to express that. + sdeps.add(sp, 0, + SingletonDeps::KeyList(), + SingletonDeps::KeyList(sp->mDepends.begin(), sp->mDepends.end())); + } + vec_t ret; + ret.reserve(master.size()); + // We should be able to effect this with a transform_iterator that + // extracts just the first (key) element from each sorted_iterator, then + // uses vec_t's range constructor... but frankly this is more + // straightforward, as long as we remember the above reserve() call! + BOOST_FOREACH(SingletonDeps::sorted_iterator::value_type pair, sdeps.sort()) + { + ret.push_back(pair.first); + } + // The master list is not itself pushed onto the master list. Add it as + // the very last entry -- it is the LLSingleton on which ALL others + // depend! -- so our caller will process it. + ret.push_back(MasterList::getInstance()); + return ret; +} + +//static +void LLSingletonBase::cleanupAll() +{ + // It's essential to traverse these in dependency order. + BOOST_FOREACH(LLSingletonBase* sp, dep_sort()) + { + // Call cleanupSingleton() only if we haven't already done so for this + // instance. + if (! sp->mCleaned) + { + sp->mCleaned = true; + + log(LLError::LEVEL_DEBUG, "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()"); + } + } + } +} + +//static +void LLSingletonBase::deleteAll() +{ + // It's essential to traverse these in dependency order. + BOOST_FOREACH(LLSingletonBase* sp, dep_sort()) + { + // Capture the class name first: in case of exception, don't count on + // being able to extract it later. + const std::string name = demangle(typeid(*sp).name()); + try + { + // Call static method through instance function pointer. + if (! sp->mDeleteSingleton) + { + // This Should Not Happen... but carry on. + logwarns(name.c_str(), "::mDeleteSingleton not initialized!"); + } + else + { + // properly initialized: call it. + log(LLError::LEVEL_DEBUG, "calling ", name.c_str(), "::deleteSingleton()"); + // From this point on, DO NOT DEREFERENCE sp! + sp->mDeleteSingleton(); + } + } + catch (const std::exception& e) + { + logwarns("Exception in ", name.c_str(), "::deleteSingleton(): ", e.what()); + } + catch (...) + { + logwarns("Unknown exception in ", name.c_str(), "::deleteSingleton()"); + } + } +} + +/*------------------------ Final cleanup management ------------------------*/ +class LLSingletonBase::MasterRefcount +{ +public: + // store a POD int so it will be statically initialized to 0 + int refcount; +}; +static LLSingletonBase::MasterRefcount sMasterRefcount; + +LLSingletonBase::ref_ptr_t LLSingletonBase::get_master_refcount() +{ + // Calling this method constructs a new ref_ptr_t, which implicitly calls + // intrusive_ptr_add_ref(MasterRefcount*). + return &sMasterRefcount; +} + +void intrusive_ptr_add_ref(LLSingletonBase::MasterRefcount* mrc) +{ + // Count outstanding SingletonLifetimeManager instances. + ++mrc->refcount; +} + +void intrusive_ptr_release(LLSingletonBase::MasterRefcount* mrc) +{ + // Notice when each SingletonLifetimeManager instance is destroyed. + if (! --mrc->refcount) + { + // The last instance was destroyed. Time to kill any remaining + // LLSingletons -- but in dependency order. + LLSingletonBase::deleteAll(); + } +} + +/*---------------------------- Logging helpers -----------------------------*/ +namespace { +void log(LLError::ELevel level, + const char* p1, const char* p2, const char* p3, const char* p4) +{ + // Check whether we're in the implicit final LLSingletonBase::deleteAll() + // call. We've carefully arranged for deleteAll() to be called when the + // last SingletonLifetimeManager instance is destroyed -- in other words, + // when the last translation unit containing an LLSingleton instance + // cleans up static data. That could happen after std::cerr is destroyed! + // The is_available() test below ensures that we'll stop logging once + // LLError has been cleaned up. If we had a similar portable test for + // std::cerr, this would be a good place to use it. As we do not, just + // don't log anything during implicit final deleteAll(). Detect that by + // the master refcount having gone to zero. + if (sMasterRefcount.refcount == 0) + return; + + // Check LLError::is_available() because some of LLError's infrastructure + // is itself an LLSingleton. If that LLSingleton has not yet been + // initialized, trying to log will engage LLSingleton machinery... and + // around and around we go. + if (LLError::is_available()) + { + lllog(level, false, "LLSingleton") << p1 << p2 << p3 << p4 << LL_ENDL; + } + else + { + // Caller may be a test program, or something else whose stderr is + // visible to the user. + std::cerr << p1 << p2 << p3 << p4 << std::endl; + } +} +} // anonymous namespace + +//static +void LLSingletonBase::logwarns(const char* p1, const char* p2, const char* p3, const char* p4) +{ + log(LLError::LEVEL_WARN, p1, p2, p3, p4); +} + +//static +void LLSingletonBase::logerrs(const char* p1, const char* p2, const char* p3, const char* p4) +{ + log(LLError::LEVEL_ERROR, p1, p2, p3, p4); + // The other important side effect of LL_ERRS() is + // https://www.youtube.com/watch?v=OMG7paGJqhQ (emphasis on OMG) + LLError::crashAndLoop(std::string()); +} +std::string LLSingletonBase::demangle(const char* mangled) +{ + return LLError::Log::demangle(mangled); +} |