/** * @file llinstancetracker.h * @brief LLInstanceTracker is a mixin class that automatically tracks object * instances with or without an associated key * * $LicenseInfo:firstyear=2000&license=viewerlgpl$ * Second Life Viewer Source Code * Copyright (C) 2010, Linden Research, Inc. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; * version 2.1 of the License only. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * * Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA * $/LicenseInfo$ */ #ifndef LL_LLINSTANCETRACKER_H #define LL_LLINSTANCETRACKER_H #include <map> #include "string_table.h" #include <boost/utility.hpp> #include <boost/function.hpp> #include <boost/bind.hpp> #include <boost/iterator/transform_iterator.hpp> #include <boost/iterator/indirect_iterator.hpp> class LL_COMMON_API LLInstanceTrackerBase : public boost::noncopyable { protected: static void * & getInstances(std::type_info const & info); }; /// This mix-in class adds support for tracking all instances of the specified class parameter T /// The (optional) key associates a value of type KEY with a given instance of T, for quick lookup /// If KEY is not provided, then instances are stored in a simple set /// @NOTE: see explicit specialization below for default KEY==T* case template<typename T, typename KEY = T*> class LLInstanceTracker : public LLInstanceTrackerBase { typedef typename std::map<KEY, T*> InstanceMap; typedef LLInstanceTracker<T, KEY> MyT; typedef boost::function<const KEY&(typename InstanceMap::value_type&)> KeyGetter; typedef boost::function<T*(typename InstanceMap::value_type&)> InstancePtrGetter; public: /// Dereferencing key_iter gives you a const KEY& typedef boost::transform_iterator<KeyGetter, typename InstanceMap::iterator> key_iter; /// Dereferencing instance_iter gives you a T& typedef boost::indirect_iterator< boost::transform_iterator<InstancePtrGetter, typename InstanceMap::iterator> > instance_iter; static T* getInstance(const KEY& k) { typename InstanceMap::const_iterator found = getMap_().find(k); return (found == getMap_().end()) ? NULL : found->second; } static key_iter beginKeys() { return boost::make_transform_iterator(getMap_().begin(), boost::bind(&InstanceMap::value_type::first, _1)); } static key_iter endKeys() { return boost::make_transform_iterator(getMap_().end(), boost::bind(&InstanceMap::value_type::first, _1)); } static instance_iter beginInstances() { return instance_iter(boost::make_transform_iterator(getMap_().begin(), boost::bind(&InstanceMap::value_type::second, _1))); } static instance_iter endInstances() { return instance_iter(boost::make_transform_iterator(getMap_().end(), boost::bind(&InstanceMap::value_type::second, _1))); } static S32 instanceCount() { return getMap_().size(); } protected: LLInstanceTracker(KEY key) { add_(key); } virtual ~LLInstanceTracker() { remove_(); } virtual void setKey(KEY key) { remove_(); add_(key); } virtual const KEY& getKey() const { return mKey; } private: void add_(KEY key) { mKey = key; getMap_()[key] = static_cast<T*>(this); } void remove_() { getMap_().erase(mKey); } static InstanceMap& getMap_() { void * & instances = getInstances(typeid(MyT)); if (! instances) { instances = new InstanceMap; } return * static_cast<InstanceMap*>(instances); } private: KEY mKey; }; /// explicit specialization for default case where KEY is T* /// use a simple std::set<T*> template<typename T> class LLInstanceTracker<T, T*> : public LLInstanceTrackerBase { typedef typename std::set<T*> InstanceSet; typedef LLInstanceTracker<T, T*> MyT; public: /// Dereferencing key_iter gives you a T* (since T* is the key) typedef typename InstanceSet::iterator key_iter; /// Dereferencing instance_iter gives you a T& typedef boost::indirect_iterator<key_iter> instance_iter; /// for completeness of analogy with the generic implementation static T* getInstance(T* k) { return k; } static S32 instanceCount() { return getSet_().size(); } // Instantiate this to get access to iterators for this type. It's a 'guard' in the sense // that it treats deletes of this type as errors as long as there is an instance of // this class alive in scope somewhere (i.e. deleting while iterating is bad). class LLInstanceTrackerScopedGuard { public: LLInstanceTrackerScopedGuard() { ++sIterationNestDepth; } ~LLInstanceTrackerScopedGuard() { --sIterationNestDepth; } static instance_iter beginInstances() { return instance_iter(getSet_().begin()); } static instance_iter endInstances() { return instance_iter(getSet_().end()); } static key_iter beginKeys() { return getSet_().begin(); } static key_iter endKeys() { return getSet_().end(); } }; protected: LLInstanceTracker() { // it's safe but unpredictable to create instances of this type while all instances are being iterated over. I hate unpredictable. This assert will probably be turned on early in the next development cycle. //llassert(sIterationNestDepth == 0); getSet_().insert(static_cast<T*>(this)); } virtual ~LLInstanceTracker() { // it's unsafe to delete instances of this type while all instances are being iterated over. llassert(sIterationNestDepth == 0); getSet_().erase(static_cast<T*>(this)); } LLInstanceTracker(const LLInstanceTracker& other) { //llassert(sIterationNestDepth == 0); getSet_().insert(static_cast<T*>(this)); } static InstanceSet& getSet_() { void * & instances = getInstances(typeid(MyT)); if (! instances) { instances = new InstanceSet; } return * static_cast<InstanceSet *>(instances); } static S32 sIterationNestDepth; }; template <typename T> S32 LLInstanceTracker<T, T*>::sIterationNestDepth = 0; #endif