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/**
* @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
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