LLInstanceTracker and LLSingleton updated yet again.

indra/llcommon/llinstancetracker.cpp

@@ -35,13 +35,15 @@
 //static 
 void * & LLInstanceTrackerBase::getInstances(std::type_info const & info)
 {
-	static std::map<std::string, void *> instances;
+	typedef std::map<std::string, void *> InstancesMap;
+	static InstancesMap instances;
 
-	std::string k = info.name();
+	// std::map::insert() is just what we want here. You attempt to insert a
-	if(instances.find(k) == instances.end())
+	// (key, value) pair. If the specified key doesn't yet exist, it inserts
-	{
+	// the pair and returns a std::pair of (iterator, true). If the specified
-		instances[k] = NULL;
+	// key DOES exist, insert() simply returns (iterator, false). One lookup
-	}
+	// handles both cases.
-
+	return instances.insert(InstancesMap::value_type(info.name(),
-	return instances[k];
+													 InstancesMap::mapped_type()))
+		.first->second;
 }

indra/llcommon/llinstancetracker.h

@@ -36,6 +36,7 @@
 #define LL_LLINSTANCETRACKER_H
 
 #include <map>
+#include <typeinfo>
 
 #include "string_table.h"
 #include <boost/utility.hpp>
@@ -48,6 +49,30 @@ class LL_COMMON_API LLInstanceTrackerBase : public boost::noncopyable
 {
 	protected:
 		static void * & getInstances(std::type_info const & info);
+
+	/// Find or create a STATICDATA instance for the specified TRACKED class.
+	/// STATICDATA must be default-constructible.
+	template<typename STATICDATA, class TRACKED>
+	static STATICDATA& getStatic()
+	{
+		void *& instances = getInstances(typeid(TRACKED));
+		if (! instances)
+		{
+			instances = new STATICDATA;
+		}
+		return *static_cast<STATICDATA*>(instances);
+	}
+
+    /// It's not essential to derive your STATICDATA (for use with
+    /// getStatic()) from StaticBase; it's just that both known
+    /// implementations do.
+    struct StaticBase
+    {
+        StaticBase():
+            sIterationNestDepth(0)
+        {}
+        S32 sIterationNestDepth;
+    };
 };
 
 /// This mix-in class adds support for tracking all instances of the specified class parameter T
@@ -57,8 +82,15 @@ class LL_COMMON_API LLInstanceTrackerBase : public boost::noncopyable
 template<typename T, typename KEY = T*>
 class LLInstanceTracker : public LLInstanceTrackerBase
 {
-	typedef typename std::map<KEY, T*> InstanceMap;
 	typedef LLInstanceTracker<T, KEY> MyT;
+	typedef typename std::map<KEY, T*> InstanceMap;
+	struct StaticData: public StaticBase
+	{
+		InstanceMap sMap;
+	};
+	static StaticData& getStatic() { return LLInstanceTrackerBase::getStatic<StaticData, MyT>(); }
+	static InstanceMap& getMap_() { return getStatic().sMap; }
+
 public:
 	class instance_iter : public boost::iterator_facade<instance_iter, T, boost::forward_traversal_tag>
 	{
@@ -68,12 +100,12 @@ public:
 		instance_iter(const typename InstanceMap::iterator& it)
 		:	mIterator(it)
 		{
-			++sIterationNestDepth;
+			++getStatic().sIterationNestDepth;
 		}
 
 		~instance_iter()
 		{
-			--sIterationNestDepth;
+			--getStatic().sIterationNestDepth;
 		}
 
 
@@ -102,18 +134,18 @@ public:
 		key_iter(typename InstanceMap::iterator it)
 			:	mIterator(it)
 		{
-			++sIterationNestDepth;
+			++getStatic().sIterationNestDepth;
 		}
 
 		key_iter(const key_iter& other)
 			:	mIterator(other.mIterator)
 		{
-			++sIterationNestDepth;
+			++getStatic().sIterationNestDepth;
 		}
 
 		~key_iter()
 		{
-			--sIterationNestDepth;
+			--getStatic().sIterationNestDepth;
 		}
 
 
@@ -166,7 +198,7 @@ protected:
 	virtual ~LLInstanceTracker() 
 	{ 
 		// it's unsafe to delete instances of this type while all instances are being iterated over.
-		llassert(sIterationNestDepth == 0);
+		llassert_always(getStatic().sIterationNestDepth == 0);
 		remove_();		
 	}
 	virtual void setKey(KEY key) { remove_(); add_(key); }
@@ -183,31 +215,24 @@ private:
 		getMap_().erase(mInstanceKey);
 	}
 
-    static InstanceMap& getMap_()
-    {
-		void * & instances = getInstances(typeid(MyT));
-        if (! instances)
-        {
-            instances = new InstanceMap;
-        }
-        return * static_cast<InstanceMap*>(instances);
-    }
-
 private:
-
 	KEY mInstanceKey;
-	static S32 sIterationNestDepth;
 };
 
-template <typename T, typename KEY> S32 LLInstanceTracker<T, KEY>::sIterationNestDepth = 0;
-
 /// 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;
+	typedef typename std::set<T*> InstanceSet;
+	struct StaticData: public StaticBase
+	{
+		InstanceSet sSet;
+	};
+	static StaticData& getStatic() { return LLInstanceTrackerBase::getStatic<StaticData, MyT>(); }
+	static InstanceSet& getSet_() { return getStatic().sSet; }
+
 public:
 
 	/// for completeness of analogy with the generic implementation
@@ -220,18 +245,18 @@ public:
 		instance_iter(const typename InstanceSet::iterator& it)
 		:	mIterator(it)
 		{
-			++sIterationNestDepth;
+			++getStatic().sIterationNestDepth;
 		}
 
 		instance_iter(const instance_iter& other)
 		:	mIterator(other.mIterator)
 		{
-			++sIterationNestDepth;
+			++getStatic().sIterationNestDepth;
 		}
 
 		~instance_iter()
 		{
-			--sIterationNestDepth;
+			--getStatic().sIterationNestDepth;
 		}
 
 	private:
@@ -263,7 +288,7 @@ protected:
 	virtual ~LLInstanceTracker()
 	{
 		// it's unsafe to delete instances of this type while all instances are being iterated over.
-		llassert(sIterationNestDepth == 0);
+		llassert_always(getStatic().sIterationNestDepth == 0);
 		getSet_().erase(static_cast<T*>(this));
 	}
 
@@ -271,20 +296,6 @@ protected:
 	{
 		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

indra/llcommon/llsingleton.h

@@ -114,8 +114,7 @@ private:
 
 		~SingletonInstanceData()
 		{
-			SingletonInstanceData& data = getData();
+			if (mInitState != DELETED)
-			if (data.mInitState != DELETED)
 			{
 				deleteSingleton();
 			}
@@ -130,7 +129,26 @@ public:
 		data.mInitState = DELETED;
 	}
 
-	// Can be used to control when the singleton is deleted.  Not normally needed.
+	/**
+	 * @brief Immediately delete the singleton.
+	 *
+	 * A subsequent call to LLProxy::getInstance() will construct a new
+	 * instance of the class.
+	 *
+	 * LLSingletons are normally 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.
+	 */
 	static void deleteSingleton()
 	{
 		delete getData().mSingletonInstance;