Automated merge with ssh://bitbucket.org/lindenlab/viewer-release

14 files changed, 1559 insertions, 216 deletions

diff --git a/indra/llcommon/CMakeLists.txt b/indra/llcommon/CMakeLists.txt
index 5863310162..e86e6951b2 100755
--- a/indra/llcommon/CMakeLists.txt
+++ b/indra/llcommon/CMakeLists.txt
@@ -164,6 +164,7 @@ set(llcommon_HEADER_FILES
     llhash.h
     llheartbeat.h
     llindexedvector.h
+    llinitdestroyclass.h
     llinitparam.h
     llinstancetracker.h
     llkeythrottle.h
@@ -180,6 +181,7 @@ set(llcommon_HEADER_FILES
     llmortician.h
     llnametable.h
     llpointer.h
+    llpounceable.h
     llpredicate.h
     llpreprocessor.h
     llpriqueuemap.h
@@ -312,6 +314,7 @@ if (LL_TESTS)
   LL_ADD_INTEGRATION_TEST(llprocess "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(llleap "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(llstreamqueue "" "${test_libs}")
+  LL_ADD_INTEGRATION_TEST(llpounceable "" "${test_libs}")
 
   # *TODO - reenable these once tcmalloc libs no longer break the build.
   #ADD_BUILD_TEST(llallocator llcommon)
diff --git a/indra/llcommon/llapp.cpp b/indra/llcommon/llapp.cpp
index 5a40845e7d..2c52b11594 100755
--- a/indra/llcommon/llapp.cpp
+++ b/indra/llcommon/llapp.cpp
@@ -48,6 +48,7 @@
 #include "lleventtimer.h"
 #include "google_breakpad/exception_handler.h"
 #include "stringize.h"
+#include "llcleanup.h"
 
 //
 // Signal handling
@@ -177,7 +178,7 @@ LLApp::~LLApp()
 	
 	if(mExceptionHandler != 0) delete mExceptionHandler;
 
-	LLCommon::cleanupClass();
+	SUBSYSTEM_CLEANUP(LLCommon);
 }
 
 // static
diff --git a/indra/llcommon/llcleanup.h b/indra/llcommon/llcleanup.h
new file mode 100644
index 0000000000..8eda9a7fb3
--- /dev/null
+++ b/indra/llcommon/llcleanup.h
@@ -0,0 +1,30 @@
+/**
+ * @file   llcleanup.h
+ * @author Nat Goodspeed
+ * @date   2015-05-20
+ * @brief  Mechanism for cleaning up subsystem resources
+ * 
+ * $LicenseInfo:firstyear=2015&license=viewerlgpl$
+ * Copyright (c) 2015, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_LLCLEANUP_H)
+#define LL_LLCLEANUP_H
+
+#include "llerror.h"
+
+// Instead of directly calling SomeClass::cleanupClass(), use
+// SUBSYSTEM_CLEANUP(SomeClass);
+// This logs the call as well as performing it. That gives us a baseline
+// subsystem shutdown order against which to compare subsequent dynamic
+// shutdown schemes.
+#define SUBSYSTEM_CLEANUP(CLASSNAME)                                    \
+    do {                                                                \
+        LL_INFOS("Cleanup") << "Calling " #CLASSNAME "::cleanupClass()" << LL_ENDL; \
+        CLASSNAME::cleanupClass();                                      \
+    } while (0)
+// Use ancient do { ... } while (0) macro trick to permit a block of
+// statements with the same syntax as a single statement.
+
+#endif /* ! defined(LL_LLCLEANUP_H) */
diff --git a/indra/llcommon/llcommon.cpp b/indra/llcommon/llcommon.cpp
index 19642b0982..439ff4e628 100755
--- a/indra/llcommon/llcommon.cpp
+++ b/indra/llcommon/llcommon.cpp
@@ -31,6 +31,7 @@
 #include "llthread.h"
 #include "lltrace.h"
 #include "lltracethreadrecorder.h"
+#include "llcleanup.h"
 
 //static
 BOOL LLCommon::sAprInitialized = FALSE;
@@ -63,11 +64,11 @@ void LLCommon::cleanupClass()
 	sMasterThreadRecorder = NULL;
 	LLTrace::set_master_thread_recorder(NULL);
 	LLThreadSafeRefCount::cleanupThreadSafeRefCount();
-	LLTimer::cleanupClass();
+	SUBSYSTEM_CLEANUP(LLTimer);
 	if (sAprInitialized)
 	{
 		ll_cleanup_apr();
 		sAprInitialized = FALSE;
 	}
-	LLMemory::cleanupClass();
+	SUBSYSTEM_CLEANUP(LLMemory);
 }
diff --git a/indra/llcommon/llerror.cpp b/indra/llcommon/llerror.cpp
index 5ed348e13c..638cecb054 100755
--- a/indra/llcommon/llerror.cpp
+++ b/indra/llcommon/llerror.cpp
@@ -239,6 +239,14 @@ namespace
 {
 	std::string className(const std::type_info& type)
 	{
+		return LLError::Log::demangle(type.name());
+	}
+} // anonymous
+
+namespace LLError
+{
+	std::string Log::demangle(const char* mangled)
+	{
 #ifdef __GNUC__
 		// GCC: type_info::name() returns a mangled class name,st demangle
 
@@ -252,18 +260,18 @@ namespace
 			// but gcc 3.3 libstc++'s implementation of demangling is broken
 			// and fails without.
 			
-		char* name = abi::__cxa_demangle(type.name(),
+		char* name = abi::__cxa_demangle(mangled,
 										abi_name_buf, &abi_name_len, &status);
 			// this call can realloc the abi_name_buf pointer (!)
 
-		return name ? name : type.name();
+		return name ? name : mangled;
 
 #elif LL_WINDOWS
 		// DevStudio: type_info::name() includes the text "class " at the start
 
 		static const std::string class_prefix = "class ";
 
-		std::string name = type.name();
+		std::string name = mangled;
 		std::string::size_type p = name.find(class_prefix);
 		if (p == std::string::npos)
 		{
@@ -272,11 +280,14 @@ namespace
 
 		return name.substr(p + class_prefix.size());
 
-#else		
-		return type.name();
+#else
+		return mangled;
 #endif
 	}
+} // LLError
 
+namespace
+{
 	std::string functionName(const std::string& preprocessor_name)
 	{
 #if LL_WINDOWS
@@ -403,6 +414,11 @@ namespace
 
 namespace LLError
 {
+	bool is_available()
+	{
+		return Globals::instanceExists();
+	}
+
 	class SettingsConfig : public LLRefCount
 	{
 		friend class Settings;
diff --git a/indra/llcommon/llerror.h b/indra/llcommon/llerror.h
index 63040e1772..d0ddb5e8e9 100755
--- a/indra/llcommon/llerror.h
+++ b/indra/llcommon/llerror.h
@@ -189,6 +189,7 @@ namespace LLError
 		static std::ostringstream* out();
 		static void flush(std::ostringstream* out, char* message);
 		static void flush(std::ostringstream*, const CallSite&);
+		static std::string demangle(const char* mangled);
 	};
 	
 	struct LL_COMMON_API CallSite
diff --git a/indra/llcommon/llerrorcontrol.h b/indra/llcommon/llerrorcontrol.h
index 56ac52e5de..56e84f7172 100755
--- a/indra/llcommon/llerrorcontrol.h
+++ b/indra/llcommon/llerrorcontrol.h
@@ -189,6 +189,11 @@ namespace LLError
 
 	LL_COMMON_API std::string abbreviateFile(const std::string& filePath);
 	LL_COMMON_API int shouldLogCallCount();
+
+	// Check whether Globals exists. This should only be used by LLSingleton
+	// infrastructure to avoid trying to log when our internal LLSingleton is
+	// unavailable -- circularity ensues.
+	LL_COMMON_API bool is_available();
 };
 
 #endif // LL_LLERRORCONTROL_H
diff --git a/indra/llcommon/llinitdestroyclass.h b/indra/llcommon/llinitdestroyclass.h
new file mode 100644
index 0000000000..49bcefc33d
--- /dev/null
+++ b/indra/llcommon/llinitdestroyclass.h
@@ -0,0 +1,190 @@
+/**
+ * @file   llinitdestroyclass.h
+ * @author Nat Goodspeed
+ * @date   2015-05-27
+ * @brief  LLInitClass / LLDestroyClass mechanism
+ *
+ * The LLInitClass template, extracted from llui.h, ensures that control will
+ * reach a static initClass() method. LLDestroyClass does the same for a
+ * static destroyClass() method.
+ *
+ * The distinguishing characteristics of these templates are:
+ *
+ * - All LLInitClass<T>::initClass() methods are triggered by an explicit call
+ *   to LLInitClassList::instance().fireCallbacks(). Presumably this call
+ *   happens sometime after all static objects in the program have been
+ *   initialized. In other words, each LLInitClass<T>::initClass() method
+ *   should be able to make some assumptions about global program state.
+ *
+ * - Similarly, LLDestroyClass<T>::destroyClass() methods are triggered by
+ *   LLDestroyClassList::instance().fireCallbacks(). Again, presumably this
+ *   happens at a well-defined moment in the program's shutdown sequence.
+ *
+ * - The initClass() calls happen in an unspecified sequence. You may not rely
+ *   on the relative ordering of LLInitClass<T>::initClass() versus another
+ *   LLInitClass<U>::initClass() method. If you need such a guarantee, use
+ *   LLSingleton instead and make the dependency explicit.
+ *
+ * - Similarly, LLDestroyClass<T>::destroyClass() may happen either before or
+ *   after LLDestroyClass<U>::destroyClass(). You cannot rely on that order.
+ *
+ * $LicenseInfo:firstyear=2015&license=viewerlgpl$
+ * Copyright (c) 2015, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_LLINITDESTROYCLASS_H)
+#define LL_LLINITDESTROYCLASS_H
+
+#include "llerror.h"
+#include "llsingleton.h"
+#include <boost/function.hpp>
+#include <boost/signals2/signal.hpp>
+#include <typeinfo>
+
+/**
+ * LLCallbackRegistry is an implementation detail base class for
+ * LLInitClassList and LLDestroyClassList. It's a very thin wrapper around a
+ * Boost.Signals2 signal object.
+ */
+class LLCallbackRegistry
+{
+public:
+	typedef boost::signals2::signal<void()> callback_signal_t;
+	
+	void registerCallback(const callback_signal_t::slot_type& slot)
+	{
+		mCallbacks.connect(slot);
+	}
+
+	void fireCallbacks()
+	{
+		mCallbacks();
+	}
+
+private:
+	callback_signal_t mCallbacks;
+};
+
+/**
+ * LLInitClassList is the LLCallbackRegistry for LLInitClass. It stores the
+ * registered initClass() methods. It must be an LLSingleton because
+ * LLInitClass registers its initClass() method at static construction time
+ * (before main()), requiring LLInitClassList to be fully constructed on
+ * demand regardless of module initialization order.
+ */
+class LLInitClassList : 
+	public LLCallbackRegistry, 
+	public LLSingleton<LLInitClassList>
+{
+	friend class LLSingleton<LLInitClassList>;
+private:
+	LLInitClassList() {}
+};
+
+/**
+ * LLDestroyClassList is the LLCallbackRegistry for LLDestroyClass. It stores
+ * the registered destroyClass() methods. It must be an LLSingleton because
+ * LLDestroyClass registers its destroyClass() method at static construction
+ * time (before main()), requiring LLDestroyClassList to be fully constructed
+ * on demand regardless of module initialization order.
+ */
+class LLDestroyClassList : 
+	public LLCallbackRegistry, 
+	public LLSingleton<LLDestroyClassList>
+{
+	friend class LLSingleton<LLDestroyClassList>;
+private:
+	LLDestroyClassList() {}
+};
+
+/**
+ * LLRegisterWith is an implementation detail for LLInitClass and
+ * LLDestroyClass. It is intended to be used as a static class member whose
+ * constructor registers the specified callback with the LLMumbleClassList
+ * singleton registry specified as the template argument.
+ */
+template<typename T>
+class LLRegisterWith
+{
+public:
+	LLRegisterWith(boost::function<void ()> func)
+	{
+		T::instance().registerCallback(func);
+	}
+
+	// this avoids a MSVC bug where non-referenced static members are "optimized" away
+	// even if their constructors have side effects
+	S32 reference()
+	{
+		S32 dummy;
+		dummy = 0;
+		return dummy;
+	}
+};
+
+/**
+ * Derive MyClass from LLInitClass<MyClass> (the Curiously Recurring Template
+ * Pattern) to ensure that the static method MyClass::initClass() will be
+ * called (along with all other LLInitClass<T> subclass initClass() methods)
+ * when someone calls LLInitClassList::instance().fireCallbacks(). This gives
+ * the application specific control over the timing of all such
+ * initializations, without having to insert calls for every such class into
+ * generic application code.
+ */
+template<typename T>
+class LLInitClass
+{
+public:
+	LLInitClass() { sRegister.reference(); }
+
+	// When this static member is initialized, the subclass initClass() method
+	// is registered on LLInitClassList. See sRegister definition below.
+	static LLRegisterWith<LLInitClassList> sRegister;
+private:
+
+	// Provide a default initClass() method in case subclass misspells (or
+	// omits) initClass(). This turns a potential build error into a fatal
+	// runtime error.
+	static void initClass()
+	{
+		LL_ERRS() << "No static initClass() method defined for " << typeid(T).name() << LL_ENDL;
+	}
+};
+
+/**
+ * Derive MyClass from LLDestroyClass<MyClass> (the Curiously Recurring
+ * Template Pattern) to ensure that the static method MyClass::destroyClass()
+ * will be called (along with other LLDestroyClass<T> subclass destroyClass()
+ * methods) when someone calls LLDestroyClassList::instance().fireCallbacks().
+ * This gives the application specific control over the timing of all such
+ * cleanup calls, without having to insert calls for every such class into
+ * generic application code.
+ */
+template<typename T>
+class LLDestroyClass
+{
+public:
+	LLDestroyClass() { sRegister.reference(); }
+
+	// When this static member is initialized, the subclass destroyClass()
+	// method is registered on LLInitClassList. See sRegister definition
+	// below.
+	static LLRegisterWith<LLDestroyClassList> sRegister;
+private:
+
+	// Provide a default destroyClass() method in case subclass misspells (or
+	// omits) destroyClass(). This turns a potential build error into a fatal
+	// runtime error.
+	static void destroyClass()
+	{
+		LL_ERRS() << "No static destroyClass() method defined for " << typeid(T).name() << LL_ENDL;
+	}
+};
+
+// Here's where LLInitClass<T> specifies the subclass initClass() method.
+template <typename T> LLRegisterWith<LLInitClassList> LLInitClass<T>::sRegister(&T::initClass);
+// Here's where LLDestroyClass<T> specifies the subclass destroyClass() method.
+template <typename T> LLRegisterWith<LLDestroyClassList> LLDestroyClass<T>::sRegister(&T::destroyClass);
+
+#endif /* ! defined(LL_LLINITDESTROYCLASS_H) */
diff --git a/indra/llcommon/llpounceable.h b/indra/llcommon/llpounceable.h
new file mode 100644
index 0000000000..77b711bdc6
--- /dev/null
+++ b/indra/llcommon/llpounceable.h
@@ -0,0 +1,215 @@
+/**
+ * @file   llpounceable.h
+ * @author Nat Goodspeed
+ * @date   2015-05-22
+ * @brief  LLPounceable is tangentially related to a future: it's a holder for
+ *         a value that may or may not exist yet. Unlike a future, though,
+ *         LLPounceable freely allows reading the held value. (If the held
+ *         type T does not have a distinguished "empty" value, consider using
+ *         LLPounceable<boost::optional<T>>.)
+ *
+ *         LLPounceable::callWhenReady() is this template's claim to fame. It
+ *         allows its caller to "pounce" on the held value as soon as it
+ *         becomes non-empty. Call callWhenReady() with any C++ callable
+ *         accepting T. If the held value is already non-empty, callWhenReady()
+ *         will immediately call the callable with the held value. If the held
+ *         value is empty, though, callWhenReady() will enqueue the callable
+ *         for later. As soon as LLPounceable is assigned a non-empty held
+ *         value, it will flush the queue of deferred callables.
+ *
+ *         Consider a global LLMessageSystem* gMessageSystem. Message system
+ *         initialization happens at a very specific point during viewer
+ *         initialization. Other subsystems want to register callbacks on the
+ *         LLMessageSystem instance as soon as it's initialized, but their own
+ *         initialization may precede that. If we define gMessageSystem to be
+ *         an LLPounceable<LLMessageSystem*>, a subsystem can use
+ *         callWhenReady() to either register immediately (if gMessageSystem
+ *         is already up and runnning) or register as soon as gMessageSystem
+ *         is set with a new, initialized instance.
+ *
+ * $LicenseInfo:firstyear=2015&license=viewerlgpl$
+ * Copyright (c) 2015, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_LLPOUNCEABLE_H)
+#define LL_LLPOUNCEABLE_H
+
+#include "llsingleton.h"
+#include <boost/noncopyable.hpp>
+#include <boost/call_traits.hpp>
+#include <boost/type_traits/remove_pointer.hpp>
+#include <boost/utility/value_init.hpp>
+#include <boost/unordered_map.hpp>
+#include <boost/signals2/signal.hpp>
+
+// Forward declare the user template, since we want to be able to point to it
+// in some of its implementation classes.
+template <typename T, class TAG>
+class LLPounceable;
+
+template <typename T, typename TAG>
+struct LLPounceableTraits
+{
+    // Our "queue" is a signal object with correct signature.
+    typedef boost::signals2::signal<void (typename boost::call_traits<T>::param_type)> signal_t;
+    // Call callWhenReady() with any callable accepting T.
+    typedef typename signal_t::slot_type func_t;
+    // owner pointer type
+    typedef LLPounceable<T, TAG>* owner_ptr;
+};
+
+// Tag types distinguish the two different implementations of LLPounceable's
+// queue.
+struct LLPounceableQueue {};
+struct LLPounceableStatic {};
+
+// generic LLPounceableQueueImpl deliberately omitted: only the above tags are
+// legal
+template <typename T, class TAG>
+class LLPounceableQueueImpl;
+
+// The implementation selected by LLPounceableStatic uses an LLSingleton
+// because we can't count on a data member queue being initialized at the time
+// we start getting callWhenReady() calls. This is that LLSingleton.
+template <typename T>
+class LLPounceableQueueSingleton:
+    public LLSingleton<LLPounceableQueueSingleton<T> >
+{
+private:
+    typedef LLPounceableTraits<T, LLPounceableStatic> traits;
+    typedef typename traits::owner_ptr owner_ptr;
+    typedef typename traits::signal_t signal_t;
+
+    // For a given held type T, every LLPounceable<T, LLPounceableStatic>
+    // instance will call on the SAME LLPounceableQueueSingleton instance --
+    // given how class statics work. We must keep a separate queue for each
+    // LLPounceable instance. Use a hash map for that.
+    typedef boost::unordered_map<owner_ptr, signal_t> map_t;
+
+public:
+    // Disambiguate queues belonging to different LLPounceables.
+    signal_t& get(owner_ptr owner)
+    {
+        // operator[] has find-or-create semantics -- just what we want!
+        return mMap[owner];
+    }
+
+private:
+    map_t mMap;
+};
+
+// LLPounceableQueueImpl that uses the above LLSingleton
+template <typename T>
+class LLPounceableQueueImpl<T, LLPounceableStatic>
+{
+public:
+    typedef LLPounceableTraits<T, LLPounceableStatic> traits;
+    typedef typename traits::owner_ptr owner_ptr;
+    typedef typename traits::signal_t signal_t;
+
+    signal_t& get(owner_ptr owner) const
+    {
+        // this Impl contains nothing; it delegates to the Singleton
+        return LLPounceableQueueSingleton<T>::instance().get(owner);
+    }
+};
+
+// The implementation selected by LLPounceableQueue directly contains the
+// queue of interest, suitable for an LLPounceable we can trust to be fully
+// initialized when it starts getting callWhenReady() calls.
+template <typename T>
+class LLPounceableQueueImpl<T, LLPounceableQueue>
+{
+public:
+    typedef LLPounceableTraits<T, LLPounceableQueue> traits;
+    typedef typename traits::owner_ptr owner_ptr;
+    typedef typename traits::signal_t signal_t;
+
+    signal_t& get(owner_ptr)
+    {
+        return mQueue;
+    }
+
+private:
+    signal_t mQueue;
+};
+
+// LLPounceable<T> is for an LLPounceable instance on the heap or the stack.
+// LLPounceable<T, LLPounceableStatic> is for a static LLPounceable instance.
+template <typename T, class TAG=LLPounceableQueue>
+class LLPounceable: public boost::noncopyable
+{
+private:
+    typedef LLPounceableTraits<T, TAG> traits;
+    typedef typename traits::owner_ptr owner_ptr;
+    typedef typename traits::signal_t signal_t;
+
+public:
+    typedef typename traits::func_t func_t;
+
+    // By default, both the initial value and the distinguished empty value
+    // are a default-constructed T instance. However you can explicitly
+    // specify each.
+    LLPounceable(typename boost::call_traits<T>::value_type init =boost::value_initialized<T>(),
+                 typename boost::call_traits<T>::param_type empty=boost::value_initialized<T>()):
+        mHeld(init),
+        mEmpty(empty)
+    {}
+
+    // make read access to mHeld as cheap and transparent as possible
+    operator T () const { return mHeld; }
+    typename boost::remove_pointer<T>::type operator*() const { return *mHeld; }
+    typename boost::call_traits<T>::value_type operator->() const { return mHeld; }
+    // uncomment 'explicit' as soon as we allow C++11 compilation
+    /*explicit*/ operator bool() const { return bool(mHeld); }
+    bool operator!() const { return ! mHeld; }
+
+    // support both assignment (dumb ptr idiom) and reset() (smart ptr)
+    void operator=(typename boost::call_traits<T>::param_type value)
+    {
+        reset(value);
+    }
+
+    void reset(typename boost::call_traits<T>::param_type value)
+    {
+        mHeld = value;
+        // If this new value is non-empty, flush anything pending in the queue.
+        if (mHeld != mEmpty)
+        {
+            signal_t& signal(get_signal());
+            signal(mHeld);
+            signal.disconnect_all_slots();
+        }
+    }
+
+    // our claim to fame
+    void callWhenReady(const func_t& func)
+    {
+        if (mHeld != mEmpty)
+        {
+            // If the held value is already non-empty, immediately call func()
+            func(mHeld);
+        }
+        else
+        {
+            // Held value still empty, queue func() for later. By default,
+            // connect() enqueues slots in FIFO order.
+            get_signal().connect(func);
+        }
+    }
+
+private:
+    signal_t& get_signal() { return mQueue.get(this); }
+
+    // Store both the current and the empty value.
+    // MAYBE: Might be useful to delegate to LLPounceableTraits the meaning of
+    // testing for "empty." For some types we want operator!(); for others we
+    // want to compare to a distinguished value.
+    typename boost::call_traits<T>::value_type mHeld, mEmpty;
+    // This might either contain the queue (LLPounceableQueue) or delegate to
+    // an LLSingleton (LLPounceableStatic).
+    LLPounceableQueueImpl<T, TAG> mQueue;
+};
+
+#endif /* ! defined(LL_LLPOUNCEABLE_H) */
diff --git a/indra/llcommon/llregistry.h b/indra/llcommon/llregistry.h
index 29950c108d..fde729f8f9 100755
--- a/indra/llcommon/llregistry.h
+++ b/indra/llcommon/llregistry.h
@@ -269,7 +269,7 @@ public:
 
 		~ScopedRegistrar()
 		{
-			if (!singleton_t::destroyed())
+			if (singleton_t::instanceExists())
 			{
 				popScope();
 			}
diff --git a/indra/llcommon/llsingleton.cpp b/indra/llcommon/llsingleton.cpp
index 9b49e52377..b78110296f 100755
--- a/indra/llcommon/llsingleton.cpp
+++ b/indra/llcommon/llsingleton.cpp
@@ -25,7 +25,332 @@
  */
 
 #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>
+
+// 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)
+    {
+        logerrs("Push/pop mismatch in stack of currently-initializing LLSingletons: ",
+                demangle(typeid(*this).name()).c_str(), "::getInstance() trying to pop ",
+                demangle(typeid(*list.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.
+                out << demangle(typeid(**found).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.
+            initializing.back()->mDepends.insert(this);
+        }
+    }
+}
+
+//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;
+
+            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.
+                // 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 -----------------------------*/
+//static
+void LLSingletonBase::logerrs(const char* p1, const char* p2, const char* p3, const char* p4)
+{
+    // 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())
+    {
+        LL_ERRS() << 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;
+        // The other important side effect of LL_ERRS() is
+        // https://www.youtube.com/watch?v=OMG7paGJqhQ (emphasis on OMG)
+        LLError::crashAndLoop(std::string());
+    }
+}
+
+//static
+void LLSingletonBase::logwarns(const char* p1, const char* p2, const char* p3, const char* p4)
+{
+    // See logerrs() remarks about is_available().
+    if (LLError::is_available())
+    {
+        LL_WARNS() << p1 << p2 << p3 << p4 << LL_ENDL;
+    }
+    else
+    {
+        std::cerr << p1 << p2 << p3 << p4 << std::endl;
+    }
+}
 
+std::string LLSingletonBase::demangle(const char* mangled)
+{
+    return LLError::Log::demangle(mangled);
+}
diff --git a/indra/llcommon/llsingleton.h b/indra/llcommon/llsingleton.h
index 6e6291a165..6a7f27bed4 100755
--- a/indra/llcommon/llsingleton.h
+++ b/indra/llcommon/llsingleton.h
@@ -25,185 +25,387 @@
 #ifndef LLSINGLETON_H
 #define LLSINGLETON_H
 
-#include "llerror.h"	// *TODO: eliminate this
-
-#include <typeinfo>
 #include <boost/noncopyable.hpp>
+#include <boost/unordered_set.hpp>
+#include <boost/intrusive_ptr.hpp>
+#include <list>
+#include <vector>
+#include <typeinfo>
+
+class LLSingletonBase: private boost::noncopyable
+{
+public:
+    class MasterList;
+    class MasterRefcount;
+    typedef boost::intrusive_ptr<MasterRefcount> ref_ptr_t;
+
+private:
+    // All existing LLSingleton instances are tracked in this master list.
+    typedef std::list<LLSingletonBase*> list_t;
+    static list_t& get_master();
+    // This, on the other hand, is a stack whose top indicates the LLSingleton
+    // currently being initialized.
+    static list_t& get_initializing();
+    // Produce a vector<LLSingletonBase*> of master list, in dependency order.
+    typedef std::vector<LLSingletonBase*> vec_t;
+    static vec_t dep_sort();
+
+    bool mCleaned;                  // cleanupSingleton() has been called
+    // we directly depend on these other LLSingletons
+    typedef boost::unordered_set<LLSingletonBase*> set_t;
+    set_t mDepends;
+
+protected:
+    typedef enum e_init_state
+    {
+        UNINITIALIZED = 0,          // must be default-initialized state
+        CONSTRUCTING,
+        INITIALIZING,
+        INITIALIZED,
+        DELETED
+    } EInitState;
+
+    // Base-class constructor should only be invoked by the DERIVED_TYPE
+    // constructor.
+    LLSingletonBase();
+    virtual ~LLSingletonBase();
+
+    // Every new LLSingleton should be added to/removed from the master list
+    void add_master();
+    void remove_master();
+    // with a little help from our friends.
+    template <class T> friend struct LLSingleton_manage_master;
+
+    // Maintain a stack of the LLSingleton subclass instance currently being
+    // initialized. We use this to notice direct dependencies: we want to know
+    // if A requires B. We deduce a dependency if while initializing A,
+    // control reaches B::getInstance().
+    // We want &A to be at the top of that stack during both A::A() and
+    // A::initSingleton(), since a call to B::getInstance() might occur during
+    // either.
+    // Unfortunately the desired timespan does not correspond neatly with a
+    // single C++ scope, else we'd use RAII to track it. But we do know that
+    // LLSingletonBase's constructor definitely runs just before
+    // LLSingleton's, which runs just before the specific subclass's.
+    void push_initializing();
+    // LLSingleton is, and must remain, the only caller to initSingleton().
+    // That being the case, we control exactly when it happens -- and we can
+    // pop the stack immediately thereafter.
+    void pop_initializing();
+    // If a given call to B::getInstance() happens during either A::A() or
+    // A::initSingleton(), record that A directly depends on B.
+    void capture_dependency(EInitState);
+
+    // delegate LL_ERRS() logging to llsingleton.cpp
+    static void logerrs(const char* p1, const char* p2="",
+                        const char* p3="", const char* p4="");
+    // delegate LL_WARNS() logging to llsingleton.cpp
+    static void logwarns(const char* p1, const char* p2="",
+                         const char* p3="", const char* p4="");
+    static std::string demangle(const char* mangled);
+
+    // obtain canonical ref_ptr_t
+    static ref_ptr_t get_master_refcount();
+
+    // Default methods in case subclass doesn't declare them.
+    virtual void initSingleton() {}
+    virtual void cleanupSingleton() {}
+
+    // 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
+    // deleteSingleton()) store a pointer here. Since we know it's a static
+    // class method, a classic-C function pointer will do.
+    void (*mDeleteSingleton)();
 
-// LLSingleton implements the getInstance() method part of the Singleton
-// pattern. It can't make the derived class constructors protected, though, so
-// you have to do that yourself.
-//
-// There are two ways to use LLSingleton. The first way is to inherit from it
-// while using the typename that you'd like to be static as the template
-// parameter, like so:
-//
-//   class Foo: public LLSingleton<Foo>{};
-//
-//   Foo& instance = Foo::instance();
-//
-// The second way is to use the singleton class directly, without inheritance:
-//
-//   typedef LLSingleton<Foo> FooSingleton;
-//
-//   Foo& instance = FooSingleton::instance();
-//
-// In this case, the class being managed as a singleton needs to provide an
-// initSingleton() method since the LLSingleton virtual method won't be
-// available
-//
-// As currently written, it is not thread-safe.
+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.
+     *
+     * The most important property of deleteAll() is that deleteSingleton()
+     * 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 deleteSingleton() method throws an exception, the exception is
+     * logged, but deleteAll() attempts to continue calling the rest of the
+     * deleteSingleton() methods.
+     */
+    static void deleteAll();
+};
+
+// support ref_ptr_t
+void intrusive_ptr_add_ref(LLSingletonBase::MasterRefcount*);
+void intrusive_ptr_release(LLSingletonBase::MasterRefcount*);
+
+// Most of the time, we want LLSingleton_manage_master() to forward its
+// methods to LLSingletonBase::add_master() and remove_master().
+template <class T>
+struct LLSingleton_manage_master
+{
+    void add(LLSingletonBase* sb) { sb->add_master(); }
+    void remove(LLSingletonBase* sb) { sb->remove_master(); }
+};
+
+// But for the specific case of LLSingletonBase::MasterList, don't.
+template <>
+struct LLSingleton_manage_master<LLSingletonBase::MasterList>
+{
+    void add(LLSingletonBase*) {}
+    void remove(LLSingletonBase*) {}
+};
 
+/**
+ * LLSingleton implements the getInstance() method part of the Singleton
+ * pattern. It can't make the derived class constructors protected, though, so
+ * you have to do that yourself.
+ *
+ * Derive your class from LLSingleton, passing your subclass name as
+ * LLSingleton's template parameter, like so:
+ *
+ *   class Foo: public LLSingleton<Foo>{};
+ *
+ *   Foo& instance = Foo::instance();
+ *
+ * LLSingleton recognizes a couple special methods in your derived class.
+ *
+ * If you override LLSingleton<T>::initSingleton(), your method will be called
+ * immediately after the instance is constructed. This is useful for breaking
+ * circular dependencies: if you find that your LLSingleton subclass
+ * constructor references other LLSingleton subclass instances in a chain
+ * leading back to yours, move the instance reference from your constructor to
+ * your initSingleton() method.
+ *
+ * If you override LLSingleton<T>::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.
+ *
+ * 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
+ * B::instance() or B::getInstance(), and C::instance() or C::getInstance().
+ * 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().
+ * 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 <typename DERIVED_TYPE>
-class LLSingleton : private boost::noncopyable
+class LLSingleton : public LLSingletonBase
 {
-	
 private:
-	typedef enum e_init_state
-	{
-		UNINITIALIZED,
-		CONSTRUCTING,
-		INITIALIZING,
-		INITIALIZED,
-		DELETED
-	} EInitState;
-    
     static DERIVED_TYPE* constructSingleton()
     {
         return new DERIVED_TYPE();
     }
-	
-	// stores pointer to singleton instance
-	struct SingletonLifetimeManager
-	{
-		SingletonLifetimeManager()
-		{
-			construct();
-		}
-
-		static void construct()
-		{
-			sData.mInitState = CONSTRUCTING;
-			sData.mInstance = constructSingleton();
-			sData.mInitState = INITIALIZING;
-		}
-
-		~SingletonLifetimeManager()
-		{
-			if (sData.mInitState != DELETED)
-			{
-				deleteSingleton();
-			}
-		}
-	};
-	
+
+    // stores pointer to singleton instance
+    struct SingletonLifetimeManager
+    {
+        SingletonLifetimeManager():
+            mMasterRefcount(LLSingletonBase::get_master_refcount())
+        {
+            construct();
+        }
+
+        static void construct()
+        {
+            sData.mInitState = CONSTRUCTING;
+            sData.mInstance = constructSingleton();
+            sData.mInitState = INITIALIZING;
+        }
+
+        ~SingletonLifetimeManager()
+        {
+            // The dependencies between LLSingletons, and the arbitrary order
+            // of static-object destruction, mean that we DO NOT WANT this
+            // destructor to delete this LLSingleton. This destructor will run
+            // without regard to any other LLSingleton whose cleanup might
+            // depend on its existence. What we really want is to count the
+            // runtime's attempts to cleanup LLSingleton static data -- and on
+            // the very last one, call LLSingletonBase::deleteAll(). That
+            // method will properly honor cross-LLSingleton dependencies. This
+            // is why we store an intrusive_ptr to a MasterRefcount: our
+            // ref_ptr_t member counts SingletonLifetimeManager instances.
+            // Once the runtime destroys the last of these, THEN we can delete
+            // every remaining LLSingleton.
+        }
+
+        LLSingletonBase::ref_ptr_t mMasterRefcount;
+    };
+
+protected:
+    LLSingleton()
+    {
+        // populate base-class function pointer with the static
+        // deleteSingleton() function for this particular specialization
+        mDeleteSingleton = &deleteSingleton;
+
+        // add this new instance to the master list
+        LLSingleton_manage_master<DERIVED_TYPE>().add(this);
+    }
+
 public:
-	virtual ~LLSingleton()
-	{
-		sData.mInstance = NULL;
-		sData.mInitState = DELETED;
-	}
-
-	/**
-	 * @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 sData.mInstance;
-		sData.mInstance = NULL;
-		sData.mInitState = DELETED;
-	}
-
-
-	static DERIVED_TYPE* getInstance()
-	{
-		static SingletonLifetimeManager sLifeTimeMgr;
-
-		switch (sData.mInitState)
-		{
-		case UNINITIALIZED:
-			// should never be uninitialized at this point
-			llassert(false);
-			return NULL;
-		case CONSTRUCTING:
-			LL_ERRS() << "Tried to access singleton " << typeid(DERIVED_TYPE).name() << " from singleton constructor!" << LL_ENDL;
-			return NULL;
-		case INITIALIZING:
-			// go ahead and flag ourselves as initialized so we can be reentrant during initialization
-			sData.mInitState = INITIALIZED;	
-			// initialize singleton after constructing it so that it can reference other singletons which in turn depend on it,
-			// thus breaking cyclic dependencies
-			sData.mInstance->initSingleton(); 
-			return sData.mInstance;
-		case INITIALIZED:
-			return sData.mInstance;
-		case DELETED:
-			LL_WARNS() << "Trying to access deleted singleton " << typeid(DERIVED_TYPE).name() << " creating new instance" << LL_ENDL;
-			SingletonLifetimeManager::construct();
-			// same as first time construction
-			sData.mInitState = INITIALIZED;	
-			sData.mInstance->initSingleton(); 
-			return sData.mInstance;
-		}
-
-		return NULL;
-	}
-
-	static DERIVED_TYPE* getIfExists()
-	{
-		return sData.mInstance;
-	}
-
-	// Reference version of getInstance()
-	// Preferred over getInstance() as it disallows checking for NULL
-	static DERIVED_TYPE& instance()
-	{
-		return *getInstance();
-	}
-	
-	// Has this singleton been created uet?
-	// Use this to avoid accessing singletons before the can safely be constructed
-	static bool instanceExists()
-	{
-		return sData.mInitState == INITIALIZED;
-	}
-	
-	// Has this singleton already been deleted?
-	// Use this to avoid accessing singletons from a static object's destructor
-	static bool destroyed()
-	{
-		return sData.mInitState == DELETED;
-	}
+    virtual ~LLSingleton()
+    {
+        // remove this instance from the master list
+        LLSingleton_manage_master<DERIVED_TYPE>().remove(this);
+        sData.mInstance = NULL;
+        sData.mInitState = DELETED;
+    }
 
-private:
+    /**
+     * @brief Immediately delete the singleton.
+     *
+     * A subsequent call to LLProxy::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.
+     */
+    static void deleteSingleton()
+    {
+        delete sData.mInstance;
+        sData.mInstance = NULL;
+        sData.mInitState = DELETED;
+    }
+
+    static DERIVED_TYPE* getInstance()
+    {
+        static SingletonLifetimeManager sLifeTimeMgr;
+
+        switch (sData.mInitState)
+        {
+        case UNINITIALIZED:
+            // should never be uninitialized at this point
+            logerrs("Uninitialized singleton ",
+                    demangle(typeid(DERIVED_TYPE).name()).c_str());
+            return NULL;
+
+        case CONSTRUCTING:
+            logerrs("Tried to access singleton ",
+                    demangle(typeid(DERIVED_TYPE).name()).c_str(),
+                    " from singleton constructor!");
+            return NULL;
 
-	virtual void initSingleton() {}
+        case INITIALIZING:
+            // go ahead and flag ourselves as initialized so we can be
+            // reentrant during initialization
+            sData.mInitState = INITIALIZED; 
+            // initialize singleton after constructing it so that it can
+            // reference other singletons which in turn depend on it, thus
+            // breaking cyclic dependencies
+            sData.mInstance->initSingleton();
+            // pop this off stack of initializing singletons
+            sData.mInstance->pop_initializing();
+            break;
+
+        case INITIALIZED:
+            break;
+
+        case DELETED:
+            logwarns("Trying to access deleted singleton ",
+                     demangle(typeid(DERIVED_TYPE).name()).c_str(),
+                     " -- creating new instance");
+            SingletonLifetimeManager::construct();
+            // same as first time construction
+            sData.mInitState = INITIALIZED; 
+            sData.mInstance->initSingleton(); 
+            // pop this off stack of initializing singletons
+            sData.mInstance->pop_initializing();
+            break;
+        }
+
+        // By this point, if DERIVED_TYPE was pushed onto the initializing
+        // stack, it has been popped off. So the top of that stack, if any, is
+        // an LLSingleton that directly depends on DERIVED_TYPE. If this call
+        // came from another LLSingleton, rather than from vanilla application
+        // code, record the dependency.
+        sData.mInstance->capture_dependency(sData.mInitState);
+        return sData.mInstance;
+    }
 
-	struct SingletonData
-	{
-		// explicitly has a default constructor so that member variables are zero initialized in BSS
-		// and only changed by singleton logic, not constructor running during startup
-		EInitState		mInitState;
-		DERIVED_TYPE*	mInstance;
-	};
-	static SingletonData sData;
+    // Reference version of getInstance()
+    // Preferred over getInstance() as it disallows checking for NULL
+    static DERIVED_TYPE& instance()
+    {
+        return *getInstance();
+    }
+
+    // Has this singleton been created yet?
+    // Use this to avoid accessing singletons before they can safely be constructed.
+    static bool instanceExists()
+    {
+        return sData.mInitState == INITIALIZED;
+    }
+
+private:
+    struct SingletonData
+    {
+        // explicitly has a default constructor so that member variables are zero initialized in BSS
+        // and only changed by singleton logic, not constructor running during startup
+        EInitState      mInitState;
+        DERIVED_TYPE*   mInstance;
+    };
+    static SingletonData sData;
 };
 
 template<typename T>
diff --git a/indra/llcommon/tests/llpounceable_test.cpp b/indra/llcommon/tests/llpounceable_test.cpp
new file mode 100644
index 0000000000..2f4915ce11
--- /dev/null
+++ b/indra/llcommon/tests/llpounceable_test.cpp
@@ -0,0 +1,230 @@
+/**
+ * @file   llpounceable_test.cpp
+ * @author Nat Goodspeed
+ * @date   2015-05-22
+ * @brief  Test for llpounceable.
+ * 
+ * $LicenseInfo:firstyear=2015&license=viewerlgpl$
+ * Copyright (c) 2015, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+// Precompiled header
+#include "linden_common.h"
+// associated header
+#include "llpounceable.h"
+// STL headers
+// std headers
+// external library headers
+#include <boost/bind.hpp>
+// other Linden headers
+#include "../test/lltut.h"
+
+/*----------------------------- string testing -----------------------------*/
+void append(std::string* dest, const std::string& src)
+{
+    dest->append(src);
+}
+
+/*-------------------------- Data-struct testing ---------------------------*/
+struct Data
+{
+    Data(const std::string& data):
+        mData(data)
+    {}
+    const std::string mData;
+};
+
+void setter(Data** dest, Data* ptr)
+{
+    *dest = ptr;
+}
+
+static Data* static_check = 0;
+
+// Set up an extern pointer to an LLPounceableStatic so the linker will fill
+// in the forward reference from below, before runtime.
+extern LLPounceable<Data*, LLPounceableStatic> gForward;
+
+struct EnqueueCall
+{
+    EnqueueCall()
+    {
+        // Intentionally use a forward reference to an LLPounceableStatic that
+        // we believe is NOT YET CONSTRUCTED. This models the scenario in
+        // which a constructor in another translation unit runs before
+        // constructors in this one. We very specifically want callWhenReady()
+        // to work even in that case: we need the LLPounceableQueueImpl to be
+        // initialized even if the LLPounceable itself is not.
+        gForward.callWhenReady(boost::bind(setter, &static_check, _1));
+    }
+} nqcall;
+// When this declaration is processed, we should enqueue the
+// setter(&static_check, _1) call for when gForward is set non-NULL. Needless
+// to remark, we want this call not to crash.
+
+// Now declare gForward. Its constructor should not run until after nqcall's.
+LLPounceable<Data*, LLPounceableStatic> gForward;
+
+/*****************************************************************************
+*   TUT
+*****************************************************************************/
+namespace tut
+{
+    struct llpounceable_data
+    {
+    };
+    typedef test_group<llpounceable_data> llpounceable_group;
+    typedef llpounceable_group::object object;
+    llpounceable_group llpounceablegrp("llpounceable");
+
+    template<> template<>
+    void object::test<1>()
+    {
+        set_test_name("LLPounceableStatic out-of-order test");
+        // LLPounceable<T, LLPounceableStatic>::callWhenReady() must work even
+        // before LLPounceable's constructor runs. That's the whole point of
+        // implementing it with an LLSingleton queue. This models (say)
+        // LLPounceableStatic<LLMessageSystem*, LLPounceableStatic>.
+        ensure("static_check should still be null", ! static_check);
+        Data myData("test<1>");
+        gForward = &myData;         // should run setter
+        ensure_equals("static_check should be &myData", static_check, &myData);
+    }
+
+    template<> template<>
+    void object::test<2>()
+    {
+        set_test_name("LLPounceableQueue different queues");
+        // We expect that LLPounceable<T, LLPounceableQueue> should have
+        // different queues because that specialization stores the queue
+        // directly in the LLPounceable instance.
+        Data *aptr = 0, *bptr = 0;
+        LLPounceable<Data*> a, b;
+        a.callWhenReady(boost::bind(setter, &aptr, _1));
+        b.callWhenReady(boost::bind(setter, &bptr, _1));
+        ensure("aptr should be null", ! aptr);
+        ensure("bptr should be null", ! bptr);
+        Data adata("a"), bdata("b");
+        a = &adata;
+        ensure_equals("aptr should be &adata", aptr, &adata);
+        // but we haven't yet set b
+        ensure("bptr should still be null", !bptr);
+        b = &bdata;
+        ensure_equals("bptr should be &bdata", bptr, &bdata);
+    }
+
+    template<> template<>
+    void object::test<3>()
+    {
+        set_test_name("LLPounceableStatic different queues");
+        // LLPounceable<T, LLPounceableStatic> should also have a distinct
+        // queue for each instance, but that engages an additional map lookup
+        // because there's only one LLSingleton for each T.
+        Data *aptr = 0, *bptr = 0;
+        LLPounceable<Data*, LLPounceableStatic> a, b;
+        a.callWhenReady(boost::bind(setter, &aptr, _1));
+        b.callWhenReady(boost::bind(setter, &bptr, _1));
+        ensure("aptr should be null", ! aptr);
+        ensure("bptr should be null", ! bptr);
+        Data adata("a"), bdata("b");
+        a = &adata;
+        ensure_equals("aptr should be &adata", aptr, &adata);
+        // but we haven't yet set b
+        ensure("bptr should still be null", !bptr);
+        b = &bdata;
+        ensure_equals("bptr should be &bdata", bptr, &bdata);
+    }
+
+    template<> template<>
+    void object::test<4>()
+    {
+        set_test_name("LLPounceable<T> looks like T");
+        // We want LLPounceable<T, TAG> to be drop-in replaceable for a plain
+        // T for read constructs. In particular, it should behave like a dumb
+        // pointer -- and with zero abstraction cost for such usage.
+        Data* aptr = 0;
+        Data a("a");
+        // should be able to initialize a pounceable (when its constructor
+        // runs)
+        LLPounceable<Data*> pounceable(&a);
+        // should be able to pass LLPounceable<T> to function accepting T
+        setter(&aptr, pounceable);
+        ensure_equals("aptr should be &a", aptr, &a);
+        // should be able to dereference with *
+        ensure_equals("deref with *", (*pounceable).mData, "a");
+        // should be able to dereference with ->
+        ensure_equals("deref with ->", pounceable->mData, "a");
+        // bool operations
+        ensure("test with operator bool()", pounceable);
+        ensure("test with operator !()", ! (! pounceable));
+    }
+
+    template<> template<>
+    void object::test<5>()
+    {
+        set_test_name("Multiple callWhenReady() queue items");
+        Data *p1 = 0, *p2 = 0, *p3 = 0;
+        Data a("a");
+        LLPounceable<Data*> pounceable;
+        // queue up a couple setter() calls for later
+        pounceable.callWhenReady(boost::bind(setter, &p1, _1));
+        pounceable.callWhenReady(boost::bind(setter, &p2, _1));
+        // should still be pending
+        ensure("p1 should be null", !p1);
+        ensure("p2 should be null", !p2);
+        ensure("p3 should be null", !p3);
+        pounceable = 0;
+        // assigning a new empty value shouldn't flush the queue
+        ensure("p1 should still be null", !p1);
+        ensure("p2 should still be null", !p2);
+        ensure("p3 should still be null", !p3);
+        // using whichever syntax
+        pounceable.reset(0);
+        // try to make ensure messages distinct... tough to pin down which
+        // ensure() failed if multiple ensure() calls in the same test<n> have
+        // the same message!
+        ensure("p1 should again be null", !p1);
+        ensure("p2 should again be null", !p2);
+        ensure("p3 should again be null", !p3);
+        pounceable.reset(&a);       // should flush queue
+        ensure_equals("p1 should be &a", p1, &a);
+        ensure_equals("p2 should be &a", p2, &a);
+        ensure("p3 still not set", !p3);
+        // immediate call
+        pounceable.callWhenReady(boost::bind(setter, &p3, _1));
+        ensure_equals("p3 should be &a", p3, &a);
+    }
+
+    template<> template<>
+    void object::test<6>()
+    {
+        set_test_name("queue order");
+        std::string data;
+        LLPounceable<std::string*> pounceable;
+        pounceable.callWhenReady(boost::bind(append, _1, "a"));
+        pounceable.callWhenReady(boost::bind(append, _1, "b"));
+        pounceable.callWhenReady(boost::bind(append, _1, "c"));
+        pounceable = &data;
+        ensure_equals("callWhenReady() must preserve chronological order",
+                      data, "abc");
+
+        std::string data2;
+        pounceable = NULL;
+        pounceable.callWhenReady(boost::bind(append, _1, "d"));
+        pounceable.callWhenReady(boost::bind(append, _1, "e"));
+        pounceable.callWhenReady(boost::bind(append, _1, "f"));
+        pounceable = &data2;
+        ensure_equals("LLPounceable must reset queue when fired",
+                      data2, "def");
+    }
+
+    template<> template<>
+    void object::test<7>()
+    {
+        set_test_name("compile-fail test, uncomment to check");
+        // The following declaration should fail: only LLPounceableQueue and
+        // LLPounceableStatic should work as tags.
+//      LLPounceable<Data*, int> pounceable;
+    }
+} // namespace tut
diff --git a/indra/llcommon/tests/llsingleton_test.cpp b/indra/llcommon/tests/llsingleton_test.cpp
index 385289aefe..a05f650f25 100755
--- a/indra/llcommon/tests/llsingleton_test.cpp
+++ b/indra/llcommon/tests/llsingleton_test.cpp
@@ -30,47 +30,171 @@
 #include "llsingleton.h"
 #include "../test/lltut.h"
 
+
+// Capture execution sequence by appending to log string.
+std::string sLog;
+
+#define DECLARE_CLASS(CLS)                      \
+struct CLS: public LLSingleton<CLS>             \
+{                                               \
+    static enum dep_flag {                      \
+        DEP_NONE, /* no dependency */           \
+        DEP_CTOR, /* dependency in ctor */      \
+        DEP_INIT  /* dependency in initSingleton */ \
+    } sDepFlag;                                 \
+                                                \
+    CLS();                                      \
+    void initSingleton();                       \
+    void cleanupSingleton();                    \
+    ~CLS();                                     \
+};                                              \
+                                                \
+CLS::dep_flag CLS::sDepFlag = DEP_NONE
+
+DECLARE_CLASS(A);
+DECLARE_CLASS(B);
+
+#define DEFINE_MEMBERS(CLS, OTHER)              \
+CLS::CLS()                                      \
+{                                               \
+    sLog.append(#CLS);                          \
+    if (sDepFlag == DEP_CTOR)                   \
+    {                                           \
+        (void)OTHER::instance();                \
+    }                                           \
+}                                               \
+                                                \
+void CLS::initSingleton()                       \
+{                                               \
+    sLog.append("i" #CLS);                      \
+    if (sDepFlag == DEP_INIT)                   \
+    {                                           \
+        (void)OTHER::instance();                \
+    }                                           \
+}                                               \
+                                                \
+void CLS::cleanupSingleton()                    \
+{                                               \
+    sLog.append("x" #CLS);                      \
+}                                               \
+                                                \
+CLS::~CLS()                                     \
+{                                               \
+    sLog.append("~" #CLS);                      \
+}
+
+DEFINE_MEMBERS(A, B)
+DEFINE_MEMBERS(B, A)
+
 namespace tut
 {
-	struct singleton
-	{
-		// We need a class created with the LLSingleton template to test with.
-		class LLSingletonTest: public LLSingleton<LLSingletonTest>
-		{
-
-		};
-	};
-
-	typedef test_group<singleton> singleton_t;
-	typedef singleton_t::object singleton_object_t;
-	tut::singleton_t tut_singleton("LLSingleton");
-
-	template<> template<>
-	void singleton_object_t::test<1>()
-	{
-
-	}
-	template<> template<>
-	void singleton_object_t::test<2>()
-	{
-		LLSingletonTest* singleton_test = LLSingletonTest::getInstance();
-		ensure(singleton_test);
-	}
-	template<> template<>
-	void singleton_object_t::test<3>()
-	{
-		//Construct the instance
-		LLSingletonTest::getInstance();
-		ensure(LLSingletonTest::instanceExists());
-
-		//Delete the instance
-		LLSingletonTest::deleteSingleton();
-		ensure(LLSingletonTest::destroyed());
-		ensure(!LLSingletonTest::instanceExists());
-
-		//Construct it again.
-		LLSingletonTest* singleton_test = LLSingletonTest::getInstance();
-		ensure(singleton_test);
-		ensure(LLSingletonTest::instanceExists());
-	}
+    struct singleton
+    {
+        // We need a class created with the LLSingleton template to test with.
+        class LLSingletonTest: public LLSingleton<LLSingletonTest>
+        {
+
+        };
+    };
+
+    typedef test_group<singleton> singleton_t;
+    typedef singleton_t::object singleton_object_t;
+    tut::singleton_t tut_singleton("LLSingleton");
+
+    template<> template<>
+    void singleton_object_t::test<1>()
+    {
+
+    }
+    template<> template<>
+    void singleton_object_t::test<2>()
+    {
+        LLSingletonTest* singleton_test = LLSingletonTest::getInstance();
+        ensure(singleton_test);
+    }
+
+    template<> template<>
+    void singleton_object_t::test<3>()
+    {
+        //Construct the instance
+        LLSingletonTest::getInstance();
+        ensure(LLSingletonTest::instanceExists());
+
+        //Delete the instance
+        LLSingletonTest::deleteSingleton();
+        ensure(!LLSingletonTest::instanceExists());
+
+        //Construct it again.
+        LLSingletonTest* singleton_test = LLSingletonTest::getInstance();
+        ensure(singleton_test);
+        ensure(LLSingletonTest::instanceExists());
+    }
+
+#define TESTS(CLS, OTHER, N0, N1, N2, N3)                               \
+    template<> template<>                                               \
+    void singleton_object_t::test<N0>()                                 \
+    {                                                                   \
+        set_test_name("just " #CLS);                                    \
+        CLS::sDepFlag = CLS::DEP_NONE;                                  \
+        OTHER::sDepFlag = OTHER::DEP_NONE;                              \
+        sLog.clear();                                                   \
+                                                                        \
+        (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);           \
+    }                                                                   \
+                                                                        \
+    template<> template<>                                               \
+    void singleton_object_t::test<N1>()                                 \
+    {                                                                   \
+        set_test_name(#CLS " ctor depends " #OTHER);                    \
+        CLS::sDepFlag = CLS::DEP_CTOR;                                  \
+        OTHER::sDepFlag = OTHER::DEP_NONE;                              \
+        sLog.clear();                                                   \
+                                                                        \
+        (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); \
+    }                                                                   \
+                                                                        \
+    template<> template<>                                               \
+    void singleton_object_t::test<N2>()                                 \
+    {                                                                   \
+        set_test_name(#CLS " init depends " #OTHER);                    \
+        CLS::sDepFlag = CLS::DEP_INIT;                                  \
+        OTHER::sDepFlag = OTHER::DEP_NONE;                              \
+        sLog.clear();                                                   \
+                                                                        \
+        (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); \
+    }                                                                   \
+                                                                        \
+    template<> template<>                                               \
+    void singleton_object_t::test<N3>()                                 \
+    {                                                                   \
+        set_test_name(#CLS " circular init");                           \
+        CLS::sDepFlag = CLS::DEP_INIT;                                  \
+        OTHER::sDepFlag = OTHER::DEP_CTOR;                              \
+        sLog.clear();                                                   \
+                                                                        \
+        (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); \
+    }
+
+    TESTS(A, B, 4, 5, 6, 7)
+    TESTS(B, A, 8, 9, 10, 11)
 }