Merge from viewer-experience-merge

1 files changed, 21 insertions, 3 deletions

diff --git a/indra/llcommon/llsingleton.h b/indra/llcommon/llsingleton.h
index 00757be277..49d99f2cd0 100644
--- a/indra/llcommon/llsingleton.h
+++ b/indra/llcommon/llsingleton.h
@@ -114,8 +114,7 @@ private:
 
 		~SingletonInstanceData()
 		{
-			SingletonInstanceData& data = getData();
-			if (data.mInitState != DELETED)
+			if (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;