1 files changed, 26 insertions, 1 deletions
diff --git a/indra/llcommon/llerror.h b/indra/llcommon/llerror.h
index 624a5fb37a..05dd88ee51 100644
--- a/indra/llcommon/llerror.h
+++ b/indra/llcommon/llerror.h
@@ -82,9 +82,11 @@ const int LL_ERR_NOERR = 0;
 
 #ifdef SHOW_ASSERT
 #define llassert(func)			llassert_always_msg(func, #func)
+#define llassert_msg(func, msg)	llassert_always_msg(func, msg)
 #define llverify(func)			llassert_always_msg(func, #func)
 #else
 #define llassert(func)
+#define llassert_msg(func, msg)
 #define llverify(func)			do {if (func) {}} while(0)
 #endif
 
@@ -462,8 +464,31 @@ typedef LLError::NoClassInfo _LL_CLASS_TO_LOG;
 		LLError::CallSite& _site(_sites[which]);                        \
 		lllog_test_()
 
-// Check at run-time whether logging is enabled, without generating output
+/*
+// Check at run-time whether logging is enabled, without generating output.
+Resist the temptation to add a function like this because it incurs the
+expense of locking and map-searching every time control reaches it.
 bool debugLoggingEnabled(const std::string& tag);
+
+Instead of:
+
+if debugLoggingEnabled("SomeTag")
+{
+    // ... presumably expensive operation ...
+    LL_DEBUGS("SomeTag") << ... << LL_ENDL;
+}
+
+Use this:
+
+LL_DEBUGS("SomeTag");
+// ... presumably expensive operation ...
+LL_CONT << ...;
+LL_ENDL;
+
+LL_DEBUGS("SomeTag") performs the locking and map-searching ONCE, then caches
+the result in a static variable.
+*/ 
+
 // used by LLERROR_CRASH
 void crashdriver(void (*)(int*));