ICU 56 update step 1

source/i18n/rbt.cpp

Index: source/i18n/rbt.cpp
diff --git a/source/i18n/rbt.cpp b/source/i18n/rbt.cpp
index beb6067b943f196fa04bba555cbb53b45b9a610f..5c4d3beaee5ece34a2951ef7d06b04009da29deb 100644
--- a/source/i18n/rbt.cpp
+++ b/source/i18n/rbt.cpp
@@ -1,6 +1,6 @@
 /*
 **********************************************************************
-*   Copyright (C) 1999-2013, International Business Machines
+*   Copyright (C) 1999-2015, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 **********************************************************************
 *   Date        Name        Description
@@ -18,6 +18,7 @@
 #include "rbt_data.h"
 #include "rbt_rule.h"
 #include "rbt.h"
+#include "mutex.h"
 #include "umutex.h"
 
 U_NAMESPACE_BEGIN
@@ -244,17 +245,23 @@ RuleBasedTransliterator::handleTransliterate(Replaceable& text, UTransPosition&
     //   so no concurrent access from multiple threads is possible.
     UBool    lockedMutexAtThisLevel = FALSE;
     if (isDataOwned == FALSE) {
-        // Test whether this request is operating on the same text string as some
+        // Test whether this request is operating on the same text string as
         //   some other transliteration that is still in progress and holding the 
         //   transliteration mutex.  If so, do not lock the transliteration
         //    mutex again.
+        //
+        //  gLockedText variable is protected by the global ICU mutex.
+        //  Shared RBT data protected by transliteratorDataMutex.
+        //
         // TODO(andy): Need a better scheme for handling this.
         UBool needToLock;
-        umtx_lock(NULL);
-        needToLock = (&text != gLockedText);
-        umtx_unlock(NULL);
+        {
+            Mutex m;
+            needToLock = (&text != gLockedText);
+        }
         if (needToLock) {
-            umtx_lock(&transliteratorDataMutex);
+            umtx_lock(&transliteratorDataMutex);  // Contention, longish waits possible here.
+            Mutex m;
             gLockedText = &text;
             lockedMutexAtThisLevel = TRUE;
         }
@@ -269,7 +276,10 @@ RuleBasedTransliterator::handleTransliterate(Replaceable& text, UTransPosition&
 	    }
     }
     if (lockedMutexAtThisLevel) {
-        gLockedText = NULL;
+        {
+            Mutex m;
+            gLockedText = NULL;
+        }
         umtx_unlock(&transliteratorDataMutex);
     }
 }