From 36663e12265c7656ead62831869ad93649e9c291 Mon Sep 17 00:00:00 2001
From: Markus Scherer <markus.icu@gmail.com>
Date: Tue, 17 Sep 2013 21:59:18 +0000
Subject: [PATCH] ICU-10407 more efficient UnicodeString::refCount()

X-SVN-Rev: 34367
---
 icu4c/source/common/unistr.cpp | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/icu4c/source/common/unistr.cpp b/icu4c/source/common/unistr.cpp
index 5066fb4137a..a21c1b4a265 100644
--- a/icu4c/source/common/unistr.cpp
+++ b/icu4c/source/common/unistr.cpp
@@ -117,23 +117,19 @@ operator+ (const UnicodeString &s1, const UnicodeString &s2) {
 //========================================
 
 void
-UnicodeString::addRef()
-{  umtx_atomic_inc((u_atomic_int32_t *)fUnion.fFields.fArray - 1);}
+UnicodeString::addRef() {
+  umtx_atomic_inc((u_atomic_int32_t *)fUnion.fFields.fArray - 1);
+}
 
 int32_t
-UnicodeString::removeRef()
-{ return umtx_atomic_dec((u_atomic_int32_t *)fUnion.fFields.fArray - 1);}
+UnicodeString::removeRef() {
+  return umtx_atomic_dec((u_atomic_int32_t *)fUnion.fFields.fArray - 1);
+}
 
 int32_t
-UnicodeString::refCount() const 
-{ 
-    umtx_lock(NULL);
-    // Note: without the lock to force a memory barrier, we might see a very
-    //       stale value on some multi-processor systems.
-    int32_t  count = *((int32_t *)fUnion.fFields.fArray - 1);
-    umtx_unlock(NULL);
-    return count;
- }
+UnicodeString::refCount() const {
+  return umtx_loadAcquire(*((u_atomic_int32_t *)fUnion.fFields.fArray - 1));
+}
 
 void
 UnicodeString::releaseArray() {