ICU-62123.0.1.tar.gz

[apple/icu.git] / icuSources / common / sharedobject.cpp

diff --git a/icuSources/common/sharedobject.cpp b/icuSources/common/sharedobject.cpp
index bad79801d7d6f078c675023c1e3cc30069cd9299..6eeca8605f00021e358fc8f01e68f1c4590557d5 100644 (file)
--- a/icuSources/common/sharedobject.cpp
+++ b/icuSources/common/sharedobject.cpp
@@ -1,35 +1,60 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
 /*
 ******************************************************************************
-* Copyright (C) 2014, International Business Machines
+* Copyright (C) 2015, International Business Machines
 * Corporation and others.  All Rights Reserved.
 ******************************************************************************
 * sharedobject.cpp
 */
 #include "sharedobject.h"
+#include "mutex.h"
+#include "uassert.h"
+#include "umutex.h"
+#include "unifiedcache.h"
 
 U_NAMESPACE_BEGIN
+
 SharedObject::~SharedObject() {}
 
+UnifiedCacheBase::~UnifiedCacheBase() {}
+
 void
 SharedObject::addRef() const {
-    umtx_atomic_inc(&refCount);
+    umtx_atomic_inc(&hardRefCount);
 }
 
+// removeRef Decrement the reference count and delete if it is zero.
+//           Note that SharedObjects with a non-null cachePtr are owned by the
+//           unified cache, and the cache will be responsible for the actual deletion.
+//           The deletion could be as soon as immediately following the
+//           update to the reference count, if another thread is running
+//           a cache eviction cycle concurrently.
+//           NO ACCESS TO *this PERMITTED AFTER REFERENCE COUNT == 0 for cached objects.
+//           THE OBJECT MAY ALREADY BE GONE.
 void
 SharedObject::removeRef() const {
-    if(umtx_atomic_dec(&refCount) == 0) {
-        delete this;
+    const UnifiedCacheBase *cache = this->cachePtr;
+    int32_t updatedRefCount = umtx_atomic_dec(&hardRefCount);
+    U_ASSERT(updatedRefCount >= 0);
+    if (updatedRefCount == 0) {
+        if (cache) {
+            cache->handleUnreferencedObject();
+        } else {
+            delete this;
+        }
     }
 }
 
+
 int32_t
 SharedObject::getRefCount() const {
-    return umtx_loadAcquire(refCount);
+    return umtx_loadAcquire(hardRefCount);
 }
 
 void
 SharedObject::deleteIfZeroRefCount() const {
-    if(getRefCount() == 0) {
+    if (this->cachePtr == nullptr && getRefCount() == 0) {
         delete this;
     }
 }