initial commit, 4.5 stable

thirdparty/icu4c/common/sharedobject.cpp

@@ -0,0 +1,62 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+******************************************************************************
+* 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(&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 {
+    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(hardRefCount);
+}
+
+void
+SharedObject::deleteIfZeroRefCount() const {
+    if (this->cachePtr == nullptr && getRefCount() == 0) {
+        delete this;
+    }
+}
+
+U_NAMESPACE_END