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1 // © 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4 ******************************************************************************
5 * Copyright (C) 2015, International Business Machines
6 * Corporation and others.  All Rights Reserved.
7 ******************************************************************************
8 * sharedobject.cpp
9 */
10 #include "sharedobject.h"
11 #include "mutex.h"
12 #include "uassert.h"
13 #include "umutex.h"
14 #include "unifiedcache.h"
15 
16 U_NAMESPACE_BEGIN
17 
~SharedObject()18 SharedObject::~SharedObject() {}
19 
~UnifiedCacheBase()20 UnifiedCacheBase::~UnifiedCacheBase() {}
21 
22 void
addRef() const23 SharedObject::addRef() const {
24     umtx_atomic_inc(&hardRefCount);
25 }
26 
27 // removeRef Decrement the reference count and delete if it is zero.
28 //           Note that SharedObjects with a non-null cachePtr are owned by the
29 //           unified cache, and the cache will be responsible for the actual deletion.
30 //           The deletion could be as soon as immediately following the
31 //           update to the reference count, if another thread is running
32 //           a cache eviction cycle concurrently.
33 //           NO ACCESS TO *this PERMITTED AFTER REFERENCE COUNT == 0 for cached objects.
34 //           THE OBJECT MAY ALREADY BE GONE.
35 void
removeRef() const36 SharedObject::removeRef() const {
37     const UnifiedCacheBase *cache = this->cachePtr;
38     int32_t updatedRefCount = umtx_atomic_dec(&hardRefCount);
39     U_ASSERT(updatedRefCount >= 0);
40     if (updatedRefCount == 0) {
41         if (cache) {
42             cache->handleUnreferencedObject();
43         } else {
44             delete this;
45         }
46     }
47 }
48 
49 
50 int32_t
getRefCount() const51 SharedObject::getRefCount() const {
52     return umtx_loadAcquire(hardRefCount);
53 }
54 
55 void
deleteIfZeroRefCount() const56 SharedObject::deleteIfZeroRefCount() const {
57     if (this->cachePtr == nullptr && getRefCount() == 0) {
58         delete this;
59     }
60 }
61 
62 U_NAMESPACE_END
63