icuSources/common/sharedobject.cpp

   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
  18 SharedObject::~SharedObject() {}
  19
  20 UnifiedCacheBase::~UnifiedCacheBase() {}
  21
  22 void
  23 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
  36 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
  51 SharedObject::getRefCount() const {
  52     return umtx_loadAcquire(hardRefCount);
  53 }
  54
  55 void
  56 SharedObject::deleteIfZeroRefCount() const {
  57     if (this->cachePtr == nullptr && getRefCount() == 0) {
  58         delete this;
  59     }
  60 }
  61
  62 U_NAMESPACE_END