tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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sharedobject.cpp (1841B)

      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