ICU-62107.0.1.tar.gz

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

diff --git a/icuSources/common/sharedobject.cpp b/icuSources/common/sharedobject.cpp
index 37aa458e00f98f8ee5a7a32c609239cd716d9e85..6eeca8605f00021e358fc8f01e68f1c4590557d5 100644 (file)
--- a/icuSources/common/sharedobject.cpp
+++ b/icuSources/common/sharedobject.cpp
@@ -8,7 +8,10 @@
 * sharedobject.cpp
 */
 #include "sharedobject.h"
+#include "mutex.h"
 #include "uassert.h"
+#include "umutex.h"
+#include "unifiedcache.h"
 
 U_NAMESPACE_BEGIN
 
@@ -17,69 +20,41 @@ SharedObject::~SharedObject() {}
 UnifiedCacheBase::~UnifiedCacheBase() {}
 
 void
-SharedObject::addRef(UBool fromWithinCache) const {
-    umtx_atomic_inc(&totalRefCount);
-
-    // Although items in use may not be correct immediately, it
-    // will be correct eventually.
-    if (umtx_atomic_inc(&hardRefCount) == 1 && cachePtr != NULL) {
-        // If this object is cached, and the hardRefCount goes from 0 to 1,
-        // then the increment must happen from within the cache while the
-        // cache global mutex is locked. In this way, we can be rest assured
-        // that data races can't happen if the cache performs some task if
-        // the hardRefCount is zero while the global cache mutex is locked.
-        (void)fromWithinCache;   // Suppress unused variable warning in non-debug builds.
-        U_ASSERT(fromWithinCache);
-        cachePtr->incrementItemsInUse();
-    }
+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(UBool fromWithinCache) const {
-    UBool decrementItemsInUse = (umtx_atomic_dec(&hardRefCount) == 0);
-    UBool allReferencesGone = (umtx_atomic_dec(&totalRefCount) == 0);
-
-    // Although items in use may not be correct immediately, it
-    // will be correct eventually.
-    if (decrementItemsInUse && cachePtr != NULL) {
-        if (fromWithinCache) {
-            cachePtr->decrementItemsInUse();
+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 {
-            cachePtr->decrementItemsInUseWithLockingAndEviction();
+            delete this;
         }
     }
-    if (allReferencesGone) {
-        delete this;
-    }
 }
 
-void
-SharedObject::addSoftRef() const {
-    umtx_atomic_inc(&totalRefCount);
-    ++softRefCount;
-}
-
-void
-SharedObject::removeSoftRef() const {
-    --softRefCount;
-    if (umtx_atomic_dec(&totalRefCount) == 0) {
-        delete this;
-    }
-}
 
 int32_t
 SharedObject::getRefCount() const {
-    return umtx_loadAcquire(totalRefCount);
-}
-
-int32_t
-SharedObject::getHardRefCount() const {
     return umtx_loadAcquire(hardRefCount);
 }
 
 void
 SharedObject::deleteIfZeroRefCount() const {
-    if(getRefCount() == 0) {
+    if (this->cachePtr == nullptr && getRefCount() == 0) {
         delete this;
     }
 }