X-Git-Url: https://git.saurik.com/apple/icu.git/blobdiff_plain/38fbf2fd31f5cd99b500914d6037b1d06b608645..0f5d89e82340278ed3d7d50029f37cab2c41a57e:/icuSources/common/sharedobject.h

diff --git a/icuSources/common/sharedobject.h b/icuSources/common/sharedobject.h
index d1326518..75c4ec38 100644
--- a/icuSources/common/sharedobject.h
+++ b/icuSources/common/sharedobject.h
@@ -17,6 +17,8 @@
 
 U_NAMESPACE_BEGIN
 
+class SharedObject;
+
 /**
  * Base class for unified cache exposing enough methods to SharedObject
  * instances to allow their addRef() and removeRef() methods to
@@ -28,22 +30,12 @@ public:
     UnifiedCacheBase() { }
 
     /**
-     * Called by addRefWhileHoldingCacheLock() when the hard reference count
-     * of its instance goes from 0 to 1.
+     * Notify the cache implementation that an object was seen transitioning to
+     * zero hard references. The cache may use this to keep track the number of
+     * unreferenced SharedObjects, and to trigger evictions.
      */
-    virtual void incrementItemsInUse() const = 0;
+    virtual void handleUnreferencedObject() const = 0;
 
-    /**
-     * Called by removeRef() when the hard reference count of its instance
-     * drops from 1 to 0.
-     */
-    virtual void decrementItemsInUseWithLockingAndEviction() const = 0;
-
-    /**
-     * Called by removeRefWhileHoldingCacheLock() when the hard reference
-     * count of its instance drops from 1 to 0.
-     */
-    virtual void decrementItemsInUse() const = 0;
     virtual ~UnifiedCacheBase();
 private:
     UnifiedCacheBase(const UnifiedCacheBase &);
@@ -63,7 +55,6 @@ class U_COMMON_API SharedObject : public UObject {
 public:
     /** Initializes totalRefCount, softRefCount to 0. */
     SharedObject() :
-            totalRefCount(0),
             softRefCount(0),
             hardRefCount(0),
             cachePtr(NULL) {}
@@ -71,7 +62,6 @@ public:
     /** Initializes totalRefCount, softRefCount to 0. */
     SharedObject(const SharedObject &other) :
             UObject(other),
-            totalRefCount(0),
             softRefCount(0),
             hardRefCount(0),
             cachePtr(NULL) {}
@@ -79,93 +69,45 @@ public:
     virtual ~SharedObject();
 
     /**
-     * Increments the number of references to this object. Thread-safe.
-     */
-    void addRef() const { addRef(FALSE); }
-
-    /**
-     * Increments the number of references to this object.
-     * Must be called only from within the internals of UnifiedCache and
-     * only while the cache global mutex is held.
-     */
-    void addRefWhileHoldingCacheLock() const { addRef(TRUE); }
-
-    /**
-     * Increments the number of soft references to this object.
-     * Must be called only from within the internals of UnifiedCache and
-     * only while the cache global mutex is held.
-     */
-    void addSoftRef() const;
-
-    /**
-     * Decrements the number of references to this object. Thread-safe.
-     */
-    void removeRef() const { removeRef(FALSE); }
-
-    /**
-     * Decrements the number of references to this object.
-     * Must be called only from within the internals of UnifiedCache and
-     * only while the cache global mutex is held.
+     * Increments the number of hard references to this object. Thread-safe.
+     * Not for use from within the Unified Cache implementation.
      */
-    void removeRefWhileHoldingCacheLock() const { removeRef(TRUE); }
+    void addRef() const;
 
     /**
-     * Decrements the number of soft references to this object.
-     * Must be called only from within the internals of UnifiedCache and
-     * only while the cache global mutex is held.
+     * Decrements the number of hard references to this object, and
+     * arrange for possible cache-eviction and/or deletion if ref
+     * count goes to zero. Thread-safe.
+     * 
+     * Not for use from within the UnifiedCache implementation.
      */
-    void removeSoftRef() const;
+    void removeRef() const;
 
     /**
-     * Returns the reference counter including soft references.
+     * Returns the number of hard references for this object.
      * Uses a memory barrier.
      */
     int32_t getRefCount() const;
 
-    /**
-     * Returns the count of soft references only.
-     * Must be called only from within the internals of UnifiedCache and
-     * only while the cache global mutex is held.
-     */
-    int32_t getSoftRefCount() const { return softRefCount; }
-
-    /**
-     * Returns the count of hard references only. Uses a memory barrier.
-     * Used for testing the cache. Regular clients won't need this.
-     */
-    int32_t getHardRefCount() const;
-
     /**
      * If noHardReferences() == TRUE then this object has no hard references.
      * Must be called only from within the internals of UnifiedCache.
      */
-    inline UBool noHardReferences() const { return getHardRefCount() == 0; }
+    inline UBool noHardReferences() const { return getRefCount() == 0; }
 
     /**
      * If hasHardReferences() == TRUE then this object has hard references.
      * Must be called only from within the internals of UnifiedCache.
      */
-    inline UBool hasHardReferences() const { return getHardRefCount() != 0; }
+    inline UBool hasHardReferences() const { return getRefCount() != 0; }
 
     /**
-     * If noSoftReferences() == TRUE then this object has no soft references.
-     * Must be called only from within the internals of UnifiedCache and
-     * only while the cache global mutex is held.
-     */
-    UBool noSoftReferences() const { return (softRefCount == 0); }
-
-    /**
-     * Deletes this object if it has no references or soft references.
+     * Deletes this object if it has no references.
+     * Available for non-cached SharedObjects only. Ownership of cached objects
+     * is with the UnifiedCache, which is soley responsible for eviction and deletion.
      */
     void deleteIfZeroRefCount() const;
 
-    /**
-     * @internal For UnifedCache use only to register this object with itself.
-     *   Must be called before this object is exposed to multiple threads.
-     */ 
-    void registerWithCache(const UnifiedCacheBase *ptr) const {
-        cachePtr = ptr;
-    }
         
     /**
      * Returns a writable version of ptr.
@@ -219,15 +161,21 @@ public:
     }
 
 private:
-    mutable u_atomic_int32_t totalRefCount;
-
-    // Any thread modifying softRefCount must hold the global cache mutex
+    /**
+     * The number of references from the UnifiedCache, which is
+     * the number of times that the sharedObject is stored as a hash table value.
+     * For use by UnifiedCache implementation code only.
+     * All access is synchronized by UnifiedCache's gCacheMutex
+     */
     mutable int32_t softRefCount;
+    friend class UnifiedCache;
 
+    /**
+     * Reference count, excluding references from within the UnifiedCache implementation.
+     */
     mutable u_atomic_int32_t hardRefCount;
+    
     mutable const UnifiedCacheBase *cachePtr;
-    void addRef(UBool withCacheLock) const;
-    void removeRef(UBool withCacheLock) const;
 
 };