/src/icu/source/common/sharedobject.h

Source (jump to first uncovered line)
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
******************************************************************************
* Copyright (C) 2015-2016, International Business Machines
* Corporation and others.  All Rights Reserved.
******************************************************************************
* sharedobject.h
*/

#ifndef __SHAREDOBJECT_H__
#define __SHAREDOBJECT_H__


#include "unicode/uobject.h"
#include "umutex.h"

U_NAMESPACE_BEGIN

class SharedObject;

/**
 * Base class for unified cache exposing enough methods to SharedObject
 * instances to allow their addRef() and removeRef() methods to
 * update cache metrics. No other part of ICU, except for SharedObject,
 * should directly call the methods of this base class.
 */
class U_COMMON_API UnifiedCacheBase : public UObject {
public:
    UnifiedCacheBase() { }

    /**
     * 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 handleUnreferencedObject() const = 0;

    virtual ~UnifiedCacheBase();
private:
    UnifiedCacheBase(const UnifiedCacheBase &);
    UnifiedCacheBase &operator=(const UnifiedCacheBase &);
};

/**
 * Base class for shared, reference-counted, auto-deleted objects.
 * Subclasses can be immutable.
 * If they are mutable, then they must implement their copy constructor
 * so that copyOnWrite() works.
 *
 * Either stack-allocate, use LocalPointer, or use addRef()/removeRef().
 * Sharing requires reference-counting.
 */
class U_COMMON_API SharedObject : public UObject {
public:
    /** Initializes totalRefCount, softRefCount to 0. */
    SharedObject() :
            softRefCount(0),
            hardRefCount(0),
            cachePtr(NULL) {}

    /** Initializes totalRefCount, softRefCount to 0. */
    SharedObject(const SharedObject &other) :
            UObject(other),
            softRefCount(0),
            hardRefCount(0),
            cachePtr(NULL) {}

    virtual ~SharedObject();

    /**
     * Increments the number of hard references to this object. Thread-safe.
     * Not for use from within the Unified Cache implementation.
     */
    void addRef() const;

    /**
     * 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 removeRef() const;

    /**
     * Returns the number of hard references for this object.
     * Uses a memory barrier.
     */
    int32_t getRefCount() 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 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 getRefCount() != 0; }

    /**
     * Deletes this object if it has no references.
     * Available for non-cached SharedObjects only. Ownership of cached objects
     * is with the UnifiedCache, which is solely responsible for eviction and deletion.
     */
    void deleteIfZeroRefCount() const;

        
    /**
     * Returns a writable version of ptr.
     * If there is exactly one owner, then ptr itself is returned as a
     *  non-const pointer.
     * If there are multiple owners, then ptr is replaced with a 
     * copy-constructed clone,
     * and that is returned.
     * Returns NULL if cloning failed.
     *
     * T must be a subclass of SharedObject.
     */
    template<typename T>
    static T *copyOnWrite(const T *&ptr) {
        const T *p = ptr;
        if(p->getRefCount() <= 1) { return const_cast<T *>(p); }
        T *p2 = new T(*p);
        if(p2 == NULL) { return NULL; }
        p->removeRef();
        ptr = p2;
        p2->addRef();
        return p2;
    }

    /**
     * Makes dest an owner of the object pointed to by src while adjusting
     * reference counts and deleting the previous object dest pointed to
     * if necessary. Before this call is made, dest must either be NULL or
     * be included in the reference count of the object it points to. 
     *
     * T must be a subclass of SharedObject.
     */
    template<typename T>
    static void copyPtr(const T *src, const T *&dest) {
        if(src != dest) {
            if(dest != NULL) { dest->removeRef(); }
            dest = src;
            if(src != NULL) { src->addRef(); }
        }
    }

    /**
     * Equivalent to copyPtr(NULL, dest).
     */
    template<typename T>
    static void clearPtr(const T *&ptr) {
        if (ptr != NULL) {
            ptr->removeRef();
            ptr = NULL;
        }
    }

private:
    /**
     * 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;

};

U_NAMESPACE_END

#endif

Line	Count	Source (jump to first uncovered line)
1		// © 2016 and later: Unicode, Inc. and others.
2		// License & terms of use: http://www.unicode.org/copyright.html
3		/*
4		******************************************************************************
5		* Copyright (C) 2015-2016, International Business Machines
6		* Corporation and others. All Rights Reserved.
7		******************************************************************************
8		* sharedobject.h
9		*/
10
11		#ifndef __SHAREDOBJECT_H__
12		#define __SHAREDOBJECT_H__
13
14
15		#include "unicode/uobject.h"
16		#include "umutex.h"
17
18		U_NAMESPACE_BEGIN
19
20		class SharedObject;
21
22		/**
23		* Base class for unified cache exposing enough methods to SharedObject
24		* instances to allow their addRef() and removeRef() methods to
25		* update cache metrics. No other part of ICU, except for SharedObject,
26		* should directly call the methods of this base class.
27		*/
28		class U_COMMON_API UnifiedCacheBase : public UObject {
29		public:
30	0	UnifiedCacheBase() { }
31
32		/**
33		* Notify the cache implementation that an object was seen transitioning to
34		* zero hard references. The cache may use this to keep track the number of
35		* unreferenced SharedObjects, and to trigger evictions.
36		*/
37		virtual void handleUnreferencedObject() const = 0;
38
39		virtual ~UnifiedCacheBase();
40		private:
41		UnifiedCacheBase(const UnifiedCacheBase &);
42		UnifiedCacheBase &operator=(const UnifiedCacheBase &);
43		};
44
45		/**
46		* Base class for shared, reference-counted, auto-deleted objects.
47		* Subclasses can be immutable.
48		* If they are mutable, then they must implement their copy constructor
49		* so that copyOnWrite() works.
50		*
51		* Either stack-allocate, use LocalPointer, or use addRef()/removeRef().
52		* Sharing requires reference-counting.
53		*/
54		class U_COMMON_API SharedObject : public UObject {
55		public:
56		/** Initializes totalRefCount, softRefCount to 0. */
57		SharedObject() :
58	0	softRefCount(0),
59	0	hardRefCount(0),
60	0	cachePtr(NULL) {}
61
62		/** Initializes totalRefCount, softRefCount to 0. */
63		SharedObject(const SharedObject &other) :
64	0	UObject(other),
65	0	softRefCount(0),
66	0	hardRefCount(0),
67	0	cachePtr(NULL) {}
68
69		virtual ~SharedObject();
70
71		/**
72		* Increments the number of hard references to this object. Thread-safe.
73		* Not for use from within the Unified Cache implementation.
74		*/
75		void addRef() const;
76
77		/**
78		* Decrements the number of hard references to this object, and
79		* arrange for possible cache-eviction and/or deletion if ref
80		* count goes to zero. Thread-safe.
81		*
82		* Not for use from within the UnifiedCache implementation.
83		*/
84		void removeRef() const;
85
86		/**
87		* Returns the number of hard references for this object.
88		* Uses a memory barrier.
89		*/
90		int32_t getRefCount() const;
91
92		/**
93		* If noHardReferences() == true then this object has no hard references.
94		* Must be called only from within the internals of UnifiedCache.
95		*/
96	0	inline UBool noHardReferences() const { return getRefCount() == 0; }
97
98		/**
99		* If hasHardReferences() == true then this object has hard references.
100		* Must be called only from within the internals of UnifiedCache.
101		*/
102	0	inline UBool hasHardReferences() const { return getRefCount() != 0; }
103
104		/**
105		* Deletes this object if it has no references.
106		* Available for non-cached SharedObjects only. Ownership of cached objects
107		* is with the UnifiedCache, which is solely responsible for eviction and deletion.
108		*/
109		void deleteIfZeroRefCount() const;
110
111
112		/**
113		* Returns a writable version of ptr.
114		* If there is exactly one owner, then ptr itself is returned as a
115		* non-const pointer.
116		* If there are multiple owners, then ptr is replaced with a
117		* copy-constructed clone,
118		* and that is returned.
119		* Returns NULL if cloning failed.
120		*
121		* T must be a subclass of SharedObject.
122		*/
123		template<typename T>
124	0	static T copyOnWrite(const T &ptr) {
125	0	const T *p = ptr;
126	0	if(p->getRefCount() <= 1) { return const_cast<T *>(p); }
127	0	T p2 = new T(p);
128	0	if(p2 == NULL) { return NULL; }
129	0	p->removeRef();
130	0	ptr = p2;
131	0	p2->addRef();
132	0	return p2;
133	0	}
134
135		/**
136		* Makes dest an owner of the object pointed to by src while adjusting
137		* reference counts and deleting the previous object dest pointed to
138		* if necessary. Before this call is made, dest must either be NULL or
139		* be included in the reference count of the object it points to.
140		*
141		* T must be a subclass of SharedObject.
142		*/
143		template<typename T>
144	0	static void copyPtr(const T src, const T &dest) {
145	0	if(src != dest) {
146	0	if(dest != NULL) { dest->removeRef(); }
147	0	dest = src;
148	0	if(src != NULL) { src->addRef(); }
149	0	}
150	0	} Unexecuted instantiation: void icu_70::SharedObject::copyPtr<icu_70::CollationCacheEntry>(icu_70::CollationCacheEntry const, icu_70::CollationCacheEntry const&) Unexecuted instantiation: void icu_70::SharedObject::copyPtr<icu_70::DateFmtBestPattern>(icu_70::DateFmtBestPattern const, icu_70::DateFmtBestPattern const&) Unexecuted instantiation: void icu_70::SharedObject::copyPtr<icu_70::SharedDateFormatSymbols>(icu_70::SharedDateFormatSymbols const, icu_70::SharedDateFormatSymbols const&) Unexecuted instantiation: void icu_70::SharedObject::copyPtr<icu_70::CollationSettings>(icu_70::CollationSettings const, icu_70::CollationSettings const&) Unexecuted instantiation: void icu_70::SharedObject::copyPtr<icu_70::SharedNumberFormat>(icu_70::SharedNumberFormat const, icu_70::SharedNumberFormat const&) Unexecuted instantiation: void icu_70::SharedObject::copyPtr<icu_70::SharedCalendar>(icu_70::SharedCalendar const, icu_70::SharedCalendar const&) Unexecuted instantiation: void icu_70::SharedObject::copyPtr<icu_70::SharedPluralRules>(icu_70::SharedPluralRules const, icu_70::SharedPluralRules const&) Unexecuted instantiation: void icu_70::SharedObject::copyPtr<icu_70::SharedObject>(icu_70::SharedObject const, icu_70::SharedObject const&)
151
152		/**
153		* Equivalent to copyPtr(NULL, dest).
154		*/
155		template<typename T>
156	0	static void clearPtr(const T *&ptr) {
157	0	if (ptr != NULL) {
158	0	ptr->removeRef();
159	0	ptr = NULL;
160	0	}
161	0	} Unexecuted instantiation: void icu_70::SharedObject::clearPtr<icu_70::CollationCacheEntry>(icu_70::CollationCacheEntry const&) Unexecuted instantiation: void icu_70::SharedObject::clearPtr<icu_70::CollationSettings>(icu_70::CollationSettings const&) Unexecuted instantiation: void icu_70::SharedObject::clearPtr<icu_70::CollationTailoring>(icu_70::CollationTailoring const&) Unexecuted instantiation: void icu_70::SharedObject::clearPtr<icu_70::DateFmtBestPattern>(icu_70::DateFmtBestPattern const&) Unexecuted instantiation: void icu_70::SharedObject::clearPtr<icu_70::SharedDateFormatSymbols>(icu_70::SharedDateFormatSymbols const&) Unexecuted instantiation: void icu_70::SharedObject::clearPtr<icu_70::SharedNumberFormat>(icu_70::SharedNumberFormat const&) Unexecuted instantiation: void icu_70::SharedObject::clearPtr<icu_70::SharedCalendar>(icu_70::SharedCalendar const&) Unexecuted instantiation: void icu_70::SharedObject::clearPtr<icu_70::SharedPluralRules>(icu_70::SharedPluralRules const&) Unexecuted instantiation: void icu_70::SharedObject::clearPtr<icu_70::SharedObject>(icu_70::SharedObject const*&)
162
163		private:
164		/**
165		* The number of references from the UnifiedCache, which is
166		* the number of times that the sharedObject is stored as a hash table value.
167		* For use by UnifiedCache implementation code only.
168		* All access is synchronized by UnifiedCache's gCacheMutex
169		*/
170		mutable int32_t softRefCount;
171		friend class UnifiedCache;
172
173		/**
174		* Reference count, excluding references from within the UnifiedCache implementation.
175		*/
176		mutable u_atomic_int32_t hardRefCount;
177
178		mutable const UnifiedCacheBase *cachePtr;
179
180		};
181
182		U_NAMESPACE_END
183
184		#endif

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Created: 2025-01-28 06:38