RefBase.h revision 63ad28fb53a1b3b652495e57eb5fe52eb2a0ec80 
1/*
2 * Copyright (C) 2005 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_REF_BASE_H
18#define ANDROID_REF_BASE_H
19
20#include <cutils/atomic.h>
21
22#include <stdint.h>
23#include <sys/types.h>
24#include <stdlib.h>
25#include <string.h>
26
27#include <utils/StrongPointer.h>
28
29// ---------------------------------------------------------------------------
30namespace android {
31
32class TextOutput;
33TextOutput& printWeakPointer(TextOutput& to, const void* val);
34
35// ---------------------------------------------------------------------------
36
37#define COMPARE_WEAK(_op_)                                      \
38inline bool operator _op_ (const sp<T>& o) const {              \
39    return m_ptr _op_ o.m_ptr;                                  \
40}                                                               \
41inline bool operator _op_ (const T* o) const {                  \
42    return m_ptr _op_ o;                                        \
43}                                                               \
44template<typename U>                                            \
45inline bool operator _op_ (const sp<U>& o) const {              \
46    return m_ptr _op_ o.m_ptr;                                  \
47}                                                               \
48template<typename U>                                            \
49inline bool operator _op_ (const U* o) const {                  \
50    return m_ptr _op_ o;                                        \
51}
52
53// ---------------------------------------------------------------------------
54
55class ReferenceMover;
56class ReferenceConverterBase {
57public:
58    virtual size_t getReferenceTypeSize() const = 0;
59    virtual void* getReferenceBase(void const*) const = 0;
60    inline virtual ~ReferenceConverterBase() { }
61};
62
63// ---------------------------------------------------------------------------
64
65class RefBase
66{
67public:
68            void            incStrong(const void* id) const;
69            void            decStrong(const void* id) const;
70
71            void            forceIncStrong(const void* id) const;
72
73            //! DEBUGGING ONLY: Get current strong ref count.
74            int32_t         getStrongCount() const;
75
76    class weakref_type
77    {
78    public:
79        RefBase*            refBase() const;
80
81        void                incWeak(const void* id);
82        void                decWeak(const void* id);
83
84        bool                attemptIncStrong(const void* id);
85
86        //! This is only safe if you have set OBJECT_LIFETIME_FOREVER.
87        bool                attemptIncWeak(const void* id);
88
89        //! DEBUGGING ONLY: Get current weak ref count.
90        int32_t             getWeakCount() const;
91
92        //! DEBUGGING ONLY: Print references held on object.
93        void                printRefs() const;
94
95        //! DEBUGGING ONLY: Enable tracking for this object.
96        // enable -- enable/disable tracking
97        // retain -- when tracking is enable, if true, then we save a stack trace
98        //           for each reference and dereference; when retain == false, we
99        //           match up references and dereferences and keep only the
100        //           outstanding ones.
101
102        void                trackMe(bool enable, bool retain);
103    };
104
105            weakref_type*   createWeak(const void* id) const;
106
107            weakref_type*   getWeakRefs() const;
108
109            //! DEBUGGING ONLY: Print references held on object.
110    inline  void            printRefs() const { getWeakRefs()->printRefs(); }
111
112            //! DEBUGGING ONLY: Enable tracking of object.
113    inline  void            trackMe(bool enable, bool retain)
114    {
115        getWeakRefs()->trackMe(enable, retain);
116    }
117
118    typedef RefBase basetype;
119
120    // used to override the RefBase destruction.
121    class Destroyer {
122        friend class RefBase;
123        friend class weakref_type;
124    public:
125        virtual ~Destroyer();
126    private:
127        virtual void destroy(RefBase const* base) = 0;
128    };
129
130    // Make sure to never acquire a strong reference from this function. The
131    // same restrictions than for destructors apply.
132    void setDestroyer(Destroyer* destroyer);
133
134protected:
135                            RefBase();
136    virtual                 ~RefBase();
137
138    //! Flags for extendObjectLifetime()
139    enum {
140        OBJECT_LIFETIME_WEAK    = 0x0001,
141        OBJECT_LIFETIME_FOREVER = 0x0003
142    };
143
144            void            extendObjectLifetime(int32_t mode);
145
146    //! Flags for onIncStrongAttempted()
147    enum {
148        FIRST_INC_STRONG = 0x0001
149    };
150
151    virtual void            onFirstRef();
152    virtual void            onLastStrongRef(const void* id);
153    virtual bool            onIncStrongAttempted(uint32_t flags, const void* id);
154    virtual void            onLastWeakRef(const void* id);
155
156private:
157    friend class ReferenceMover;
158    static void moveReferences(void* d, void const* s, size_t n,
159            const ReferenceConverterBase& caster);
160
161private:
162    friend class weakref_type;
163    class weakref_impl;
164
165                            RefBase(const RefBase& o);
166            RefBase&        operator=(const RefBase& o);
167
168        weakref_impl* const mRefs;
169};
170
171// ---------------------------------------------------------------------------
172
173template <class T>
174class LightRefBase
175{
176public:
177    inline LightRefBase() : mCount(0) { }
178    inline void incStrong(const void* id) const {
179        android_atomic_inc(&mCount);
180    }
181    inline void decStrong(const void* id) const {
182        if (android_atomic_dec(&mCount) == 1) {
183            delete static_cast<const T*>(this);
184        }
185    }
186    //! DEBUGGING ONLY: Get current strong ref count.
187    inline int32_t getStrongCount() const {
188        return mCount;
189    }
190
191    typedef LightRefBase<T> basetype;
192
193protected:
194    inline ~LightRefBase() { }
195
196private:
197    friend class ReferenceMover;
198    inline static void moveReferences(void* d, void const* s, size_t n,
199            const ReferenceConverterBase& caster) { }
200
201private:
202    mutable volatile int32_t mCount;
203};
204
205// ---------------------------------------------------------------------------
206
207template <typename T>
208class wp
209{
210public:
211    typedef typename RefBase::weakref_type weakref_type;
212
213    inline wp() : m_ptr(0) { }
214
215    wp(T* other);
216    wp(const wp<T>& other);
217    wp(const sp<T>& other);
218    template<typename U> wp(U* other);
219    template<typename U> wp(const sp<U>& other);
220    template<typename U> wp(const wp<U>& other);
221
222    ~wp();
223
224    // Assignment
225
226    wp& operator = (T* other);
227    wp& operator = (const wp<T>& other);
228    wp& operator = (const sp<T>& other);
229
230    template<typename U> wp& operator = (U* other);
231    template<typename U> wp& operator = (const wp<U>& other);
232    template<typename U> wp& operator = (const sp<U>& other);
233
234    void set_object_and_refs(T* other, weakref_type* refs);
235
236    // promotion to sp
237
238    sp<T> promote() const;
239
240    // Reset
241
242    void clear();
243
244    // Accessors
245
246    inline  weakref_type* get_refs() const { return m_refs; }
247
248    inline  T* unsafe_get() const { return m_ptr; }
249
250    // Operators
251
252    COMPARE_WEAK(==)
253    COMPARE_WEAK(!=)
254    COMPARE_WEAK(>)
255    COMPARE_WEAK(<)
256    COMPARE_WEAK(<=)
257    COMPARE_WEAK(>=)
258
259    inline bool operator == (const wp<T>& o) const {
260        return (m_ptr == o.m_ptr) && (m_refs == o.m_refs);
261    }
262    template<typename U>
263    inline bool operator == (const wp<U>& o) const {
264        return m_ptr == o.m_ptr;
265    }
266
267    inline bool operator > (const wp<T>& o) const {
268        return (m_ptr == o.m_ptr) ? (m_refs > o.m_refs) : (m_ptr > o.m_ptr);
269    }
270    template<typename U>
271    inline bool operator > (const wp<U>& o) const {
272        return (m_ptr == o.m_ptr) ? (m_refs > o.m_refs) : (m_ptr > o.m_ptr);
273    }
274
275    inline bool operator < (const wp<T>& o) const {
276        return (m_ptr == o.m_ptr) ? (m_refs < o.m_refs) : (m_ptr < o.m_ptr);
277    }
278    template<typename U>
279    inline bool operator < (const wp<U>& o) const {
280        return (m_ptr == o.m_ptr) ? (m_refs < o.m_refs) : (m_ptr < o.m_ptr);
281    }
282                         inline bool operator != (const wp<T>& o) const { return m_refs != o.m_refs; }
283    template<typename U> inline bool operator != (const wp<U>& o) const { return !operator == (o); }
284                         inline bool operator <= (const wp<T>& o) const { return !operator > (o); }
285    template<typename U> inline bool operator <= (const wp<U>& o) const { return !operator > (o); }
286                         inline bool operator >= (const wp<T>& o) const { return !operator < (o); }
287    template<typename U> inline bool operator >= (const wp<U>& o) const { return !operator < (o); }
288
289private:
290    template<typename Y> friend class sp;
291    template<typename Y> friend class wp;
292
293    T*              m_ptr;
294    weakref_type*   m_refs;
295};
296
297template <typename T>
298TextOutput& operator<<(TextOutput& to, const wp<T>& val);
299
300#undef COMPARE_WEAK
301
302// ---------------------------------------------------------------------------
303// No user serviceable parts below here.
304
305template<typename T>
306wp<T>::wp(T* other)
307    : m_ptr(other)
308{
309    if (other) m_refs = other->createWeak(this);
310}
311
312template<typename T>
313wp<T>::wp(const wp<T>& other)
314    : m_ptr(other.m_ptr), m_refs(other.m_refs)
315{
316    if (m_ptr) m_refs->incWeak(this);
317}
318
319template<typename T>
320wp<T>::wp(const sp<T>& other)
321    : m_ptr(other.m_ptr)
322{
323    if (m_ptr) {
324        m_refs = m_ptr->createWeak(this);
325    }
326}
327
328template<typename T> template<typename U>
329wp<T>::wp(U* other)
330    : m_ptr(other)
331{
332    if (other) m_refs = other->createWeak(this);
333}
334
335template<typename T> template<typename U>
336wp<T>::wp(const wp<U>& other)
337    : m_ptr(other.m_ptr)
338{
339    if (m_ptr) {
340        m_refs = other.m_refs;
341        m_refs->incWeak(this);
342    }
343}
344
345template<typename T> template<typename U>
346wp<T>::wp(const sp<U>& other)
347    : m_ptr(other.m_ptr)
348{
349    if (m_ptr) {
350        m_refs = m_ptr->createWeak(this);
351    }
352}
353
354template<typename T>
355wp<T>::~wp()
356{
357    if (m_ptr) m_refs->decWeak(this);
358}
359
360template<typename T>
361wp<T>& wp<T>::operator = (T* other)
362{
363    weakref_type* newRefs =
364        other ? other->createWeak(this) : 0;
365    if (m_ptr) m_refs->decWeak(this);
366    m_ptr = other;
367    m_refs = newRefs;
368    return *this;
369}
370
371template<typename T>
372wp<T>& wp<T>::operator = (const wp<T>& other)
373{
374    weakref_type* otherRefs(other.m_refs);
375    T* otherPtr(other.m_ptr);
376    if (otherPtr) otherRefs->incWeak(this);
377    if (m_ptr) m_refs->decWeak(this);
378    m_ptr = otherPtr;
379    m_refs = otherRefs;
380    return *this;
381}
382
383template<typename T>
384wp<T>& wp<T>::operator = (const sp<T>& other)
385{
386    weakref_type* newRefs =
387        other != NULL ? other->createWeak(this) : 0;
388    T* otherPtr(other.m_ptr);
389    if (m_ptr) m_refs->decWeak(this);
390    m_ptr = otherPtr;
391    m_refs = newRefs;
392    return *this;
393}
394
395template<typename T> template<typename U>
396wp<T>& wp<T>::operator = (U* other)
397{
398    weakref_type* newRefs =
399        other ? other->createWeak(this) : 0;
400    if (m_ptr) m_refs->decWeak(this);
401    m_ptr = other;
402    m_refs = newRefs;
403    return *this;
404}
405
406template<typename T> template<typename U>
407wp<T>& wp<T>::operator = (const wp<U>& other)
408{
409    weakref_type* otherRefs(other.m_refs);
410    U* otherPtr(other.m_ptr);
411    if (otherPtr) otherRefs->incWeak(this);
412    if (m_ptr) m_refs->decWeak(this);
413    m_ptr = otherPtr;
414    m_refs = otherRefs;
415    return *this;
416}
417
418template<typename T> template<typename U>
419wp<T>& wp<T>::operator = (const sp<U>& other)
420{
421    weakref_type* newRefs =
422        other != NULL ? other->createWeak(this) : 0;
423    U* otherPtr(other.m_ptr);
424    if (m_ptr) m_refs->decWeak(this);
425    m_ptr = otherPtr;
426    m_refs = newRefs;
427    return *this;
428}
429
430template<typename T>
431void wp<T>::set_object_and_refs(T* other, weakref_type* refs)
432{
433    if (other) refs->incWeak(this);
434    if (m_ptr) m_refs->decWeak(this);
435    m_ptr = other;
436    m_refs = refs;
437}
438
439template<typename T>
440sp<T> wp<T>::promote() const
441{
442    sp<T> result;
443    if (m_ptr && m_refs->attemptIncStrong(&result)) {
444        result.set_pointer(m_ptr);
445    }
446    return result;
447}
448
449template<typename T>
450void wp<T>::clear()
451{
452    if (m_ptr) {
453        m_refs->decWeak(this);
454        m_ptr = 0;
455    }
456}
457
458template <typename T>
459inline TextOutput& operator<<(TextOutput& to, const wp<T>& val)
460{
461    return printWeakPointer(to, val.unsafe_get());
462}
463
464// ---------------------------------------------------------------------------
465
466// this class just serves as a namespace so TYPE::moveReferences can stay
467// private.
468
469class ReferenceMover {
470    // StrongReferenceCast and WeakReferenceCast do the impedance matching
471    // between the generic (void*) implementation in Refbase and the strongly typed
472    // template specializations below.
473
474    template <typename TYPE>
475    struct StrongReferenceCast : public ReferenceConverterBase {
476        virtual size_t getReferenceTypeSize() const { return sizeof( sp<TYPE> ); }
477        virtual void* getReferenceBase(void const* p) const {
478            sp<TYPE> const* sptr(reinterpret_cast<sp<TYPE> const*>(p));
479            return static_cast<typename TYPE::basetype *>(sptr->get());
480        }
481    };
482
483    template <typename TYPE>
484    struct WeakReferenceCast : public ReferenceConverterBase {
485        virtual size_t getReferenceTypeSize() const { return sizeof( wp<TYPE> ); }
486        virtual void* getReferenceBase(void const* p) const {
487            wp<TYPE> const* sptr(reinterpret_cast<wp<TYPE> const*>(p));
488            return static_cast<typename TYPE::basetype *>(sptr->unsafe_get());
489        }
490    };
491
492public:
493    template<typename TYPE> static inline
494    void move_references(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
495        memmove(d, s, n*sizeof(sp<TYPE>));
496        StrongReferenceCast<TYPE> caster;
497        TYPE::moveReferences(d, s, n, caster);
498    }
499    template<typename TYPE> static inline
500    void move_references(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
501        memmove(d, s, n*sizeof(wp<TYPE>));
502        WeakReferenceCast<TYPE> caster;
503        TYPE::moveReferences(d, s, n, caster);
504    }
505};
506
507// specialization for moving sp<> and wp<> types.
508// these are used by the [Sorted|Keyed]Vector<> implementations
509// sp<> and wp<> need to be handled specially, because they do not
510// have trivial copy operation in the general case (see RefBase.cpp
511// when DEBUG ops are enabled), but can be implemented very
512// efficiently in most cases.
513
514template<typename TYPE> inline
515void move_forward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
516    ReferenceMover::move_references(d, s, n);
517}
518
519template<typename TYPE> inline
520void move_backward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
521    ReferenceMover::move_references(d, s, n);
522}
523
524template<typename TYPE> inline
525void move_forward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
526    ReferenceMover::move_references(d, s, n);
527}
528
529template<typename TYPE> inline
530void move_backward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
531    ReferenceMover::move_references(d, s, n);
532}
533
534
535}; // namespace android
536
537// ---------------------------------------------------------------------------
538
539#endif // ANDROID_REF_BASE_H
540