RefBase.h revision bf950e76f6efee2ddc26f5012b1aef855980f3eb 
1/*
2 * Copyright (C) 2013 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 RS_REF_BASE_H
18#define RS_REF_BASE_H
19
20
21#include <stdint.h>
22#include <sys/types.h>
23#include <stdlib.h>
24#include <string.h>
25
26#include "StrongPointer.h"
27#include "TypeHelpers.h"
28
29// ---------------------------------------------------------------------------
30namespace android{
31namespace RSC {
32
33class TextOutput;
34TextOutput& printWeakPointer(TextOutput& to, const void* val);
35
36// ---------------------------------------------------------------------------
37
38#define COMPARE_WEAK(_op_)                                      \
39inline bool operator _op_ (const sp<T>& o) const {              \
40    return m_ptr _op_ o.m_ptr;                                  \
41}                                                               \
42inline bool operator _op_ (const T* o) const {                  \
43    return m_ptr _op_ o;                                        \
44}                                                               \
45template<typename U>                                            \
46inline bool operator _op_ (const sp<U>& o) const {              \
47    return m_ptr _op_ o.m_ptr;                                  \
48}                                                               \
49template<typename U>                                            \
50inline bool operator _op_ (const U* o) const {                  \
51    return m_ptr _op_ o;                                        \
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        // acquires a strong reference if there is already one.
85        bool                attemptIncStrong(const void* id);
86
87        // acquires a weak reference if there is already one.
88        // This is not always safe. see ProcessState.cpp and BpBinder.cpp
89        // for proper use.
90        bool                attemptIncWeak(const void* id);
91
92        //! DEBUGGING ONLY: Get current weak ref count.
93        int32_t             getWeakCount() const;
94
95        //! DEBUGGING ONLY: Print references held on object.
96        void                printRefs() const;
97
98        //! DEBUGGING ONLY: Enable tracking for this object.
99        // enable -- enable/disable tracking
100        // retain -- when tracking is enable, if true, then we save a stack trace
101        //           for each reference and dereference; when retain == false, we
102        //           match up references and dereferences and keep only the
103        //           outstanding ones.
104
105        void                trackMe(bool enable, bool retain);
106    };
107
108            weakref_type*   createWeak(const void* id) const;
109
110            weakref_type*   getWeakRefs() const;
111
112            //! DEBUGGING ONLY: Print references held on object.
113    inline  void            printRefs() const { getWeakRefs()->printRefs(); }
114
115            //! DEBUGGING ONLY: Enable tracking of object.
116    inline  void            trackMe(bool enable, bool retain)
117    {
118        getWeakRefs()->trackMe(enable, retain);
119    }
120
121    typedef RefBase basetype;
122
123protected:
124                            RefBase();
125    virtual                 ~RefBase();
126
127    //! Flags for extendObjectLifetime()
128    enum {
129        OBJECT_LIFETIME_STRONG  = 0x0000,
130        OBJECT_LIFETIME_WEAK    = 0x0001,
131        OBJECT_LIFETIME_MASK    = 0x0001
132    };
133
134            void            extendObjectLifetime(int32_t mode);
135
136    //! Flags for onIncStrongAttempted()
137    enum {
138        FIRST_INC_STRONG = 0x0001
139    };
140
141    virtual void            onFirstRef();
142    virtual void            onLastStrongRef(const void* id);
143    virtual bool            onIncStrongAttempted(uint32_t flags, const void* id);
144    virtual void            onLastWeakRef(const void* id);
145
146private:
147    friend class ReferenceMover;
148    static void moveReferences(void* d, void const* s, size_t n,
149            const ReferenceConverterBase& caster);
150
151private:
152    friend class weakref_type;
153    class weakref_impl;
154
155                            RefBase(const RefBase& o);
156            RefBase&        operator=(const RefBase& o);
157
158        weakref_impl* const mRefs;
159};
160
161// ---------------------------------------------------------------------------
162
163template <class T>
164class LightRefBase
165{
166public:
167    inline LightRefBase() : mCount(0) { }
168    inline void incStrong(__attribute__((unused)) const void* id) const {
169        __sync_fetch_and_add(&mCount, 1);
170    }
171    inline void decStrong(__attribute__((unused)) const void* id) const {
172        if (__sync_fetch_and_sub(&mCount, 1) == 1) {
173            delete static_cast<const T*>(this);
174        }
175    }
176    //! DEBUGGING ONLY: Get current strong ref count.
177    inline int32_t getStrongCount() const {
178        return mCount;
179    }
180
181    typedef LightRefBase<T> basetype;
182
183protected:
184    inline ~LightRefBase() { }
185
186private:
187    friend class ReferenceMover;
188    inline static void moveReferences(void*, void const*, size_t,
189            const ReferenceConverterBase&) { }
190
191private:
192    mutable volatile int32_t mCount;
193};
194
195// ---------------------------------------------------------------------------
196
197template <typename T>
198class wp
199{
200public:
201    typedef typename RefBase::weakref_type weakref_type;
202
203    inline wp() : m_ptr(0) { }
204
205    wp(T* other);
206    wp(const wp<T>& other);
207    wp(const sp<T>& other);
208    template<typename U> wp(U* other);
209    template<typename U> wp(const sp<U>& other);
210    template<typename U> wp(const wp<U>& other);
211
212    ~wp();
213
214    // Assignment
215
216    wp& operator = (T* other);
217    wp& operator = (const wp<T>& other);
218    wp& operator = (const sp<T>& other);
219
220    template<typename U> wp& operator = (U* other);
221    template<typename U> wp& operator = (const wp<U>& other);
222    template<typename U> wp& operator = (const sp<U>& other);
223
224    void set_object_and_refs(T* other, weakref_type* refs);
225
226    // promotion to sp
227
228    sp<T> promote() const;
229
230    // Reset
231
232    void clear();
233
234    // Accessors
235
236    inline  weakref_type* get_refs() const { return m_refs; }
237
238    inline  T* unsafe_get() const { return m_ptr; }
239
240    // Operators
241
242    COMPARE_WEAK(==)
243    COMPARE_WEAK(!=)
244    COMPARE_WEAK(>)
245    COMPARE_WEAK(<)
246    COMPARE_WEAK(<=)
247    COMPARE_WEAK(>=)
248
249    inline bool operator == (const wp<T>& o) const {
250        return (m_ptr == o.m_ptr) && (m_refs == o.m_refs);
251    }
252    template<typename U>
253    inline bool operator == (const wp<U>& o) const {
254        return m_ptr == o.m_ptr;
255    }
256
257    inline bool operator > (const wp<T>& o) const {
258        return (m_ptr == o.m_ptr) ? (m_refs > o.m_refs) : (m_ptr > o.m_ptr);
259    }
260    template<typename U>
261    inline bool operator > (const wp<U>& o) const {
262        return (m_ptr == o.m_ptr) ? (m_refs > o.m_refs) : (m_ptr > o.m_ptr);
263    }
264
265    inline bool operator < (const wp<T>& o) const {
266        return (m_ptr == o.m_ptr) ? (m_refs < o.m_refs) : (m_ptr < o.m_ptr);
267    }
268    template<typename U>
269    inline bool operator < (const wp<U>& o) const {
270        return (m_ptr == o.m_ptr) ? (m_refs < o.m_refs) : (m_ptr < o.m_ptr);
271    }
272                         inline bool operator != (const wp<T>& o) const { return m_refs != o.m_refs; }
273    template<typename U> inline bool operator != (const wp<U>& o) const { return !operator == (o); }
274                         inline bool operator <= (const wp<T>& o) const { return !operator > (o); }
275    template<typename U> inline bool operator <= (const wp<U>& o) const { return !operator > (o); }
276                         inline bool operator >= (const wp<T>& o) const { return !operator < (o); }
277    template<typename U> inline bool operator >= (const wp<U>& o) const { return !operator < (o); }
278
279private:
280    template<typename Y> friend class sp;
281    template<typename Y> friend class wp;
282
283    T*              m_ptr;
284    weakref_type*   m_refs;
285};
286
287template <typename T>
288TextOutput& operator<<(TextOutput& to, const wp<T>& val);
289
290#undef COMPARE_WEAK
291
292// ---------------------------------------------------------------------------
293// No user serviceable parts below here.
294
295template<typename T>
296wp<T>::wp(T* other)
297    : m_ptr(other)
298{
299    if (other) m_refs = other->createWeak(this);
300}
301
302template<typename T>
303wp<T>::wp(const wp<T>& other)
304    : m_ptr(other.m_ptr), m_refs(other.m_refs)
305{
306    if (m_ptr) m_refs->incWeak(this);
307}
308
309template<typename T>
310wp<T>::wp(const sp<T>& other)
311    : m_ptr(other.m_ptr)
312{
313    if (m_ptr) {
314        m_refs = m_ptr->createWeak(this);
315    }
316}
317
318template<typename T> template<typename U>
319wp<T>::wp(U* other)
320    : m_ptr(other)
321{
322    if (other) m_refs = other->createWeak(this);
323}
324
325template<typename T> template<typename U>
326wp<T>::wp(const wp<U>& other)
327    : m_ptr(other.m_ptr)
328{
329    if (m_ptr) {
330        m_refs = other.m_refs;
331        m_refs->incWeak(this);
332    }
333}
334
335template<typename T> template<typename U>
336wp<T>::wp(const sp<U>& other)
337    : m_ptr(other.m_ptr)
338{
339    if (m_ptr) {
340        m_refs = m_ptr->createWeak(this);
341    }
342}
343
344template<typename T>
345wp<T>::~wp()
346{
347    if (m_ptr) m_refs->decWeak(this);
348}
349
350template<typename T>
351wp<T>& wp<T>::operator = (T* other)
352{
353    weakref_type* newRefs =
354        other ? other->createWeak(this) : 0;
355    if (m_ptr) m_refs->decWeak(this);
356    m_ptr = other;
357    m_refs = newRefs;
358    return *this;
359}
360
361template<typename T>
362wp<T>& wp<T>::operator = (const wp<T>& other)
363{
364    weakref_type* otherRefs(other.m_refs);
365    T* otherPtr(other.m_ptr);
366    if (otherPtr) otherRefs->incWeak(this);
367    if (m_ptr) m_refs->decWeak(this);
368    m_ptr = otherPtr;
369    m_refs = otherRefs;
370    return *this;
371}
372
373template<typename T>
374wp<T>& wp<T>::operator = (const sp<T>& other)
375{
376    weakref_type* newRefs =
377        other != NULL ? other->createWeak(this) : 0;
378    T* otherPtr(other.m_ptr);
379    if (m_ptr) m_refs->decWeak(this);
380    m_ptr = otherPtr;
381    m_refs = newRefs;
382    return *this;
383}
384
385template<typename T> template<typename U>
386wp<T>& wp<T>::operator = (U* other)
387{
388    weakref_type* newRefs =
389        other ? other->createWeak(this) : 0;
390    if (m_ptr) m_refs->decWeak(this);
391    m_ptr = other;
392    m_refs = newRefs;
393    return *this;
394}
395
396template<typename T> template<typename U>
397wp<T>& wp<T>::operator = (const wp<U>& other)
398{
399    weakref_type* otherRefs(other.m_refs);
400    U* otherPtr(other.m_ptr);
401    if (otherPtr) otherRefs->incWeak(this);
402    if (m_ptr) m_refs->decWeak(this);
403    m_ptr = otherPtr;
404    m_refs = otherRefs;
405    return *this;
406}
407
408template<typename T> template<typename U>
409wp<T>& wp<T>::operator = (const sp<U>& other)
410{
411    weakref_type* newRefs =
412        other != NULL ? other->createWeak(this) : 0;
413    U* otherPtr(other.m_ptr);
414    if (m_ptr) m_refs->decWeak(this);
415    m_ptr = otherPtr;
416    m_refs = newRefs;
417    return *this;
418}
419
420template<typename T>
421void wp<T>::set_object_and_refs(T* other, weakref_type* refs)
422{
423    if (other) refs->incWeak(this);
424    if (m_ptr) m_refs->decWeak(this);
425    m_ptr = other;
426    m_refs = refs;
427}
428
429template<typename T>
430sp<T> wp<T>::promote() const
431{
432    sp<T> result;
433    if (m_ptr && m_refs->attemptIncStrong(&result)) {
434        result.set_pointer(m_ptr);
435    }
436    return result;
437}
438
439template<typename T>
440void wp<T>::clear()
441{
442    if (m_ptr) {
443        m_refs->decWeak(this);
444        m_ptr = 0;
445    }
446}
447
448template <typename T>
449inline TextOutput& operator<<(TextOutput& to, const wp<T>& val)
450{
451    return printWeakPointer(to, val.unsafe_get());
452}
453
454// ---------------------------------------------------------------------------
455
456// this class just serves as a namespace so TYPE::moveReferences can stay
457// private.
458
459class ReferenceMover {
460    // StrongReferenceCast and WeakReferenceCast do the impedance matching
461    // between the generic (void*) implementation in Refbase and the strongly typed
462    // template specializations below.
463
464    template <typename TYPE>
465    struct StrongReferenceCast : public ReferenceConverterBase {
466        virtual size_t getReferenceTypeSize() const { return sizeof( sp<TYPE> ); }
467        virtual void* getReferenceBase(void const* p) const {
468            sp<TYPE> const* sptr(reinterpret_cast<sp<TYPE> const*>(p));
469            return static_cast<typename TYPE::basetype *>(sptr->get());
470        }
471    };
472
473    template <typename TYPE>
474    struct WeakReferenceCast : public ReferenceConverterBase {
475        virtual size_t getReferenceTypeSize() const { return sizeof( wp<TYPE> ); }
476        virtual void* getReferenceBase(void const* p) const {
477            wp<TYPE> const* sptr(reinterpret_cast<wp<TYPE> const*>(p));
478            return static_cast<typename TYPE::basetype *>(sptr->unsafe_get());
479        }
480    };
481
482public:
483    template<typename TYPE> static inline
484    void move_references(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
485        memmove(d, s, n*sizeof(sp<TYPE>));
486        StrongReferenceCast<TYPE> caster;
487        TYPE::moveReferences(d, s, n, caster);
488    }
489    template<typename TYPE> static inline
490    void move_references(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
491        memmove(d, s, n*sizeof(wp<TYPE>));
492        WeakReferenceCast<TYPE> caster;
493        TYPE::moveReferences(d, s, n, caster);
494    }
495};
496
497// specialization for moving sp<> and wp<> types.
498// these are used by the [Sorted|Keyed]Vector<> implementations
499// sp<> and wp<> need to be handled specially, because they do not
500// have trivial copy operation in the general case (see RefBase.cpp
501// when DEBUG ops are enabled), but can be implemented very
502// efficiently in most cases.
503
504template<typename TYPE> inline
505void move_forward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
506    ReferenceMover::move_references(d, s, n);
507}
508
509template<typename TYPE> inline
510void move_backward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
511    ReferenceMover::move_references(d, s, n);
512}
513
514template<typename TYPE> inline
515void move_forward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
516    ReferenceMover::move_references(d, s, n);
517}
518
519template<typename TYPE> inline
520void move_backward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
521    ReferenceMover::move_references(d, s, n);
522}
523
524
525}; // namespace RSC
526}; // namespace android
527// ---------------------------------------------------------------------------
528
529#endif // RS_REF_BASE_H
530