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 #include <utils/TypeHelpers.h>
29
30 // ---------------------------------------------------------------------------
31 namespace android {
32
33 class TextOutput;
34 TextOutput& printWeakPointer(TextOutput& to, const void* val);
35
36 // ---------------------------------------------------------------------------
37
38 #define COMPARE_WEAK(_op_) \
39 inline bool operator _op_ (const sp<T>& o) const { \
40 return m_ptr _op_ o.m_ptr; \
41 } \
42 inline bool operator _op_ (const T* o) const { \
43 return m_ptr _op_ o; \
44 } \
45 template<typename U> \
46 inline bool operator _op_ (const sp<U>& o) const { \
47 return m_ptr _op_ o.m_ptr; \
48 } \
49 template<typename U> \
50 inline bool operator _op_ (const U* o) const { \
51 return m_ptr _op_ o; \
52 }
53
54 // ---------------------------------------------------------------------------
55
56 class ReferenceRenamer {
57 protected:
58 // destructor is purposedly not virtual so we avoid code overhead from
59 // subclasses; we have to make it protected to guarantee that it
60 // cannot be called from this base class (and to make strict compilers
61 // happy).
~ReferenceRenamer()62 ~ReferenceRenamer() { }
63 public:
64 virtual void operator()(size_t i) const = 0;
65 };
66
67 // ---------------------------------------------------------------------------
68
69 class RefBase
70 {
71 public:
72 void incStrong(const void* id) const;
73 void decStrong(const void* id) const;
74
75 void forceIncStrong(const void* id) const;
76
77 //! DEBUGGING ONLY: Get current strong ref count.
78 int32_t getStrongCount() const;
79
80 class weakref_type
81 {
82 public:
83 RefBase* refBase() const;
84
85 void incWeak(const void* id);
86 void decWeak(const void* id);
87
88 // acquires a strong reference if there is already one.
89 bool attemptIncStrong(const void* id);
90
91 // acquires a weak reference if there is already one.
92 // This is not always safe. see ProcessState.cpp and BpBinder.cpp
93 // for proper use.
94 bool attemptIncWeak(const void* id);
95
96 //! DEBUGGING ONLY: Get current weak ref count.
97 int32_t getWeakCount() const;
98
99 //! DEBUGGING ONLY: Print references held on object.
100 void printRefs() const;
101
102 //! DEBUGGING ONLY: Enable tracking for this object.
103 // enable -- enable/disable tracking
104 // retain -- when tracking is enable, if true, then we save a stack trace
105 // for each reference and dereference; when retain == false, we
106 // match up references and dereferences and keep only the
107 // outstanding ones.
108
109 void trackMe(bool enable, bool retain);
110 };
111
112 weakref_type* createWeak(const void* id) const;
113
114 weakref_type* getWeakRefs() const;
115
116 //! DEBUGGING ONLY: Print references held on object.
printRefs()117 inline void printRefs() const { getWeakRefs()->printRefs(); }
118
119 //! DEBUGGING ONLY: Enable tracking of object.
trackMe(bool enable,bool retain)120 inline void trackMe(bool enable, bool retain)
121 {
122 getWeakRefs()->trackMe(enable, retain);
123 }
124
125 typedef RefBase basetype;
126
127 protected:
128 RefBase();
129 virtual ~RefBase();
130
131 //! Flags for extendObjectLifetime()
132 enum {
133 OBJECT_LIFETIME_STRONG = 0x0000,
134 OBJECT_LIFETIME_WEAK = 0x0001,
135 OBJECT_LIFETIME_MASK = 0x0001
136 };
137
138 void extendObjectLifetime(int32_t mode);
139
140 //! Flags for onIncStrongAttempted()
141 enum {
142 FIRST_INC_STRONG = 0x0001
143 };
144
145 virtual void onFirstRef();
146 virtual void onLastStrongRef(const void* id);
147 virtual bool onIncStrongAttempted(uint32_t flags, const void* id);
148 virtual void onLastWeakRef(const void* id);
149
150 private:
151 friend class weakref_type;
152 class weakref_impl;
153
154 RefBase(const RefBase& o);
155 RefBase& operator=(const RefBase& o);
156
157 private:
158 friend class ReferenceMover;
159
160 static void renameRefs(size_t n, const ReferenceRenamer& renamer);
161
162 static void renameRefId(weakref_type* ref,
163 const void* old_id, const void* new_id);
164
165 static void renameRefId(RefBase* ref,
166 const void* old_id, const void* new_id);
167
168 weakref_impl* const mRefs;
169 };
170
171 // ---------------------------------------------------------------------------
172
173 template <class T>
174 class LightRefBase
175 {
176 public:
LightRefBase()177 inline LightRefBase() : mCount(0) { }
incStrong(const void * id)178 inline void incStrong(__attribute__((unused)) const void* id) const {
179 android_atomic_inc(&mCount);
180 }
decStrong(const void * id)181 inline void decStrong(__attribute__((unused)) 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.
getStrongCount()187 inline int32_t getStrongCount() const {
188 return mCount;
189 }
190
191 typedef LightRefBase<T> basetype;
192
193 protected:
~LightRefBase()194 inline ~LightRefBase() { }
195
196 private:
197 friend class ReferenceMover;
renameRefs(size_t n,const ReferenceRenamer & renamer)198 inline static void renameRefs(size_t n, const ReferenceRenamer& renamer) { }
renameRefId(T * ref,const void * old_id,const void * new_id)199 inline static void renameRefId(T* ref,
200 const void* old_id, const void* new_id) { }
201
202 private:
203 mutable volatile int32_t mCount;
204 };
205
206 // This is a wrapper around LightRefBase that simply enforces a virtual
207 // destructor to eliminate the template requirement of LightRefBase
208 class VirtualLightRefBase : public LightRefBase<VirtualLightRefBase> {
209 public:
~VirtualLightRefBase()210 virtual ~VirtualLightRefBase() {}
211 };
212
213 // ---------------------------------------------------------------------------
214
215 template <typename T>
216 class wp
217 {
218 public:
219 typedef typename RefBase::weakref_type weakref_type;
220
wp()221 inline wp() : m_ptr(0) { }
222
223 wp(T* other);
224 wp(const wp<T>& other);
225 wp(const sp<T>& other);
226 template<typename U> wp(U* other);
227 template<typename U> wp(const sp<U>& other);
228 template<typename U> wp(const wp<U>& other);
229
230 ~wp();
231
232 // Assignment
233
234 wp& operator = (T* other);
235 wp& operator = (const wp<T>& other);
236 wp& operator = (const sp<T>& other);
237
238 template<typename U> wp& operator = (U* other);
239 template<typename U> wp& operator = (const wp<U>& other);
240 template<typename U> wp& operator = (const sp<U>& other);
241
242 void set_object_and_refs(T* other, weakref_type* refs);
243
244 // promotion to sp
245
246 sp<T> promote() const;
247
248 // Reset
249
250 void clear();
251
252 // Accessors
253
get_refs()254 inline weakref_type* get_refs() const { return m_refs; }
255
unsafe_get()256 inline T* unsafe_get() const { return m_ptr; }
257
258 // Operators
259
260 COMPARE_WEAK(==)
261 COMPARE_WEAK(!=)
262 COMPARE_WEAK(>)
263 COMPARE_WEAK(<)
264 COMPARE_WEAK(<=)
265 COMPARE_WEAK(>=)
266
267 inline bool operator == (const wp<T>& o) const {
268 return (m_ptr == o.m_ptr) && (m_refs == o.m_refs);
269 }
270 template<typename U>
271 inline bool operator == (const wp<U>& o) const {
272 return 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
283 inline bool operator < (const wp<T>& o) const {
284 return (m_ptr == o.m_ptr) ? (m_refs < o.m_refs) : (m_ptr < o.m_ptr);
285 }
286 template<typename U>
287 inline bool operator < (const wp<U>& o) const {
288 return (m_ptr == o.m_ptr) ? (m_refs < o.m_refs) : (m_ptr < o.m_ptr);
289 }
290 inline bool operator != (const wp<T>& o) const { return m_refs != o.m_refs; }
291 template<typename U> inline bool operator != (const wp<U>& o) const { return !operator == (o); }
292 inline bool operator <= (const wp<T>& o) const { return !operator > (o); }
293 template<typename U> inline bool operator <= (const wp<U>& o) const { return !operator > (o); }
294 inline bool operator >= (const wp<T>& o) const { return !operator < (o); }
295 template<typename U> inline bool operator >= (const wp<U>& o) const { return !operator < (o); }
296
297 private:
298 template<typename Y> friend class sp;
299 template<typename Y> friend class wp;
300
301 T* m_ptr;
302 weakref_type* m_refs;
303 };
304
305 template <typename T>
306 TextOutput& operator<<(TextOutput& to, const wp<T>& val);
307
308 #undef COMPARE_WEAK
309
310 // ---------------------------------------------------------------------------
311 // No user serviceable parts below here.
312
313 template<typename T>
wp(T * other)314 wp<T>::wp(T* other)
315 : m_ptr(other)
316 {
317 if (other) m_refs = other->createWeak(this);
318 }
319
320 template<typename T>
wp(const wp<T> & other)321 wp<T>::wp(const wp<T>& other)
322 : m_ptr(other.m_ptr), m_refs(other.m_refs)
323 {
324 if (m_ptr) m_refs->incWeak(this);
325 }
326
327 template<typename T>
wp(const sp<T> & other)328 wp<T>::wp(const sp<T>& other)
329 : m_ptr(other.m_ptr)
330 {
331 if (m_ptr) {
332 m_refs = m_ptr->createWeak(this);
333 }
334 }
335
336 template<typename T> template<typename U>
wp(U * other)337 wp<T>::wp(U* other)
338 : m_ptr(other)
339 {
340 if (other) m_refs = other->createWeak(this);
341 }
342
343 template<typename T> template<typename U>
wp(const wp<U> & other)344 wp<T>::wp(const wp<U>& other)
345 : m_ptr(other.m_ptr)
346 {
347 if (m_ptr) {
348 m_refs = other.m_refs;
349 m_refs->incWeak(this);
350 }
351 }
352
353 template<typename T> template<typename U>
wp(const sp<U> & other)354 wp<T>::wp(const sp<U>& other)
355 : m_ptr(other.m_ptr)
356 {
357 if (m_ptr) {
358 m_refs = m_ptr->createWeak(this);
359 }
360 }
361
362 template<typename T>
~wp()363 wp<T>::~wp()
364 {
365 if (m_ptr) m_refs->decWeak(this);
366 }
367
368 template<typename T>
369 wp<T>& wp<T>::operator = (T* other)
370 {
371 weakref_type* newRefs =
372 other ? other->createWeak(this) : 0;
373 if (m_ptr) m_refs->decWeak(this);
374 m_ptr = other;
375 m_refs = newRefs;
376 return *this;
377 }
378
379 template<typename T>
380 wp<T>& wp<T>::operator = (const wp<T>& other)
381 {
382 weakref_type* otherRefs(other.m_refs);
383 T* otherPtr(other.m_ptr);
384 if (otherPtr) otherRefs->incWeak(this);
385 if (m_ptr) m_refs->decWeak(this);
386 m_ptr = otherPtr;
387 m_refs = otherRefs;
388 return *this;
389 }
390
391 template<typename T>
392 wp<T>& wp<T>::operator = (const sp<T>& other)
393 {
394 weakref_type* newRefs =
395 other != NULL ? other->createWeak(this) : 0;
396 T* otherPtr(other.m_ptr);
397 if (m_ptr) m_refs->decWeak(this);
398 m_ptr = otherPtr;
399 m_refs = newRefs;
400 return *this;
401 }
402
403 template<typename T> template<typename U>
404 wp<T>& wp<T>::operator = (U* other)
405 {
406 weakref_type* newRefs =
407 other ? other->createWeak(this) : 0;
408 if (m_ptr) m_refs->decWeak(this);
409 m_ptr = other;
410 m_refs = newRefs;
411 return *this;
412 }
413
414 template<typename T> template<typename U>
415 wp<T>& wp<T>::operator = (const wp<U>& other)
416 {
417 weakref_type* otherRefs(other.m_refs);
418 U* otherPtr(other.m_ptr);
419 if (otherPtr) otherRefs->incWeak(this);
420 if (m_ptr) m_refs->decWeak(this);
421 m_ptr = otherPtr;
422 m_refs = otherRefs;
423 return *this;
424 }
425
426 template<typename T> template<typename U>
427 wp<T>& wp<T>::operator = (const sp<U>& other)
428 {
429 weakref_type* newRefs =
430 other != NULL ? other->createWeak(this) : 0;
431 U* otherPtr(other.m_ptr);
432 if (m_ptr) m_refs->decWeak(this);
433 m_ptr = otherPtr;
434 m_refs = newRefs;
435 return *this;
436 }
437
438 template<typename T>
set_object_and_refs(T * other,weakref_type * refs)439 void wp<T>::set_object_and_refs(T* other, weakref_type* refs)
440 {
441 if (other) refs->incWeak(this);
442 if (m_ptr) m_refs->decWeak(this);
443 m_ptr = other;
444 m_refs = refs;
445 }
446
447 template<typename T>
promote()448 sp<T> wp<T>::promote() const
449 {
450 sp<T> result;
451 if (m_ptr && m_refs->attemptIncStrong(&result)) {
452 result.set_pointer(m_ptr);
453 }
454 return result;
455 }
456
457 template<typename T>
clear()458 void wp<T>::clear()
459 {
460 if (m_ptr) {
461 m_refs->decWeak(this);
462 m_ptr = 0;
463 }
464 }
465
466 template <typename T>
467 inline TextOutput& operator<<(TextOutput& to, const wp<T>& val)
468 {
469 return printWeakPointer(to, val.unsafe_get());
470 }
471
472 // ---------------------------------------------------------------------------
473
474 // this class just serves as a namespace so TYPE::moveReferences can stay
475 // private.
476 class ReferenceMover {
477 public:
478 // it would be nice if we could make sure no extra code is generated
479 // for sp<TYPE> or wp<TYPE> when TYPE is a descendant of RefBase:
480 // Using a sp<RefBase> override doesn't work; it's a bit like we wanted
481 // a template<typename TYPE inherits RefBase> template...
482
483 template<typename TYPE> static inline
move_references(sp<TYPE> * d,sp<TYPE> const * s,size_t n)484 void move_references(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
485
486 class Renamer : public ReferenceRenamer {
487 sp<TYPE>* d;
488 sp<TYPE> const* s;
489 virtual void operator()(size_t i) const {
490 // The id are known to be the sp<>'s this pointer
491 TYPE::renameRefId(d[i].get(), &s[i], &d[i]);
492 }
493 public:
494 Renamer(sp<TYPE>* d, sp<TYPE> const* s) : d(d), s(s) { }
495 virtual ~Renamer() { }
496 };
497
498 memmove(d, s, n*sizeof(sp<TYPE>));
499 TYPE::renameRefs(n, Renamer(d, s));
500 }
501
502
503 template<typename TYPE> static inline
move_references(wp<TYPE> * d,wp<TYPE> const * s,size_t n)504 void move_references(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
505
506 class Renamer : public ReferenceRenamer {
507 wp<TYPE>* d;
508 wp<TYPE> const* s;
509 virtual void operator()(size_t i) const {
510 // The id are known to be the wp<>'s this pointer
511 TYPE::renameRefId(d[i].get_refs(), &s[i], &d[i]);
512 }
513 public:
514 Renamer(wp<TYPE>* d, wp<TYPE> const* s) : d(d), s(s) { }
515 virtual ~Renamer() { }
516 };
517
518 memmove(d, s, n*sizeof(wp<TYPE>));
519 TYPE::renameRefs(n, Renamer(d, s));
520 }
521 };
522
523 // specialization for moving sp<> and wp<> types.
524 // these are used by the [Sorted|Keyed]Vector<> implementations
525 // sp<> and wp<> need to be handled specially, because they do not
526 // have trivial copy operation in the general case (see RefBase.cpp
527 // when DEBUG ops are enabled), but can be implemented very
528 // efficiently in most cases.
529
530 template<typename TYPE> inline
move_forward_type(sp<TYPE> * d,sp<TYPE> const * s,size_t n)531 void move_forward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
532 ReferenceMover::move_references(d, s, n);
533 }
534
535 template<typename TYPE> inline
move_backward_type(sp<TYPE> * d,sp<TYPE> const * s,size_t n)536 void move_backward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
537 ReferenceMover::move_references(d, s, n);
538 }
539
540 template<typename TYPE> inline
move_forward_type(wp<TYPE> * d,wp<TYPE> const * s,size_t n)541 void move_forward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
542 ReferenceMover::move_references(d, s, n);
543 }
544
545 template<typename TYPE> inline
move_backward_type(wp<TYPE> * d,wp<TYPE> const * s,size_t n)546 void move_backward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
547 ReferenceMover::move_references(d, s, n);
548 }
549
550
551 }; // namespace android
552
553 // ---------------------------------------------------------------------------
554
555 #endif // ANDROID_REF_BASE_H
556