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 // ---------------------------------------------------------------------------
207
208 template <typename T>
209 class wp
210 {
211 public:
212 typedef typename RefBase::weakref_type weakref_type;
213
wp()214 inline wp() : m_ptr(0) { }
215
216 wp(T* other);
217 wp(const wp<T>& other);
218 wp(const sp<T>& other);
219 template<typename U> wp(U* other);
220 template<typename U> wp(const sp<U>& other);
221 template<typename U> wp(const wp<U>& other);
222
223 ~wp();
224
225 // Assignment
226
227 wp& operator = (T* other);
228 wp& operator = (const wp<T>& other);
229 wp& operator = (const sp<T>& other);
230
231 template<typename U> wp& operator = (U* other);
232 template<typename U> wp& operator = (const wp<U>& other);
233 template<typename U> wp& operator = (const sp<U>& other);
234
235 void set_object_and_refs(T* other, weakref_type* refs);
236
237 // promotion to sp
238
239 sp<T> promote() const;
240
241 // Reset
242
243 void clear();
244
245 // Accessors
246
get_refs()247 inline weakref_type* get_refs() const { return m_refs; }
248
unsafe_get()249 inline T* unsafe_get() const { return m_ptr; }
250
251 // Operators
252
253 COMPARE_WEAK(==)
254 COMPARE_WEAK(!=)
255 COMPARE_WEAK(>)
256 COMPARE_WEAK(<)
257 COMPARE_WEAK(<=)
258 COMPARE_WEAK(>=)
259
260 inline bool operator == (const wp<T>& o) const {
261 return (m_ptr == o.m_ptr) && (m_refs == o.m_refs);
262 }
263 template<typename U>
264 inline bool operator == (const wp<U>& o) const {
265 return m_ptr == o.m_ptr;
266 }
267
268 inline bool operator > (const wp<T>& o) const {
269 return (m_ptr == o.m_ptr) ? (m_refs > o.m_refs) : (m_ptr > o.m_ptr);
270 }
271 template<typename U>
272 inline bool operator > (const wp<U>& o) const {
273 return (m_ptr == o.m_ptr) ? (m_refs > o.m_refs) : (m_ptr > o.m_ptr);
274 }
275
276 inline bool operator < (const wp<T>& o) const {
277 return (m_ptr == o.m_ptr) ? (m_refs < o.m_refs) : (m_ptr < o.m_ptr);
278 }
279 template<typename U>
280 inline bool operator < (const wp<U>& o) const {
281 return (m_ptr == o.m_ptr) ? (m_refs < o.m_refs) : (m_ptr < o.m_ptr);
282 }
283 inline bool operator != (const wp<T>& o) const { return m_refs != o.m_refs; }
284 template<typename U> inline bool operator != (const wp<U>& o) const { return !operator == (o); }
285 inline bool operator <= (const wp<T>& o) const { return !operator > (o); }
286 template<typename U> inline bool operator <= (const wp<U>& o) const { return !operator > (o); }
287 inline bool operator >= (const wp<T>& o) const { return !operator < (o); }
288 template<typename U> inline bool operator >= (const wp<U>& o) const { return !operator < (o); }
289
290 private:
291 template<typename Y> friend class sp;
292 template<typename Y> friend class wp;
293
294 T* m_ptr;
295 weakref_type* m_refs;
296 };
297
298 template <typename T>
299 TextOutput& operator<<(TextOutput& to, const wp<T>& val);
300
301 #undef COMPARE_WEAK
302
303 // ---------------------------------------------------------------------------
304 // No user serviceable parts below here.
305
306 template<typename T>
wp(T * other)307 wp<T>::wp(T* other)
308 : m_ptr(other)
309 {
310 if (other) m_refs = other->createWeak(this);
311 }
312
313 template<typename T>
wp(const wp<T> & other)314 wp<T>::wp(const wp<T>& other)
315 : m_ptr(other.m_ptr), m_refs(other.m_refs)
316 {
317 if (m_ptr) m_refs->incWeak(this);
318 }
319
320 template<typename T>
wp(const sp<T> & other)321 wp<T>::wp(const sp<T>& other)
322 : m_ptr(other.m_ptr)
323 {
324 if (m_ptr) {
325 m_refs = m_ptr->createWeak(this);
326 }
327 }
328
329 template<typename T> template<typename U>
wp(U * other)330 wp<T>::wp(U* other)
331 : m_ptr(other)
332 {
333 if (other) m_refs = other->createWeak(this);
334 }
335
336 template<typename T> template<typename U>
wp(const wp<U> & other)337 wp<T>::wp(const wp<U>& other)
338 : m_ptr(other.m_ptr)
339 {
340 if (m_ptr) {
341 m_refs = other.m_refs;
342 m_refs->incWeak(this);
343 }
344 }
345
346 template<typename T> template<typename U>
wp(const sp<U> & other)347 wp<T>::wp(const sp<U>& other)
348 : m_ptr(other.m_ptr)
349 {
350 if (m_ptr) {
351 m_refs = m_ptr->createWeak(this);
352 }
353 }
354
355 template<typename T>
~wp()356 wp<T>::~wp()
357 {
358 if (m_ptr) m_refs->decWeak(this);
359 }
360
361 template<typename T>
362 wp<T>& wp<T>::operator = (T* other)
363 {
364 weakref_type* newRefs =
365 other ? other->createWeak(this) : 0;
366 if (m_ptr) m_refs->decWeak(this);
367 m_ptr = other;
368 m_refs = newRefs;
369 return *this;
370 }
371
372 template<typename T>
373 wp<T>& wp<T>::operator = (const wp<T>& other)
374 {
375 weakref_type* otherRefs(other.m_refs);
376 T* otherPtr(other.m_ptr);
377 if (otherPtr) otherRefs->incWeak(this);
378 if (m_ptr) m_refs->decWeak(this);
379 m_ptr = otherPtr;
380 m_refs = otherRefs;
381 return *this;
382 }
383
384 template<typename T>
385 wp<T>& wp<T>::operator = (const sp<T>& other)
386 {
387 weakref_type* newRefs =
388 other != NULL ? other->createWeak(this) : 0;
389 T* otherPtr(other.m_ptr);
390 if (m_ptr) m_refs->decWeak(this);
391 m_ptr = otherPtr;
392 m_refs = newRefs;
393 return *this;
394 }
395
396 template<typename T> template<typename U>
397 wp<T>& wp<T>::operator = (U* other)
398 {
399 weakref_type* newRefs =
400 other ? other->createWeak(this) : 0;
401 if (m_ptr) m_refs->decWeak(this);
402 m_ptr = other;
403 m_refs = newRefs;
404 return *this;
405 }
406
407 template<typename T> template<typename U>
408 wp<T>& wp<T>::operator = (const wp<U>& other)
409 {
410 weakref_type* otherRefs(other.m_refs);
411 U* otherPtr(other.m_ptr);
412 if (otherPtr) otherRefs->incWeak(this);
413 if (m_ptr) m_refs->decWeak(this);
414 m_ptr = otherPtr;
415 m_refs = otherRefs;
416 return *this;
417 }
418
419 template<typename T> template<typename U>
420 wp<T>& wp<T>::operator = (const sp<U>& other)
421 {
422 weakref_type* newRefs =
423 other != NULL ? other->createWeak(this) : 0;
424 U* otherPtr(other.m_ptr);
425 if (m_ptr) m_refs->decWeak(this);
426 m_ptr = otherPtr;
427 m_refs = newRefs;
428 return *this;
429 }
430
431 template<typename T>
set_object_and_refs(T * other,weakref_type * refs)432 void wp<T>::set_object_and_refs(T* other, weakref_type* refs)
433 {
434 if (other) refs->incWeak(this);
435 if (m_ptr) m_refs->decWeak(this);
436 m_ptr = other;
437 m_refs = refs;
438 }
439
440 template<typename T>
promote()441 sp<T> wp<T>::promote() const
442 {
443 sp<T> result;
444 if (m_ptr && m_refs->attemptIncStrong(&result)) {
445 result.set_pointer(m_ptr);
446 }
447 return result;
448 }
449
450 template<typename T>
clear()451 void wp<T>::clear()
452 {
453 if (m_ptr) {
454 m_refs->decWeak(this);
455 m_ptr = 0;
456 }
457 }
458
459 template <typename T>
460 inline TextOutput& operator<<(TextOutput& to, const wp<T>& val)
461 {
462 return printWeakPointer(to, val.unsafe_get());
463 }
464
465 // ---------------------------------------------------------------------------
466
467 // this class just serves as a namespace so TYPE::moveReferences can stay
468 // private.
469 class ReferenceMover {
470 public:
471 // it would be nice if we could make sure no extra code is generated
472 // for sp<TYPE> or wp<TYPE> when TYPE is a descendant of RefBase:
473 // Using a sp<RefBase> override doesn't work; it's a bit like we wanted
474 // a template<typename TYPE inherits RefBase> template...
475
476 template<typename TYPE> static inline
move_references(sp<TYPE> * d,sp<TYPE> const * s,size_t n)477 void move_references(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
478
479 class Renamer : public ReferenceRenamer {
480 sp<TYPE>* d;
481 sp<TYPE> const* s;
482 virtual void operator()(size_t i) const {
483 // The id are known to be the sp<>'s this pointer
484 TYPE::renameRefId(d[i].get(), &s[i], &d[i]);
485 }
486 public:
487 Renamer(sp<TYPE>* d, sp<TYPE> const* s) : s(s), d(d) { }
488 };
489
490 memmove(d, s, n*sizeof(sp<TYPE>));
491 TYPE::renameRefs(n, Renamer(d, s));
492 }
493
494
495 template<typename TYPE> static inline
move_references(wp<TYPE> * d,wp<TYPE> const * s,size_t n)496 void move_references(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
497
498 class Renamer : public ReferenceRenamer {
499 wp<TYPE>* d;
500 wp<TYPE> const* s;
501 virtual void operator()(size_t i) const {
502 // The id are known to be the wp<>'s this pointer
503 TYPE::renameRefId(d[i].get_refs(), &s[i], &d[i]);
504 }
505 public:
506 Renamer(wp<TYPE>* d, wp<TYPE> const* s) : s(s), d(d) { }
507 };
508
509 memmove(d, s, n*sizeof(wp<TYPE>));
510 TYPE::renameRefs(n, Renamer(d, s));
511 }
512 };
513
514 // specialization for moving sp<> and wp<> types.
515 // these are used by the [Sorted|Keyed]Vector<> implementations
516 // sp<> and wp<> need to be handled specially, because they do not
517 // have trivial copy operation in the general case (see RefBase.cpp
518 // when DEBUG ops are enabled), but can be implemented very
519 // efficiently in most cases.
520
521 template<typename TYPE> inline
move_forward_type(sp<TYPE> * d,sp<TYPE> const * s,size_t n)522 void move_forward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
523 ReferenceMover::move_references(d, s, n);
524 }
525
526 template<typename TYPE> inline
move_backward_type(sp<TYPE> * d,sp<TYPE> const * s,size_t n)527 void move_backward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
528 ReferenceMover::move_references(d, s, n);
529 }
530
531 template<typename TYPE> inline
move_forward_type(wp<TYPE> * d,wp<TYPE> const * s,size_t n)532 void move_forward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
533 ReferenceMover::move_references(d, s, n);
534 }
535
536 template<typename TYPE> inline
move_backward_type(wp<TYPE> * d,wp<TYPE> const * s,size_t n)537 void move_backward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
538 ReferenceMover::move_references(d, s, n);
539 }
540
541
542 }; // namespace android
543
544 // ---------------------------------------------------------------------------
545
546 #endif // ANDROID_REF_BASE_H
547