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 #define LOG_TAG "RefBase"
18 // #define LOG_NDEBUG 0
19
20 #include <fcntl.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <sys/stat.h>
24 #include <sys/types.h>
25 #include <typeinfo>
26 #include <unistd.h>
27
28 #include <utils/RefBase.h>
29
30 #include <utils/CallStack.h>
31 #include <utils/Log.h>
32 #include <utils/threads.h>
33
34 #ifndef __unused
35 #define __unused __attribute__((__unused__))
36 #endif
37
38 // compile with refcounting debugging enabled
39 #define DEBUG_REFS 0
40
41 // whether ref-tracking is enabled by default, if not, trackMe(true, false)
42 // needs to be called explicitly
43 #define DEBUG_REFS_ENABLED_BY_DEFAULT 0
44
45 // whether callstack are collected (significantly slows things down)
46 #define DEBUG_REFS_CALLSTACK_ENABLED 1
47
48 // folder where stack traces are saved when DEBUG_REFS is enabled
49 // this folder needs to exist and be writable
50 #define DEBUG_REFS_CALLSTACK_PATH "/data/debug"
51
52 // log all reference counting operations
53 #define PRINT_REFS 0
54
55 // ---------------------------------------------------------------------------
56
57 namespace android {
58
59 // Usage, invariants, etc:
60
61 // It is normally OK just to keep weak pointers to an object. The object will
62 // be deallocated by decWeak when the last weak reference disappears.
63 // Once a a strong reference has been created, the object will disappear once
64 // the last strong reference does (decStrong).
65 // AttemptIncStrong will succeed if the object has a strong reference, or if it
66 // has a weak reference and has never had a strong reference.
67 // AttemptIncWeak really does succeed only if there is already a WEAK
68 // reference, and thus may fail when attemptIncStrong would succeed.
69 // OBJECT_LIFETIME_WEAK changes this behavior to retain the object
70 // unconditionally until the last reference of either kind disappears. The
71 // client ensures that the extendObjectLifetime call happens before the dec
72 // call that would otherwise have deallocated the object, or before an
73 // attemptIncStrong call that might rely on it. We do not worry about
74 // concurrent changes to the object lifetime.
75 // mStrong is the strong reference count. mWeak is the weak reference count.
76 // Between calls, and ignoring memory ordering effects, mWeak includes strong
77 // references, and is thus >= mStrong.
78 //
79 // A weakref_impl is allocated as the value of mRefs in a RefBase object on
80 // construction.
81 // In the OBJECT_LIFETIME_STRONG case, it is deallocated in the RefBase
82 // destructor iff the strong reference count was never incremented. The
83 // destructor can be invoked either from decStrong, or from decWeak if there
84 // was never a strong reference. If the reference count had been incremented,
85 // it is deallocated directly in decWeak, and hence still lives as long as
86 // the last weak reference.
87 // In the OBJECT_LIFETIME_WEAK case, it is always deallocated from the RefBase
88 // destructor, which is always invoked by decWeak. DecStrong explicitly avoids
89 // the deletion in this case.
90 //
91 // Memory ordering:
92 // The client must ensure that every inc() call, together with all other
93 // accesses to the object, happens before the corresponding dec() call.
94 //
95 // We try to keep memory ordering constraints on atomics as weak as possible,
96 // since memory fences or ordered memory accesses are likely to be a major
97 // performance cost for this code. All accesses to mStrong, mWeak, and mFlags
98 // explicitly relax memory ordering in some way.
99 //
100 // The only operations that are not memory_order_relaxed are reference count
101 // decrements. All reference count decrements are release operations. In
102 // addition, the final decrement leading the deallocation is followed by an
103 // acquire fence, which we can view informally as also turning it into an
104 // acquire operation. (See 29.8p4 [atomics.fences] for details. We could
105 // alternatively use acq_rel operations for all decrements. This is probably
106 // slower on most current (2016) hardware, especially on ARMv7, but that may
107 // not be true indefinitely.)
108 //
109 // This convention ensures that the second-to-last decrement synchronizes with
110 // (in the language of 1.10 in the C++ standard) the final decrement of a
111 // reference count. Since reference counts are only updated using atomic
112 // read-modify-write operations, this also extends to any earlier decrements.
113 // (See "release sequence" in 1.10.)
114 //
115 // Since all operations on an object happen before the corresponding reference
116 // count decrement, and all reference count decrements happen before the final
117 // one, we are guaranteed that all other object accesses happen before the
118 // object is destroyed.
119
120
121 #define INITIAL_STRONG_VALUE (1<<28)
122
123 // ---------------------------------------------------------------------------
124
125 class RefBase::weakref_impl : public RefBase::weakref_type
126 {
127 public:
128 std::atomic<int32_t> mStrong;
129 std::atomic<int32_t> mWeak;
130 RefBase* const mBase;
131 std::atomic<int32_t> mFlags;
132
133 #if !DEBUG_REFS
134
weakref_impl(RefBase * base)135 weakref_impl(RefBase* base)
136 : mStrong(INITIAL_STRONG_VALUE)
137 , mWeak(0)
138 , mBase(base)
139 , mFlags(0)
140 {
141 }
142
addStrongRef(const void *)143 void addStrongRef(const void* /*id*/) { }
removeStrongRef(const void *)144 void removeStrongRef(const void* /*id*/) { }
renameStrongRefId(const void *,const void *)145 void renameStrongRefId(const void* /*old_id*/, const void* /*new_id*/) { }
addWeakRef(const void *)146 void addWeakRef(const void* /*id*/) { }
removeWeakRef(const void *)147 void removeWeakRef(const void* /*id*/) { }
renameWeakRefId(const void *,const void *)148 void renameWeakRefId(const void* /*old_id*/, const void* /*new_id*/) { }
printRefs() const149 void printRefs() const { }
trackMe(bool,bool)150 void trackMe(bool, bool) { }
151
152 #else
153
weakref_impl(RefBase * base)154 weakref_impl(RefBase* base)
155 : mStrong(INITIAL_STRONG_VALUE)
156 , mWeak(0)
157 , mBase(base)
158 , mFlags(0)
159 , mStrongRefs(NULL)
160 , mWeakRefs(NULL)
161 , mTrackEnabled(!!DEBUG_REFS_ENABLED_BY_DEFAULT)
162 , mRetain(false)
163 {
164 }
165
~weakref_impl()166 ~weakref_impl()
167 {
168 bool dumpStack = false;
169 if (!mRetain && mStrongRefs != NULL) {
170 dumpStack = true;
171 ALOGE("Strong references remain:");
172 ref_entry* refs = mStrongRefs;
173 while (refs) {
174 char inc = refs->ref >= 0 ? '+' : '-';
175 ALOGD("\t%c ID %p (ref %d):", inc, refs->id, refs->ref);
176 #if DEBUG_REFS_CALLSTACK_ENABLED
177 refs->stack.log(LOG_TAG);
178 #endif
179 refs = refs->next;
180 }
181 }
182
183 if (!mRetain && mWeakRefs != NULL) {
184 dumpStack = true;
185 ALOGE("Weak references remain!");
186 ref_entry* refs = mWeakRefs;
187 while (refs) {
188 char inc = refs->ref >= 0 ? '+' : '-';
189 ALOGD("\t%c ID %p (ref %d):", inc, refs->id, refs->ref);
190 #if DEBUG_REFS_CALLSTACK_ENABLED
191 refs->stack.log(LOG_TAG);
192 #endif
193 refs = refs->next;
194 }
195 }
196 if (dumpStack) {
197 ALOGE("above errors at:");
198 CallStack stack(LOG_TAG);
199 }
200 }
201
addStrongRef(const void * id)202 void addStrongRef(const void* id) {
203 //ALOGD_IF(mTrackEnabled,
204 // "addStrongRef: RefBase=%p, id=%p", mBase, id);
205 addRef(&mStrongRefs, id, mStrong.load(std::memory_order_relaxed));
206 }
207
removeStrongRef(const void * id)208 void removeStrongRef(const void* id) {
209 //ALOGD_IF(mTrackEnabled,
210 // "removeStrongRef: RefBase=%p, id=%p", mBase, id);
211 if (!mRetain) {
212 removeRef(&mStrongRefs, id);
213 } else {
214 addRef(&mStrongRefs, id, -mStrong.load(std::memory_order_relaxed));
215 }
216 }
217
renameStrongRefId(const void * old_id,const void * new_id)218 void renameStrongRefId(const void* old_id, const void* new_id) {
219 //ALOGD_IF(mTrackEnabled,
220 // "renameStrongRefId: RefBase=%p, oid=%p, nid=%p",
221 // mBase, old_id, new_id);
222 renameRefsId(mStrongRefs, old_id, new_id);
223 }
224
addWeakRef(const void * id)225 void addWeakRef(const void* id) {
226 addRef(&mWeakRefs, id, mWeak.load(std::memory_order_relaxed));
227 }
228
removeWeakRef(const void * id)229 void removeWeakRef(const void* id) {
230 if (!mRetain) {
231 removeRef(&mWeakRefs, id);
232 } else {
233 addRef(&mWeakRefs, id, -mWeak.load(std::memory_order_relaxed));
234 }
235 }
236
renameWeakRefId(const void * old_id,const void * new_id)237 void renameWeakRefId(const void* old_id, const void* new_id) {
238 renameRefsId(mWeakRefs, old_id, new_id);
239 }
240
trackMe(bool track,bool retain)241 void trackMe(bool track, bool retain)
242 {
243 mTrackEnabled = track;
244 mRetain = retain;
245 }
246
printRefs() const247 void printRefs() const
248 {
249 String8 text;
250
251 {
252 Mutex::Autolock _l(mMutex);
253 char buf[128];
254 sprintf(buf, "Strong references on RefBase %p (weakref_type %p):\n", mBase, this);
255 text.append(buf);
256 printRefsLocked(&text, mStrongRefs);
257 sprintf(buf, "Weak references on RefBase %p (weakref_type %p):\n", mBase, this);
258 text.append(buf);
259 printRefsLocked(&text, mWeakRefs);
260 }
261
262 {
263 char name[100];
264 snprintf(name, 100, DEBUG_REFS_CALLSTACK_PATH "/%p.stack", this);
265 int rc = open(name, O_RDWR | O_CREAT | O_APPEND, 644);
266 if (rc >= 0) {
267 write(rc, text.string(), text.length());
268 close(rc);
269 ALOGD("STACK TRACE for %p saved in %s", this, name);
270 }
271 else ALOGE("FAILED TO PRINT STACK TRACE for %p in %s: %s", this,
272 name, strerror(errno));
273 }
274 }
275
276 private:
277 struct ref_entry
278 {
279 ref_entry* next;
280 const void* id;
281 #if DEBUG_REFS_CALLSTACK_ENABLED
282 CallStack stack;
283 #endif
284 int32_t ref;
285 };
286
addRef(ref_entry ** refs,const void * id,int32_t mRef)287 void addRef(ref_entry** refs, const void* id, int32_t mRef)
288 {
289 if (mTrackEnabled) {
290 AutoMutex _l(mMutex);
291
292 ref_entry* ref = new ref_entry;
293 // Reference count at the time of the snapshot, but before the
294 // update. Positive value means we increment, negative--we
295 // decrement the reference count.
296 ref->ref = mRef;
297 ref->id = id;
298 #if DEBUG_REFS_CALLSTACK_ENABLED
299 ref->stack.update(2);
300 #endif
301 ref->next = *refs;
302 *refs = ref;
303 }
304 }
305
removeRef(ref_entry ** refs,const void * id)306 void removeRef(ref_entry** refs, const void* id)
307 {
308 if (mTrackEnabled) {
309 AutoMutex _l(mMutex);
310
311 ref_entry* const head = *refs;
312 ref_entry* ref = head;
313 while (ref != NULL) {
314 if (ref->id == id) {
315 *refs = ref->next;
316 delete ref;
317 return;
318 }
319 refs = &ref->next;
320 ref = *refs;
321 }
322
323 ALOGE("RefBase: removing id %p on RefBase %p"
324 "(weakref_type %p) that doesn't exist!",
325 id, mBase, this);
326
327 ref = head;
328 while (ref) {
329 char inc = ref->ref >= 0 ? '+' : '-';
330 ALOGD("\t%c ID %p (ref %d):", inc, ref->id, ref->ref);
331 ref = ref->next;
332 }
333
334 CallStack stack(LOG_TAG);
335 }
336 }
337
renameRefsId(ref_entry * r,const void * old_id,const void * new_id)338 void renameRefsId(ref_entry* r, const void* old_id, const void* new_id)
339 {
340 if (mTrackEnabled) {
341 AutoMutex _l(mMutex);
342 ref_entry* ref = r;
343 while (ref != NULL) {
344 if (ref->id == old_id) {
345 ref->id = new_id;
346 }
347 ref = ref->next;
348 }
349 }
350 }
351
printRefsLocked(String8 * out,const ref_entry * refs) const352 void printRefsLocked(String8* out, const ref_entry* refs) const
353 {
354 char buf[128];
355 while (refs) {
356 char inc = refs->ref >= 0 ? '+' : '-';
357 sprintf(buf, "\t%c ID %p (ref %d):\n",
358 inc, refs->id, refs->ref);
359 out->append(buf);
360 #if DEBUG_REFS_CALLSTACK_ENABLED
361 out->append(refs->stack.toString("\t\t"));
362 #else
363 out->append("\t\t(call stacks disabled)");
364 #endif
365 refs = refs->next;
366 }
367 }
368
369 mutable Mutex mMutex;
370 ref_entry* mStrongRefs;
371 ref_entry* mWeakRefs;
372
373 bool mTrackEnabled;
374 // Collect stack traces on addref and removeref, instead of deleting the stack references
375 // on removeref that match the address ones.
376 bool mRetain;
377
378 #endif
379 };
380
381 // ---------------------------------------------------------------------------
382
incStrong(const void * id) const383 void RefBase::incStrong(const void* id) const
384 {
385 weakref_impl* const refs = mRefs;
386 refs->incWeak(id);
387
388 refs->addStrongRef(id);
389 const int32_t c = refs->mStrong.fetch_add(1, std::memory_order_relaxed);
390 ALOG_ASSERT(c > 0, "incStrong() called on %p after last strong ref", refs);
391 #if PRINT_REFS
392 ALOGD("incStrong of %p from %p: cnt=%d\n", this, id, c);
393 #endif
394 if (c != INITIAL_STRONG_VALUE) {
395 return;
396 }
397
398 int32_t old = refs->mStrong.fetch_sub(INITIAL_STRONG_VALUE,
399 std::memory_order_relaxed);
400 // A decStrong() must still happen after us.
401 ALOG_ASSERT(old > INITIAL_STRONG_VALUE, "0x%x too small", old);
402 refs->mBase->onFirstRef();
403 }
404
decStrong(const void * id) const405 void RefBase::decStrong(const void* id) const
406 {
407 weakref_impl* const refs = mRefs;
408 refs->removeStrongRef(id);
409 const int32_t c = refs->mStrong.fetch_sub(1, std::memory_order_release);
410 #if PRINT_REFS
411 ALOGD("decStrong of %p from %p: cnt=%d\n", this, id, c);
412 #endif
413 ALOG_ASSERT(c >= 1, "decStrong() called on %p too many times", refs);
414 if (c == 1) {
415 std::atomic_thread_fence(std::memory_order_acquire);
416 refs->mBase->onLastStrongRef(id);
417 int32_t flags = refs->mFlags.load(std::memory_order_relaxed);
418 if ((flags&OBJECT_LIFETIME_MASK) == OBJECT_LIFETIME_STRONG) {
419 delete this;
420 // Since mStrong had been incremented, the destructor did not
421 // delete refs.
422 }
423 }
424 // Note that even with only strong reference operations, the thread
425 // deallocating this may not be the same as the thread deallocating refs.
426 // That's OK: all accesses to this happen before its deletion here,
427 // and all accesses to refs happen before its deletion in the final decWeak.
428 // The destructor can safely access mRefs because either it's deleting
429 // mRefs itself, or it's running entirely before the final mWeak decrement.
430 refs->decWeak(id);
431 }
432
forceIncStrong(const void * id) const433 void RefBase::forceIncStrong(const void* id) const
434 {
435 // Allows initial mStrong of 0 in addition to INITIAL_STRONG_VALUE.
436 // TODO: Better document assumptions.
437 weakref_impl* const refs = mRefs;
438 refs->incWeak(id);
439
440 refs->addStrongRef(id);
441 const int32_t c = refs->mStrong.fetch_add(1, std::memory_order_relaxed);
442 ALOG_ASSERT(c >= 0, "forceIncStrong called on %p after ref count underflow",
443 refs);
444 #if PRINT_REFS
445 ALOGD("forceIncStrong of %p from %p: cnt=%d\n", this, id, c);
446 #endif
447
448 switch (c) {
449 case INITIAL_STRONG_VALUE:
450 refs->mStrong.fetch_sub(INITIAL_STRONG_VALUE,
451 std::memory_order_relaxed);
452 // fall through...
453 case 0:
454 refs->mBase->onFirstRef();
455 }
456 }
457
getStrongCount() const458 int32_t RefBase::getStrongCount() const
459 {
460 // Debugging only; No memory ordering guarantees.
461 return mRefs->mStrong.load(std::memory_order_relaxed);
462 }
463
refBase() const464 RefBase* RefBase::weakref_type::refBase() const
465 {
466 return static_cast<const weakref_impl*>(this)->mBase;
467 }
468
incWeak(const void * id)469 void RefBase::weakref_type::incWeak(const void* id)
470 {
471 weakref_impl* const impl = static_cast<weakref_impl*>(this);
472 impl->addWeakRef(id);
473 const int32_t c __unused = impl->mWeak.fetch_add(1,
474 std::memory_order_relaxed);
475 ALOG_ASSERT(c >= 0, "incWeak called on %p after last weak ref", this);
476 }
477
478
decWeak(const void * id)479 void RefBase::weakref_type::decWeak(const void* id)
480 {
481 weakref_impl* const impl = static_cast<weakref_impl*>(this);
482 impl->removeWeakRef(id);
483 const int32_t c = impl->mWeak.fetch_sub(1, std::memory_order_release);
484 ALOG_ASSERT(c >= 1, "decWeak called on %p too many times", this);
485 if (c != 1) return;
486 atomic_thread_fence(std::memory_order_acquire);
487
488 int32_t flags = impl->mFlags.load(std::memory_order_relaxed);
489 if ((flags&OBJECT_LIFETIME_MASK) == OBJECT_LIFETIME_STRONG) {
490 // This is the regular lifetime case. The object is destroyed
491 // when the last strong reference goes away. Since weakref_impl
492 // outlive the object, it is not destroyed in the dtor, and
493 // we'll have to do it here.
494 if (impl->mStrong.load(std::memory_order_relaxed)
495 == INITIAL_STRONG_VALUE) {
496 // Special case: we never had a strong reference, so we need to
497 // destroy the object now.
498 delete impl->mBase;
499 } else {
500 // ALOGV("Freeing refs %p of old RefBase %p\n", this, impl->mBase);
501 delete impl;
502 }
503 } else {
504 // This is the OBJECT_LIFETIME_WEAK case. The last weak-reference
505 // is gone, we can destroy the object.
506 impl->mBase->onLastWeakRef(id);
507 delete impl->mBase;
508 }
509 }
510
attemptIncStrong(const void * id)511 bool RefBase::weakref_type::attemptIncStrong(const void* id)
512 {
513 incWeak(id);
514
515 weakref_impl* const impl = static_cast<weakref_impl*>(this);
516 int32_t curCount = impl->mStrong.load(std::memory_order_relaxed);
517
518 ALOG_ASSERT(curCount >= 0,
519 "attemptIncStrong called on %p after underflow", this);
520
521 while (curCount > 0 && curCount != INITIAL_STRONG_VALUE) {
522 // we're in the easy/common case of promoting a weak-reference
523 // from an existing strong reference.
524 if (impl->mStrong.compare_exchange_weak(curCount, curCount+1,
525 std::memory_order_relaxed)) {
526 break;
527 }
528 // the strong count has changed on us, we need to re-assert our
529 // situation. curCount was updated by compare_exchange_weak.
530 }
531
532 if (curCount <= 0 || curCount == INITIAL_STRONG_VALUE) {
533 // we're now in the harder case of either:
534 // - there never was a strong reference on us
535 // - or, all strong references have been released
536 int32_t flags = impl->mFlags.load(std::memory_order_relaxed);
537 if ((flags&OBJECT_LIFETIME_MASK) == OBJECT_LIFETIME_STRONG) {
538 // this object has a "normal" life-time, i.e.: it gets destroyed
539 // when the last strong reference goes away
540 if (curCount <= 0) {
541 // the last strong-reference got released, the object cannot
542 // be revived.
543 decWeak(id);
544 return false;
545 }
546
547 // here, curCount == INITIAL_STRONG_VALUE, which means
548 // there never was a strong-reference, so we can try to
549 // promote this object; we need to do that atomically.
550 while (curCount > 0) {
551 if (impl->mStrong.compare_exchange_weak(curCount, curCount+1,
552 std::memory_order_relaxed)) {
553 break;
554 }
555 // the strong count has changed on us, we need to re-assert our
556 // situation (e.g.: another thread has inc/decStrong'ed us)
557 // curCount has been updated.
558 }
559
560 if (curCount <= 0) {
561 // promote() failed, some other thread destroyed us in the
562 // meantime (i.e.: strong count reached zero).
563 decWeak(id);
564 return false;
565 }
566 } else {
567 // this object has an "extended" life-time, i.e.: it can be
568 // revived from a weak-reference only.
569 // Ask the object's implementation if it agrees to be revived
570 if (!impl->mBase->onIncStrongAttempted(FIRST_INC_STRONG, id)) {
571 // it didn't so give-up.
572 decWeak(id);
573 return false;
574 }
575 // grab a strong-reference, which is always safe due to the
576 // extended life-time.
577 curCount = impl->mStrong.fetch_add(1, std::memory_order_relaxed);
578 // If the strong reference count has already been incremented by
579 // someone else, the implementor of onIncStrongAttempted() is holding
580 // an unneeded reference. So call onLastStrongRef() here to remove it.
581 // (No, this is not pretty.) Note that we MUST NOT do this if we
582 // are in fact acquiring the first reference.
583 if (curCount != 0 && curCount != INITIAL_STRONG_VALUE) {
584 impl->mBase->onLastStrongRef(id);
585 }
586 }
587 }
588
589 impl->addStrongRef(id);
590
591 #if PRINT_REFS
592 ALOGD("attemptIncStrong of %p from %p: cnt=%d\n", this, id, curCount);
593 #endif
594
595 // curCount is the value of mStrong before we incremented it.
596 // Now we need to fix-up the count if it was INITIAL_STRONG_VALUE.
597 // This must be done safely, i.e.: handle the case where several threads
598 // were here in attemptIncStrong().
599 // curCount > INITIAL_STRONG_VALUE is OK, and can happen if we're doing
600 // this in the middle of another incStrong. The subtraction is handled
601 // by the thread that started with INITIAL_STRONG_VALUE.
602 if (curCount == INITIAL_STRONG_VALUE) {
603 impl->mStrong.fetch_sub(INITIAL_STRONG_VALUE,
604 std::memory_order_relaxed);
605 }
606
607 return true;
608 }
609
attemptIncWeak(const void * id)610 bool RefBase::weakref_type::attemptIncWeak(const void* id)
611 {
612 weakref_impl* const impl = static_cast<weakref_impl*>(this);
613
614 int32_t curCount = impl->mWeak.load(std::memory_order_relaxed);
615 ALOG_ASSERT(curCount >= 0, "attemptIncWeak called on %p after underflow",
616 this);
617 while (curCount > 0) {
618 if (impl->mWeak.compare_exchange_weak(curCount, curCount+1,
619 std::memory_order_relaxed)) {
620 break;
621 }
622 // curCount has been updated.
623 }
624
625 if (curCount > 0) {
626 impl->addWeakRef(id);
627 }
628
629 return curCount > 0;
630 }
631
getWeakCount() const632 int32_t RefBase::weakref_type::getWeakCount() const
633 {
634 // Debug only!
635 return static_cast<const weakref_impl*>(this)->mWeak
636 .load(std::memory_order_relaxed);
637 }
638
printRefs() const639 void RefBase::weakref_type::printRefs() const
640 {
641 static_cast<const weakref_impl*>(this)->printRefs();
642 }
643
trackMe(bool enable,bool retain)644 void RefBase::weakref_type::trackMe(bool enable, bool retain)
645 {
646 static_cast<weakref_impl*>(this)->trackMe(enable, retain);
647 }
648
createWeak(const void * id) const649 RefBase::weakref_type* RefBase::createWeak(const void* id) const
650 {
651 mRefs->incWeak(id);
652 return mRefs;
653 }
654
getWeakRefs() const655 RefBase::weakref_type* RefBase::getWeakRefs() const
656 {
657 return mRefs;
658 }
659
RefBase()660 RefBase::RefBase()
661 : mRefs(new weakref_impl(this))
662 {
663 }
664
~RefBase()665 RefBase::~RefBase()
666 {
667 if (mRefs->mStrong.load(std::memory_order_relaxed)
668 == INITIAL_STRONG_VALUE) {
669 // we never acquired a strong (and/or weak) reference on this object.
670 delete mRefs;
671 } else {
672 // life-time of this object is extended to WEAK, in
673 // which case weakref_impl doesn't out-live the object and we
674 // can free it now.
675 int32_t flags = mRefs->mFlags.load(std::memory_order_relaxed);
676 if ((flags & OBJECT_LIFETIME_MASK) != OBJECT_LIFETIME_STRONG) {
677 // It's possible that the weak count is not 0 if the object
678 // re-acquired a weak reference in its destructor
679 if (mRefs->mWeak.load(std::memory_order_relaxed) == 0) {
680 delete mRefs;
681 }
682 }
683 }
684 // for debugging purposes, clear this.
685 const_cast<weakref_impl*&>(mRefs) = NULL;
686 }
687
extendObjectLifetime(int32_t mode)688 void RefBase::extendObjectLifetime(int32_t mode)
689 {
690 // Must be happens-before ordered with respect to construction or any
691 // operation that could destroy the object.
692 mRefs->mFlags.fetch_or(mode, std::memory_order_relaxed);
693 }
694
onFirstRef()695 void RefBase::onFirstRef()
696 {
697 }
698
onLastStrongRef(const void *)699 void RefBase::onLastStrongRef(const void* /*id*/)
700 {
701 }
702
onIncStrongAttempted(uint32_t flags,const void *)703 bool RefBase::onIncStrongAttempted(uint32_t flags, const void* /*id*/)
704 {
705 return (flags&FIRST_INC_STRONG) ? true : false;
706 }
707
onLastWeakRef(const void *)708 void RefBase::onLastWeakRef(const void* /*id*/)
709 {
710 }
711
712 // ---------------------------------------------------------------------------
713
714 #if DEBUG_REFS
renameRefs(size_t n,const ReferenceRenamer & renamer)715 void RefBase::renameRefs(size_t n, const ReferenceRenamer& renamer) {
716 for (size_t i=0 ; i<n ; i++) {
717 renamer(i);
718 }
719 }
720 #else
renameRefs(size_t,const ReferenceRenamer &)721 void RefBase::renameRefs(size_t /*n*/, const ReferenceRenamer& /*renamer*/) { }
722 #endif
723
renameRefId(weakref_type * ref,const void * old_id,const void * new_id)724 void RefBase::renameRefId(weakref_type* ref,
725 const void* old_id, const void* new_id) {
726 weakref_impl* const impl = static_cast<weakref_impl*>(ref);
727 impl->renameStrongRefId(old_id, new_id);
728 impl->renameWeakRefId(old_id, new_id);
729 }
730
renameRefId(RefBase * ref,const void * old_id,const void * new_id)731 void RefBase::renameRefId(RefBase* ref,
732 const void* old_id, const void* new_id) {
733 ref->mRefs->renameStrongRefId(old_id, new_id);
734 ref->mRefs->renameWeakRefId(old_id, new_id);
735 }
736
737 }; // namespace android
738