| /* |
| * Copyright (C) 2005 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #define LOG_TAG "RefBase" |
| |
| #include <utils/RefBase.h> |
| |
| #include <utils/Atomic.h> |
| #include <utils/CallStack.h> |
| #include <utils/KeyedVector.h> |
| #include <utils/Log.h> |
| #include <utils/threads.h> |
| |
| #include <stdlib.h> |
| #include <stdio.h> |
| #include <typeinfo> |
| #include <sys/types.h> |
| #include <sys/stat.h> |
| #include <fcntl.h> |
| #include <unistd.h> |
| |
| // compile with refcounting debugging enabled |
| #define DEBUG_REFS 0 |
| #define DEBUG_REFS_ENABLED_BY_DEFAULT 1 |
| #define DEBUG_REFS_CALLSTACK_ENABLED 1 |
| |
| // log all reference counting operations |
| #define PRINT_REFS 0 |
| |
| // --------------------------------------------------------------------------- |
| |
| namespace android { |
| |
| #define INITIAL_STRONG_VALUE (1<<28) |
| |
| // --------------------------------------------------------------------------- |
| |
| RefBase::Destroyer::~Destroyer() { |
| } |
| |
| // --------------------------------------------------------------------------- |
| |
| class RefBase::weakref_impl : public RefBase::weakref_type |
| { |
| public: |
| volatile int32_t mStrong; |
| volatile int32_t mWeak; |
| RefBase* const mBase; |
| volatile int32_t mFlags; |
| Destroyer* mDestroyer; |
| |
| #if !DEBUG_REFS |
| |
| weakref_impl(RefBase* base) |
| : mStrong(INITIAL_STRONG_VALUE) |
| , mWeak(0) |
| , mBase(base) |
| , mFlags(0) |
| , mDestroyer(0) |
| { |
| } |
| |
| void addStrongRef(const void* /*id*/) { } |
| void removeStrongRef(const void* /*id*/) { } |
| void addWeakRef(const void* /*id*/) { } |
| void removeWeakRef(const void* /*id*/) { } |
| void printRefs() const { } |
| void trackMe(bool, bool) { } |
| |
| #else |
| |
| weakref_impl(RefBase* base) |
| : mStrong(INITIAL_STRONG_VALUE) |
| , mWeak(0) |
| , mBase(base) |
| , mFlags(0) |
| , mStrongRefs(NULL) |
| , mWeakRefs(NULL) |
| , mTrackEnabled(!!DEBUG_REFS_ENABLED_BY_DEFAULT) |
| , mRetain(false) |
| { |
| //LOGI("NEW weakref_impl %p for RefBase %p", this, base); |
| } |
| |
| ~weakref_impl() |
| { |
| LOG_ALWAYS_FATAL_IF(!mRetain && mStrongRefs != NULL, "Strong references remain!"); |
| LOG_ALWAYS_FATAL_IF(!mRetain && mWeakRefs != NULL, "Weak references remain!"); |
| } |
| |
| void addStrongRef(const void* id) |
| { |
| addRef(&mStrongRefs, id, mStrong); |
| } |
| |
| void removeStrongRef(const void* id) |
| { |
| if (!mRetain) |
| removeRef(&mStrongRefs, id); |
| else |
| addRef(&mStrongRefs, id, -mStrong); |
| } |
| |
| void addWeakRef(const void* id) |
| { |
| addRef(&mWeakRefs, id, mWeak); |
| } |
| |
| void removeWeakRef(const void* id) |
| { |
| if (!mRetain) |
| removeRef(&mWeakRefs, id); |
| else |
| addRef(&mWeakRefs, id, -mWeak); |
| } |
| |
| void trackMe(bool track, bool retain) |
| { |
| mTrackEnabled = track; |
| mRetain = retain; |
| } |
| |
| void printRefs() const |
| { |
| String8 text; |
| |
| { |
| AutoMutex _l(const_cast<weakref_impl*>(this)->mMutex); |
| |
| char buf[128]; |
| sprintf(buf, "Strong references on RefBase %p (weakref_type %p):\n", mBase, this); |
| text.append(buf); |
| printRefsLocked(&text, mStrongRefs); |
| sprintf(buf, "Weak references on RefBase %p (weakref_type %p):\n", mBase, this); |
| text.append(buf); |
| printRefsLocked(&text, mWeakRefs); |
| } |
| |
| { |
| char name[100]; |
| snprintf(name, 100, "/data/%p.stack", this); |
| int rc = open(name, O_RDWR | O_CREAT | O_APPEND); |
| if (rc >= 0) { |
| write(rc, text.string(), text.length()); |
| close(rc); |
| LOGD("STACK TRACE for %p saved in %s", this, name); |
| } |
| else LOGE("FAILED TO PRINT STACK TRACE for %p in %s: %s", this, |
| name, strerror(errno)); |
| } |
| } |
| |
| private: |
| struct ref_entry |
| { |
| ref_entry* next; |
| const void* id; |
| #if DEBUG_REFS_CALLSTACK_ENABLED |
| CallStack stack; |
| #endif |
| int32_t ref; |
| }; |
| |
| void addRef(ref_entry** refs, const void* id, int32_t mRef) |
| { |
| if (mTrackEnabled) { |
| AutoMutex _l(mMutex); |
| ref_entry* ref = new ref_entry; |
| // Reference count at the time of the snapshot, but before the |
| // update. Positive value means we increment, negative--we |
| // decrement the reference count. |
| ref->ref = mRef; |
| ref->id = id; |
| #if DEBUG_REFS_CALLSTACK_ENABLED |
| ref->stack.update(2); |
| #endif |
| |
| ref->next = *refs; |
| *refs = ref; |
| } |
| } |
| |
| void removeRef(ref_entry** refs, const void* id) |
| { |
| if (mTrackEnabled) { |
| AutoMutex _l(mMutex); |
| |
| ref_entry* ref = *refs; |
| while (ref != NULL) { |
| if (ref->id == id) { |
| *refs = ref->next; |
| delete ref; |
| return; |
| } |
| |
| refs = &ref->next; |
| ref = *refs; |
| } |
| |
| LOG_ALWAYS_FATAL("RefBase: removing id %p on RefBase %p (weakref_type %p) that doesn't exist!", |
| id, mBase, this); |
| } |
| } |
| |
| void printRefsLocked(String8* out, const ref_entry* refs) const |
| { |
| char buf[128]; |
| while (refs) { |
| char inc = refs->ref >= 0 ? '+' : '-'; |
| sprintf(buf, "\t%c ID %p (ref %d):\n", |
| inc, refs->id, refs->ref); |
| out->append(buf); |
| #if DEBUG_REFS_CALLSTACK_ENABLED |
| out->append(refs->stack.toString("\t\t")); |
| #else |
| out->append("\t\t(call stacks disabled)"); |
| #endif |
| refs = refs->next; |
| } |
| } |
| |
| Mutex mMutex; |
| ref_entry* mStrongRefs; |
| ref_entry* mWeakRefs; |
| |
| bool mTrackEnabled; |
| // Collect stack traces on addref and removeref, instead of deleting the stack references |
| // on removeref that match the address ones. |
| bool mRetain; |
| |
| #if 0 |
| void addRef(KeyedVector<const void*, int32_t>* refs, const void* id) |
| { |
| AutoMutex _l(mMutex); |
| ssize_t i = refs->indexOfKey(id); |
| if (i >= 0) { |
| ++(refs->editValueAt(i)); |
| } else { |
| i = refs->add(id, 1); |
| } |
| } |
| |
| void removeRef(KeyedVector<const void*, int32_t>* refs, const void* id) |
| { |
| AutoMutex _l(mMutex); |
| ssize_t i = refs->indexOfKey(id); |
| LOG_ALWAYS_FATAL_IF(i < 0, "RefBase: removing id %p that doesn't exist!", id); |
| if (i >= 0) { |
| int32_t val = --(refs->editValueAt(i)); |
| if (val == 0) { |
| refs->removeItemsAt(i); |
| } |
| } |
| } |
| |
| void printRefs(const KeyedVector<const void*, int32_t>& refs) |
| { |
| const size_t N=refs.size(); |
| for (size_t i=0; i<N; i++) { |
| printf("\tID %p: %d remain\n", refs.keyAt(i), refs.valueAt(i)); |
| } |
| } |
| |
| mutable Mutex mMutex; |
| KeyedVector<const void*, int32_t> mStrongRefs; |
| KeyedVector<const void*, int32_t> mWeakRefs; |
| #endif |
| |
| #endif |
| }; |
| |
| // --------------------------------------------------------------------------- |
| |
| void RefBase::incStrong(const void* id) const |
| { |
| weakref_impl* const refs = mRefs; |
| refs->addWeakRef(id); |
| refs->incWeak(id); |
| |
| refs->addStrongRef(id); |
| const int32_t c = android_atomic_inc(&refs->mStrong); |
| LOG_ASSERT(c > 0, "incStrong() called on %p after last strong ref", refs); |
| #if PRINT_REFS |
| LOGD("incStrong of %p from %p: cnt=%d\n", this, id, c); |
| #endif |
| if (c != INITIAL_STRONG_VALUE) { |
| return; |
| } |
| |
| android_atomic_add(-INITIAL_STRONG_VALUE, &refs->mStrong); |
| const_cast<RefBase*>(this)->onFirstRef(); |
| } |
| |
| void RefBase::decStrong(const void* id) const |
| { |
| weakref_impl* const refs = mRefs; |
| refs->removeStrongRef(id); |
| const int32_t c = android_atomic_dec(&refs->mStrong); |
| #if PRINT_REFS |
| LOGD("decStrong of %p from %p: cnt=%d\n", this, id, c); |
| #endif |
| LOG_ASSERT(c >= 1, "decStrong() called on %p too many times", refs); |
| if (c == 1) { |
| const_cast<RefBase*>(this)->onLastStrongRef(id); |
| if ((refs->mFlags&OBJECT_LIFETIME_WEAK) != OBJECT_LIFETIME_WEAK) { |
| if (refs->mDestroyer) { |
| refs->mDestroyer->destroy(this); |
| } else { |
| delete this; |
| } |
| } |
| } |
| refs->removeWeakRef(id); |
| refs->decWeak(id); |
| } |
| |
| void RefBase::forceIncStrong(const void* id) const |
| { |
| weakref_impl* const refs = mRefs; |
| refs->addWeakRef(id); |
| refs->incWeak(id); |
| |
| refs->addStrongRef(id); |
| const int32_t c = android_atomic_inc(&refs->mStrong); |
| LOG_ASSERT(c >= 0, "forceIncStrong called on %p after ref count underflow", |
| refs); |
| #if PRINT_REFS |
| LOGD("forceIncStrong of %p from %p: cnt=%d\n", this, id, c); |
| #endif |
| |
| switch (c) { |
| case INITIAL_STRONG_VALUE: |
| android_atomic_add(-INITIAL_STRONG_VALUE, &refs->mStrong); |
| // fall through... |
| case 0: |
| const_cast<RefBase*>(this)->onFirstRef(); |
| } |
| } |
| |
| int32_t RefBase::getStrongCount() const |
| { |
| return mRefs->mStrong; |
| } |
| |
| void RefBase::setDestroyer(RefBase::Destroyer* destroyer) { |
| mRefs->mDestroyer = destroyer; |
| } |
| |
| RefBase* RefBase::weakref_type::refBase() const |
| { |
| return static_cast<const weakref_impl*>(this)->mBase; |
| } |
| |
| void RefBase::weakref_type::incWeak(const void* id) |
| { |
| weakref_impl* const impl = static_cast<weakref_impl*>(this); |
| impl->addWeakRef(id); |
| const int32_t c = android_atomic_inc(&impl->mWeak); |
| LOG_ASSERT(c >= 0, "incWeak called on %p after last weak ref", this); |
| } |
| |
| void RefBase::weakref_type::decWeak(const void* id) |
| { |
| weakref_impl* const impl = static_cast<weakref_impl*>(this); |
| impl->removeWeakRef(id); |
| const int32_t c = android_atomic_dec(&impl->mWeak); |
| LOG_ASSERT(c >= 1, "decWeak called on %p too many times", this); |
| if (c != 1) return; |
| |
| if ((impl->mFlags&OBJECT_LIFETIME_WEAK) != OBJECT_LIFETIME_WEAK) { |
| if (impl->mStrong == INITIAL_STRONG_VALUE) { |
| if (impl->mBase) { |
| if (impl->mDestroyer) { |
| impl->mDestroyer->destroy(impl->mBase); |
| } else { |
| delete impl->mBase; |
| } |
| } |
| } else { |
| // LOGV("Freeing refs %p of old RefBase %p\n", this, impl->mBase); |
| delete impl; |
| } |
| } else { |
| impl->mBase->onLastWeakRef(id); |
| if ((impl->mFlags&OBJECT_LIFETIME_FOREVER) != OBJECT_LIFETIME_FOREVER) { |
| if (impl->mBase) { |
| if (impl->mDestroyer) { |
| impl->mDestroyer->destroy(impl->mBase); |
| } else { |
| delete impl->mBase; |
| } |
| } |
| } |
| } |
| } |
| |
| bool RefBase::weakref_type::attemptIncStrong(const void* id) |
| { |
| incWeak(id); |
| |
| weakref_impl* const impl = static_cast<weakref_impl*>(this); |
| |
| int32_t curCount = impl->mStrong; |
| LOG_ASSERT(curCount >= 0, "attemptIncStrong called on %p after underflow", |
| this); |
| while (curCount > 0 && curCount != INITIAL_STRONG_VALUE) { |
| if (android_atomic_cmpxchg(curCount, curCount+1, &impl->mStrong) == 0) { |
| break; |
| } |
| curCount = impl->mStrong; |
| } |
| |
| if (curCount <= 0 || curCount == INITIAL_STRONG_VALUE) { |
| bool allow; |
| if (curCount == INITIAL_STRONG_VALUE) { |
| // Attempting to acquire first strong reference... this is allowed |
| // if the object does NOT have a longer lifetime (meaning the |
| // implementation doesn't need to see this), or if the implementation |
| // allows it to happen. |
| allow = (impl->mFlags&OBJECT_LIFETIME_WEAK) != OBJECT_LIFETIME_WEAK |
| || impl->mBase->onIncStrongAttempted(FIRST_INC_STRONG, id); |
| } else { |
| // Attempting to revive the object... this is allowed |
| // if the object DOES have a longer lifetime (so we can safely |
| // call the object with only a weak ref) and the implementation |
| // allows it to happen. |
| allow = (impl->mFlags&OBJECT_LIFETIME_WEAK) == OBJECT_LIFETIME_WEAK |
| && impl->mBase->onIncStrongAttempted(FIRST_INC_STRONG, id); |
| } |
| if (!allow) { |
| decWeak(id); |
| return false; |
| } |
| curCount = android_atomic_inc(&impl->mStrong); |
| |
| // If the strong reference count has already been incremented by |
| // someone else, the implementor of onIncStrongAttempted() is holding |
| // an unneeded reference. So call onLastStrongRef() here to remove it. |
| // (No, this is not pretty.) Note that we MUST NOT do this if we |
| // are in fact acquiring the first reference. |
| if (curCount > 0 && curCount < INITIAL_STRONG_VALUE) { |
| impl->mBase->onLastStrongRef(id); |
| } |
| } |
| |
| impl->addWeakRef(id); |
| impl->addStrongRef(id); |
| |
| #if PRINT_REFS |
| LOGD("attemptIncStrong of %p from %p: cnt=%d\n", this, id, curCount); |
| #endif |
| |
| if (curCount == INITIAL_STRONG_VALUE) { |
| android_atomic_add(-INITIAL_STRONG_VALUE, &impl->mStrong); |
| impl->mBase->onFirstRef(); |
| } |
| |
| return true; |
| } |
| |
| bool RefBase::weakref_type::attemptIncWeak(const void* id) |
| { |
| weakref_impl* const impl = static_cast<weakref_impl*>(this); |
| |
| int32_t curCount = impl->mWeak; |
| LOG_ASSERT(curCount >= 0, "attemptIncWeak called on %p after underflow", |
| this); |
| while (curCount > 0) { |
| if (android_atomic_cmpxchg(curCount, curCount+1, &impl->mWeak) == 0) { |
| break; |
| } |
| curCount = impl->mWeak; |
| } |
| |
| if (curCount > 0) { |
| impl->addWeakRef(id); |
| } |
| |
| return curCount > 0; |
| } |
| |
| int32_t RefBase::weakref_type::getWeakCount() const |
| { |
| return static_cast<const weakref_impl*>(this)->mWeak; |
| } |
| |
| void RefBase::weakref_type::printRefs() const |
| { |
| static_cast<const weakref_impl*>(this)->printRefs(); |
| } |
| |
| void RefBase::weakref_type::trackMe(bool enable, bool retain) |
| { |
| static_cast<const weakref_impl*>(this)->trackMe(enable, retain); |
| } |
| |
| RefBase::weakref_type* RefBase::createWeak(const void* id) const |
| { |
| mRefs->incWeak(id); |
| return mRefs; |
| } |
| |
| RefBase::weakref_type* RefBase::getWeakRefs() const |
| { |
| return mRefs; |
| } |
| |
| RefBase::RefBase() |
| : mRefs(new weakref_impl(this)) |
| { |
| // LOGV("Creating refs %p with RefBase %p\n", mRefs, this); |
| } |
| |
| RefBase::~RefBase() |
| { |
| if ((mRefs->mFlags & OBJECT_LIFETIME_WEAK) == OBJECT_LIFETIME_WEAK) { |
| if (mRefs->mWeak == 0) { |
| delete mRefs; |
| } |
| } |
| } |
| |
| void RefBase::extendObjectLifetime(int32_t mode) |
| { |
| android_atomic_or(mode, &mRefs->mFlags); |
| } |
| |
| void RefBase::onFirstRef() |
| { |
| } |
| |
| void RefBase::onLastStrongRef(const void* /*id*/) |
| { |
| } |
| |
| bool RefBase::onIncStrongAttempted(uint32_t flags, const void* id) |
| { |
| return (flags&FIRST_INC_STRONG) ? true : false; |
| } |
| |
| void RefBase::onLastWeakRef(const void* /*id*/) |
| { |
| } |
| |
| }; // namespace android |