diff options
Diffstat (limited to 'media/libstagefright/system/core/libutils/RefBase.cpp')
| -rw-r--r-- | media/libstagefright/system/core/libutils/RefBase.cpp | 657 |
1 files changed, 657 insertions, 0 deletions
diff --git a/media/libstagefright/system/core/libutils/RefBase.cpp b/media/libstagefright/system/core/libutils/RefBase.cpp new file mode 100644 index 000000000..259b0a4e6 --- /dev/null +++ b/media/libstagefright/system/core/libutils/RefBase.cpp @@ -0,0 +1,657 @@ +/* + * 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" +// #define LOG_NDEBUG 0 + +#include <utils/RefBase.h> + +#include <utils/Atomic.h> +#ifdef _MSC_VER +class CallStack { +public: + CallStack(int x) {} +}; +#else +#include <utils/CallStack.h> +#endif +#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 + +// whether ref-tracking is enabled by default, if not, trackMe(true, false) +// needs to be called explicitly +#define DEBUG_REFS_ENABLED_BY_DEFAULT 0 + +// whether callstack are collected (significantly slows things down) +#define DEBUG_REFS_CALLSTACK_ENABLED 0 + +// folder where stack traces are saved when DEBUG_REFS is enabled +// this folder needs to exist and be writable +#define DEBUG_REFS_CALLSTACK_PATH "/data/debug" + +// log all reference counting operations +#define PRINT_REFS 0 + +// --------------------------------------------------------------------------- + +namespace stagefright { + +#define INITIAL_STRONG_VALUE (1<<28) + +// --------------------------------------------------------------------------- + +class RefBase::weakref_impl : public RefBase::weakref_type +{ +public: + volatile int32_t mStrong; + volatile int32_t mWeak; + RefBase* const mBase; + volatile int32_t mFlags; + +#if !DEBUG_REFS + + weakref_impl(RefBase* base) + : mStrong(INITIAL_STRONG_VALUE) + , mWeak(0) + , mBase(base) + , mFlags(0) + { + } + + void addStrongRef(const void* /*id*/) { } + void removeStrongRef(const void* /*id*/) { } + void renameStrongRefId(const void* /*old_id*/, const void* /*new_id*/) { } + void addWeakRef(const void* /*id*/) { } + void removeWeakRef(const void* /*id*/) { } + void renameWeakRefId(const void* /*old_id*/, const void* /*new_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) + { + } + + ~weakref_impl() + { + bool dumpStack = false; + if (!mRetain && mStrongRefs != NULL) { + dumpStack = true; + ALOGE("Strong references remain:"); + ref_entry* refs = mStrongRefs; + while (refs) { + char inc = refs->ref >= 0 ? '+' : '-'; + ALOGD("\t%c ID %p (ref %d):", inc, refs->id, refs->ref); +#if DEBUG_REFS_CALLSTACK_ENABLED + refs->stack.dump(LOG_TAG); +#endif + refs = refs->next; + } + } + + if (!mRetain && mWeakRefs != NULL) { + dumpStack = true; + ALOGE("Weak references remain!"); + ref_entry* refs = mWeakRefs; + while (refs) { + char inc = refs->ref >= 0 ? '+' : '-'; + ALOGD("\t%c ID %p (ref %d):", inc, refs->id, refs->ref); +#if DEBUG_REFS_CALLSTACK_ENABLED + refs->stack.dump(LOG_TAG); +#endif + refs = refs->next; + } + } + if (dumpStack) { + ALOGE("above errors at:"); + CallStack stack(LOG_TAG); + } + } + + void addStrongRef(const void* id) { + //ALOGD_IF(mTrackEnabled, + // "addStrongRef: RefBase=%p, id=%p", mBase, id); + addRef(&mStrongRefs, id, mStrong); + } + + void removeStrongRef(const void* id) { + //ALOGD_IF(mTrackEnabled, + // "removeStrongRef: RefBase=%p, id=%p", mBase, id); + if (!mRetain) { + removeRef(&mStrongRefs, id); + } else { + addRef(&mStrongRefs, id, -mStrong); + } + } + + void renameStrongRefId(const void* old_id, const void* new_id) { + //ALOGD_IF(mTrackEnabled, + // "renameStrongRefId: RefBase=%p, oid=%p, nid=%p", + // mBase, old_id, new_id); + renameRefsId(mStrongRefs, old_id, new_id); + } + + 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 renameWeakRefId(const void* old_id, const void* new_id) { + renameRefsId(mWeakRefs, old_id, new_id); + } + + void trackMe(bool track, bool retain) + { + mTrackEnabled = track; + mRetain = retain; + } + + void printRefs() const + { + String8 text; + + { + Mutex::Autolock _l(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, DEBUG_REFS_CALLSTACK_PATH "/%p.stack", this); + int rc = open(name, O_RDWR | O_CREAT | O_APPEND, 644); + if (rc >= 0) { + write(rc, text.string(), text.length()); + close(rc); + ALOGD("STACK TRACE for %p saved in %s", this, name); + } + else ALOGE("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* const head = *refs; + ref_entry* ref = head; + while (ref != NULL) { + if (ref->id == id) { + *refs = ref->next; + delete ref; + return; + } + refs = &ref->next; + ref = *refs; + } + + ALOGE("RefBase: removing id %p on RefBase %p" + "(weakref_type %p) that doesn't exist!", + id, mBase, this); + + ref = head; + while (ref) { + char inc = ref->ref >= 0 ? '+' : '-'; + ALOGD("\t%c ID %p (ref %d):", inc, ref->id, ref->ref); + ref = ref->next; + } + + CallStack stack(LOG_TAG); + } + } + + void renameRefsId(ref_entry* r, const void* old_id, const void* new_id) + { + if (mTrackEnabled) { + AutoMutex _l(mMutex); + ref_entry* ref = r; + while (ref != NULL) { + if (ref->id == old_id) { + ref->id = new_id; + } + ref = ref->next; + } + } + } + + 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; + } + } + + mutable 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; + +#endif +}; + +// --------------------------------------------------------------------------- + +void RefBase::incStrong(const void* id) const +{ + weakref_impl* const refs = mRefs; + refs->incWeak(id); + + refs->addStrongRef(id); + const int32_t c = android_atomic_inc(&refs->mStrong); + ALOG_ASSERT(c > 0, "incStrong() called on %p after last strong ref", refs); +#if PRINT_REFS + ALOGD("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); + refs->mBase->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 + ALOGD("decStrong of %p from %p: cnt=%d\n", this, id, c); +#endif + ALOG_ASSERT(c >= 1, "decStrong() called on %p too many times", refs); + if (c == 1) { + refs->mBase->onLastStrongRef(id); + if ((refs->mFlags&OBJECT_LIFETIME_MASK) == OBJECT_LIFETIME_STRONG) { + delete this; + } + } + refs->decWeak(id); +} + +void RefBase::forceIncStrong(const void* id) const +{ + weakref_impl* const refs = mRefs; + refs->incWeak(id); + + refs->addStrongRef(id); + const int32_t c = android_atomic_inc(&refs->mStrong); + ALOG_ASSERT(c >= 0, "forceIncStrong called on %p after ref count underflow", + refs); +#if PRINT_REFS + ALOGD("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: + refs->mBase->onFirstRef(); + } +} + +int32_t RefBase::getStrongCount() const +{ + return mRefs->mStrong; +} + +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); + ALOG_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); + ALOG_ASSERT(c >= 1, "decWeak called on %p too many times", this); + if (c != 1) return; + + if ((impl->mFlags&OBJECT_LIFETIME_WEAK) == OBJECT_LIFETIME_STRONG) { + // This is the regular lifetime case. The object is destroyed + // when the last strong reference goes away. Since weakref_impl + // outlive the object, it is not destroyed in the dtor, and + // we'll have to do it here. + if (impl->mStrong == INITIAL_STRONG_VALUE) { + // Special case: we never had a strong reference, so we need to + // destroy the object now. + delete impl->mBase; + } else { + // ALOGV("Freeing refs %p of old RefBase %p\n", this, impl->mBase); + delete impl; + } + } else { + // less common case: lifetime is OBJECT_LIFETIME_{WEAK|FOREVER} + impl->mBase->onLastWeakRef(id); + if ((impl->mFlags&OBJECT_LIFETIME_MASK) == OBJECT_LIFETIME_WEAK) { + // this is the OBJECT_LIFETIME_WEAK case. The last weak-reference + // is gone, we can destroy the object. + 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; + + ALOG_ASSERT(curCount >= 0, + "attemptIncStrong called on %p after underflow", this); + + while (curCount > 0 && curCount != INITIAL_STRONG_VALUE) { + // we're in the easy/common case of promoting a weak-reference + // from an existing strong reference. + if (android_atomic_cmpxchg(curCount, curCount+1, &impl->mStrong) == 0) { + break; + } + // the strong count has changed on us, we need to re-assert our + // situation. + curCount = impl->mStrong; + } + + if (curCount <= 0 || curCount == INITIAL_STRONG_VALUE) { + // we're now in the harder case of either: + // - there never was a strong reference on us + // - or, all strong references have been released + if ((impl->mFlags&OBJECT_LIFETIME_WEAK) == OBJECT_LIFETIME_STRONG) { + // this object has a "normal" life-time, i.e.: it gets destroyed + // when the last strong reference goes away + if (curCount <= 0) { + // the last strong-reference got released, the object cannot + // be revived. + decWeak(id); + return false; + } + + // here, curCount == INITIAL_STRONG_VALUE, which means + // there never was a strong-reference, so we can try to + // promote this object; we need to do that atomically. + while (curCount > 0) { + if (android_atomic_cmpxchg(curCount, curCount + 1, + &impl->mStrong) == 0) { + break; + } + // the strong count has changed on us, we need to re-assert our + // situation (e.g.: another thread has inc/decStrong'ed us) + curCount = impl->mStrong; + } + + if (curCount <= 0) { + // promote() failed, some other thread destroyed us in the + // meantime (i.e.: strong count reached zero). + decWeak(id); + return false; + } + } else { + // this object has an "extended" life-time, i.e.: it can be + // revived from a weak-reference only. + // Ask the object's implementation if it agrees to be revived + if (!impl->mBase->onIncStrongAttempted(FIRST_INC_STRONG, id)) { + // it didn't so give-up. + decWeak(id); + return false; + } + // grab a strong-reference, which is always safe due to the + // extended life-time. + 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->addStrongRef(id); + +#if PRINT_REFS + ALOGD("attemptIncStrong of %p from %p: cnt=%d\n", this, id, curCount); +#endif + + // now we need to fix-up the count if it was INITIAL_STRONG_VALUE + // this must be done safely, i.e.: handle the case where several threads + // were here in attemptIncStrong(). + curCount = impl->mStrong; + while (curCount >= INITIAL_STRONG_VALUE) { + ALOG_ASSERT(curCount > INITIAL_STRONG_VALUE, + "attemptIncStrong in %p underflowed to INITIAL_STRONG_VALUE", + this); + if (android_atomic_cmpxchg(curCount, curCount-INITIAL_STRONG_VALUE, + &impl->mStrong) == 0) { + break; + } + // the strong-count changed on us, we need to re-assert the situation, + // for e.g.: it's possible the fix-up happened in another thread. + curCount = impl->mStrong; + } + + return true; +} + +bool RefBase::weakref_type::attemptIncWeak(const void* id) +{ + weakref_impl* const impl = static_cast<weakref_impl*>(this); + + int32_t curCount = impl->mWeak; + ALOG_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<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)) +{ +} + +RefBase::~RefBase() +{ + if (mRefs->mStrong == INITIAL_STRONG_VALUE) { + // we never acquired a strong (and/or weak) reference on this object. + delete mRefs; + } else { + // life-time of this object is extended to WEAK or FOREVER, in + // which case weakref_impl doesn't out-live the object and we + // can free it now. + if ((mRefs->mFlags & OBJECT_LIFETIME_MASK) != OBJECT_LIFETIME_STRONG) { + // It's possible that the weak count is not 0 if the object + // re-acquired a weak reference in its destructor + if (mRefs->mWeak == 0) { + delete mRefs; + } + } + } + // for debugging purposes, clear this. + const_cast<weakref_impl*&>(mRefs) = NULL; +} + +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*/) +{ +} + +// --------------------------------------------------------------------------- + +void RefBase::renameRefs(size_t n, const ReferenceRenamer& renamer) { +#if DEBUG_REFS + for (size_t i=0 ; i<n ; i++) { + renamer(i); + } +#endif +} + +void RefBase::renameRefId(weakref_type* ref, + const void* old_id, const void* new_id) { + weakref_impl* const impl = static_cast<weakref_impl*>(ref); + impl->renameStrongRefId(old_id, new_id); + impl->renameWeakRefId(old_id, new_id); +} + +void RefBase::renameRefId(RefBase* ref, + const void* old_id, const void* new_id) { + ref->mRefs->renameStrongRefId(old_id, new_id); + ref->mRefs->renameWeakRefId(old_id, new_id); +} + +}; // namespace stagefright |