auto import from //depot/cupcake/@135843

1 files changed, 534 insertions, 0 deletions

diff --git a/libs/utils/RefBase.cpp b/libs/utils/RefBase.cpp
new file mode 100644
index 0000000..0bd1af4
--- /dev/null
+++ b/libs/utils/RefBase.cpp
@@ -0,0 +1,534 @@
+/*
+ * 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)
+
+// ---------------------------------------------------------------------------
+
+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 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) {
+            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;
+}
+
+
+
+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)
+            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) {
+            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()
+{
+//    LOGV("Destroying RefBase %p (refs %p)\n", this, mRefs);
+    if (mRefs->mWeak == 0) {
+//        LOGV("Freeing refs %p of old RefBase %p\n", mRefs, this);
+        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