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Commit c1053339 authored by Jeff Brown's avatar Jeff Brown
Browse files

Minor code cleanups in vector. 

Fixed a potential bug where calling replaceAt with a reference to
an existing element in the vector at the same index would cause
the element to be destroyed while being copied to itself.

Refactored the conditions in _grow and _shrink for clarity.
The computations are exactly the same but I think it reads better
this way.  In particular, the ssize_t variable 's' is gone: it didn't
need to be signed anyways because its value could never be negative.

Change-Id: If087841c15e6a87160eee874720c4a77eb0e99a6
parent 686f62fc

libs/utils/VectorImpl.cpp

+24 −26
Original line number Diff line number Diff line
@@ -252,6 +252,7 @@ ssize_t VectorImpl::replaceAt(const void* prototype, size_t index) 
        "[%p] replace: index=%d, size=%d", this, (int)index, (int)size());



    void* item = editItemLocation(index);

    if (item != prototype) {

        if (item == 0)

            return NO_MEMORY;

        _do_destroy(item, 1);
@@ -260,6 +261,7 @@ ssize_t VectorImpl::replaceAt(const void* prototype, size_t index) 
        } else {

            _do_copy(item, prototype, 1);

        }

    }

    return ssize_t(index);

}
@@ -367,10 +369,10 @@ void* VectorImpl::_grow(size_t where, size_t amount) 
            SharedBuffer* sb = SharedBuffer::alloc(new_capacity * mItemSize);

            if (sb) {

                void* array = sb->data();

                if (where>0) {

                if (where != 0) {

                    _do_copy(array, mStorage, where);

                }

                if (mCount>where) {

                if (where != mCount) {

                    const void* from = reinterpret_cast<const uint8_t *>(mStorage) + where*mItemSize;

                    void* dest = reinterpret_cast<uint8_t *>(array) + (where+amount)*mItemSize;

                    _do_copy(dest, from, mCount-where);
@@ -380,15 +382,14 @@ void* VectorImpl::_grow(size_t where, size_t amount) 
            }

        }

    } else {

        ssize_t s = mCount-where;

        if (s>0) {

        if (where != mCount) {

            void* array = editArrayImpl();

            void* to = reinterpret_cast<uint8_t *>(array) + (where+amount)*mItemSize;

            const void* from = reinterpret_cast<const uint8_t *>(array) + where*mItemSize;

            _do_move_forward(to, from, s);

            void* to = reinterpret_cast<uint8_t *>(array) + (where+amount)*mItemSize;

            _do_move_forward(to, from, mCount - where);

        }

    }

    mCount += amount;

    mCount = new_size;

    void* free_space = const_cast<void*>(itemLocation(where));

    return free_space;

}
@@ -409,7 +410,7 @@ void VectorImpl::_shrink(size_t where, size_t amount) 
    if (new_size*3 < capacity()) {

        const size_t new_capacity = max(kMinVectorCapacity, new_size*2);

//        LOGV("shrink vector %p, new_capacity=%d", this, (int)new_capacity);

        if ((where == mCount-amount) &&

        if ((where == new_size) &&

            (mFlags & HAS_TRIVIAL_COPY) &&

            (mFlags & HAS_TRIVIAL_DTOR))

        {
@@ -420,13 +421,13 @@ void VectorImpl::_shrink(size_t where, size_t amount) 
            SharedBuffer* sb = SharedBuffer::alloc(new_capacity * mItemSize);

            if (sb) {

                void* array = sb->data();

                if (where>0) {

                if (where != 0) {

                    _do_copy(array, mStorage, where);

                }

                if (mCount > where+amount) {

                if (where != new_size) {

                    const void* from = reinterpret_cast<const uint8_t *>(mStorage) + (where+amount)*mItemSize;

                    void* dest = reinterpret_cast<uint8_t *>(array) + where*mItemSize;

                    _do_copy(dest, from, mCount-(where+amount));

                    _do_copy(dest, from, new_size - where);

                }

                release_storage();

                mStorage = const_cast<void*>(array);
@@ -436,15 +437,12 @@ void VectorImpl::_shrink(size_t where, size_t amount) 
        void* array = editArrayImpl();

        void* to = reinterpret_cast<uint8_t *>(array) + where*mItemSize;

        _do_destroy(to, amount);

        ssize_t s = mCount-(where+amount);

        if (s>0) {

        if (where != new_size) {

            const void* from = reinterpret_cast<uint8_t *>(array) + (where+amount)*mItemSize;

            _do_move_backward(to, from, s);

            _do_move_backward(to, from, new_size - where);

        }

    }



    // adjust the number of items...

    mCount -= amount;

    mCount = new_size;

}



size_t VectorImpl::itemSize() const {