Merge "SharedBuffer: Refactor release() logic"

int32_t SharedBuffer::release(uint32_t flags) const

{

    int32_t prev = 1;

    if (onlyOwner()

            || (((prev = mRefs.fetch_sub(1, std::memory_order_release)) == 1)

                && (atomic_thread_fence(std::memory_order_acquire), true))) {

    const bool useDealloc = ((flags & eKeepStorage) == 0);

    if (onlyOwner()) {

        // Since we're the only owner, our reference count goes to zero.

        mRefs.store(0, std::memory_order_relaxed);

        if ((flags & eKeepStorage) == 0) {

            free(const_cast<SharedBuffer*>(this));

        if (useDealloc) {

            dealloc(this);

        }

        // As the only owner, our previous reference count was 1.

        return 1;

    }

    // There's multiple owners, we need to use an atomic decrement.

    int32_t prevRefCount = mRefs.fetch_sub(1, std::memory_order_release);

    if (prevRefCount == 1) {

        // We're the last reference, we need the acquire fence.

        atomic_thread_fence(std::memory_order_acquire);

        if (useDealloc) {

            dealloc(this);

        }

    }

    return prev;

    return prevRefCount;

}