Method update

source/MRMesh/MRSharedThreadSafeOwner.cpp:57–70

template<typename T>
void SharedThreadSafeOwner<T>::update( const std::function<void(T&)> & updater )
{
    assert( !construction_ ); // one thread constructs the object, and this thread updates it
    auto myPtr = atomic_exchange( &obj_, {} );
    if ( !myPtr )
        return;
    assert( myPtr.use_count() >= 1 );
    if ( myPtr.use_count() > 1 ) // create the copy if we was not the unique owner
        myPtr.reset( new T( *myPtr ) );
    assert( myPtr.use_count() == 1 );
    updater( *myPtr );
    assert( !construction_ ); // one thread constructs the object, and this thread updates it
    atomic_store( &obj_, std::move( myPtr ) );
}

template<typename T>
const T & SharedThreadSafeOwner<T>::getOrCreate( const std::function<T()> & creator )