Boost interprocess_mutex copy/move constructor?

Question

I'm trying to create a vector of objects in shared memory that each own an interprocess_mutex as follows:

struct test
{
    test(){}
    interprocess_mutex mutex;
};

using namespace boost::interprocess;
managed_shared_memory seg(open_or_create, "MySharedMemory", 65536);
allocator<void, managed_shared_memory::segment_manager> void_alloc_(seg.get_segment_manager());
vector<test, allocator<test, managed_shared_memory::segment_manager>> vec(void_alloc_);
vec.push_back(test());

However interprocess_mutex is explicitly missing a copy/move constructor and clang fails to compile with this error:

copy constructor of 'test' is implicitly deleted because field 'mutex' has an inaccessible copy constructor
interprocess_mutex mutex;

Is there a reason for this? It looks like boost::thread mutex has a copy constructor. How can I accomplish this using interprocess_mutex?

Answer 1

I solved the problem by changing the vector to contain shared_ptr instead of test directly. test() gets called only once and the object is owned by the shared_ptr object, which is move/copyable:

    using namespace boost::interprocess;

    typedef managed_shared_memory::segment_manager SegmentManager;
    typedef allocator<void, SegmentManager> test_allocator;
    typedef deleter<test, SegmentManager> test_deleter;
    typedef shared_ptr<test, test_allocator, test_deleter> test_pointer;
    typedef vector<test_pointer, allocator<test_pointer, SegmentManager>> test_pointer_vector;

    managed_shared_memory seg(open_or_create, "MySharedMemory", 65536);

    test_allocator alloc(seg.get_segment_manager());
    test_deleter del(seg.get_segment_manager());

    test_pointer& p = *seg.construct<test_pointer>(anonymous_instance)(seg.construct<test>(anonymous_instance)(), alloc, del);
    test_pointer_vector& vec = *seg.construct<test_pointer_vector>(anonymous_instance)(alloc);

    vec.push_back(p);
    p.get()->mutex_.try_lock();