Using boost::interprocess offset_ptr

0
votes

I need to store the structure for Quadtree in shared memory.

It is a class with 4 pointers for tree-node regions and vector of points:

class CSNode4
{
...
CSNode4* node0;
CSNode4* node1;
CSNode4* node2;
CSNode4* node3;
vector<vec2> pointArray;
};

I have tried with

class CSNode4
{
...
offset_ptr<CSNode4> node0;
offset_ptr<CSNode4> node1;
...
};

and using as:

typedef allocator<void,  managed_shared_memory::segment_manager> void_allocator;
const void_allocator alloc_void(segment.get_segment_manager());
CSNode4* rootNode = segment.construct<CSNode4> (_RootNode) (alloc_void);
rootNode->node0 = new CSNode4(alloc_void,...);

this works OK until I try to static_cast node0:

offset_ptr<CSNode4> N1 = static_cast<CSNode4*>(rootNode->node0);

I get:

error C2440: 'static_cast' : cannot convert from 'boost::interprocess::offset_ptr' to 'CSNode4 *'

(MSVC 2010, boost 1.42)

What am I doing wrong and how can I fix it?

1
c++boost

1 Answers

1
votes

I assume that the CSNode4 is equivalent to CNode4. Since node0 is a offset_ptr, of course you can't static_cast it to a pointer of CSNode4. You should use the copy constructor of offset_ptr directly:

boost::interprocess::offset_ptr<CSNode4> N1(rootNode->node0);