GeezerVison is showing github.com — interprocess/example/doc_managed_aligned_allocation.cpp at develop · boostorg/interprocess

Expand file tree

doc_managed_aligned_allocation.cpp

Copy path

More file actions

Latest commit

History

77 lines (60 loc) · 2.36 KB

doc_managed_aligned_allocation.cpp

Copy path

File metadata and controls

77 lines (60 loc) · 2.36 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

//////////////////////////////////////////////////////////////////////////////

// (C) Copyright Ion Gaztanaga 2006-2012. Distributed under the Boost

// Software License, Version 1.0. (See accompanying file

// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

// See http://www.boost.org/libs/interprocess for documentation.

//////////////////////////////////////////////////////////////////////////////

#ifdef NDEBUG

#undef NDEBUG

#endif

//[doc_managed_aligned_allocation

#include <boost/interprocess/managed_shared_memory.hpp>

#include <cassert>

//<-

#include "../test/get_process_id_name.hpp"

//->

int main()

{

using namespace boost::interprocess;

//Remove shared memory on construction and destruction

struct shm_remove

{

shm_remove() { shared_memory_object::remove(test::get_process_id_name()); }

~shm_remove(){ shared_memory_object::remove(test::get_process_id_name()); }

} remover;

//<-

(void)remover;

//->

//Managed memory segment that allocates portions of a shared memory

//segment with the default management algorithm

managed_shared_memory managed_shm(create_only, test::get_process_id_name(), 65536);

const std::size_t Alignment = 128;

//Allocate 100 bytes aligned to Alignment from segment, throwing version

void *ptr = managed_shm.allocate_aligned(100, Alignment);

//Check alignment

assert(std::size_t(static_cast<char*>(ptr)-static_cast<char*>(0)) % Alignment == 0);

//Deallocate it

managed_shm.deallocate(ptr);

//Non throwing version

ptr = managed_shm.allocate_aligned(100, Alignment, std::nothrow);

//Check alignment

assert(std::size_t(static_cast<char*>(ptr)-static_cast<char*>(0)) % Alignment == 0);

//Deallocate it

managed_shm.deallocate(ptr);

//If we want to efficiently allocate aligned blocks of memory

//use managed_shared_memory::PayloadPerAllocation value

assert(Alignment > managed_shared_memory::PayloadPerAllocation);

//This allocation will maximize the size of the aligned memory

//and will increase the possibility of finding more aligned memory

ptr = managed_shm.allocate_aligned

(3u*Alignment - managed_shared_memory::PayloadPerAllocation, Alignment);

//Check alignment

assert(std::size_t(static_cast<char*>(ptr)-static_cast<char*>(0)) % Alignment == 0);

//Deallocate it

managed_shm.deallocate(ptr);

return 0;

}

//]