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

// (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_allocation_command

#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(), 10000*sizeof(std::size_t));

//Allocate at least 100 bytes, 1000 bytes if possible

managed_shared_memory::size_type min_size = 100;

managed_shared_memory::size_type first_received_size = 1000;

std::size_t *hint = 0;

std::size_t *ptr = managed_shm.allocation_command<std::size_t>

(boost::interprocess::allocate_new, min_size, first_received_size, hint);

//Received size must be bigger than min_size

assert(first_received_size >= min_size);

//Get free memory

managed_shared_memory::size_type free_memory_after_allocation = managed_shm.get_free_memory();

//<-

(void)free_memory_after_allocation;

//->

//Now write the data

for(std::size_t i = 0; i < first_received_size; ++i) ptr[i] = i;

//Now try to triplicate the buffer. We won't admit an expansion

//lower to the double of the original buffer.

//This "should" be successful since no other class is allocating

//memory from the segment

min_size = first_received_size*2;

managed_shared_memory::size_type expanded_size = first_received_size*3;

std::size_t * ret = managed_shm.allocation_command

(boost::interprocess::expand_fwd, min_size, expanded_size, ptr);

//<-

(void)ret;

//->

//Check invariants

assert(ptr != 0);

assert(ret == ptr);

assert(expanded_size >= first_received_size*2);

//Get free memory and compare

managed_shared_memory::size_type free_memory_after_expansion = managed_shm.get_free_memory();

assert(free_memory_after_expansion < free_memory_after_allocation);

//<-

(void)free_memory_after_expansion;

//->

//Write new values

for(std::size_t i = first_received_size; i < expanded_size; ++i) ptr[i] = i;

//Try to shrink approximately to min_size, but the new size

//should be smaller than min_size*2.

//This "should" be successful since no other class is allocating

//memory from the segment

managed_shared_memory::size_type shrunk_size = min_size;

ret = managed_shm.allocation_command

(boost::interprocess::shrink_in_place, min_size*2, shrunk_size, ptr);

//Check invariants

assert(ptr != 0);

assert(ret == ptr);

assert(shrunk_size <= min_size*2);

assert(shrunk_size >= min_size);

//Get free memory and compare

managed_shared_memory::size_type free_memory_after_shrinking = managed_shm.get_free_memory();

assert(free_memory_after_shrinking > free_memory_after_expansion);

//<-

(void)free_memory_after_shrinking;

//->

//Deallocate the buffer

managed_shm.deallocate(ptr);

return 0;

}

//]