////////////////////////////////////////////////////////////////////////////// // // (C) Copyright Ion Gaztanaga 2006-2009. 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. // ////////////////////////////////////////////////////////////////////////////// #include <boost/interprocess/detail/config_begin.hpp> //[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 { //<- #if 1 shm_remove() { shared_memory_object::remove(test::get_process_id_name()); } ~shm_remove(){ shared_memory_object::remove(test::get_process_id_name()); } #else //-> shm_remove() { shared_memory_object::remove("MySharedMemory"); } ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); } //<- #endif //-> } remover; //Managed memory segment that allocates portions of a shared memory //segment with the default management algorithm //<- #if 1 managed_shared_memory managed_shm(create_only, test::get_process_id_name(), 10000*sizeof(std::size_t)); #else //-> managed_shared_memory managed_shm(create_only, "MySharedMemory", 10000*sizeof(std::size_t)); //<- #endif //-> //Allocate at least 100 bytes, 1000 bytes if possible std::size_t received_size, min_size = 100, preferred_size = 1000; std::size_t *ptr = managed_shm.allocation_command<std::size_t> (boost::interprocess::allocate_new, min_size, preferred_size, received_size).first; //Received size must be bigger than min_size assert(received_size >= min_size); //Get free memory std::size_t free_memory_after_allocation = managed_shm.get_free_memory(); //Now write the data for(std::size_t i = 0; i < 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 std::size_t expanded_size; std::pair<std::size_t *, bool> ret = managed_shm.allocation_command (boost::interprocess::expand_fwd, received_size*2, received_size*3, expanded_size, ptr); //Check invariants assert(ret.second == true); assert(ret.first == ptr); assert(expanded_size >= received_size*2); //Get free memory and compare std::size_t free_memory_after_expansion = managed_shm.get_free_memory(); assert(free_memory_after_expansion < free_memory_after_allocation); //Write new values for(std::size_t i = 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 std::size_t shrunk_size; ret = managed_shm.allocation_command (boost::interprocess::shrink_in_place, min_size*2, min_size, shrunk_size, ptr); //Check invariants assert(ret.second == true); assert(ret.first == ptr); assert(shrunk_size <= min_size*2); assert(shrunk_size >= min_size); //Get free memory and compare std::size_t free_memory_after_shrinking = managed_shm.get_free_memory(); assert(free_memory_after_shrinking > free_memory_after_expansion); //Deallocate the buffer managed_shm.deallocate(ptr); return 0; } //] #include <boost/interprocess/detail/config_end.hpp>