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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.
- //
- //////////////////////////////////////////////////////////////////////////////
- #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;
- //<-
- (void)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
- 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;
- }
- //]
- #include <boost/interprocess/detail/config_end.hpp>
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