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91 lines
2.6 KiB
C++
91 lines
2.6 KiB
C++
//////////////////////////////////////////////////////////////////////////////
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//
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// (C) Copyright Ion Gaztanaga 2006-2012. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// See http://www.boost.org/libs/interprocess for documentation.
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//
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//////////////////////////////////////////////////////////////////////////////
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//[doc_managed_aligned_allocation
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#include <boost/interprocess/managed_shared_memory.hpp>
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#include <cassert>
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//<-
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#include "../test/get_process_id_name.hpp"
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//->
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int main()
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{
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using namespace boost::interprocess;
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//Remove shared memory on construction and destruction
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struct shm_remove
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{
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//<-
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#if 1
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shm_remove() { shared_memory_object::remove(test::get_process_id_name()); }
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~shm_remove(){ shared_memory_object::remove(test::get_process_id_name()); }
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#else
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//->
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shm_remove() { shared_memory_object::remove("MySharedMemory"); }
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~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
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//<-
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#endif
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//->
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} remover;
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//<-
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(void)remover;
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//->
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//Managed memory segment that allocates portions of a shared memory
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//segment with the default management algorithm
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//<-
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#if 1
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managed_shared_memory managed_shm(create_only, test::get_process_id_name(), 65536);
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#else
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//->
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managed_shared_memory managed_shm(create_only, "MySharedMemory", 65536);
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//<-
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#endif
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//->
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const std::size_t Alignment = 128;
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//Allocate 100 bytes aligned to Alignment from segment, throwing version
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void *ptr = managed_shm.allocate_aligned(100, Alignment);
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//Check alignment
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assert((static_cast<char*>(ptr)-static_cast<char*>(0)) % Alignment == 0);
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//Deallocate it
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managed_shm.deallocate(ptr);
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//Non throwing version
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ptr = managed_shm.allocate_aligned(100, Alignment, std::nothrow);
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//Check alignment
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assert((static_cast<char*>(ptr)-static_cast<char*>(0)) % Alignment == 0);
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//Deallocate it
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managed_shm.deallocate(ptr);
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//If we want to efficiently allocate aligned blocks of memory
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//use managed_shared_memory::PayloadPerAllocation value
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assert(Alignment > managed_shared_memory::PayloadPerAllocation);
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//This allocation will maximize the size of the aligned memory
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//and will increase the possibility of finding more aligned memory
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ptr = managed_shm.allocate_aligned
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(3*Alignment - managed_shared_memory::PayloadPerAllocation, Alignment);
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//Check alignment
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assert((static_cast<char*>(ptr)-static_cast<char*>(0)) % Alignment == 0);
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//Deallocate it
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managed_shm.deallocate(ptr);
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return 0;
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}
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//]
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