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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2006-2007. 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_multiple_allocation
#include <boost/interprocess/managed_shared_memory.hpp>
#include <cassert>//assert
#include <cstring>//std::memset
#include <new> //std::nothrow
#include <vector> //std::vector
int main()
{
using namespace boost::interprocess;
typedef managed_shared_memory::multiallocation_iterator multiallocation_iterator;
//Try to erase any previous managed segment with the same name
shared_memory_object::remove("MyManagedShm");
try{
managed_shared_memory managed_shm(create_only, "MyManagedShm", 65536);
//Allocate 16 elements of 100 bytes in a single call. Non-throwing version.
multiallocation_iterator beg_it = managed_shm.allocate_many(100, 16, std::nothrow);
//To check for an error, we can use a boolean expression
//or compare it with a default constructed iterator
assert(!beg_it == (beg_it == multiallocation_iterator()));
//Check if the memory allocation was successful
if(!beg_it) return 1;
//Allocated buffers
std::vector<char*> allocated_buffers;
//Initialize our data
for( multiallocation_iterator it = beg_it, end_it; it != end_it; ){
allocated_buffers.push_back(&*it);
//The iterator must be incremented before overwriting memory
//because otherwise, the iterator is invalidated.
std::memset(&*it++, 0, 100);
}
//Now deallocate
while(!allocated_buffers.empty()){
managed_shm.deallocate(allocated_buffers.back());
allocated_buffers.pop_back();
}
//Allocate 10 buffers of different sizes in a single call. Throwing version
std::size_t sizes[10];
for(std::size_t i = 0; i < 10; ++i)
sizes[i] = i*3;
beg_it = managed_shm.allocate_many(sizes, 10);
//Iterate each allocated buffer and deallocate
//The "end" condition can be also checked with operator!
for(multiallocation_iterator it = beg_it; it;){
//The iterator must be incremented before overwriting memory
//because otherwise, the iterator is invalidated.
managed_shm.deallocate(&*it++);
}
}
catch(...){
shared_memory_object::remove("MyManagedShm");
throw;
}
shared_memory_object::remove("MyManagedShm");
return 0;
}
//]
#include <boost/interprocess/detail/config_end.hpp>
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