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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/workaround.hpp>

//[doc_shared_ptr

#include <boost/interprocess/managed_mapped_file.hpp>

#include <boost/interprocess/smart_ptr/shared_ptr.hpp>

#include <boost/interprocess/smart_ptr/weak_ptr.hpp>

#include <cassert>

//<-

#include "../test/get_process_id_name.hpp"

//->

using namespace boost::interprocess;

//This is type of the object we want to share

struct type_to_share

{};

//This is the type of a shared pointer to the previous type

//that will be built in the mapped file

typedef managed_shared_ptr<type_to_share, managed_mapped_file>::type shared_ptr_type;

typedef managed_weak_ptr<type_to_share, managed_mapped_file>::type weak_ptr_type;

//This is a type holding a shared pointer

struct shared_ptr_owner

{

shared_ptr_owner(const shared_ptr_type &other_shared_ptr)

: shared_ptr_(other_shared_ptr)

{}

shared_ptr_owner(const shared_ptr_owner &other_owner)

: shared_ptr_(other_owner.shared_ptr_)

{}

shared_ptr_type shared_ptr_;

//...

};

int main ()

{

//Define file names

//<-

#if 1

std::string mapped_file(boost::interprocess::ipcdetail::get_temporary_path());

mapped_file += "/"; mapped_file += test::get_process_id_name();

const char *MappedFile = mapped_file.c_str();

#else

//->

const char *MappedFile = "MyMappedFile";

//<-

#endif

//->

//Destroy any previous file with the name to be used.

struct file_remove

{

file_remove(const char *MappedFile)

: MappedFile_(MappedFile) { file_mapping::remove(MappedFile_); }

~file_remove(){ file_mapping::remove(MappedFile_); }

const char *MappedFile_;

} remover(MappedFile);

{

managed_mapped_file file(create_only, MappedFile, 65536);

//Construct the shared type in the file and

//pass ownership to this local shared pointer

shared_ptr_type local_shared_ptr = make_managed_shared_ptr

(file.construct<type_to_share>("object to share")(), file);

assert(local_shared_ptr.use_count() == 1);

//Share ownership of the object between local_shared_ptr and a new "owner1"

shared_ptr_owner *owner1 =

file.construct<shared_ptr_owner>("owner1")(local_shared_ptr);

assert(local_shared_ptr.use_count() == 2);

//local_shared_ptr releases object ownership

local_shared_ptr.reset();

assert(local_shared_ptr.use_count() == 0);

assert(owner1->shared_ptr_.use_count() == 1);

//Share ownership of the object between "owner1" and a new "owner2"

shared_ptr_owner *owner2 =

file.construct<shared_ptr_owner>("owner2")(*owner1);

assert(owner1->shared_ptr_.use_count() == 2);

assert(owner2->shared_ptr_.use_count() == 2);

assert(owner1->shared_ptr_.get() == owner2->shared_ptr_.get());

//<-

(void)owner2;

//->

//The mapped file is unmapped here. Objects have been flushed to disk

}

{

//Reopen the mapped file and find again all owners

managed_mapped_file file(open_only, MappedFile);

shared_ptr_owner *owner1 = file.find<shared_ptr_owner>("owner1").first;

shared_ptr_owner *owner2 = file.find<shared_ptr_owner>("owner2").first;

assert(owner1 && owner2);

//Check everything is as expected

assert(file.find<type_to_share>("object to share").first != 0);

assert(owner1->shared_ptr_.use_count() == 2);

assert(owner2->shared_ptr_.use_count() == 2);

assert(owner1->shared_ptr_.get() == owner2->shared_ptr_.get());

//Now destroy one of the owners, the reference count drops.

file.destroy_ptr(owner1);

assert(owner2->shared_ptr_.use_count() == 1);

//Create a weak pointer

weak_ptr_type local_observer1(owner2->shared_ptr_);

assert(local_observer1.use_count() == owner2->shared_ptr_.use_count());

{ //Create a local shared pointer from the weak pointer

shared_ptr_type local_shared_ptr = local_observer1.lock();

assert(local_observer1.use_count() == owner2->shared_ptr_.use_count());

assert(local_observer1.use_count() == 2);

}

//Now destroy the remaining owner. "object to share" will be destroyed

file.destroy_ptr(owner2);

assert(file.find<type_to_share>("object to share").first == 0);

//Test observer

assert(local_observer1.expired());

assert(local_observer1.use_count() == 0);

//The reference count will be deallocated when all weak pointers

//disappear. After that, the file is unmapped.

}

return 0;

}

//]

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