June 2014 - Boost-users - lists.preview.boost.org

[Graph] Newbie on A*
by Sensei 04 Jul '14

04 Jul '14

Dear all, I am fiddling with the A* example on cities in order to learn how to use the A* search. Obviously, I cannot make it work :) The main goal is this, but I'm way too far from this: make A* fail when the path is longer, **not costlier**, than a constant. But right now I'd just like to have A* working on a graph. :) In order to see the different results, I've paired it with a Dijkstra search, and my A* heuristics is quite simple: constant. Dijkstra works fine, but A* stops at the first node, and the target isn't reached (but a path is available). What am I doing wrong? Forgive me if I'm making a stupid mistake bu I'm completely a newbie! If you need the graph, here's the link: https://dl.dropboxusercontent.com/u/15635416/g.txt Thanks! #include <cstdio> #include <cstdlib> #include <iostream> #include <utility> #include <algorithm> #include <numeric> #include <deque> #include <unordered_set> #include <vector> #include <fstream> #include <list> #include <boost/graph/graph_traits.hpp> #include <boost/graph/compressed_sparse_row_graph.hpp> #include <boost/graph/dijkstra_shortest_paths.hpp> #include <boost/graph/breadth_first_search.hpp> #include <boost/graph/depth_first_search.hpp> #include <boost/pending/indirect_cmp.hpp> #include <boost/range/irange.hpp> #include <boost/property_map/property_map.hpp> #include <boost/graph/astar_search.hpp> // Properties: weights are int typedef boost::property<boost::edge_weight_t, int> edge_weight; // The graph itself as a compressed sparse row matrix typedef boost::compressed_sparse_row_graph<boost::bidirectionalS, boost::no_property, edge_weight> boost_graph; // Vertex iterator typedef boost::graph_traits<boost_graph>::vertex_iterator vertex_iterator; // Edge iterator typedef boost::graph_traits<boost_graph>::edge_iterator edge_iterator; // Adjacent nodes iterator typedef boost::graph_traits<boost_graph>::adjacency_iterator adjacency_iterator; typedef boost::graph_traits<boost_graph>::out_edge_iterator outward_iterator; typedef boost::graph_traits<boost_graph>::in_edge_iterator inward_iterator; // Property maps typedef boost::property_map<boost_graph, boost::vertex_index_t>::type index_map; //typedef boost::property_map<boost_graph, boost::vertex_name_t> name_map; // Property iterators typedef boost::iterator_property_map<std::size_t*, index_map, std::size_t, std::size_t&> predecessor_map; typedef boost::iterator_property_map<std::size_t*, index_map, std::size_t, std::size_t&> distance_map; bool isValid(std::size_t index) { return (index >= 0) && (index <= 12); } // **************************************************************************** // A* heuristics template <class graph_type> class astar_heuristic : public boost::astar_heuristic<graph_type, std::size_t> { public: typedef typename boost::graph_traits<graph_type>::vertex_descriptor vertex_type; astar_heuristic(vertex_type goal) : goal_(goal) { }; std::size_t operator()(vertex_type u) { return 3; } private: vertex_type goal_; }; // Class to be used to terminate the A* algorithm class exit_astar { public: exit_astar(bool found) { }; }; // A* visitor that terminates when we find the goal template <class vertex_type> class astar_visitor : public boost::default_astar_visitor { public: astar_visitor(vertex_type goal) : goal_(goal) { }; template <class Graph> void examine_vertex(vertex_type u, Graph& g) { //std::cout << "EXAM: " << u << std::endl; if (u == goal_) throw exit_astar(true); } private: vertex_type goal_; }; // **************************************************************************** int main(int argc, const char * argv[]) { std::vector<std::pair<std::size_t, std::size_t>> graph_edges; std::vector<int> edge_weight; int n_nodes; int read_a, read_b, read_w; n_nodes = -1; std::ifstream igraph("/Users/senseiwa/Documents/Projects/scratch/tbb/g.txt"); while(igraph >> read_a >> read_b >> read_w) { if (read_a > n_nodes) n_nodes = read_a; if (read_b > n_nodes) n_nodes = read_b; read_a--; read_b--; graph_edges.push_back(std::make_pair(read_a, read_b)); edge_weight.push_back(read_w); } std::cout << "+++ READ # NODES: " << n_nodes << std::endl; // Create the graph boost_graph graph(boost::edges_are_unsorted_multi_pass, graph_edges.begin(), graph_edges.end(), edge_weight.data(), n_nodes); std::cout << "Graph statistics: " << std::endl; std::cout << "Nodes: " << boost::num_vertices(graph) << std::endl; std::cout << "Edges: " << graph_edges.size() << std::endl; edge_iterator ei, ee; std::size_t source_node = std::stoul(argv[1]); std::size_t destination_node = std::stoul(argv[2]); std::cout << ">> SOURCE NODE " << source_node << std::endl; std::cout << "Degrees in/out: " << source_node << std::endl; std::cout << boost::in_degree(boost::vertex(source_node, graph), graph) << std::endl; std::cout << boost::out_degree(boost::vertex(source_node, graph), graph) << std::endl; std::cout << "Degrees in/out: " << destination_node << std::endl; std::cout << boost::in_degree(boost::vertex(destination_node, graph), graph) << std::endl; std::cout << boost::out_degree(boost::vertex(destination_node, graph), graph) << std::endl; std::vector<std::size_t> preds(boost::num_vertices(graph)); std::vector<std::size_t> dists(boost::num_vertices(graph)); index_map idx_map = boost::get(boost::vertex_index, graph); predecessor_map pred_map(preds.data(), idx_map); distance_map dist_map(dists.data(), idx_map); boost::dijkstra_shortest_paths(graph, source_node, boost::distance_map(dist_map).predecessor_map(pred_map)); typedef std::vector<boost_graph::edge_descriptor> path_type; path_type spath; std::cout << ">> SOURCE NODE " << source_node << std::endl; std::cout << ">> DESTINATION NODE " << destination_node << std::endl; // ******* DIJKSTRA ******************************************************** std::size_t v = destination_node; // We want to start at the destination and work our way back to the source for(std::size_t u = pred_map[v]; // Start by setting 'u' to the destintaion node's predecessor u != v; // Keep tracking the path until we get to the source v = u, u = pred_map[v]) // Set the current vertex to the current predecessor, and the predecessor to one level up { std::pair<boost_graph::edge_descriptor, bool> edgePair = boost::edge(u, v, graph); boost_graph::edge_descriptor edge = edgePair.first; spath.push_back(edge); } // Write shortest path int totalDistance = 0; for(path_type::reverse_iterator pathIterator = spath.rbegin(); pathIterator != spath.rend(); ++pathIterator) { std::cout << boost::source(*pathIterator, graph) << " - " << boost::target(*pathIterator, graph) << " = " << boost::get(boost::edge_weight, graph, *pathIterator) << std::endl; totalDistance += boost::get(boost::edge_weight, graph, *pathIterator); } std::cout << "Shortest Dijkstra path from " << source_node << " to " << destination_node << " cost " << totalDistance << std::endl; // ******* A* ************************************************************** // A* search predecessor and cost std::vector<std::size_t> p(boost::num_vertices(graph)); std::vector<std::size_t> d(boost::num_vertices(graph)); try { // A* parameter interface astar_search(graph, source_node, astar_heuristic<boost_graph>(destination_node), boost::predecessor_map(&p[0]).distance_map(&d[0]).visitor(astar_visitor<std::size_t>(destination_node))); } catch(exit_astar fg) { std::list<std::size_t> shortest_path; for(std::size_t v = source_node; ; v = p[v]) { shortest_path.push_front(v); if(p[v] == v) break; } auto spi = shortest_path.begin(); std::cout << "node " << source_node << std::endl; for(++spi; spi != shortest_path.end(); ++spi) std::cout << "node " << *spi << std::endl; std::cout << "Shortest A* path from " << source_node << " to " << destination_node << " cost " << d[destination_node] << std::endl; std::cout << shortest_path.size() << std::endl; return 0; } std::cout << "Didn't find a path from " << source_node << "to" << destination_node << "!" << std::endl; return 0; } +++ READ # NODES: 200 Graph statistics: Nodes: 200 Edges: 4000 >> SOURCE NODE 1 Degrees in/out: 1 0 35 Degrees in/out: 192 39 1 >> SOURCE NODE 1 >> DESTINATION NODE 192 1 - 47 = 2 47 - 91 = 3 91 - 120 = 1 120 - 175 = 1 175 - 192 = 10 Shortest Dijkstra path from 1 to 192 cost 17 node 1 Shortest A* path from 1 to 192 cost 17 1

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Why does async_connect() call listen()?
by Soren Dreijer 01 Jul '14

01 Jul '14

Hi there, By coincidence, I ended up looking at a stack trace where my application calls async_connect() on a asio::ip::tcp::socket. Two things took me by surprise: 1. Asio calls listen() under the hood. Why does it do that when I'm just trying to make an outbound TCP connection? 2. If the listen() call above is indeed required, why does it happen on the same thread where I call async_connect()? I thought the point of the method was to defer the work to the reactor? (For what it's worth, I've had a case on a customer's machine where the call to listen() would hang for 30 seconds before returning -- probably because of a bad firewall -- causing my entire app to hang since the code assumes async_connect() is indeed async.) I've included the full stack trace below. Thanks, Soren 0:000> k ChildEBP RetAddr 0117db50 0f681c65 WS2_32!listen 0117db70 0f691013 EvoClr!boost::asio::detail::socket_ops::listen+0x35 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\socket_ops.ipp @ 658] 0117dbd8 0f690e9f EvoClr!boost::asio::detail::socket_select_interrupter::open_descriptors+0x163 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\socket_select_interrupter.ipp @ 78] 0117dbe4 0f690cc0 EvoClr!boost::asio::detail::socket_select_interrupter::socket_select_interrupter+0xf [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\socket_select_interrupter.ipp @ 42] 0117dc1c 0f690c1e EvoClr!boost::asio::detail::select_reactor::select_reactor+0x70 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\select_reactor.ipp @ 48] 0117dc44 0f17837e EvoClr!boost::asio::detail::service_registry::create<boost::asio::detail::select_reactor>+0x4e [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\service_registry.hpp @ 81] 0117dc80 0f6909e9 EvoClr!boost::asio::detail::service_registry::do_use_service+0x9e [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\service_registry.ipp @ 123] 0117dca0 0f6908ee EvoClr!boost::asio::detail::service_registry::use_service<boost::asio::detail::select_reactor>+0x39 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\service_registry.hpp @ 49] 0117dca8 0f68fab0 EvoClr!boost::asio::use_service<boost::asio::detail::select_reactor>+0xe [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\impl\io_service.hpp @ 34] 0117dcbc 0f68f731 EvoClr!boost::asio::detail::win_iocp_socket_service_base::get_reactor+0x30 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\win_iocp_socket_service_base.ipp @ 620] 0117dce4 0f68f6f1 EvoClr!boost::asio::detail::win_iocp_socket_service_base::start_connect_op+0x11 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\win_iocp_socket_service_base.ipp @ 550] 0117dd28 0f68ed22 EvoClr!boost::asio::detail::win_iocp_socket_service<boost::asio::ip::tcp>::async_connect<boost::_bi::bind_t<void,boost::_mfi::mf1<void,Swift::BoostConnection,boost::system::error_code const &>,boost::_bi::list2<boost::_bi::value<boost::shared_ptr<Swift::BoostConnection> >,boost::arg<1> > > >+0xc1 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\win_iocp_socket_service.hpp @ 515] 0117dd68 0f68c41a EvoClr!boost::asio::stream_socket_service<boost::asio::ip::tcp>::async_connect<boost::_bi::bind_t<void,boost::_mfi::mf1<void,Swift::BoostConnection,boost::system::error_code const &>,boost::_bi::list2<boost::_bi::value<boost::shared_ptr<Swift::BoostConnection> >,boost::arg<1> > > >+0x52 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\stream_socket_service.hpp @ 234] 0117ddec 0f68a32e EvoClr!boost::asio::basic_socket<boost::asio::ip::tcp,boost::asio::stream_socket_service<boost::asio::ip::tcp> >::async_connect<boost::_bi::bind_t<void,boost::_mfi::mf1<void,Swift::BoostConnection,boost::system::error_code const &>,boost::_bi::list2<boost::_bi::value<boost::shared_ptr<Swift::BoostConnection> >,boost::arg<1> > > >+0x11a [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\basic_socket.hpp @ 779] 0117de9c 0f210146 EvoClr!Swift::BoostConnection::connect+0x11e [c:\private\src\vendor\swift\swiften\network\boostconnection.cpp @ 70]

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[atomic] ThreadSanitizer reports a data race when using the code from "reference counting" example
by Adam Romanek 01 Jul '14

01 Jul '14

Hi Boosters! I'd like to draw your attention to an issue with Boost.Atomic that I encountered when using ThreadSanitizer. The problem is that when using the code shown in "reference counting" example [1] from the docs, the ThreadSanitizer reports a data race. Everything is described in detail in a StackOverflow thread [2] so I don't want to repeat all that here. Please help me determine whether it's a false positive, an issue in Boost.Atomic or a wrong usage of the code. Additionally, I don't understand this: Write of size 1 at 0x7d040000f7f0 by thread T2: #0 operator delete(void*) <null>:0 (a.out+0x00000004738b) What kind of write does ThreadSanitizer might refer to? WBR, Adam Romanek [1] http://www.boost.org/doc/libs/1_55_0/doc/html/atomic/usage_examples.html#bo… [2] http://stackoverflow.com/questions/24446561/threadsanitizer-reports-data-ra…

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Oneshot fixture per test suit
by Florian Lindner 30 Jun '14

30 Jun '14

Hello, is it possible to have a test fixture that is created once per test suite and is destroyed after the last test of the test suite has been ran? A test suite level fixture is created before each and every test, a global fixture just once for the entire test programm. Thanks, Florian

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Re: [Boost-users] [fusion] maps and arrays
by Seeger, Steven D. (GSFC-444.0)[Embedded Flight Systems, Inc] 29 Jun '14

29 Jun '14

From: Agust?n K-ballo Berg? Subject: Re: [Boost-users] [fusion] maps and arrays >Not an official answer in any way, but considering it's not explicitly >documented as supported and your test case also fails when replacing >`fusion::map` with `std::tuple` I would consider it just a fluke in the >past. On the other hand, the following code compiles correctly (albeit >with possibly a warning): Hi Agustin thanks for your reply. You are correct that what I'm doing is not documented. In fact, it doesn't really make sense now that I look at it. The for_each should be called on each type. If the type is an array it doesn't make sense for a for_each to break down the array. That said, there should be some way to specialize operator() in the functor passed to it in order to correctly handle array types. > typedef std::tuple<short, > int, > std::array<int, 2>, // note std::array > std::string > test_t; You inspired me with your use of std::array to try it out in my example. I changed "print_me" to use t.second instead of just t (which is correct) and then made a template function to support std::array with std::cout. That did the trick. Of course, the real goal here would be to handle it on the for_each side not the cout side, as outputting the types is not always the goal. > test_t test{1, 2, {}, {"hello"}}; You know one other weird thing, is that with boost 1.53 I could initialize this with std::array<int, 2> as: test_1 test{1,2, {{3,4}}, {"hello"}}; Now with 1.55 it's only working with: test_1 test{1,2,std::int<array, 2>{3, 4}, "hello"}; //missing braces on string correct I'm using both gcc 4.8.3 and clang 3.4.1. Steven

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[thread] mutex is locked
by gast128 29 Jun '14

29 Jun '14

Dear all, does anybody know if there is a possibility to check if a mutex is locked? There is an 'owns_lock' on the lock type but not on the mutex. The main use case for me is debugging (and documentation) purposes: void MyClass::Process() { boost::unique_lock<boost::mutex> lck(m_mtx); ProcessImpl(); } void MyClass::ProcessImpl() { _ASSERT(m_mtx.is_locked()); //does not exist :( }

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Selecting one element per fusion sequence using mpl::int_s
by gsermaid 29 Jun '14

29 Jun '14

Dear all, I am trying to create a fusion sequence whose elements are non-const references to the elements of given set of sequences. In particular, for a given sequence of integral constants, say vector< int_<2>, int_<1> >, and two fusion sequences, say X = vector< X0, X1, X2, X3 > and Y = vector< Y0, Y1, Y2 >, I would like to create the following sequence R = vector< X2&, Y1& >, such that at<0>(R) == at<2>(X) and at<1>(R) == at<1>(Y). I am using fusion::transform to achieve the above but the transform function takes the sequences as const references so I end up with R = vector<const X2&, const Y1&>, which is not what I want. Below is my code; any ideas on how to get a sequence of non-const references would be greatly appreciated. Thanks for reading! #include <boost/fusion/include/vector.hpp> #include <boost/fusion/include/transform.hpp> #include <boost/fusion/sequence/io/out.hpp> #include <boost/fusion/include/at.hpp> #include <boost/mpl/assert.hpp> #include <boost/type_traits.hpp> #include <iostream> using namespace boost::fusion; using boost::mpl::int_; using my_ints = vector< int_<2>, int_<1> >; using my_x = vector<int, double, unsigned, float>; using my_y = vector<unsigned, float, long>; using joined = vector<my_x, my_y>; struct my_functor { template <class I, class Seq> typename result_of::at<Seq, I>::type operator()(I& i, Seq& seq) const { return boost::fusion::at<I>(seq); } }; int main() { my_ints ints; my_x x(-2, 3.5, 15, -1.3); my_y y(4, 10.1, 100); joined jv(x, y); auto tv = transform(ints, jv, my_functor()); std::cout << tv << std::endl; // prints (15 10.1) // these two fail to compile because the first argument is const-qualified BOOST_MPL_ASSERT(( boost::is_same< decltype(at_c<0>(tv)), unsigned& > )); BOOST_MPL_ASSERT(( boost::is_same< decltype(at_c<1>(tv)), float& > )); }

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[fusion] maps and arrays
by Seeger, Steven D. (GSFC-444.0)[Embedded Flight Systems, Inc] 28 Jun '14

28 Jun '14

I've had some code written with boost 1.53 a while ago that uses fusion maps to define at compile-time packet structures. There is then compile time generated code that handles marshaling, unmarshaling, and packet size calculation on these structures. One of the big reasons for going this route was the ability to have arrays contained in the packets. When upgrading from boost 1.53 to 1.55 on my Gentoo box, this all broke. I posted a bug report at https://svn.boost.org/trac/boost/ticket/10133 but it seems fusion bug reports don't get much activity here. I'm contacting the list to ask if the use of arrays in containers was just a fluke or if it should be working and something happened in 1.55 (or possibly 1.54 which I never tried.) If this is not something that should be supported then I will abandon this code and go with something else. It's been really nice to work on some client/server stuff with it because the work that went in to handle the code generation saves a lot of time going forward. Thanks, Steven

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Boost.Coroutine with segmentation fault
by Van Pers 27 Jun '14

27 Jun '14

Hi all, I am writting a code with Coroutines lib, this code uses coroutines in a recursive way but when I create a large number of coroutines the program crashes (segmentation fault). I write a simplified version that reproduces this error: #include<iostream> #include<cstdlib> #include<boost/coroutine/all.hpp> #include <boost/bind.hpp> #include <boost/shared_ptr.hpp> class FClass{ private: int n; public: boost::coroutines::coroutine<void>::pull_type* startResume; FClass(int n) : n(n){ startResume = NULL; } void resume(){ if(startResume && *(startResume)) (*(startResume))(); } void doSomething ( boost::coroutines::coroutine< void >::push_type & fPause){ if (n > 2){ FClass* tc1 = new FClass(--n); tc1->startResume = new boost::coroutines::coroutine<void>::pull_type( boost::bind( &FClass::doSomething, tc1, _1) ); FClass* tc2 = new FClass(--n); tc2->startResume = new boost::coroutines::coroutine<void>::pull_type( boost::bind( &FClass::doSomething, tc2, _1) ); fPause(); tc1->resume(); tc2->resume(); } return; } }; int main(int argc, char** argv){ int max = 10; if (argc > 1){ max = atoi(argv[1]); } FClass* firstObject = new FClass (max) ; firstObject->startResume = new boost::coroutines::coroutine<void>::pull_type( boost::bind(&FClass::doSomething, firstObject, _1) ); firstObject->resume(); } gdb output reports:"memset () at ../sysdeps/x86_64/memset.S:78 ../sysdeps/x86_64/memset.S:No such file or directory." Anybody can help me? Regards, Van

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core when using managed shared memory -- file based
by Sean K 27 Jun '14

27 Jun '14

I have a client and server set up where the client would write to the shared memory via a managed memory vector. And then the server would read that shared memory via the managed mapped file. It works for most situations. However, I just ran into a situation where the client -- writing to the vector, crashes. and I am trying to figure out what caused the crash. Below are the client (writer) and the server (reader) source code.... as close as to the current. Any insights as to why the vector.push_back() crashed? (this is happening on RH 5.9 64 bit OS.. but the code is compiled for 32 bit.) client: #include <iostream> #include <iostream> #include <string> #include <cstdlib> using namespace std; #include "fileheader.h" int main() { std::string data = "Hello"; char myinput[1024]; printf("enter number of count \n"); scanf("%s", &myinput); printf("You entered %s \n", myinput); data = myinput; int count = std::atoi(myinput); for (int counter = 0; counter < count; counter ++) { try { std::string tmpPath = "/var/tmp/log/testfile/ManagedMappedFile";; printf("temp directory: %s \n", tmpPath.c_str()); managed_mapped_file segment(open_or_create, tmpPath.c_str(), SHARED_MEMORY_SIZE); printf("initialized managed shared memory \n"); BString bstrData(segment.get_segment_manager()); bstrData = "hello world"; StrAllocator alloc_init(segment.get_segment_manager()); printf("ALLOCATED memory successfully\n"); BStrVector *myvec = segment.find_or_construct<BStrVector> (SHARED_VECTOR_NAME)(alloc_init); myvec->push_back(bstrData); segment.flush(); printf("inserted mystring into shmvector %d\n", counter); } catch (boost::interprocess::bad_alloc e) { printf("we caught bad alloc\n"); printf("explanation: %s\n", e.what()); printf("error code: %d\n", e.get_error_code()); printf("native: %d\n", e.get_native_error()); break; } catch (...) { printf("caught unknown exception\n"); } } printf("wrote number"); return 0; } contents of fileheader.h #ifndef FILEHEADER_H_ #define FILEHEADER_H_ #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/interprocess/managed_mapped_file.hpp> #include <boost/thread/thread.hpp> #include <boost/interprocess/containers/vector.hpp> #include <boost/interprocess/containers/string.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <boost/interprocess/detail/tmp_dir_helpers.hpp> using namespace boost::interprocess; typedef boost::interprocess::managed_mapped_file::segment_manager segment_manager_t; typedef boost::interprocess::allocator<char, segment_manager_t> ShmemAllocator; typedef boost::interprocess::basic_string<char, std::char_traits<char>, ShmemAllocator> BString; typedef boost::interprocess::allocator<BString, segment_manager_t> StrAllocator; typedef boost::interprocess::vector<BString, StrAllocator> BStrVector; typedef std::pair<BString *, std::size_t> BStringPair; typedef std::pair<BStrVector *, std::size_t> BStrVectorPair; const char * SHARED_VECTOR_NAME = "MyVector"; const int SHARED_MEMORY_SIZE = 65536; #endif /* FILEHEADER_H_ */ g++ -m32 -fPIC -Xlinker -zmuldefs filewriter.cpp -o writer -I/cots/boost_1_42_0/include -L/cots/boost_1_42_0/lib -lboost_thread -lboost_system -pthread Server: #include <iostream> #include <string> #include <cstdlib> using namespace std; #include "../../filewriter/src/fileheader.h" int main() { int count = 0; std::string tmpPath = "/var/tmp/log/testfile"; //boost::interprocess::detail::get_tmp_base_dir(tmpPath); printf("temp directory: %s \n", tmpPath.c_str()); //boost::interprocess::detail::create_tmp_dir_and_get_filename("ManagedMappedFile", tmpPath); printf("temp file: %s \n", tmpPath.c_str()); // file_mapping::remove(tmpPath.c_str()); while (true) { try { managed_mapped_file segment(open_only, tmpPath.c_str()); if (segment.get_num_named_objects() > 0){ BStrVectorPair message = segment.find<BStrVector> (SHARED_VECTOR_NAME); printf("stuff in memory\n"); int size = message.first->size(); int retcode = 0; bool success=true; printf("PROCESS: Number of messages: %d\n", size); for (int imessage=0; imessage < size ; imessage++){ const char * const buffer = message.first->at(imessage).c_str(); int len = message.first->at(imessage).length(); printf("PROCESS: going to process this message: %s\n" , buffer); } printf("p.second: %d \n", message.second); segment.destroy<BStrVectorPair>(SHARED_VECTOR_NAME); } } catch (exception& e){ printf("exception %s", e.what()); } catch (...){ printf("unexpected exception"); } int msecs = 2000; boost::this_thread::sleep(boost::posix_time::milliseconds(msecs)); printf("sleeping...\n"); } return 0; } g++ -m32 -fPIC -Xlinker -zmuldefs filereader.cpp -o reader -I/cots/boost_1_42_0/include -L/cots/boost_1_42_0/lib -lboost_thread -lboost_system -pthread

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