| 1 | ////////////////////////////////////////////////////////////////////////////// |
|---|---|
| 2 | // |
| 3 | // (C) Copyright Ion Gaztanaga 2006-2012. |
| 4 | // Distributed under the Boost Software License, Version 1.0. |
| 5 | // (See accompanying file LICENSE_1_0.txt or copy at |
| 6 | // http://www.boost.org/LICENSE_1_0.txt) |
| 7 | // |
| 8 | // See http://www.boost.org/libs/interprocess for documentation. |
| 9 | // |
| 10 | ////////////////////////////////////////////////////////////////////////////// |
| 11 | |
| 12 | #include <boost/interprocess/detail/workaround.hpp> |
| 13 | |
| 14 | //[doc_shared_ptr |
| 15 | #include <boost/interprocess/managed_mapped_file.hpp> |
| 16 | #include <boost/interprocess/smart_ptr/shared_ptr.hpp> |
| 17 | #include <boost/interprocess/smart_ptr/weak_ptr.hpp> |
| 18 | #include <cassert> |
| 19 | //<- |
| 20 | #include "../test/get_process_id_name.hpp" |
| 21 | //-> |
| 22 | |
| 23 | using namespace boost::interprocess; |
| 24 | |
| 25 | //This is type of the object we want to share |
| 26 | struct type_to_share |
| 27 | {}; |
| 28 | |
| 29 | //This is the type of a shared pointer to the previous type |
| 30 | //that will be built in the mapped file |
| 31 | typedef managed_shared_ptr<type_to_share, managed_mapped_file>::type shared_ptr_type; |
| 32 | typedef managed_weak_ptr<type_to_share, managed_mapped_file>::type weak_ptr_type; |
| 33 | |
| 34 | //This is a type holding a shared pointer |
| 35 | struct shared_ptr_owner |
| 36 | { |
| 37 | shared_ptr_owner(const shared_ptr_type &other_shared_ptr) |
| 38 | : shared_ptr_(other_shared_ptr) |
| 39 | {} |
| 40 | |
| 41 | shared_ptr_owner(const shared_ptr_owner &other_owner) |
| 42 | : shared_ptr_(other_owner.shared_ptr_) |
| 43 | {} |
| 44 | |
| 45 | shared_ptr_type shared_ptr_; |
| 46 | //... |
| 47 | }; |
| 48 | |
| 49 | int main () |
| 50 | { |
| 51 | //Define file names |
| 52 | //<- |
| 53 | #if 1 |
| 54 | std::string mapped_file(boost::interprocess::ipcdetail::get_temporary_path()); |
| 55 | mapped_file += "/"; mapped_file += test::get_process_id_name(); |
| 56 | const char *MappedFile = mapped_file.c_str(); |
| 57 | #else |
| 58 | //-> |
| 59 | const char *MappedFile = "MyMappedFile"; |
| 60 | //<- |
| 61 | #endif |
| 62 | //-> |
| 63 | |
| 64 | //Destroy any previous file with the name to be used. |
| 65 | struct file_remove |
| 66 | { |
| 67 | file_remove(const char *MappedFile) |
| 68 | : MappedFile_(MappedFile) { file_mapping::remove(filename: MappedFile_); } |
| 69 | ~file_remove(){ file_mapping::remove(filename: MappedFile_); } |
| 70 | const char *MappedFile_; |
| 71 | } remover(MappedFile); |
| 72 | { |
| 73 | managed_mapped_file file(create_only, MappedFile, 65536); |
| 74 | |
| 75 | //Construct the shared type in the file and |
| 76 | //pass ownership to this local shared pointer |
| 77 | shared_ptr_type local_shared_ptr = make_managed_shared_ptr |
| 78 | (constructed_object: file.construct<type_to_share>(name: "object to share")(), managed_memory&: file); |
| 79 | assert(local_shared_ptr.use_count() == 1); |
| 80 | |
| 81 | //Share ownership of the object between local_shared_ptr and a new "owner1" |
| 82 | shared_ptr_owner *owner1 = |
| 83 | file.construct<shared_ptr_owner>(name: "owner1")(local_shared_ptr); |
| 84 | assert(local_shared_ptr.use_count() == 2); |
| 85 | |
| 86 | //local_shared_ptr releases object ownership |
| 87 | local_shared_ptr.reset(); |
| 88 | assert(local_shared_ptr.use_count() == 0); |
| 89 | assert(owner1->shared_ptr_.use_count() == 1); |
| 90 | |
| 91 | //Share ownership of the object between "owner1" and a new "owner2" |
| 92 | shared_ptr_owner *owner2 = |
| 93 | file.construct<shared_ptr_owner>(name: "owner2")(*owner1); |
| 94 | assert(owner1->shared_ptr_.use_count() == 2); |
| 95 | assert(owner2->shared_ptr_.use_count() == 2); |
| 96 | assert(owner1->shared_ptr_.get() == owner2->shared_ptr_.get()); |
| 97 | //<- |
| 98 | (void)owner2; |
| 99 | //-> |
| 100 | //The mapped file is unmapped here. Objects have been flushed to disk |
| 101 | } |
| 102 | { |
| 103 | //Reopen the mapped file and find again all owners |
| 104 | managed_mapped_file file(open_only, MappedFile); |
| 105 | |
| 106 | shared_ptr_owner *owner1 = file.find<shared_ptr_owner>(name: "owner1").first; |
| 107 | shared_ptr_owner *owner2 = file.find<shared_ptr_owner>(name: "owner2").first; |
| 108 | assert(owner1 && owner2); |
| 109 | |
| 110 | //Check everything is as expected |
| 111 | assert(file.find<type_to_share>("object to share").first != 0); |
| 112 | assert(owner1->shared_ptr_.use_count() == 2); |
| 113 | assert(owner2->shared_ptr_.use_count() == 2); |
| 114 | assert(owner1->shared_ptr_.get() == owner2->shared_ptr_.get()); |
| 115 | |
| 116 | //Now destroy one of the owners, the reference count drops. |
| 117 | file.destroy_ptr(ptr: owner1); |
| 118 | assert(owner2->shared_ptr_.use_count() == 1); |
| 119 | |
| 120 | //Create a weak pointer |
| 121 | weak_ptr_type local_observer1(owner2->shared_ptr_); |
| 122 | assert(local_observer1.use_count() == owner2->shared_ptr_.use_count()); |
| 123 | |
| 124 | { //Create a local shared pointer from the weak pointer |
| 125 | shared_ptr_type local_shared_ptr = local_observer1.lock(); |
| 126 | assert(local_observer1.use_count() == owner2->shared_ptr_.use_count()); |
| 127 | assert(local_observer1.use_count() == 2); |
| 128 | } |
| 129 | |
| 130 | //Now destroy the remaining owner. "object to share" will be destroyed |
| 131 | file.destroy_ptr(ptr: owner2); |
| 132 | assert(file.find<type_to_share>("object to share").first == 0); |
| 133 | |
| 134 | //Test observer |
| 135 | assert(local_observer1.expired()); |
| 136 | assert(local_observer1.use_count() == 0); |
| 137 | |
| 138 | //The reference count will be deallocated when all weak pointers |
| 139 | //disappear. After that, the file is unmapped. |
| 140 | } |
| 141 | return 0; |
| 142 | } |
| 143 | //] |
| 144 | |
| 145 |