/* Boost.MultiIndex example of use of Boost.Interprocess allocators. * * Copyright 2003-2008 Joaquin M Lopez Munoz. * 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/multi_index for library home page. */ #if !defined(NDEBUG) #define BOOST_MULTI_INDEX_ENABLE_INVARIANT_CHECKING #define BOOST_MULTI_INDEX_ENABLE_SAFE_MODE #endif #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */ #include <algorithm> #include <boost/interprocess/allocators/allocator.hpp> #include <boost/interprocess/containers/string.hpp> #include <boost/interprocess/managed_mapped_file.hpp> #include <boost/interprocess/sync/named_mutex.hpp> #include <boost/interprocess/sync/scoped_lock.hpp> #include <boost/multi_index_container.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/member.hpp> #include <iostream> #include <iterator> #include <sstream> #include <string> using boost::multi_index_container; using namespace boost::multi_index; namespace bip=boost::interprocess; /* shared_string is a string type placeable in shared memory, * courtesy of Boost.Interprocess. */ typedef bip::basic_string< char,std::char_traits<char>, bip::allocator<char,bip::managed_mapped_file::segment_manager> > shared_string; /* Book record. All its members can be placed in shared memory, * hence the structure itself can too. */ struct book { shared_string name; shared_string author; unsigned pages; unsigned prize; book(const shared_string::allocator_type& al): name(al),author(al),pages(0),prize(0) {} friend std::ostream& operator<<(std::ostream& os,const book& b) { os<<b.author<<": \""<<b.name<<"\", $"<<b.prize<<", "<<b.pages<<" pages\n"; return os; } }; /* partial_str_less allows for partial searches taking into account * only the first n chars of the strings compared against. See * Tutorial: Basics: Special lookup operations for more info on this * type of comparison functors. */ /* partial_string is a mere string holder used to differentiate from * a plain string. */ struct partial_string { partial_string(const shared_string& str):str(str){} shared_string str; }; struct partial_str_less { bool operator()(const shared_string& x,const shared_string& y)const { return x<y; } bool operator()(const shared_string& x,const partial_string& y)const { return x.substr(0,y.str.size())<y.str; } bool operator()(const partial_string& x,const shared_string& y)const { return x.str<y.substr(0,x.str.size()); } }; /* Define a multi_index_container of book records with indices on * author, name and prize. The index on names allows for partial * searches. This container can be placed in shared memory because: * * book can be placed in shared memory. * * We are using a Boost.Interprocess specific allocator. */ /* see Compiler specifics: Use of member_offset for info on * BOOST_MULTI_INDEX_MEMBER */ typedef multi_index_container< book, indexed_by< ordered_non_unique< BOOST_MULTI_INDEX_MEMBER(book,shared_string,author) >, ordered_non_unique< BOOST_MULTI_INDEX_MEMBER(book,shared_string,name), partial_str_less >, ordered_non_unique< BOOST_MULTI_INDEX_MEMBER(book,unsigned,prize) > >, bip::allocator<book,bip::managed_mapped_file::segment_manager> > book_container; /* A small utility to get data entered via std::cin */ template<typename T> void enter(const char* msg,T& t) { std::cout<<msg; std::string str; std::getline(std::cin,str); std::istringstream iss(str); iss>>t; } void enter(const char* msg,std::string& str) { std::cout<<msg; std::getline(std::cin,str); } void enter(const char* msg,shared_string& str) { std::cout<<msg; std::string stdstr; std::getline(std::cin,stdstr); str=stdstr.c_str(); } int main() { /* Create (or open) the memory mapped file where the book container * is stored, along with a mutex for synchronized access. */ bip::managed_mapped_file seg( bip::open_or_create,"./book_container.db", 65536); bip::named_mutex mutex( bip::open_or_create,"7FD6D7E8-320B-11DC-82CF-F0B655D89593"); /* create or open the book container in shared memory */ book_container* pbc=seg.find_or_construct<book_container>("book container")( book_container::ctor_args_list(), book_container::allocator_type(seg.get_segment_manager())); std::string command_info= "1. list books by author\n" "2. list all books by prize\n" "3. insert a book\n" "4. delete a book\n" "0. exit\n"; std::cout<<command_info; /* main loop */ for(bool exit=false;!exit;){ int command=-1; enter("command: ",command); switch(command){ case 0:{ /* exit */ exit=true; break; } case 1:{ /* list books by author */ std::string author; enter("author (empty=all authors): ",author); /* operations with the container must be mutex protected */ bip::scoped_lock<bip::named_mutex> lock(mutex); std::pair<book_container::iterator,book_container::iterator> rng; if(author.empty()){ rng=std::make_pair(pbc->begin(),pbc->end()); } else{ rng=pbc->equal_range( shared_string( author.c_str(), shared_string::allocator_type(seg.get_segment_manager()))); } if(rng.first==rng.second){ std::cout<<"no entries\n"; } else{ std::copy( rng.first,rng.second,std::ostream_iterator<book>(std::cout)); } break; } case 2:{ /* list all books by prize */ bip::scoped_lock<bip::named_mutex> lock(mutex); std::copy( get<2>(*pbc).begin(),get<2>(*pbc).end(), std::ostream_iterator<book>(std::cout)); break; } case 3:{ /* insert a book */ book b(shared_string::allocator_type(seg.get_segment_manager())); enter("author: ",b.author); enter("name: " ,b.name); enter("prize: " ,b.prize); enter("pages: " ,b.pages); std::cout<<"insert the following?\n"<<b<<"(y/n): "; char yn='n'; enter("",yn); if(yn=='y'||yn=='Y'){ bip::scoped_lock<bip::named_mutex> lock(mutex); pbc->insert(b); } break; } case 4:{ /* delete a book */ shared_string name( shared_string::allocator_type(seg.get_segment_manager())); enter( "name of the book (you can enter\nonly the first few characters): ", name); typedef nth_index<book_container,1>::type index_by_name; index_by_name& idx=get<1>(*pbc); index_by_name::iterator it; book b(shared_string::allocator_type(seg.get_segment_manager())); { /* Look for a book whose title begins with name. Note that we * are unlocking after doing the search so as to not leave the * container blocked during user prompting. That is also why a * local copy of the book is done. */ bip::scoped_lock<bip::named_mutex> lock(mutex); it=idx.find(partial_string(name)); if(it==idx.end()){ std::cout<<"no such book found\n"; break; } b=*it; } std::cout<<"delete the following?\n"<<b<<"(y/n): "; char yn='n'; enter("",yn); if(yn=='y'||yn=='Y'){ bip::scoped_lock<bip::named_mutex> lock(mutex); idx.erase(it); } break; } default:{ std::cout<<"select one option:\n"<<command_info; break; } } } return 0; }