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- /* 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;
- }
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