使用boost :: iostreams mapped_file_source和filtering_streambuf来解压缩文件

Question

我打算处理大型压缩文件，并且我想将内存映射到文件以加速读取。我采用了现有的常规文件输入示例，但无法编译或工作:-)我正在使用C++ Boost 1.49

任何建议欢迎！

#include<iostream> 
#include<boost/iostreams/filtering_streambuf.hpp> 
#include<boost/iostreams/copy.hpp> 
#include<boost/iostreams/filter/zlib.hpp> 
#include<boost/iostreams/device/file.hpp> 
#include<boost/iostreams/device/mapped_file.hpp> 

void test_decoder_mmf() 
{ 
    using namespace std; 
    using namespace boost::iostreams; 
    //ifstream file("my_file.txt", ios_base::in | ios_base::binary); 
    mapped_file_source file("my_file.txt"); 
    filtering_streambuf<input> in; 
    in.push(zlib_decompressor()); 
    in.push(file); 
    copy(in,cout); 
} 

int main() 
{ 
    test_decoder_mmf(); 
    return 0; 
} 

In file included from /usr/local/include/boost/iostreams/operations.hpp:20:0, 
       from /usr/local/include/boost/iostreams/detail/adapter/mode_adapter.hpp:24, 
       from /usr/local/include/boost/iostreams/detail/resolve.hpp:19, 
       from /usr/local/include/boost/iostreams/detail/push.hpp:24, 
       from /usr/local/include/boost/iostreams/chain.hpp:29, 
       from /usr/local/include/boost/iostreams/filtering_streambuf.hpp:17, 
       from test_boost_iostreams2.cc:2: 
/usr/local/include/boost/iostreams/optimal_buffer_size.hpp: In function ‘std::streamsize boost::iostreams::optimal_buffer_size(const T&) [with T = boost::iostreams::mapped_file_source, std::streamsize = long int]’: 
/usr/local/include/boost/iostreams/chain.hpp:248:9: instantiated from ‘void boost::iostreams::detail::chain_base<Self, Ch, Tr, Alloc, Mode>::push_impl(const T&, std::streamsize, std::streamsize) [with T = boost::iostreams::mapped_file_source, Self = boost::iostreams::chain<boost::iostreams::input, char, std::char_traits<char>, std::allocator<char> >, Ch = char, Tr = std::char_traits<char>, Alloc = std::allocator<char>, Mode = boost::iostreams::input, std::streamsize = long int]’ 
/usr/local/include/boost/iostreams/chain.hpp:216:1: instantiated from ‘void boost::iostreams::detail::chain_base<Self, Ch, Tr, Alloc, Mode>::push(const T&, std::streamsize, std::streamsize, typename boost::disable_if<boost::iostreams::is_std_io<T> >::type*) [with T = boost::iostreams::mapped_file_source, Self = boost::iostreams::chain<boost::iostreams::input, char, std::char_traits<char>, std::allocator<char> >, Ch = char, Tr = std::char_traits<char>, Alloc = std::allocator<char>, Mode = boost::iostreams::input, std::streamsize = long int, typename boost::disable_if<boost::iostreams::is_std_io<T> >::type = void]’ 
/usr/local/include/boost/iostreams/chain.hpp:500:7: instantiated from ‘void boost::iostreams::detail::chain_client<Chain>::push_impl(const T&, std::streamsize, std::streamsize) [with T = boost::iostreams::mapped_file_source, Chain = boost::iostreams::chain<boost::iostreams::input, char, std::char_traits<char>, std::allocator<char> >, std::streamsize = long int]’ 
/usr/local/include/boost/iostreams/chain.hpp:488:1: instantiated from ‘void boost::iostreams::detail::chain_client<Chain>::push(const T&, std::streamsize, std::streamsize, typename boost::disable_if<boost::iostreams::is_std_io<T> >::type*) [with T = boost::iostreams::mapped_file_source, Chain = boost::iostreams::chain<boost::iostreams::input, char, std::char_traits<char>, std::allocator<char> >, std::streamsize = long int, typename boost::disable_if<boost::iostreams::is_std_io<T> >::type = void]’ 
test_boost_iostreams2.cc:17:17: instantiated from here 
/usr/local/include/boost/iostreams/optimal_buffer_size.hpp:39:55: error: ‘optimal_buffer_size’ is not a member of ‘impl {aka boost::iostreams::detail::optimal_buffer_size_impl<boost::iostreams::mapped_file_source>}’ 

Answer 1

对于那些谁可能有兴趣在这里是工作代码：

#include<iostream> 
#include<boost/iostreams/copy.hpp> 
#include<boost/iostreams/device/mapped_file.hpp> 
#include<boost/iostreams/filter/zlib.hpp> 
#include<boost/iostreams/filtering_streambuf.hpp> 
#include<boost/iostreams/filtering_stream.hpp> 
#include<boost/iostreams/stream.hpp> 

using namespace std; 
using namespace boost::iostreams; 

void test_decoder_mmf(const std::string&filename) 
{ 
    stream<mapped_file_source> file; 
    filtering_streambuf<input> in; 
    file.open(mapped_file_source(filename)); 
    in.push(zlib_decompressor()); 
    in.push(file); 
    copy(in,cout); 
} 

int main() 
{ 
    test_decoder_mmf("zlib-compressed-file"); 
    return 0; 
}