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| <H1 CLASS="title">Memory-Mapped Files</H1> |
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| <DL class="page-index"> |
| <DT><A href="#overview">Overview</A></DT> |
| <DT><A href="#acknowledgments">Acknowledgments</A></DT> |
| <DT><A href="#installation">Installation</A></DT> |
| <DT><A href="#headers">Headers</A></DT> |
| <DT><A href="#reference">Reference</A> |
| <OL> |
| <LI CLASS="square"><A href="#mapped_file_params">Class <CODE>mapped_file_params</CODE></A></LI> |
| <LI CLASS="square"><A href="#mapped_file_source">Class <CODE>mapped_file_source</CODE></A></LI> |
| <LI CLASS="square"><A href="#mapped_file_sink">Class <CODE>mapped_file_sink</CODE></A></LI> |
| <LI CLASS="square"><A href="#mapped_file">Class <CODE>mapped_file</CODE></A></LI> |
| </OL> |
| </DT> |
| </DL> |
| |
| <HR> |
| |
| <A NAME="overview"></A> |
| <H2>Overview</H2> |
| |
| <P> |
| The classes <CODE>mapped_file_source</CODE>, <CODE>mapped_file_sink</CODE> and <CODE>mapped_file</CODE> provide access to memory-mapped files on Windows and POSIX systems. These <A HREF="../guide/concepts.html#device_concepts">Devices</A> behave much like the <A HREF="file.html">File Wrappers</A> <CODE>basic_file_source</CODE>, <CODE>basic_file_sink</CODE> and <CODE>basic_file</CODE>, with the following important differences: |
| </P> |
| <UL> |
| <LI CLASS="square">By default, files must exist before being opened, and are not truncated; attempting to write past the end of a file results in an error. To map a file which does not yet exist, use <A HREF="#mapped_file_params_size"><CODE>mapped_file_params::new_file_size</CODE></A>. |
| <LI CLASS="square">Files are always opened in binary mode. |
| <LI CLASS="square">Wide-character streams are not supported. |
| </UL> |
| <P> |
| Wide-character versions of the memory-mapped file Devices may be defined as follows, using the template <A HREF="code_converter.html"><CODE>code_converter</CODE></A>: |
| <PRE CLASS="broken_ie"> <SPAN CLASS="preprocessor">#include</SPAN> <A CLASS="header" HREF="../../../../boost/iostreams/code_converter.hpp"><SPAN CLASS="literal"><boost/iostreams/code_converter.hpp></SPAN></A> |
| <SPAN CLASS="preprocessor">#include</SPAN> <A CLASS="header" HREF="../../../../boost/iostreams/device/mapped_file.hpp"><SPAN CLASS="literal"><boost/iostreams/device/mapped_file.hpp></SPAN></A> |
| |
| <SPAN CLASS="keyword">typedef</SPAN> code_converter<mapped_file_source> <SPAN CLASS="defined">wmapped_file_source</SPAN>; |
| <SPAN CLASS="keyword">typedef</SPAN> code_converter<mapped_file_sink> <SPAN CLASS="defined">wmapped_file_sink</SPAN>;</PRE> |
| </P> |
| |
| <A NAME="acknowledgments"></A> |
| <H2>Acknowledgments</H2> |
| |
| <P> |
| The memory-mapped file Devices are based on the work of Craig Henderson (<A CLASS="bib_ref" HREF="../bibliography.html#henderson">[Henderson]</A>). Additionals features were implemented by Jonathan Graehl. |
| </P> |
| |
| <A NAME="installation"></A> |
| <H2>Installation</H2> |
| |
| <P> |
| The memory-mapped file Devices depend on the source file <A CLASS="header" HREF="../../src/mapped_file.cpp"><CODE><libs/iostreams/src/mapped_file.cpp></CODE></A>. This source file makes use of Windows or POSIX headers depending on the user's operating system. For installation instructions see <A HREF="../installation.html">Installation</A>. |
| </P> |
| |
| <A NAME="headers"></A> |
| <H2>Headers</H2> |
| |
| <DL class="page-index"> |
| <DT><A CLASS="header" HREF="../../../../boost/iostreams/device/mapped_file.hpp"><CODE><boost/iostreams/device/mapped_file.hpp></CODE></A></DT> |
| </DL> |
| |
| <A NAME="reference"></A> |
| <H2>Reference</H2> |
| |
| <A NAME="mapped_file_params"></A> |
| <H3>1. Class <CODE>mapped_file_params</CODE></H3> |
| |
| <H4>Description</H4> |
| |
| <P>Class encapsulating the parameters used to open a memory-mapped file.</P> |
| |
| <H4>Synopsis</H4> |
| |
| <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { |
| |
| <SPAN CLASS="keyword">struct</SPAN> <SPAN CLASS="defined">mapped_file_params</SPAN> { |
| <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_params(); |
| <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_params(<SPAN CLASS='keyword'>const</SPAN> std::string& path); |
| std::string <A CLASS='documented' HREF='#mapped_file_params_hint'>path</A>; |
| mapped_file::mapmode <A CLASS='documented' HREF='#mapped_file_params_flags'>flags</A>; |
| std::ios_base::openmode <A CLASS='documented' HREF='#mapped_file_params_mode'>mode</A>; // Deprecated |
| stream_offset <A CLASS='documented' HREF='#mapped_file_params_offset'>offset</A>; |
| std::size_t <A CLASS='documented' HREF='#mapped_file_params_length'>length</A>; |
| stream_offset <A CLASS="documented" HREF="#mapped_file_params_size">new_file_size</A>; |
| <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* <A CLASS='documented' HREF='#mapped_file_params_hint'>hint</A>; |
| }; |
| |
| } } // End namespace boost::io</PRE> |
| |
| <A NAME="mapped_file_params_path"></A> |
| <H4><CODE>mapped_file_params::path</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> std::string path;</PRE> |
| |
| <P>The pathname of the file to map.</P> |
| |
| <A NAME="mapped_file_params_mode"></A> |
| <H4><CODE>mapped_file_params::mode</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> std::ios_base::openmode mode;</PRE> |
| |
| <P>Indicates whether the file should be opened with read-access, write-access or both. Ignored by <CODE>mapped_file_source</CODE> and <CODE>mapped_file_sink</CODE>. This member is deprecated. Please use flags in new code instead.</P> |
| |
| <A NAME="mapped_file_params_flags"></A> |
| <H4><CODE>mapped_file_params::flags</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> mapped_file::mapmode flags;</PRE> |
| |
| <P>Indicates whether the file should be opened with read-access, read-write-access, or private access. A file opened with private access can be written to, but the changes will not affect the underlying file.</P> |
| |
| <A NAME="mapped_file_params_offset"></A> |
| <H4><CODE>mapped_file_params::offset</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> stream_offset offset;</PRE> |
| |
| <P>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be abotained via the static member function <A HREF="#mapped_file_alignment"><CODE>alignment</CODE></A> of <CODE>mapped_file_source</CODE>, <CODE>mapped_file_sink</CODE> or <CODE>mapped_file</CODE>. Defaults to <CODE>0</CODE>.</P> |
| |
| <A NAME="mapped_file_params_length"></A> |
| <H4><CODE>mapped_file_params::length</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> std::size_t length;</PRE> |
| |
| <P>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</P> |
| |
| <A NAME="mapped_file_params_size"></A> |
| <H4><CODE>mapped_file_params::new_file_size</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> stream_offset new_file_size;</PRE> |
| |
| <P>If this value is non-zero it specifies the size of a file to be created. If a file with pathname <I>path</I> already exists, it will be overwritten.</P> |
| |
| <A NAME="mapped_file_params_hint"></A> |
| <H4><CODE>mapped_file_params::hint</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* hint;</PRE> |
| |
| <P>Suggests a location in the process's address space for the mapping to begin.</P> |
| |
| <A NAME="mapped_file_source"></A> |
| <H3>2. Class <CODE>mapped_file_source</CODE></H3> |
| |
| <H4>Description</H4> |
| |
| <P>Model of <A HREF="../concepts/source.html">Source</A> providing read-only access to memory-mapped files on Windows and POSIX systems.</P> |
| |
| <H4>Synopsis</H4> |
| |
| <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { |
| |
| <SPAN CLASS="keyword">class</SPAN> <SPAN CLASS="defined">mapped_file_source</SPAN> { |
| <SPAN CLASS="keyword">public</SPAN>: |
| <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='keyword'>char</SPAN> char_type; |
| <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='omitted'>[implementation-defined]</SPAN> category; |
| <A CLASS='documented' HREF='#mapped_file_source_default_ctor'>mapped_file_source</A>(); |
| <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_source_params_ctor'>mapped_file_source</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
| <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_source_basic_ctor'>mapped_file_source</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
| void <A CLASS='documented' HREF='#mapped_file_source_params_open'>open</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
| void <A CLASS='documented' HREF='#mapped_file_source_basic_open'>open</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
| <SPAN CLASS='keyword'>bool</SPAN> <A CLASS='documented' HREF='#mapped_file_source_is_open'>is_open</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| <SPAN CLASS='keyword'>void</SPAN> <A CLASS='documented' HREF='#mapped_file_source_close'>close</A>(); |
| size_type <A CLASS='documented' HREF='#mapped_file_source_size'>size</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* <A CLASS='documented' HREF='#mapped_file_source_data'>data</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> <A CLASS='documented' HREF='#mapped_file_source_alignment'>alignment</A>(); |
| }; |
| |
| } } // End namespace boost::io</PRE> |
| |
| <A NAME="mapped_file_source_default_ctor"></A> |
| <H4><CODE>mapped_file_source::mapped_file_source</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> mapped_file_source();</PRE> |
| |
| <P>Constructs a <CODE>mapped_file_source</CODE> which must be opened before it can be used to perform i/o.</P> |
| |
| <A NAME="mapped_file_source_params_ctor"></A> |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_source(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
| |
| <P>Constructs a <CODE>mapped_file_source</CODE> from the given parameters.</P> |
| |
| <A NAME="mapped_file_source_basic_ctor"></A> |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_source( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
| |
| <P>Constructs a <CODE>mapped_file_source</CODE> to access a specified file. The parameters have the following interpretation:</P> |
| |
| <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
| <TR> |
| <TR> |
| <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The pathname of the file to map.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_source_alignment'><CODE>alignment</CODE></A>.</TD> |
| </TR> |
| </TABLE> |
| |
| <A NAME="mapped_file_source_params_open"></A> |
| <H4><CODE>mapped_file_source::open</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> void open(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
| |
| <P>Connects this <CODE>mapped_file_source</CODE> to a memory-mapped file obtained as described by the given parameters.</P> |
| |
| <A NAME="mapped_file_source_basic_open"></A> |
| <PRE CLASS="broken_ie"> void open( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
| |
| <P>Connects this <CODE>mapped_file_source</CODE> to a memory-mapped file obtained as described by the given parameters, which have the following interpretation:</P> |
| |
| <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
| <TR> |
| <TR> |
| <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The pathname of the file to map.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_source_alignment'><CODE>alignment</CODE></A>.</TD> |
| </TR> |
| </TABLE> |
| |
| <A NAME="mapped_file_source_is_open"></A> |
| <H4><CODE>mapped_file_source::is_open</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>bool</SPAN> is_open() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Returns <CODE>true</CODE> if this <CODE>mapped_file_source</CODE> has been successfully opened without subsequently having been closed.</P> |
| |
| <A NAME="mapped_file_source_close"></A> |
| <H4><CODE>mapped_file_source::close</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>void</SPAN> close();</PRE> |
| |
| <P>Frees the mapping associated with this <CODE>mapped_file_source</CODE>.</P> |
| |
| <A NAME="mapped_file_source_size"></A> |
| <H4><CODE>mapped_file_source::size</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> size_type size() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Returns the size in bytes of the mapping associated with this <CODE>mapped_file_source</CODE>.</P> |
| |
| <A NAME="mapped_file_source_data"></A> |
| <H4><CODE>mapped_file_source::data</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* data() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Returns a pointer to the first byte of data in the mapping associated with this <CODE>mapped_file_source</CODE>.</P> |
| |
| <A NAME="mapped_file_source_alignment"></A> |
| <H4><CODE>mapped_file_source::alignment</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> alignment();</PRE> |
| |
| <P>Returns the operating system's virtual memory allocation granularity.</P> |
| |
| <A NAME="mapped_file_sink"></A> |
| <H3>3. Class <CODE>mapped_file_sink</CODE></H3> |
| |
| <H4>Description</H4> |
| |
| <P>Model of <A HREF="../concepts/sink.html">Sink</A> providing write-only access to memory-mapped files on Windows and POSIX systems.</P> |
| |
| <H4>Synopsis</H4> |
| |
| <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { |
| |
| <SPAN CLASS="keyword">class</SPAN> <SPAN CLASS="defined">mapped_file_sink</SPAN> { |
| <SPAN CLASS="keyword">public</SPAN>: |
| <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='keyword'>char</SPAN> char_type; |
| <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='omitted'>[implementation-defined]</SPAN> category; |
| <SPAN CLASS='keyword'>enum</SPAN> mapmode { readwrite, priv }; |
| <A CLASS='documented' HREF='#mapped_file_sink_default_ctor'>mapped_file_sink</A>(); |
| <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_sink_params_ctor'>mapped_file_sink</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
| <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_sink_basic_ctor'>mapped_file_sink</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN>, |
| mapmode flags = readwrite ); |
| void <A CLASS='documented' HREF='#mapped_file_sink_params_open'>open</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
| void <A CLASS='documented' HREF='#mapped_file_sink_basic_open'>open</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN>, |
| mapmode flags = readwrite ); |
| <SPAN CLASS='keyword'>bool</SPAN> <A CLASS='documented' HREF='#mapped_file_sink_is_open'>is_open</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| mapmode <A CLASS='documented' HREF='#mapped_file_sink_flags'>flags</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| <SPAN CLASS='keyword'>void</SPAN> <A CLASS='documented' HREF='#mapped_file_sink_close'>close</A>(); |
| size_type <A CLASS='documented' HREF='#mapped_file_sink_size'>size</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| <SPAN CLASS='keyword'>char</SPAN>* <A CLASS='documented' HREF='#mapped_file_sink_data'>data</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> <A CLASS='documented' HREF='#mapped_file_sink_alignment'>alignment</A>(); |
| }; |
| |
| } } // End namespace boost::io</PRE> |
| |
| <A NAME="mapped_file_sink_default_ctor"></A> |
| <H4><CODE>mapped_file_sink::mapped_file_sink</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> mapped_file_sink();</PRE> |
| |
| <P>Constructs a <CODE>mapped_file_sink</CODE> which must be opened before it can be used to perform i/o.</P> |
| |
| <A NAME="mapped_file_sink_params_ctor"></A> |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_sink(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
| |
| <P>Constructs a <CODE>mapped_file_sink</CODE> from the given parameters.</P> |
| |
| <A NAME="mapped_file_sink_basic_ctor"></A> |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_sink( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN>, |
| mapmode flags );</PRE> |
| |
| <P>Constructs a <CODE>mapped_file_sink</CODE> to access a specified file. The parameters have the following interpretation:</P> |
| |
| <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
| <TR> |
| <TR> |
| <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The pathname of the file to map.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_sink_alignment'><CODE>alignment</CODE></A>.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>flags</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>Indicates whether the <CODE>mapped_file_sink</CODE> should be opened for read-write access or private access.</TD> |
| </TR> |
| </TABLE> |
| |
| <A NAME="mapped_file_sink_params_open"></A> |
| <H4><CODE>mapped_file_sink::open</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> void open(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
| |
| <P>Connects this <CODE>mapped_file_sink</CODE> to a memory-mapped file obtained as described by the given parameters.</P> |
| |
| <A NAME="mapped_file_sink_basic_open"></A> |
| <PRE CLASS="broken_ie"> void open( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> |
| mapmode flags );</PRE> |
| |
| <P>Connects this <CODE>mapped_file_sink</CODE> to a memory-mapped file obtained as described by the given parameters, which have the following interpretation:</P> |
| |
| <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
| <TR> |
| <TR> |
| <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The pathname of the file to map.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_sink_alignment'><CODE>alignment</CODE></A>.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>flags</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>Indicates whether the <CODE>mapped_file_sink</CODE> should be opened for read-write access or private access.</TD> |
| </TR> |
| </TABLE> |
| |
| <A NAME="mapped_file_sink_is_open"></A> |
| <H4><CODE>mapped_file_sink::is_open</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>bool</SPAN> is_open() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Returns <CODE>true</CODE> if this <CODE>mapped_file_sink</CODE> has been successfully opened without subsequently having been closed.</P> |
| |
| <A NAME="mapped_file_sink_flags"></A> |
| <H4><CODE>mapped_file_sink::flags</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> mapmode flags() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Indicates whether the <CODE>mapped_file_sink</CODE> was opened for read/write-access or private-access.</P> |
| |
| <A NAME="mapped_file_sink_close"></A> |
| <H4><CODE>mapped_file_sink::close</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>void</SPAN> close();</PRE> |
| |
| <P>Frees the mapping associated with this <CODE>mapped_file_sink</CODE>.</P> |
| |
| <A NAME="mapped_file_sink_size"></A> |
| <H4><CODE>mapped_file_sink::size</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> size_type size() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Returns the size in bytes of the mapping associated with this <CODE>mapped_file_sink</CODE>.</P> |
| |
| <A NAME="mapped_file_sink_data"></A> |
| <H4><CODE>mapped_file_sink::data</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>char</SPAN>* data() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Returns a pointer to the first byte of data in the mapping associated with this <CODE>mapped_file_sink</CODE>.</P> |
| |
| <A NAME="mapped_file_sink_alignment"></A> |
| <H4><CODE>mapped_file_sink::alignment</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> alignment();</PRE> |
| |
| <P>Returns the operating system's virtual memory allocation granularity.</P> |
| |
| <A NAME="mapped_file"></A> |
| <H3>4. Class <CODE>mapped_file</CODE></H3> |
| |
| <H4>Description</H4> |
| |
| <P>Model of <A HREF="../concepts/seekable_device.html">SeekableDevice</A> providing read-write access to memory-mapped files on Windows and POSIX systems.</P> |
| |
| <H4>Synopsis</H4> |
| |
| <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { |
| |
| <SPAN CLASS="keyword">class</SPAN> <SPAN CLASS="defined">mapped_file</SPAN> { |
| <SPAN CLASS="keyword">public</SPAN>: |
| <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='keyword'>char</SPAN> char_type; |
| <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='omitted'>[implementation-defined]</SPAN> category; |
| <SPAN CLASS='keyword'>enum</SPAN> mapmode { readonly, readwrite, priv }; |
| <A CLASS='documented' HREF='#mapped_file_default_ctor'>mapped_file</A>(); |
| <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_params_ctor'>mapped_file</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
| <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_basic_ctor'>mapped_file</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| std::ios_base::openmode mode = |
| std::ios_base::in | std::ios_base::out, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
| <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_mapmode_ctor'>mapped_file</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| mapmode mode, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
| <SPAN CLASS='keyword'>void</SPAN> <A CLASS='documented' HREF='#mapped_file_params_open'>open</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
| <SPAN CLASS='keyword'>void</SPAN> <A CLASS='documented' HREF='#mapped_file_basic_open'>open</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| std::ios_base::openmode mode = |
| std::ios_base | std::ios_base, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
| <SPAN CLASS='keyword'>void</SPAN> <A CLASS='documented' HREF='#mapped_file_mapmode_open'>open</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| mapmode mode, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
| <SPAN CLASS='keyword'>bool</SPAN> <A CLASS='documented' HREF='#mapped_file_is_open'>is_open</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| mapmode <A CLASS='documented' HREF='#mapped_file_flags'>flags</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| <SPAN CLASS='keyword'>void</SPAN> <A CLASS='documented' HREF='#mapped_file_close'>close</A>(); |
| size_type <A CLASS='documented' HREF='#mapped_file_size'>size</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| <SPAN CLASS='keyword'>char</SPAN>* <A CLASS='documented' HREF='#mapped_file_data'>data</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* <A CLASS='documented' HREF='#mapped_file_const_data'>const_data</A>() <SPAN CLASS='keyword'>const</SPAN>; |
| <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> <A CLASS='documented' HREF='#mapped_file_alignment'>alignment</A>(); |
| }; |
| |
| } } // End namespace boost::iostreams</PRE> |
| |
| <A NAME="mapped_file_default_ctor"></A> |
| <H4><CODE>mapped_file::mapped_file</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> mapped_file();</PRE> |
| |
| <P>Constructs a <CODE>mapped_file</CODE> which must be opened before it can be used to perform i/o.</P> |
| |
| <A NAME="mapped_file_params_ctor"></A> |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
| |
| <P>Constructs a <CODE>mapped_file</CODE> from the given parameters.</P> |
| |
| <A NAME="mapped_file_basic_ctor"></A> |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| std::ios_base::openmode mode = |
| std::ios_base | std::ios_base, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
| |
| <P>Constructs a <CODE>mapped_file</CODE> to access a specified file. The parameters have the following interpretation:</P> |
| |
| <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
| <TR> |
| <TR> |
| <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The pathname of the file to map.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>mode</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>Indicates whether the file should be opened with read-access, write-access or both. Use of <CODE>std::ios_base::openmode</CODE> with <CODE>mapped_file</CODE> is deprecated. Please use <CODE>mapmode</CODE> instead in new code.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_alignment'><CODE>alignment</CODE></A>.</TD> |
| </TR> |
| </TABLE> |
| |
| <A NAME="mapped_file_mapmode_ctor"></A> |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| mapmode mode, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
| |
| <P>Constructs a <CODE>mapped_file</CODE> to access a specified file. The parameters have the following interpretation:</P> |
| |
| <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
| <TR> |
| <TR> |
| <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The pathname of the file to map.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>mode</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>Indicates whether the file should be opened with read-access, read/write-access or private-access.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_alignment'><CODE>alignment</CODE></A>.</TD> |
| </TR> |
| </TABLE> |
| |
| <A NAME="mapped_file_params_open"></A> |
| <H4><CODE>mapped_file::open</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> void open(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
| |
| <P>Connects this <CODE>mapped_file</CODE> to a memory-mapped file obtained as described by the given parameters.</P> |
| |
| <A NAME="mapped_file_basic_open"></A> |
| <PRE CLASS="broken_ie"> void open( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| std::ios_base::openmode mode = |
| std::ios_base | std::ios_base, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
| |
| <P>Connects this <CODE>mapped_file</CODE> to a memory-mapped file obtained as described by the given parameters, which have the following interpretation:</P> |
| |
| <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
| <TR> |
| <TR> |
| <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The pathname of the file to map.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>mode</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>Indicates whether the file should be opened with read-access, write-access or both. Use of <CODE>std::ios_base::openmode</CODE> with <CODE>mapped_file</CODE> is deprecated. Please use <CODE>mapmode</CODE> in new code.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_alignment'><CODE>alignment</CODE></A>.</TD> |
| </TR> |
| </TABLE> |
| |
| <A NAME="mapped_file_mapmode_open"></A> |
| <PRE CLASS="broken_ie"> void open( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
| mapmode mode, |
| size_type length = max_length, |
| boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
| |
| <P>Connects this <CODE>mapped_file</CODE> to a memory-mapped file obtained as described by the given parameters, which have the following interpretation:</P> |
| |
| <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
| <TR> |
| <TR> |
| <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The pathname of the file to map.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>mode</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>Indicates whether the file should be opened with read-access, read/write-access or private access.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_alignment'><CODE>alignment</CODE></A>.</TD> |
| </TR> |
| </TABLE> |
| |
| <A NAME="mapped_file_is_open"></A> |
| <H4><CODE>mapped_file::is_open</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>bool</SPAN> is_open() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Returns <CODE>true</CODE> if this <CODE>mapped_file</CODE> has been successfully opened without subsequently having been closed.</P> |
| |
| <A NAME="mapped_file_flags"></A> |
| <H4><CODE>mapped_file::flags</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> mapmode flags() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Indicates whether the <CODE>mapped_file</CODE> was opened for read-access, read/write-access or private-access.</P> |
| |
| <A NAME="mapped_file_close"></A> |
| <H4><CODE>mapped_file::close</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>void</SPAN> close();</PRE> |
| |
| <P>Frees the mapping associated with this <CODE>mapped_file</CODE>.</P> |
| |
| <A NAME="mapped_file_size"></A> |
| <H4><CODE>mapped_file::size</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> size_type size() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Returns the size in bytes of the mapping associated with this <CODE>mapped_file</CODE>.</P> |
| |
| <A NAME="mapped_file_data"></A> |
| <H4><CODE>mapped_file::data</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>char</SPAN>* data() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Returns a pointer to the first byte of data in the mapping associated with this <CODE>mapped_file</CODE>, if it was opened with write-access, and a null pointer otherwise.</P> |
| |
| <A NAME="mapped_file_const_data"></A> |
| <H4><CODE>mapped_file::const_data</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* const_data() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
| |
| <P>Returns a pointer to the first byte of data in the mapping associated with this <CODE>mapped_file</CODE>.</P> |
| |
| <A NAME="mapped_file_alignment"></A> |
| <H4><CODE>mapped_file::alignment</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> alignment();</PRE> |
| |
| <P>Returns the operating system's virtual memory allocation granularity.</P> |
| |
| <!-- Begin Footer --> |
| |
| <HR> |
| <P CLASS="copyright">Revised 02 Feb 2008</P> |
| |
| <P CLASS="copyright">© Copyright 2008 <a href="http://www.coderage.com/" target="_top">CodeRage, LLC</a><br/>© Copyright 2004-2007 <a href="http://www.coderage.com/turkanis/" target="_top">Jonathan Turkanis</a></P> |
| <P CLASS="copyright"> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <A HREF="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>) |
| </P> |
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| </BODY> |