"IPC interprocess communication three" memory-mapped files mapping file
Last Update:2017-06-24
Source: Internet
Author: User
<span id="Label3"></p><span style="font-size:32px; color:rgb(153,0,0)"><span style="font-size:32px; color:rgb(153,0,0)">IPC inter-process Communication</span></span><span style="font-size:32px"><span style="font-size:32px">+ Shared Memory mapping</span></span><span style="font-size:32px"><span style="font-size:32px"> </span></span><span style="font-size:32px"><span style="font-size:32px"><span style="font-size:18px"><strong> <span style="color:rgb(204,102,0)">IPC</span>(inter-process Communication. Interprocess communication). </strong></span></span></span><span style="font-size:32px"><span style="font-size:18px"><strong><strong> <span style="color:#333333">file Mapping (Mapping) is a</span> technique for mapping the contents of a <span style="color:#cc6600">file</span> <span style="color:#333333">to</span> a <span style="color:#cc6600">memory address</span> , and <span style="color:#333333">reading and writing a file is as simple as reading and writing memory by mapping Memory.</span></strong><p><strong></strong></p></strong><p><p><strong></strong><span style="font-size:32px"><span style="font-size:18px"><strong><span style="color:#333333"></span> <span style="color:#33cc00">Multiple processes</span> <span style="color:#333333">map</span> The <span style="color:#33cc00">same file mapping object</span> , that is, <span style="color:#333333">multiple processes are mapped to the same physical storage page, So. When a process writes data to mapped memory, other processes can read the data through mapped memory. This mechanism enables inter-process Communication. </span></strong></span></span></p></p><p><span style="font-size:32px"><span style="font-size:32px"><span style="font-size:18px"><strong><span style="color:#333333"> </span></strong></span></span></span><span style="font-size:32px"><span style="font-size:32px"><span style="font-size:18px"><strong>1. The <span style="color:#cc6600">memory file mapping mapping </span>file <span style="color:#333333">:</span> <span style="color:#333333"> </span></strong></span></span></span><span style="font-size:32px"><span style="font-size:32px"><span style="font-size:18px"><strong><span style="color:#333333"><br></span></strong></span></span></span><span style="font-size:32px"><span style="font-size:32px"><span style="font-size:18px"><strong>a process <span style="color:#33cc00"></span> creates a named mapping object and writes the data that needs to be shared in the mapped memory. <span style="color:#333333"> </span> <span style="color:#333333"> </span>the <span style="color:#33cc00">b process</span> <span style="color:#333333">opens the mapping object through the object name and maps the mapping Object. Reads data from the mapped memory. </span></strong></span></span></span><span style="font-size:32px"><span style="font-size:32px"><span style="font-size:18px"><strong><span style="color:#333333"><br></span></strong></span></span></span><span style="font-size:32px"><span style="font-size:32px"><span style="font-size:18px"><strong>2. <span style="color:#cc6600">Basic API Functions</span> <span style="color:#333333">:</span> <span style="color:#333333"> </span></strong></span></span></span><strong><strong><span style="color:#cc6600"> <span style="font-size:18px">founding</span> <span style="font-size:18px">mapping objects:</span> </span></strong></strong><strong><span style="font-size:18px; color:#333333"><span style="font-size:18px; color:#333333">HANDLE</span></span><span style="font-size:18px; color:#33cc00"><span style="font-size:18px; color:#33cc00">createfilemapping</span></span><span style="font-size:18px; color:#333333"><span style="font-size:18px; color:#333333">(<br></span></span><span style="font-size:18px; color:#993399"><span style="font-size:18px; color:#993399">HANDLE hfile,</span></span><span style="font-size:18px; color:#333333"><span style="font-size:18px; color:#333333">//physical File Handle<br></span></span><span style="font-size:18px; color:#993399"><span style="font-size:18px; color:#993399">lpsecurity_attributes lpattributes,</span></span><span style="font-size:18px; color:#333333"><span style="font-size:18px; color:#333333">Security settings<br></span></span><span style="font-size:18px; color:#993399"><span style="font-size:18px; color:#993399">DWORD flprotect,</span></span><span style="font-size:18px; color:#333333"><span style="font-size:18px; color:#333333">//protection Settings<br></span></span><span style="font-size:18px; color:#993399"><span style="font-size:18px; color:#993399">DWORD dwmaximumsizehigh,</span></span><span style="font-size:18px; color:#333333"><span style="font-size:18px; color:#333333">//high File Size<br></span></span><span style="font-size:18px; color:#993399"><span style="font-size:18px; color:#993399">DWORD dwmaximumsizelow,</span></span><span style="font-size:18px; color:#333333"><span style="font-size:18px; color:#333333">//low File Size<br></span></span><span style="font-size:18px; color:#993399"><span style="font-size:18px; color:#993399">LPCTSTR lpname</span></span><span style="font-size:18px; color:#333333"><span style="font-size:18px; color:#333333">//shared Memory Name<br>);</span></span></strong><strong><strong><span style="font-size:18px; color:#333333">The function returns the created mapping Object. </span></strong></strong></p><p><span style="font-size:18px; color:#cc6600">to <span style="font-size:18px; color:#cc6600"><strong>Create a mapped memory:</strong></span></span><span style="font-size:18px"><strong><span style="color:#333333"><span style="color:#333333">lpvoid</span></span><span style="color:#33cc00"><span style="color:#33cc00">MapViewOfFile</span></span><span style="color:#333333"><span style="color:#333333">(</span></span><br><span style="color:#333333"><span style="color:#333333"></span></span><span style="color:#993399"><span style="color:#993399">HANDLE hfilemappingobject,</span></span><span style="color:#333333"><span style="color:#333333">//mapping Object</span></span><br><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:#993399"><span style="color:#993399">DWORD dwdesiredaccess,</span></span><span style="color:#333333"><span style="color:#333333">//access Categories</span></span><br><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:#993399"><span style="color:#993399">DWORD dwfileoffsethigh,</span></span><span style="color:#333333"><span style="color:#333333">//map File High</span></span><br><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:#993399"><span style="color:#993399">DWORD dwfileoffsetlow,</span></span><span style="color:#333333"><span style="color:#333333">//map file Status</span></span><br><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:#993399"><span style="color:#993399">size_t Dwnumberofbytestomap</span></span><span style="color:#333333"><span style="color:#333333">//number of mapped bytes</span></span><br><span style="color:#333333"><span style="color:#333333">);</span></span><br></strong></span><span style="font-size:18px"><span style="font-size:18px"><strong><span style="color:#333333">This function is used to create the mapped memory of the mapping object and return the mapped memory. </span></strong></span></span></p><p><span style="font-size:18px"><span style="font-size:18px"><strong> <span style="color:#cc6600">Memory Replication</span> <span style="color:#cc9933">:</span> </strong></span></span><span style="font-size:18px"><strong><span style="color:#333333"><span style="color:#333333">VOID</span></span><span style="color:#33cc00"><span style="color:#33cc00">CopyMemory</span></span><span style="color:#333333"><span style="color:#333333">(</span></span><br><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:#993399"><span style="color:#993399">PVOID Destination,</span></span><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:rgb(51,51,51)"><span style="color:rgb(51,51,51)">//the Destination Address of the memory block to be copied</span></span><br><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:#993399"><span style="color:#993399">CONST VOID *source,</span></span><span style="color:#333333"><span style="color:#333333">//to Copy the source address of the memory block</span></span><br><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:#993399"><span style="color:#993399">size_t Length</span></span><span style="color:#333333"><span style="color:#333333">//number of bytes copied</span></span><br><span style="color:#333333"><span style="color:#333333">);</span></span></strong></span><span style="font-size:18px"><span style="font-size:18px"><strong><span style="color:#333333">This function is used to copy data to mapped Memory. </span></strong></span></span></p><p><span style="font-size:18px; color:#cc6600"><span style="font-size:18px; color:#cc6600"><strong>Open the mapping object:</strong></span></span><span style="font-size:18px"><strong><span style="color:#333333"><span style="color:#333333">HANDLE</span></span><span style="color:#33cc00"><span style="color:#33cc00">openfilemapping</span></span><span style="color:#333333"><span style="color:#333333">(</span></span><br><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:#993399"><span style="color:#993399">DWORD dwdesiredaccess,</span></span><span style="color:#333333"><span style="color:#333333">//access Rights</span></span><br><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:#993399"><span style="color:#993399">BOOL binherithandle,</span></span><span style="color:#333333"><span style="color:#333333">//inheritance settings, generally set to false</span></span><br><span style="color:#333333"><span style="color:#333333"> </span></span><span style="color:#993399"><span style="color:#993399">LPCTSTR lpname</span></span><span style="color:#333333"><span style="color:#333333">//mapping Object Name</span></span><br><span style="color:#333333"><span style="color:#333333">);</span></span></strong></span><span style="font-size:18px"><span style="font-size:18px"><strong><span style="color:#333333">This function is used to open an existing mapping object. Returns a handle to the mapping Object. </span></strong></span></span><span style="font-size:18px; color:#333333"><span style="font-size:18px; color:#333333"><strong> </strong></span></span><span style="font-size:18px"><span style="font-size:18px"><strong>3. <span style="color:#cc6600">kind:</span> <span style="color:#333333"> </span></strong></span></span><span style="font-size:18px"><span style="font-size:18px"><strong>Execute the PROCESS1 program in VC6.0 first. <span style="color:#333333"></span> <span style="color:#009900"> In the execution of the Process2 program:</span> </strong></span></span><span style="font-size:18px; color:#333333"><span style="font-size:18px; color:#333333"><strong></strong></span></span></p><p><p><strong>watermark/2/text/ahr0cdovl2jsb2cuy3nkbi5uzxqvbg92zwnvzgvszxnz/font/5a6l5l2t/fontsize/400/fill/i0jbqkfcma==/ Dissolve/70/gravity/southeast "><br></strong><span style="font-size:18px"><strong><span style="color:#333333"></span> <span style="color:#33cc00">Execution effect:</span></strong></span><span style="font-size:18px; color:#333333"><strong><br></strong></span><span style="font-size:18px; color:#333333"><strong>Process1 program:</strong></span><span style="font-size:18px; color:#333333"><strong></strong></span><strong><span style="font-size:18px">process2 program:</span></strong><br><br><span style="font-size:18px"><strong><span style="color:#333333"><br></span></strong></span></p></p><p><p>"IPC interprocess communication three" memory-mapped files mapping file</p></p></span></span></span>
