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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<h1>NLMISC::CSharedMemory Class Reference</h1><code>#include <<a class="el" href="a06383.html">shared_memory.h</a>></code>
<p>
<hr><a name="_details"></a><h2>Detailed Description</h2>
Encapsulation of shared memory APIs. Using file mapping under Windows, System V shared memory (shm) under Linux.<p>
Note: under Linux, an option could be added to prevent a segment to be swapped out.<p>
<dl compact><dt><b>Author:</b></dt><dd>Olivier Cado <p>
Nevrax France </dd></dl>
<dl compact><dt><b>Date:</b></dt><dd>2002 </dd></dl>
<p>
<p>
Definition at line <a class="el" href="a06383.html#l00068">68</a> of file <a class="el" href="a06383.html">shared_memory.h</a>.<table border=0 cellpadding=0 cellspacing=0>
<tr><td></td></tr>
<tr><td colspan=2><br><h2>Static Public Member Functions</h2></td></tr>
<tr><td class="memItemLeft" nowrap align=right valign=top>void * </td><td class="memItemRight" valign=bottom><a class="el" href="a03382.html#NLMISC_1_1CSharedMemorye0">accessSharedMemory</a> (<a class="el" href="a05378.html#a232">TSharedMemId</a> sharedMemId)</td></tr>
<tr><td class="memItemLeft" nowrap align=right valign=top>bool </td><td class="memItemRight" valign=bottom><a class="el" href="a03382.html#NLMISC_1_1CSharedMemorye1">closeSharedMemory</a> (void *accessAddress)</td></tr>
<tr><td class="memItemLeft" nowrap align=right valign=top>void * </td><td class="memItemRight" valign=bottom><a class="el" href="a03382.html#NLMISC_1_1CSharedMemorye2">createSharedMemory</a> (<a class="el" href="a05378.html#a232">TSharedMemId</a> sharedMemId, <a class="el" href="a04558.html#a11">uint32</a> <a class="el" href="a04223.html#a587">size</a>)</td></tr>
<tr><td class="memItemLeft" nowrap align=right valign=top>void </td><td class="memItemRight" valign=bottom><a class="el" href="a03382.html#NLMISC_1_1CSharedMemorye3">destroySharedMemory</a> (<a class="el" href="a05378.html#a232">TSharedMemId</a> sharedMemId, bool force=false)</td></tr>
</table>
<hr><h2>Member Function Documentation</h2>
<a class="anchor" name="NLMISC_1_1CSharedMemorye0" doxytag="NLMISC::CSharedMemory::accessSharedMemory" ></a><p>
<table class="mdTable" width="100%" cellpadding="2" cellspacing="0">
<tr>
<td class="mdRow">
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<td class="md" nowrap valign="top"> void * NLMISC::CSharedMemory::accessSharedMemory </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="a05378.html#a232">TSharedMemId</a> </td>
<td class="mdname1" valign="top" nowrap> <em>sharedMemId</em> </td>
<td class="md" valign="top"> ) </td>
<td class="md" nowrap><code> [static]</code></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Get access to an existing shared memory segment. The id must be used. <dl compact><dt><b>Returns:</b></dt><dd>Access address of the segment. Its size was determined at the creation.</dd></dl>
<p>
Definition at line <a class="el" href="a06382.html#l00100">100</a> of file <a class="el" href="a06382.html">shared_memory.cpp</a>.
<p>
References <a class="el" href="a06383.html#l00041">NLMISC::TSharedMemId</a>.
<p>
<div class="fragment"><pre>00101 {
00102 <span class="preprocessor">#ifdef NL_OS_WINDOWS</span>
00103 <span class="preprocessor"></span>
00104 <span class="comment">// Open the existing file mapping by name</span>
00105 HANDLE hMapFile = OpenFileMapping( FILE_MAP_ALL_ACCESS, <span class="keyword">false</span>, sharedMemId );
00106 <span class="keywordflow">if</span> ( hMapFile == NULL )
00107 <span class="keywordflow">return</span> NULL;
00108 <span class="comment">//nldebug( "SHDMEM: Opening smid %s --> mapFile %p", sharedMemId, hMapFile );</span>
00109
00110 <span class="comment">// Map the file into memory address space</span>
00111 <span class="keywordtype">void</span> *accessAddress = MapViewOfFile( hMapFile, FILE_MAP_ALL_ACCESS, 0, 0, 0 );
00112 AccessAddressesToHandles.insert( make_pair( accessAddress, hMapFile ) );
00113 <span class="keywordflow">return</span> accessAddress;
00114
00115 <span class="preprocessor">#else</span>
00116 <span class="preprocessor"></span>
00117 <span class="comment">// Open an existing shared memory segment</span>
00118 <span class="keywordtype">int</span> shmid = shmget( sharedMemId, 0, 0666 );
00119 <span class="keywordflow">if</span> ( shmid == -1 )
00120 <span class="keywordflow">return</span> NULL;
00121
00122 <span class="comment">// Map the segment into memory address space</span>
00123 <span class="keywordtype">void</span> *accessAddress = (<span class="keywordtype">void</span>*)shmat( shmid, 0, 0 );
00124 <span class="keywordflow">if</span> ( accessAddress == (<span class="keywordtype">void</span>*)-1 )
00125 <span class="keywordflow">return</span> NULL;
00126 <span class="keywordflow">else</span>
00127 <span class="keywordflow">return</span> accessAddress;
00128
00129 <span class="preprocessor">#endif</span>
00130 <span class="preprocessor"></span>}
</pre></div> </td>
</tr>
</table>
<a class="anchor" name="NLMISC_1_1CSharedMemorye1" doxytag="NLMISC::CSharedMemory::closeSharedMemory" ></a><p>
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<td class="md" nowrap valign="top"> bool NLMISC::CSharedMemory::closeSharedMemory </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top">void * </td>
<td class="mdname1" valign="top" nowrap> <em>accessAddress</em> </td>
<td class="md" valign="top"> ) </td>
<td class="md" nowrap><code> [static]</code></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Close a shared memory segment, given the address returned by <a class="el" href="a03382.html#NLMISC_1_1CSharedMemorye2">createSharedMemory()</a> or <a class="el" href="a03382.html#NLMISC_1_1CSharedMemorye0">accessSharedMemory()</a>. Must be called by each process that called <a class="el" href="a03382.html#NLMISC_1_1CSharedMemorye2">createSharedMemory()</a> or <a class="el" href="a03382.html#NLMISC_1_1CSharedMemorye0">accessSharedMemory()</a>.
<p>
Definition at line <a class="el" href="a06382.html#l00136">136</a> of file <a class="el" href="a06382.html">shared_memory.cpp</a>.
<p>
References <a class="el" href="a05622.html#l00135">nlwarning</a>.
<p>
<div class="fragment"><pre>00137 {
00138 <span class="preprocessor">#ifdef NL_OS_WINDOWS</span>
00139 <span class="preprocessor"></span>
00140 <span class="keywordtype">bool</span> result = <span class="keyword">true</span>;
00141
00142 <span class="comment">// Unmap the file from memory address space</span>
00143 <span class="keywordflow">if</span> ( UnmapViewOfFile( accessAddress ) == 0 )
00144 {
00145 <a class="code" href="a04199.html#a2">nlwarning</a>( <span class="stringliteral">"SHDMEM: UnmapViewOfFile failed: error %u"</span>, GetLastError() );
00146 result = <span class="keyword">false</span>;
00147 }
00148
00149 <span class="comment">// Close the corresponding handle</span>
00150 map<void*,HANDLE>::iterator im = AccessAddressesToHandles.find( accessAddress );
00151 <span class="keywordflow">if</span> ( im != AccessAddressesToHandles.end() )
00152 {
00153 <span class="comment">//nldebug( "SHDMEM: CloseHandle mapFile %u", (*im).second );</span>
00154 <span class="keywordflow">if</span> ( ! CloseHandle( (*im).second ) )
00155 <a class="code" href="a04199.html#a2">nlwarning</a>( <span class="stringliteral">"SHDMEM: CloseHandle failed: error %u, mapFile %u"</span>, GetLastError(), (*im).second );
00156 AccessAddressesToHandles.erase( im );
00157 <span class="keywordflow">return</span> result;
00158 }
00159 <span class="keywordflow">else</span>
00160 {
00161 <span class="keywordflow">return</span> <span class="keyword">false</span>;
00162 }
00163
00164 <span class="preprocessor">#else</span>
00165 <span class="preprocessor"></span>
00166 <span class="comment">// Detach the shared memory segment</span>
00167 <span class="keywordflow">return</span> ( shmdt( accessAddress ) != -1 );
00168
00169 <span class="preprocessor">#endif</span>
00170 <span class="preprocessor"></span>}
</pre></div> </td>
</tr>
</table>
<a class="anchor" name="NLMISC_1_1CSharedMemorye2" doxytag="NLMISC::CSharedMemory::createSharedMemory" ></a><p>
<table class="mdTable" width="100%" cellpadding="2" cellspacing="0">
<tr>
<td class="mdRow">
<table cellpadding="0" cellspacing="0" border="0">
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<td class="md" nowrap valign="top"> void * NLMISC::CSharedMemory::createSharedMemory </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="a05378.html#a232">TSharedMemId</a> </td>
<td class="mdname" nowrap> <em>sharedMemId</em>, </td>
</tr>
<tr>
<td class="md" nowrap align="right"></td>
<td></td>
<td class="md" nowrap><a class="el" href="a04558.html#a11">uint32</a> </td>
<td class="mdname" nowrap> <em>size</em></td>
</tr>
<tr>
<td></td>
<td class="md">) </td>
<td class="md" colspan="2"><code> [static]</code></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Create a shared memory segment and get access to it. The id must not be used. The id 0x3a732235 is used by the NeL memory manager. <dl compact><dt><b>Returns:</b></dt><dd>Access address of the segment of the choosen size</dd></dl>
<p>
Definition at line <a class="el" href="a06382.html#l00055">55</a> of file <a class="el" href="a06382.html">shared_memory.cpp</a>.
<p>
References <a class="el" href="a05622.html#l00135">nlwarning</a>, <a class="el" href="a06382.html#l00048">NLMISC::SharedMemIdsToShmids</a>, <a class="el" href="a05646.html#l00645">size</a>, <a class="el" href="a06383.html#l00041">NLMISC::TSharedMemId</a>, and <a class="el" href="a05981.html#l00100">uint32</a>.
<p>
<div class="fragment"><pre>00056 {
00057 <span class="preprocessor">#ifdef NL_OS_WINDOWS</span>
00058 <span class="preprocessor"></span>
00059 <span class="comment">// Create a file mapping backed by the virtual memory swap file (not a data file)</span>
00060 HANDLE hMapFile = CreateFileMapping( INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0, size, sharedMemId );
00061 <span class="keywordflow">if</span> ( (hMapFile == NULL) || (GetLastError() == ERROR_ALREADY_EXISTS) )
00062 {
00063 <a class="code" href="a04199.html#a2">nlwarning</a>( <span class="stringliteral">"SHDMEM: Cannot create file mapping: error %u, mapFile %p"</span>, GetLastError(), hMapFile );
00064 <span class="keywordflow">return</span> NULL;
00065 }
00066 <span class="comment">//else</span>
00067 <span class="comment">// nldebug( "SHDMEM: Creating smid %s --> mapFile %p", sharedMemId, hMapFile );</span>
00068
00069
00070 <span class="comment">// Map the file into memory address space</span>
00071 <span class="keywordtype">void</span> *accessAddress = MapViewOfFile( hMapFile, FILE_MAP_ALL_ACCESS, 0, 0, 0 );
00072 AccessAddressesToHandles.insert( make_pair( accessAddress, hMapFile ) );
00073 <span class="comment">/*if ( accessAddress == NULL )</span>
00074 <span class="comment"> {</span>
00075 <span class="comment"> nlwarning( "SHDMEM: Cannot map view of file: error %u", GetLastError() );</span>
00076 <span class="comment"> }*/</span>
00077 <span class="keywordflow">return</span> accessAddress;
00078
00079 <span class="preprocessor">#else</span>
00080 <span class="preprocessor"></span>
00081 <span class="comment">// Create a shared memory segment</span>
00082 <span class="keywordtype">int</span> shmid = shmget( sharedMemId, size, IPC_CREAT | IPC_EXCL | 0666 );
00083 <span class="keywordflow">if</span> ( shmid == -1 )
00084 <span class="keywordflow">return</span> NULL;
00085 <a class="code" href="a05378.html#a36">SharedMemIdsToShmids</a>.insert( make_pair( sharedMemId, shmid ) );
00086
00087 <span class="comment">// Map the segment into memory address space</span>
00088 <span class="keywordtype">void</span> *accessAddress = (<span class="keywordtype">void</span>*)shmat( shmid, 0, 0 );
00089 <span class="keywordflow">if</span> ( accessAddress == (<span class="keywordtype">void</span>*)-1 )
00090 <span class="keywordflow">return</span> NULL;
00091 <span class="keywordflow">else</span>
00092 <span class="keywordflow">return</span> accessAddress;
00093 <span class="preprocessor">#endif</span>
00094 <span class="preprocessor"></span>}
</pre></div> </td>
</tr>
</table>
<a class="anchor" name="NLMISC_1_1CSharedMemorye3" doxytag="NLMISC::CSharedMemory::destroySharedMemory" ></a><p>
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<td class="md" nowrap valign="top"> void NLMISC::CSharedMemory::destroySharedMemory </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="a05378.html#a232">TSharedMemId</a> </td>
<td class="mdname" nowrap> <em>sharedMemId</em>, </td>
</tr>
<tr>
<td class="md" nowrap align="right"></td>
<td></td>
<td class="md" nowrap>bool </td>
<td class="mdname" nowrap> <em>force</em> = false</td>
</tr>
<tr>
<td></td>
<td class="md">) </td>
<td class="md" colspan="2"><code> [static]</code></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Destroy a shared memory segment (must be called by the process that created the segment, not by the accessors).<p>
"Rescue feature": set "force" to true if a segment was created and left out of control (meaning a new <a class="el" href="a03382.html#NLMISC_1_1CSharedMemorye2">createSharedMemory()</a> with the same sharedMemId fails), but before, make sure the segment really belongs to you!<p>
Note: this method does nothing under Windows, destroying is automatic.
<p>
Definition at line <a class="el" href="a06382.html#l00177">177</a> of file <a class="el" href="a06382.html">shared_memory.cpp</a>.
<p>
References <a class="el" href="a06382.html#l00048">NLMISC::SharedMemIdsToShmids</a>, and <a class="el" href="a06383.html#l00041">NLMISC::TSharedMemId</a>.
<p>
<div class="fragment"><pre>00178 {
00179 <span class="preprocessor">#ifndef NL_OS_WINDOWS</span>
00180 <span class="preprocessor"></span> <span class="comment">// Set the segment to auto-destroying (when the last process detaches)</span>
00181 map<TSharedMemId,int>::iterator im = <a class="code" href="a05378.html#a36">SharedMemIdsToShmids</a>.find( sharedMemId );
00182 <span class="keywordflow">if</span> ( im != <a class="code" href="a05378.html#a36">SharedMemIdsToShmids</a>.end() )
00183 {
00184 <span class="comment">// Destroy the segment created before</span>
00185 shmctl( (*im).second, IPC_RMID, 0 );
00186 <a class="code" href="a05378.html#a36">SharedMemIdsToShmids</a>.erase( im );
00187 }
00188 <span class="keywordflow">else</span> <span class="keywordflow">if</span> ( force )
00189 {
00190 <span class="comment">// Open and destroy the segment</span>
00191 <span class="keywordtype">int</span> shmid = shmget( sharedMemId, 0, 0666 );
00192 <span class="keywordflow">if</span> ( shmid != -1 )
00193 {
00194 <span class="comment">// Destroy the segment</span>
00195 shmctl( shmid, IPC_RMID, 0 );
00196 }
00197 }
00198 <span class="preprocessor">#endif</span>
00199 <span class="preprocessor"></span>}
</pre></div> </td>
</tr>
</table>
<hr>The documentation for this class was generated from the following files:<ul>
<li><a class="el" href="a06383.html">shared_memory.h</a><li><a class="el" href="a06382.html">shared_memory.cpp</a></ul>
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