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<hr><h1>ThreadFile Class Reference</h1>This class defines a database I/O file service that can be shared by multiple threads. This class defines a database I/O file service that can be shared by multiple threads.
<a href="#_details">More...</a>
<p>
<code>#include <<a class="el" href="file_8h-source.html">file.h</a>></code>
<p>
<p>Inheritance diagram for ThreadFile::
<p><center><img src="class_thread_file.gif" usemap="#ThreadFile_map" border="0"></center>
<map name="ThreadFile_map">
<area href="class_random_file.html" alt="RandomFile" shape="rect" coords="0,56,78,80">
<area href="class_mutex.html" alt="Mutex" shape="rect" coords="0,0,78,24">
</map>
<a href="class_thread_file-members.html">List of all members.</a><table border=0 cellpadding=0 cellspacing=0>
<tr><td colspan=2><br><h2>Public Methods</h2></td></tr>
<tr><td nowrap align=right valign=top> </td><td valign=bottom><a class="el" href="class_thread_file.html#a0">ThreadFile</a> (const char *path)</td></tr>
<tr><td> </td><td><font size=-1><em>Open or create a new database file.</em> <a href="#a0">More...</a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top>virtual </td><td valign=bottom><a class="el" href="class_thread_file.html#a1">~ThreadFile</a> ()</td></tr>
<tr><td> </td><td><font size=-1><em>Close and finish a database file.</em> <a href="#a1">More...</a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top><a class="el" href="file_8h.html#a54">fileerror_t</a> </td><td valign=bottom><a class="el" href="class_thread_file.html#a2">Restart</a> (void)</td></tr>
<tr><td> </td><td><font size=-1><em>Restart an existing database; close and re-open.</em> <a href="#a2">More...</a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top><a class="el" href="file_8h.html#a54">fileerror_t</a> </td><td valign=bottom><a class="el" href="class_thread_file.html#a3">Fetch</a> (char *address=NULL, <a class="el" href="file_8h.html#a11">ccxx_size_t</a> length=0, off_t position=-1)</td></tr>
<tr><td> </td><td><font size=-1><em>Fetch a portion of the file into physical memory.</em> <a href="#a3">More...</a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top><a class="el" href="file_8h.html#a54">fileerror_t</a> </td><td valign=bottom><a class="el" href="class_thread_file.html#a4">Update</a> (char *address=NULL, <a class="el" href="file_8h.html#a11">ccxx_size_t</a> length=0, off_t position=-1)</td></tr>
<tr><td> </td><td><font size=-1><em>Update a portion of a file from physical memory.</em> <a href="#a4">More...</a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top><a class="el" href="file_8h.html#a54">fileerror_t</a> </td><td valign=bottom><a class="el" href="class_thread_file.html#a5">Append</a> (char *address=NULL, <a class="el" href="file_8h.html#a11">ccxx_size_t</a> length=0)</td></tr>
<tr><td> </td><td><font size=-1><em>Add new data to the end of the file.</em> <a href="#a5">More...</a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top>off_t </td><td valign=bottom><a class="el" href="class_thread_file.html#a6">getPosition</a> (void)</td></tr>
<tr><td> </td><td><font size=-1><em>Fetch the current file position marker for this thread.</em> <a href="#a6">More...</a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top>bool </td><td valign=bottom><a class="el" href="class_thread_file.html#a7">operator++</a> (void)</td></tr>
<tr><td nowrap align=right valign=top>bool </td><td valign=bottom><a class="el" href="class_thread_file.html#a8">operator--</a> (void)</td></tr>
</table>
<hr><a name="_details"></a><h2>Detailed Description</h2>
This class defines a database I/O file service that can be shared by multiple threads. This class defines a database I/O file service that can be shared by multiple threads.
<p>
All threads access a global copy of the database object, and mutex locks can be used to preserve transaction integrety. pread/pwrite calls can be used for optimized I/O when supported.
<p>
ThreadFile is meant for use by a threaded database server where multiple threads may each perform semi-independent operations on a given database table stored on disk. A special "fcb" structure is used to hold file "state", and pread/pwrite is used whenever possible for optimized I/O. On systems that do not offer pwread/pwrite, a <a class="el" href="class_mutex.html">Mutex</a> lock is used to protect concurrent lseek and read/write operations. ThreadFile managed databases are assumed to be used only by the local server and through a single file descriptor.
<p>
<dl compact><dt><b>
Author: </b><dd>
David Sugar <<a href="mailto:dyfet@ostel.com">dyfet@ostel.com</a>> </dl>
<p>
<hr><h2>Constructor & Destructor Documentation</h2>
<a name="a0" doxytag="ThreadFile::ThreadFile"></a><p>
<table width="100%" cellpadding="2" cellspacing="0" border="0">
<tr>
<td class="md">
<table cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="md" nowrap valign="top"> ThreadFile::ThreadFile </td>
<td class="md">( </td>
<td class="md">const char *</td>
<td class="mdname1"> <em>path</em> </td>
<td class="md">) </td>
<td class="md"></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Open or create a new database file.
<p>
You should also use Initial.<dl compact><dt><b>
Parameters: </b><dd>
<table border=0 cellspacing=2 cellpadding=0>
<tr><td valign=top><em>pathname
</em> </td><td>
of database to open. </td></tr>
</table>
</dl> </td>
</tr>
</table>
<a name="a1" doxytag="ThreadFile::~ThreadFile"></a><p>
<table width="100%" cellpadding="2" cellspacing="0" border="0">
<tr>
<td class="md">
<table cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="md" nowrap valign="top"> virtual ThreadFile::~ThreadFile </td>
<td class="md">( </td>
<td class="mdname1"> </td>
<td class="md">) </td>
<td class="md"><code> [virtual]</code></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Close and finish a database file.
<p>
</td>
</tr>
</table>
<hr><h2>Member Function Documentation</h2>
<a name="a5" doxytag="ThreadFile::Append"></a><p>
<table width="100%" cellpadding="2" cellspacing="0" border="0">
<tr>
<td class="md">
<table cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="md" nowrap valign="top"> <a class="el" href="file_8h.html#a54">fileerror_t</a> ThreadFile::Append </td>
<td class="md">( </td>
<td class="md">char *</td>
<td class="mdname"> <em>address</em> = NULL, </td>
</tr>
<tr>
<td></td>
<td></td>
<td class="md"><a class="el" href="file_8h.html#a11">ccxx_size_t</a></td>
<td class="mdname"> <em>length</em> = 0</td>
</tr>
<tr>
<td></td>
<td class="md">) </td>
<td class="md" colspan="2"></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Add new data to the end of the file.
<p>
<dl compact><dt><b>
Parameters: </b><dd>
<table border=0 cellspacing=2 cellpadding=0>
<tr><td valign=top><em>address
</em> </td><td>
to use, or NULL if same as last I/O. </td></tr>
<tr><td valign=top><em>length
</em> </td><td>
to use, or 0 if same as last I/O. </td></tr>
</table>
</dl> </td>
</tr>
</table>
<a name="a3" doxytag="ThreadFile::Fetch"></a><p>
<table width="100%" cellpadding="2" cellspacing="0" border="0">
<tr>
<td class="md">
<table cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="md" nowrap valign="top"> <a class="el" href="file_8h.html#a54">fileerror_t</a> ThreadFile::Fetch </td>
<td class="md">( </td>
<td class="md">char *</td>
<td class="mdname"> <em>address</em> = NULL, </td>
</tr>
<tr>
<td></td>
<td></td>
<td class="md"><a class="el" href="file_8h.html#a11">ccxx_size_t</a></td>
<td class="mdname"> <em>length</em> = 0, </td>
</tr>
<tr>
<td></td>
<td></td>
<td class="md">off_t</td>
<td class="mdname"> <em>position</em> = -1</td>
</tr>
<tr>
<td></td>
<td class="md">) </td>
<td class="md" colspan="2"></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Fetch a portion of the file into physical memory.
<p>
This can use state information to fetch the current record multiple times.
<p>
<dl compact><dt><b>
Returns: </b><dd>
FILE_SUCCESS on success. </dl><dl compact><dt><b>
Parameters: </b><dd>
<table border=0 cellspacing=2 cellpadding=0>
<tr><td valign=top><em>address
</em> </td><td>
to use, or NULL if same as last I/O. </td></tr>
<tr><td valign=top><em>length
</em> </td><td>
to use, or 0 if same as last I/O. </td></tr>
<tr><td valign=top><em>file
</em> </td><td>
position to use -1 if same as last I/O. </td></tr>
</table>
</dl> </td>
</tr>
</table>
<a name="a2" doxytag="ThreadFile::Restart"></a><p>
<table width="100%" cellpadding="2" cellspacing="0" border="0">
<tr>
<td class="md">
<table cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="md" nowrap valign="top"> <a class="el" href="file_8h.html#a54">fileerror_t</a> ThreadFile::Restart </td>
<td class="md">( </td>
<td class="md">void</td>
<td class="mdname1"> </td>
<td class="md">) </td>
<td class="md"><code> [inline, virtual]</code></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Restart an existing database; close and re-open.
<p>
<dl compact><dt><b>
Returns: </b><dd>
FILE_SUCCESS if successful. </dl>
<p>
Reimplemented from <a class="el" href="class_random_file.html#a3">RandomFile</a>. </td>
</tr>
</table>
<a name="a4" doxytag="ThreadFile::Update"></a><p>
<table width="100%" cellpadding="2" cellspacing="0" border="0">
<tr>
<td class="md">
<table cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="md" nowrap valign="top"> <a class="el" href="file_8h.html#a54">fileerror_t</a> ThreadFile::Update </td>
<td class="md">( </td>
<td class="md">char *</td>
<td class="mdname"> <em>address</em> = NULL, </td>
</tr>
<tr>
<td></td>
<td></td>
<td class="md"><a class="el" href="file_8h.html#a11">ccxx_size_t</a></td>
<td class="mdname"> <em>length</em> = 0, </td>
</tr>
<tr>
<td></td>
<td></td>
<td class="md">off_t</td>
<td class="mdname"> <em>position</em> = -1</td>
</tr>
<tr>
<td></td>
<td class="md">) </td>
<td class="md" colspan="2"></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Update a portion of a file from physical memory.
<p>
This can use state information to commit the last read record.
<p>
<dl compact><dt><b>
Returns: </b><dd>
FILE_SUCCESS on success. </dl><dl compact><dt><b>
Parameters: </b><dd>
<table border=0 cellspacing=2 cellpadding=0>
<tr><td valign=top><em>address
</em> </td><td>
to use, or NULL if same as last I/O. </td></tr>
<tr><td valign=top><em>length
</em> </td><td>
to use, or 0 if same as last I/O. </td></tr>
<tr><td valign=top><em>file
</em> </td><td>
position to use or -1 if same as last I/O. </td></tr>
</table>
</dl> </td>
</tr>
</table>
<a name="a6" doxytag="ThreadFile::getPosition"></a><p>
<table width="100%" cellpadding="2" cellspacing="0" border="0">
<tr>
<td class="md">
<table cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="md" nowrap valign="top"> off_t ThreadFile::getPosition </td>
<td class="md">( </td>
<td class="md">void</td>
<td class="mdname1"> </td>
<td class="md">) </td>
<td class="md"></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
Fetch the current file position marker for this thread.
<p>
<dl compact><dt><b>
Returns: </b><dd>
file position offset. </dl> </td>
</tr>
</table>
<a name="a7" doxytag="ThreadFile::operator++"></a><p>
<table width="100%" cellpadding="2" cellspacing="0" border="0">
<tr>
<td class="md">
<table cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="md" nowrap valign="top"> bool ThreadFile::operator++ </td>
<td class="md">( </td>
<td class="md">void</td>
<td class="mdname1"> </td>
<td class="md">) </td>
<td class="md"></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
</td>
</tr>
</table>
<a name="a8" doxytag="ThreadFile::operator--"></a><p>
<table width="100%" cellpadding="2" cellspacing="0" border="0">
<tr>
<td class="md">
<table cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="md" nowrap valign="top"> bool ThreadFile::operator-- </td>
<td class="md">( </td>
<td class="md">void</td>
<td class="mdname1"> </td>
<td class="md">) </td>
<td class="md"></td>
</tr>
</table>
</td>
</tr>
</table>
<table cellspacing=5 cellpadding=0 border=0>
<tr>
<td>
</td>
<td>
<p>
</td>
</tr>
</table>
<hr>The documentation for this class was generated from the following file:<ul>
<li><a class="el" href="file_8h-source.html">file.h</a></ul>
<hr><address><small>Generated at Tue Nov 20 13:28:51 2001 for CommonC++ by
<a href="http://www.doxygen.org/index.html">
<img src="doxygen.gif" alt="doxygen" align="middle" border=0
width=110 height=53></a>1.2.10 written by <a href="mailto:dimitri@stack.nl">Dimitri van Heesch</a>,
© 1997-2001</small></address>
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