1<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 2<html xml:lang="en-US" lang="en-US" xmlns="http://www.w3.org/1999/xhtml"> 3 <head> 4 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 5 <meta http-equiv="Content-Style-Type" content="text/css" /> 6 <link rel="stylesheet" href="../../../css/manpage.css" type="text/css" /> 7 <style type="text/css"><!-- 8 span.static_style 9 { 10 font-size : 8pt; 11 color : white; 12 font-weight : bold; 13 background : #44f; 14 border-left : solid 1px #aaf; 15 border-top : solid 1px #aaf; 16 border-right : solid 1px #00c; 17 border-bottom : solid 1px #00c; 18 padding-left : 2px; 19 padding-right : 2px; 20 } 21 span.virtual_style 22 { 23 font-size : 8pt; 24 color : white; 25 font-weight : bold; 26 background : #0a0; 27 border-left : solid 1px #0f0; 28 border-top : solid 1px #0f0; 29 border-right : solid 1px #060; 30 border-bottom : solid 1px #060; 31 padding-left : 2px; 32 padding-right : 2px; 33 } 34 span.protected_style 35 { 36 font-size : 8pt; 37 color : white; 38 font-weight : bold; 39 background : #444; 40 border-left : solid 1px #ccc; 41 border-top : solid 1px #ccc; 42 border-right : solid 1px #222; 43 border-bottom : solid 1px #222; 44 padding-left : 2px; 45 padding-right : 2px; 46 } 47 --></style> 48<title>nn::os::Mutex</title> 49 </head> 50 <body> 51<h1><CODE><a href="../../../nn/Overview.html">nn</a>::<a href="../../../nn/os/Overview.html">os</a>::Mutex</CODE> Class</h1> 52 <div class="section"> 53<b>Header file: </b>nn/os.h</div> 54<h2>Syntax</h2> 55 <div class="section"> 56<pre class="definition">class Mutex : public <a href="../../../nn/os/WaitObject/Overview.html">nn::os::WaitObject</a></pre> 57 </div> 58<h2>Description</h2> 59 <div class="section"> 60<p>Class for handling mutexes. Mutexes are synchronization objects used for providing mutual exclusion.</p><p>Generally, use the <a href="../../../nn/os/Mutex/Overview.html"><CODE>nn::os::Mutex</CODE></a> class instead of <a href="../../../nn/os/CriticalSection/Overview.html"><CODE>nn::os::CriticalSection</CODE></a>. The <a href="../../../nn/os/CriticalSection/Overview.html"><CODE>nn::os::CriticalSection</CODE></a> class performs considerably faster than <a href="../../../nn/os/Mutex/Overview.html"><CODE>nn::os::Mutex</CODE></a> when there are no lock collisions between threads.</p><p>This mechanism prevents certain areas within programs from being run simultaneously within multiple threads. It also prevents data, registers, and other resources from being accessed by multiple threads simultaneously.</p><p>Mutexes can be locked using <a href="../../../nn/os/Mutex/Lock.html"><CODE>Lock</CODE></a>. A mutex that is locked by a certain thread cannot be locked by other threads. If another thread attempts to lock it, that thread will block until the mutex is unlocked.</p><p>The <CODE><a href="../../../nn/os/Mutex/Unlock.html">Unlock</a></CODE> method unlocks mutexes, but it can only be called from the locking thread because mutex locks are associated with their threads.</p><p>The <CODE><a href="../../../nn/os/Mutex/Overview.html">Mutex</a></CODE> class implements recursively locking mutexes. (In other words, <CODE><a href="../../../nn/os/Mutex/Lock.html">Lock</a></CODE> can be called from a locked thread.) In this case, the mutex will not be unlocked until <CODE><a href="../../../nn/os/Mutex/Unlock.html">Unlock</a></CODE> is called the same number of times that <CODE><a href="../../../nn/os/Mutex/Lock.html">Lock</a></CODE> was called.</p><p>The <CODE><a href="../../../nn/os/Mutex/Overview.html">Mutex</a></CODE> class implements priority inheritance. If a high-priority thread ("H") attempts to get a lock on a mutex that is already locked by a low-priority thread ("L"), the priority of thread L will temporarily be raised to the same priority as thread H.</p><p>The <CODE>Wait</CODE> operation of a <CODE><a href="../../../nn/os/Mutex/Overview.html">Mutex</a></CODE> object gets a lock. Once the lock can be obtained, the <CODE>Wait</CODE> operation is released.</p><p>The use of <CODE><a href="../../../nn/os/Mutex/ScopedLock/Overview.html">nn::os::Mutex::ScopedLock</a></CODE> makes it possible to lock a mutex starting when an object is created, and continuing until it goes out of scope.</p><p>You can create up to 32 <a href="../../../nn/os/Mutex/Overview.html"><CODE>Mutex</CODE></a> objects. Note also that different functions might use up resources that count against this limit.</p><!-- write here --></div> 61 <a name="class" id="class"> 62<h2>Classes</h2> 63 <div class="section"> 64 <table class="members"> 65 <tr> 66 <th> 67<a href="../../../nn/os/Mutex/ScopedLock/Overview.html"><CODE>nn::os::Mutex::ScopedLock</CODE></a> 68 </th> 69<td>Locks a mutex starting when an object is created, and continues locking it until the the object goes out of scope.</td> 70 </tr> </table> 71 </div> 72 </a> <a name="function" id="function"> 73<h2>Member Functions</h2> 74 <div class="section"> 75 <table class="members"> 76 <tr> 77 <td width="100"> </td> 78 <th> 79<a href="../../../nn/os/Mutex/Mutex.html"><CODE>Mutex</CODE></a> 80 </th> 81<td>Constructs and initializes a mutex.</td> 82 </tr> 83 <tr> 84 <td width="100"> </td> 85 <th> 86<a href="../../../nn/os/Mutex/Initialize.html"><CODE>Initialize</CODE></a> 87 </th> 88<td>Initializes a mutex.</td> 89 </tr> 90 <tr> 91 <td width="100"> </td> 92 <th> 93<a href="../../../nn/os/Mutex/TryInitialize.html"><CODE>TryInitialize</CODE></a> 94 </th> 95<td>Tries to initialize a mutex.</td> 96 </tr> 97 <tr> 98 <td width="100"> </td> 99 <th> 100<a href="../../../nn/os/Mutex/Finalize.html"><CODE>Finalize</CODE></a> 101 </th> 102<td>Destroys a mutex.</td> 103 </tr> 104 <tr> 105 <td width="100"> </td> 106 <th> 107<a href="../../../nn/os/Mutex/~Mutex.html"><CODE>~Mutex</CODE></a> 108 </th> 109<td>Destructor.</td> 110 </tr> 111 <tr> 112 <td width="100"> </td> 113 <th> 114<a href="../../../nn/os/Mutex/Lock.html"><CODE>Lock</CODE></a> 115 </th> 116<td>Locks a mutex.</td> 117 </tr> 118 <tr> 119 <td width="100"> </td> 120 <th> 121<a href="../../../nn/os/Mutex/TryLock.html"><CODE>TryLock</CODE></a> 122 </th> 123<td>Tries to lock a mutex.</td> 124 </tr> 125 <tr> 126 <td width="100"> </td> 127 <th> 128<a href="../../../nn/os/Mutex/Unlock.html"><CODE>Unlock</CODE></a> 129 </th> 130<td>Unlocks a mutex.</td> 131 </tr> </table> 132 </div> 133 </a> 134<h2>Class Hierarchy</h2> 135 <div class="section"> 136<p class="hierarchy"><span>ADLFireWall::NonCopyable</span><br /> <a href="../../../nn/os/HandleObject/Overview.html">nn::os::HandleObject</a><br /> <a href="../../../nn/os/WaitObject/Overview.html">nn::os::WaitObject</a><br /> <b>nn::os::Mutex</b> 137 </p> 138 </div> 139<h2>Revision History</h2> 140 <div class="section"> 141 <dl class="history"> 142 <dt>2010/01/07</dt> 143<dd>Initial version.<br /> 144 </dd> 145 </dl> 146 </div> 147 <hr><p>CONFIDENTIAL</p></body> 148</html> 149