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+        <title>Apache Qpid : ScopedLocking</title>
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+                            Apache Qpid : ScopedLocking
+                                                    </span>
+				    </div>
+				    <div class="pagesubheading">
+					    This page last changed on Oct 19, 2006 by <font color="#0050B2">mmccorma</font>.
+				    </div>
+
+				    <p>Always use scoped lockers to lock mutexes and the like. Don't do this:</p>
+<div class="preformatted"><div class="preformattedContent">
+<pre> lock.acquire();
+ do_stuff(); // DANGER: lock never released if exception thrown here.
+ lock.release();
+</pre>
+</div></div>
+
+<p>Instead use a "scoped locker". This is simply a class that does the "acquire" in its constructor and the "release" in its destructor:</p>
+<div class="preformatted"><div class="preformattedContent">
+<pre>  Locker locker(lock);
+  do_stuff();
+</pre>
+</div></div>
+
+<p>Not only does this save a bit of typing, it guarantees that the lock will be released even if an exception is thrown, because C++ guarantees to call destructors of all local variables on exit from a scope. This also protects you forgetting to release the lock at every exit point from a function with multiple exit points - the compiler takes care of it for you. This technique applies more generally to any situation where you have to acquire and release resources. <tt>std::auto_ptr</tt> is a similar tool for memory management.</p>
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+			    <td align="center"><font color="grey">Document generated by Confluence on Apr 22, 2008 02:47</font></td>
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