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     7     Nokia Corporation - initial contribution.

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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-18182059-859D-51CF-A940-D230D9F9CF8C" xml:lang="en"><title>How

    13 to allocate and de-allocate cleanup stacks</title><shortdesc>This document describes when and how a cleanup stack should be

    14 allocated and de-allocated.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    15 <p>The main categories of programs (GUI applications and servers) both have

    16 cleanup stacks created for them as part of their respective frameworks. Simple

    17 console programs for test and demonstration purposes though require a cleanup

    18 stack to be explicitly allocated. </p>

    19 <p>Allocate the stack at the beginning of the thread as follows:</p>

    20 <codeblock id="GUID-204BB8EA-016F-53CA-BB22-17B685BFF18A" xml:space="preserve">TheTrapCleanup=CTrapCleanup::New();</codeblock>

    21 <p>De-allocate the cleanup stack at the end of the thread as follows:</p>

    22 <codeblock id="GUID-C8A45849-E86C-5DA6-B1A5-88113B06C2B7" xml:space="preserve">delete TheTrapCleanup;</codeblock>

    23 <section id="GUID-9E86AB70-D551-4356-9001-749FBE8B2DCE"><title>Notes</title> <ul>

    24 <li id="GUID-37929EEE-F608-5754-9324-6731FEA5B1B2"><p>This explicit allocation

    25 and de-allocation is necessary for threads which use cleanup processing. Threads

    26 which do not use cleanup stack processing need not allocate a cleanup stack. </p> </li>

    27 <li id="GUID-6B30E7F5-1D29-50EF-8896-0CD8400BBBCF"><p>Note that the cleanup

    28 stack variable name (<codeph>TheTrapCleanup</codeph> in this case) is only

    29 used to reference the stack when it needs to be destroyed. Therefore the user

    30 is at liberty to give the stack any valid variable name. Multiple cleanup

    31 stacks are supported: the system holds a stack of cleanup stacks, of which

    32 the top item is the current cleanup stack. As such, when a new stack is created

    33 it is pushed onto the stack of cleanup stacks, making it the current cleanup

    34 stack. When it is destroyed, it is pushed off the stack of cleanup stacks

    35 making the previously stacked cleanup stack the current one.</p> </li>

    36 </ul> </section>

    37 </conbody></concept>