<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

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

<concept id="GUID-9C36CF76-6ED2-5674-908F-A3DF8930CEB0" xml:lang="en"><title>How

to renew a request from the active scheduler</title><shortdesc>This document describes how to maintain an outstanding request

from an active scheduler.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>It is possible to maintain an outstanding request from the active scheduler,

by overriding the <codeph>CActiveScheduler::WaitForAnyRequest()</codeph> function.</p>

<p>In this case, it is useful for the active scheduler to have a data member

which points to the active object for which it will maintain an outstanding

request. Implement the active scheduler as follows:</p>

<codeblock id="GUID-92FD6B7D-54E8-5E1D-828F-AEE77C45CA3A" xml:space="preserve">class CExampleScheduler : public CActiveScheduler

    {

public:

    void Error (TInt aError) const;

    void WaitForAnyRequest();

    void SetActiveObject(CActiveConsole* aActiveConsole);

private:

    CActiveConsole* iActiveConsole;

    };</codeblock>

<codeblock id="GUID-156BDAD4-B9EB-55AB-827A-16739A66AC2D" xml:space="preserve">void CExampleScheduler::SetActiveObject(CActiveConsole* aActiveConsole)

    {

    iActiveConsole = aActiveConsole;

    }</codeblock>

<p>where <codeph>iActiveConsole</codeph> is a pointer to an active object,

initialized by call to <codeph>SetActiveObject()</codeph> during the construction

of the controlling active object:</p>

<codeblock id="GUID-721C2A53-CE4F-5C37-9599-DE359A586C9C" xml:space="preserve">void CMessageKeyProcessor::ConstructL()

    {

    CActiveScheduler::Add(this);

    (CExampleScheduler*)(CActiveScheduler::Current())->SetActiveObject(this);

    }</codeblock>

<p>Now override <codeph>CActiveScheduler::WaitForAnyRequest()</codeph>:</p>

<codeblock id="GUID-7646ED79-B891-5F94-BCBC-37A025FA5270" xml:space="preserve">void CExampleScheduler::WaitForAnyRequest()

    {

    if (!(iActiveConsole->IsActive()))

        {

        iActiveConsole->RequestCharacter();

        }

    CActiveScheduler::WaitForAnyRequest();

    }</codeblock>

<section id="GUID-52635F6A-E5F8-4F08-A77F-136FC80C39BF"><title>Notes</title> <ul>

<li id="GUID-76CC4644-1909-5423-BF85-44F6AA4053A3"><p>The state of the active

request flag is examined and a request is not issued if it is active. This

check is important because the function may be called as a result of other

active objects completing (for example, a timed messenger) and in these cases

it would be inappropriate to renew the keyboard service request.</p> </li>

<li id="GUID-5DA7C2E5-4BB2-54B1-9800-53FB2E41793D"><p>It is no longer necessary

to call <codeph>RequestCharacter()</codeph> either before starting the active

scheduler, or as part of key processing.</p> </li>

<li id="GUID-7535854A-24C9-581C-9B49-FE17E2252E8E"><p>The static function <codeph>CActiveScheduler::Current()</codeph> is

used to fetch a pointer to the currently installed active scheduler (in this

example, an object of type <codeph>CExampleScheduler</codeph>). This is necessary

in order to access the <codeph>SetActiveObject()</codeph> member function

of <codeph>CExampleScheduler</codeph>.</p> </li>

</ul> </section>

</conbody></concept>