Symbian3/Examples/guid-6013a680-57f9-415b-8851-c4fa63356636/_real_life_wait_loop_8cpp_source.html
Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
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<h1>examples/Base/IPC/Async/RealLifeWaitLoop/RealLifeWaitLoop.cpp</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">// Copyright (c) 2000-2009 Nokia Corporation and/or its subsidiary(-ies).</span>
<a name="l00002"></a>00002 <span class="comment">// All rights reserved.</span>
<a name="l00003"></a>00003 <span class="comment">// This component and the accompanying materials are made available</span>
<a name="l00004"></a>00004 <span class="comment">// under the terms of "Eclipse Public License v1.0"</span>
<a name="l00005"></a>00005 <span class="comment">// which accompanies this distribution, and is available</span>
<a name="l00006"></a>00006 <span class="comment">// at the URL "http://www.eclipse.org/legal/epl-v10.html".</span>
<a name="l00007"></a>00007 <span class="comment">//</span>
<a name="l00008"></a>00008 <span class="comment">// Initial Contributors:</span>
<a name="l00009"></a>00009 <span class="comment">// Nokia Corporation - initial contribution.</span>
<a name="l00010"></a>00010 <span class="comment">//</span>
<a name="l00011"></a>00011 <span class="comment">// Contributors:</span>
<a name="l00012"></a>00012 <span class="comment">//</span>
<a name="l00013"></a>00013 <span class="comment">// Description:</span>
<a name="l00014"></a>00014 <span class="comment">// Show asynchronous programming (without active objects)</span>
<a name="l00015"></a>00015 <span class="comment">// Example introduces the "complications" involved in real-life</span>
<a name="l00016"></a>00016 <span class="comment">// wait loops, which always deal with multiple asynchronous</span>
<a name="l00017"></a>00017 <span class="comment">// service providers</span>
<a name="l00018"></a>00018 <span class="comment">//</span>
<a name="l00019"></a>00019
<a name="l00020"></a>00020
<a name="l00021"></a>00021
<a name="l00022"></a>00022
<a name="l00023"></a>00023 <span class="preprocessor">#include "CommonFramework.h"</span>
<a name="l00024"></a>00024 <span class="preprocessor">#include <e32math.h></span>
<a name="l00025"></a>00025
<a name="l00026"></a>00026 <span class="comment">//</span>
<a name="l00027"></a>00027 <span class="comment">// Common literal text</span>
<a name="l00028"></a>00028 <span class="comment">//</span>
<a name="l00029"></a>00029
<a name="l00030"></a>00030 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KMsgQuickCancelled,<span class="stringliteral">"Quick service request canceled\n"</span>);
<a name="l00031"></a>00031
<a name="l00032"></a>00032 <span class="comment">//</span>
<a name="l00033"></a>00033 <span class="comment">// utility functions</span>
<a name="l00034"></a>00034 <span class="comment">//</span>
<a name="l00035"></a>00035
<a name="l00036"></a>00036 LOCAL_D TInt64 smallRandSeed;
<a name="l00037"></a>00037
<a name="l00038"></a>00038 LOCAL_C TInt smallRand()
<a name="l00039"></a>00039 {
<a name="l00040"></a>00040 <span class="comment">// produce small random numbers in range 0..9</span>
<a name="l00041"></a>00041 TInt bigResult=Math::Rand(smallRandSeed);<span class="comment">// result uses full 32-bit range</span>
<a name="l00042"></a>00042 <span class="keywordflow">return</span> bigResult % 10; <span class="comment">// return result mod 10</span>
<a name="l00043"></a>00043 }
<a name="l00044"></a>00044
<a name="l00045"></a>00045 LOCAL_C <span class="keywordtype">void</span> sleep(TInt aTenths)
<a name="l00046"></a>00046 {
<a name="l00047"></a>00047 <span class="comment">// sleep for an interval measured in tenths of a second</span>
<a name="l00048"></a>00048 User::After(aTenths*100000); <span class="comment">// just let the User function do it for us</span>
<a name="l00049"></a>00049 }
<a name="l00050"></a>00050
<a name="l00051"></a>00051
<a name="l00052"></a>00052 <span class="comment">// Do the example</span>
<a name="l00053"></a>00053 LOCAL_C <span class="keywordtype">void</span> doExampleL()
<a name="l00054"></a>00054 {
<a name="l00055"></a>00055 <span class="comment">// create and initialize heartbeat timer</span>
<a name="l00056"></a>00056 RTimer heartbeat; <span class="comment">// Heartbeat timer.</span>
<a name="l00057"></a>00057 TRequestStatus heartbeatStatus; <span class="comment">// Request status associated with it.</span>
<a name="l00058"></a>00058 heartbeat.CreateLocal(); <span class="comment">// Always created for this thread.</span>
<a name="l00059"></a>00059
<a name="l00060"></a>00060 <span class="comment">// create stuff for secondary timer</span>
<a name="l00061"></a>00061 RTimer quickService; <span class="comment">// A quick service.</span>
<a name="l00062"></a>00062 TRequestStatus quickServiceStatus; <span class="comment">// Ccorresponding status.</span>
<a name="l00063"></a>00063 TBool quickServiceRequestIssued=EFalse; <span class="comment">// Whether request issued.</span>
<a name="l00064"></a>00064 quickService.CreateLocal(); <span class="comment">// Create timer.</span>
<a name="l00065"></a>00065
<a name="l00066"></a>00066 <span class="comment">// issue first heartbeat request</span>
<a name="l00067"></a>00067 heartbeat.After(heartbeatStatus,1000000); <span class="comment">// Request completion</span>
<a name="l00068"></a>00068 <span class="comment">// after 1 second.</span>
<a name="l00069"></a>00069 TInt heartbeatTick=0; <span class="comment">// Ccounts heartbeat ticks.</span>
<a name="l00070"></a>00070
<a name="l00071"></a>00071 <span class="comment">// wait loop</span>
<a name="l00072"></a>00072 <span class="keywordflow">for</span> (;;)
<a name="l00073"></a>00073 {
<a name="l00074"></a>00074 <span class="comment">// Wait for any request</span>
<a name="l00075"></a>00075 User::WaitForAnyRequest();
<a name="l00076"></a>00076 <span class="comment">// find out which request completed, and handle it</span>
<a name="l00077"></a>00077 <span class="keywordflow">if</span> (heartbeatStatus!=KRequestPending)
<a name="l00078"></a>00078 {
<a name="l00079"></a>00079 <span class="comment">// heartbeat completed so service request</span>
<a name="l00080"></a>00080 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KMsgServicing,<span class="stringliteral">"Servicing heartbeat tick %d ...\n"</span>);
<a name="l00081"></a>00081 console->Printf(KMsgServicing,heartbeatTick);
<a name="l00082"></a>00082 <span class="comment">// take some time over it</span>
<a name="l00083"></a>00083 sleep(smallRand());
<a name="l00084"></a>00084
<a name="l00085"></a>00085 <span class="keywordflow">if</span> (smallRand() < 5)
<a name="l00086"></a>00086 {
<a name="l00087"></a>00087 <span class="comment">// issue a quick request 50% of the time</span>
<a name="l00088"></a>00088 <span class="comment">// cancel any outstanding quick request</span>
<a name="l00089"></a>00089 <span class="keywordflow">if</span> (quickServiceRequestIssued)
<a name="l00090"></a>00090 {
<a name="l00091"></a>00091 quickService.Cancel(); <span class="comment">// cancel request</span>
<a name="l00092"></a>00092 User::WaitForRequest(quickServiceStatus); <span class="comment">// wait</span>
<a name="l00093"></a>00093 quickServiceRequestIssued=EFalse; <span class="comment">// indicate not issued</span>
<a name="l00094"></a>00094 console->Printf(KMsgQuickCancelled);
<a name="l00095"></a>00095 }
<a name="l00096"></a>00096 <span class="comment">// issue new quick request</span>
<a name="l00097"></a>00097 quickService.After(quickServiceStatus,(smallRand()*2)*100000);
<a name="l00098"></a>00098 <span class="comment">// request an event after 0 .. 1.8 seconds</span>
<a name="l00099"></a>00099 quickServiceRequestIssued=ETrue; <span class="comment">// indicate request issued</span>
<a name="l00100"></a>00100 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KMsgQuickIssued,<span class="stringliteral">"Quick service request issued\n"</span>);
<a name="l00101"></a>00101 console->Printf(KMsgQuickIssued);
<a name="l00102"></a>00102 }
<a name="l00103"></a>00103
<a name="l00104"></a>00104 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KMsgServiced,<span class="stringliteral">"... heartbeat tick %d serviced\n"</span>);
<a name="l00105"></a>00105 console->Printf(KMsgServiced, heartbeatTick);
<a name="l00106"></a>00106 <span class="comment">// test whether processing should finish</span>
<a name="l00107"></a>00107 <span class="keywordflow">if</span> (heartbeatTick >= 10)
<a name="l00108"></a>00108 {
<a name="l00109"></a>00109 <span class="comment">// 10 heart-beats: processing finished</span>
<a name="l00110"></a>00110 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KMsgFinishing,<span class="stringliteral">"Finishing\n"</span>);
<a name="l00111"></a>00111 console->Printf(KMsgFinishing);
<a name="l00112"></a>00112
<a name="l00113"></a>00113 <span class="comment">// cancel quick request, if outstanding</span>
<a name="l00114"></a>00114 <span class="keywordflow">if</span> (quickServiceRequestIssued)
<a name="l00115"></a>00115 {
<a name="l00116"></a>00116 <span class="comment">// only relevant if request issued</span>
<a name="l00117"></a>00117 quickService.Cancel(); <span class="comment">// request early completion</span>
<a name="l00118"></a>00118 User::WaitForRequest(quickServiceStatus); <span class="comment">// wait</span>
<a name="l00119"></a>00119 quickServiceRequestIssued=EFalse;
<a name="l00120"></a>00120 <span class="comment">// request no longer issued</span>
<a name="l00121"></a>00121 console->Printf(KMsgQuickCancelled);
<a name="l00122"></a>00122 }
<a name="l00123"></a>00123
<a name="l00124"></a>00124 <span class="keywordflow">break</span>; <span class="comment">// finish wait loop</span>
<a name="l00125"></a>00125 }
<a name="l00126"></a>00126 <span class="comment">// re-issue request</span>
<a name="l00127"></a>00127 heartbeatTick++; <span class="comment">// increment tick counter</span>
<a name="l00128"></a>00128 heartbeat.After(heartbeatStatus,1000000); <span class="comment">// another second</span>
<a name="l00129"></a>00129 }
<a name="l00130"></a>00130
<a name="l00131"></a>00131 <span class="keywordflow">else</span> <span class="keywordflow">if</span> (quickServiceRequestIssued && quickServiceStatus!=KRequestPending)
<a name="l00132"></a>00132 { <span class="comment">// if quick service request issued, and completed, then service it</span>
<a name="l00133"></a>00133 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KMsgQuickCompleted,<span class="stringliteral">"Quick request completed\n"</span>);
<a name="l00134"></a>00134 console->Printf(KMsgQuickCompleted);
<a name="l00135"></a>00135 quickServiceRequestIssued=EFalse; <span class="comment">// indicate request not issued</span>
<a name="l00136"></a>00136 }
<a name="l00137"></a>00137
<a name="l00138"></a>00138 <span class="keywordflow">else</span>
<a name="l00139"></a>00139 { <span class="comment">// stray signal</span>
<a name="l00140"></a>00140 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KMsgStraySignal,<span class="stringliteral">"Stray signal\n"</span>);
<a name="l00141"></a>00141 User::Panic(KMsgStraySignal, 1); <span class="comment">// panic!</span>
<a name="l00142"></a>00142 }
<a name="l00143"></a>00143 }
<a name="l00144"></a>00144
<a name="l00145"></a>00145 <span class="comment">// close quick service</span>
<a name="l00146"></a>00146 quickService.Close(); <span class="comment">// close</span>
<a name="l00147"></a>00147
<a name="l00148"></a>00148 <span class="comment">// close timer</span>
<a name="l00149"></a>00149 heartbeat.Close(); <span class="comment">// close timer</span>
<a name="l00150"></a>00150 }
</pre></div></div>
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