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1 <?xml version="1.0" encoding="utf-8"?> |
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2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. --> |
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3 <!-- This component and the accompanying materials are made available under the terms of the License |
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4 "Eclipse Public License v1.0" which accompanies this distribution, |
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5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". --> |
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6 <!-- Initial Contributors: |
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7 Nokia Corporation - initial contribution. |
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8 Contributors: |
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9 --> |
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10 <!DOCTYPE task |
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11 PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd"> |
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12 <task id="GUID-C4C8395E-F982-4D6A-88D3-28EDC494817F" xml:lang="en"><title>Requesting |
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13 RAM Asynchronously</title><shortdesc>This section describes how an application can request for free |
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14 RAM asynchronously.</shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody> |
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15 <prereq id="GUID-6C258B11-CE78-42F2-828D-E9C68598C193"><p>Perform the steps |
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16 described in <xref href="GUID-50CA5439-29A1-426C-83BA-EC048FE86CDE.dita">Allowing |
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17 Large Memory Allocation</xref>.</p></prereq> |
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18 <context id="GUID-D36C0590-A436-458B-B7A6-F2E8577E26C6"> <p>Requesting |
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19 free RAM asynchronously is recommended as the application is not blocked during |
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20 the method call handling.</p> </context> |
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21 <steps id="GUID-4DD07DEC-6017-4237-BE46-1D69E5FBD744-GENID-1-8-1-10-1-1-8-1-5-1-6-1-6-1-5-1-3-3"> |
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22 <step id="GUID-9A69E5AD-E938-4092-A8C2-CB65C37C8962-GENID-1-8-1-10-1-1-8-1-5-1-6-1-6-1-5-1-3-3-1"><cmd>Start an asynchronous |
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23 request for a block of memory.</cmd> |
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24 <info><codeblock xml:space="preserve">CMemoryAllocatingObject::StartFunctionalityRequiringAllocationL() |
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25 { |
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26 User::LeaveIfError(iOomMonitorSession.Connect()); |
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27 iMemoryRequester = CMemoryRequester::NewL(iOomMonitorSession, *this); |
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28 iMemoryRequester->Start(KLargeValueToAllocate); |
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29 } |
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30 </codeblock></info> |
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31 </step> |
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32 <step id="GUID-9A69E5AD-E938-4092-A8C2-CB65C37C8962-GENID-1-8-1-10-1-1-8-1-5-1-6-1-6-1-5-1-3-3-2"><cmd>Implement the active |
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33 object and request for free memory.</cmd> |
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34 <info><codeblock xml:space="preserve">void CMemoryRequester::Start(TInt aBytesRequested) |
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35 { |
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36 iOomMonitorSession.RequestFreeMemory(aBytesRequested, iStatus); |
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37 SetActive(); |
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38 } |
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39 </codeblock></info> |
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40 </step> |
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41 </steps> |
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42 <example><p>The following code snippet illustrates an asynchronous request |
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43 for free RAM allocation: </p><codeblock xml:space="preserve">const TInt KLargeValueToAllocate = 2097152; //2MB |
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44 |
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45 // Start an asynchronous request for block of memory |
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46 CMemoryAllocatingObject::StartFunctionalityRequiringAllocationL() |
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47 { |
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48 User::LeaveIfError(iOomMonitorSession.Connect()); |
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49 iMemoryRequester = CMemoryRequester::NewL(iOomMonitorSession, *this); |
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50 iMemoryRequester->Start(KLargeValueToAllocate); |
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51 } |
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52 |
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53 // Called when the asynchronous request is completed |
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54 CMemoryAllocatingObject::MemoryRequestCompleteL(TInt aResult) |
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55 { |
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56 if (aResult == KErrNone) |
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57 { |
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58 DoFunctionRequiring_KLargeValueToAllocate_BytesL(); |
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59 } |
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60 iOomMonitorSession.Close(); |
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61 } |
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62 The active object implementation is the following: |
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63 |
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64 // Start an asynchronous request for block of memory |
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65 void CMemoryRequester::Start(TInt aBytesRequested) |
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66 { |
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67 iOomMonitorSession.RequestFreeMemory(aBytesRequested, iStatus); |
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68 SetActive(); |
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69 } |
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70 |
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71 |
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72 // Called when the asynchronous request is completed |
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73 void CMemoryRequester::RunL() |
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74 { |
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75 iObserver.MemoryRequestCompleteL(iStatus.Int()); |
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76 } |
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77 </codeblock></example> |
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78 </taskbody><related-links> |
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79 <link href="GUID-CE308C71-D8B2-43B3-97FD-B868285ED5FB.dita"><linktext>OOM Monitor |
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80 Priority</linktext></link> |
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81 <link href="GUID-39A8FBC9-5FD6-4F92-B71E-5C5438ECFD46.dita"><linktext>OOM Monitor |
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82 Overview</linktext></link> |
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83 <link href="GUID-88752800-83BD-4845-80A0-6B65D8D81924.dita"><linktext>OOM Monitor |
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84 Reference</linktext></link> |
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85 </related-links></task> |