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1 // Copyright (c) 2005-2009 Nokia Corporation and/or its subsidiary(-ies). |
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2 // All rights reserved. |
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3 // This component and the accompanying materials are made available |
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4 // under the terms of "Eclipse Public License v1.0" |
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5 // which accompanies this distribution, and is available |
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6 // at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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7 // |
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8 // Initial Contributors: |
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9 // Nokia Corporation - initial contribution. |
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10 // |
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11 // Contributors: |
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12 // |
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13 // Description: |
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14 // |
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15 |
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16 #ifndef __IPCBUF_H__ |
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17 #define __IPCBUF_H__ |
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18 |
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19 #include <s32buf.h> |
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20 #include "IpcDefs.h" |
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21 |
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22 //Forward declarations |
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23 class TIpcArgs; |
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24 class RSqlDbSession; |
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25 |
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26 /** |
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27 HIpcBuf class manages the "client to server" transfer of large data blocks. |
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28 |
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29 It caches the data to be sent/retrieved on the client side and sychronises the content of the client-side cache |
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30 with the content of a similar server-side cache, sending appropriate read/write/sync commands to the server. |
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31 |
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32 An instance of TIpcStreamBuf class is uased as a client-side cache. |
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33 |
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34 The following code fragment shows how the class can be used to send to the server large blocks of data: |
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35 |
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36 @code |
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37 //Step 1: Create the HIpcBuf instance. |
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38 HIpcBuf* ipcBuf = HIpcBuf::NewLC(params, function, args); |
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39 |
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40 //Step 2: Create a stream instance. It will be used for sending the data to the server. All details about |
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41 // the data transfer will be performed by the ipcBuf object. |
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42 RWriteStream out(ipcBuf); |
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43 |
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44 //Step 3: "TheObject" is some large data object which has to be sent to the server. Let's assume |
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45 // "TheObject" has ExternalizeL() function which can be used to externalize the object into an output stream. |
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46 TheObject.ExternalizeL(out); |
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47 |
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48 //Step 4: Commit the output stream. After the commit command the server will have all the data transferred. |
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49 out.CommitL(); |
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50 |
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51 //Step 5: Cleanup. |
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52 CleanupStack::PopAndDestroy(ipcBuf); |
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53 @endcode |
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54 |
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55 @see RSqlDbSession; |
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56 @see TIpcStreamBuf |
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57 @see RSessionBase |
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58 |
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59 @internalComponent |
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60 */ |
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61 NONSHARABLE_CLASS(HIpcBuf) : public TStreamBuf |
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62 { |
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63 public: |
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64 static HIpcBuf* NewL(RSqlDbSession& aSession, TInt aFunction, TIpcArgs& aArgs); |
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65 static HIpcBuf* NewLC(RSqlDbSession& aSession, TInt aFunction, TIpcArgs& aArgs); |
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66 virtual ~HIpcBuf(); |
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67 |
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68 private: |
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69 HIpcBuf(RSqlDbSession& aSession); |
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70 void ConstructL(TInt aFunction, TIpcArgs& aArgs); |
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71 |
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72 // from TStreamBuf |
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73 TInt UnderflowL(TInt aMaxLength); |
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74 void OverflowL(); |
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75 void DoRelease(); |
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76 void DoSynchL(); |
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77 TInt DoReadL(TAny* aPtr, TInt aMaxLength); |
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78 void DoWriteL(const TAny* aPtr, TInt aLength); |
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79 TStreamPos DoSeekL(TMark aMark, TStreamLocation aLocation, TInt anOffset); |
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80 |
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81 private: |
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82 inline void SetPos(TRead, TInt aPos); |
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83 inline void SetPos(TWrite, TInt aPos); |
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84 inline TInt Pos(TRead) const; |
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85 inline TInt Pos(TWrite) const; |
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86 inline TInt MovePos(TRead, TInt aOffset); |
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87 TInt IpcReadL(TAny* aPtr, TInt aMaxLength); |
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88 void IpcWriteL(const TAny* aPtr, TInt aLength); |
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89 TInt EndL(); |
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90 |
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91 inline TInt Lag(TRead) const; |
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92 inline TInt Lag(TWrite) const; |
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93 inline TInt Mark(TRead) const; |
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94 inline TInt Mark(TWrite) const; |
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95 |
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96 private: |
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97 RSqlDbSession& iSession; |
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98 TInt iHandle; |
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99 TInt iRPos; |
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100 TInt iWPos; |
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101 TIpcStreamBuf iBuf; |
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102 }; |
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103 |
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104 #include "IPCBuf.inl" |
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105 |
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106 #endif//__IPCBUF_H__ |