TB10.1 Example Applications: examples/Base/SemaphoreExample/src/CDatabase.cpp Source File

00001 // Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).
-00002 // All rights reserved.
-00003 // This component and the accompanying materials are made available
-00004 // under the terms of "Eclipse Public License v1.0"
-00005 // which accompanies this distribution, and is available
-00006 // at the URL "http://www.eclipse.org/legal/epl-v10.html".
-00007 //
-00008 // Initial Contributors:
-00009 // Nokia Corporation - initial contribution.
-00010 //
-00011 // Contributors:
-00012 //
-00013 // Description:
-00014 // This class contains methods to create a database of integers and periodically read /write integers
-00015 // from/ to the database. The macro USE_SEMAPHORE is used at various places to show thread synchronization
-00016 // using a semaphore. 
-00017 
-00018 #include "CDatabase.h"
-00019 
-00020 //Declare a delay of 1000000 microseconds i.e. 1 sec for the periodic functions. 
-00021 const int KDelay = 1000000; 
-00022 
-00023 //The last number in the database.
-00024 const int KLastNum = 50; 
-00025 
-00029 CDatabase* CDatabase::NewL()
-00030     {
-00031     CDatabase* self=new(ELeave)CDatabase();
-00032     CleanupStack::PushL(self);
-00033     self->ConstructL();
-00034     CleanupStack::Pop(self);
-00035     return self;
-00036     }
-00037 
-00041 CDatabase::~CDatabase()
-00042     {   
-00043     iFsSession.Close();  //close the file server session. 
-00044     delete iPeriodic;    //delete the periodic object.
-00045     delete iConsole;     //delete the console. 
-00046     #ifdef USE_SEMAPHORE
-00047     iSemWrite.Close(); 
-00048     #endif
-00049     }
-00050 
-00054 void CDatabase::ConstructL()
-00055     {
-00056     iPeriodic = CPeriodic::NewL(CActive::EPriorityUserInput);
-00057     
-00058     _LIT(KDbCreateDb,"exampleDatabase.db");
-00059       
-00060     iFsSession.Connect();
-00061     
-00062     //The database exampleDatabase.db is created as a permanent file store 
-00063     //in the app's private directory.
-00064     User::LeaveIfError(iFsSession.CreatePrivatePath(RFs::GetSystemDrive()));
-00065 
-00066     User::LeaveIfError(iFsSession.PrivatePath(iDbname));
-00067     iDbname.Append(KDbCreateDb); 
-00068 
-00069     #ifdef USE_SEMAPHORE
-00070     //Open the global semaphore which was created in CSemaphoreExample. 
-00071     _LIT(KSemaphoreWrite, "WriteSemaphore");
-00072     User::LeaveIfError(iSemWrite.OpenGlobal(KSemaphoreWrite, EOwnerProcess)); 
-00073     #endif
-00074     }
-00075 
-00079 void CDatabase::CreateDatabaseL()
-00080     {
-00081     //Construct a file store object - the file to contain the
-00082     //database replaces any existing file of the same name.
-00083     CFileStore* store = CPermanentFileStore::ReplaceLC(iFsSession, iDbname, EFileRead|EFileWrite);
-00084     //Complete file store creation.
-00085     store->SetTypeL(store->Layout());
-00086     
-00087     //Create a database in the store.  
-00088     TStreamId id= iDatabase.CreateL(store);
-00089     
-00090     //Keep database id as root of store.
-00091     store->SetRootL(id);
-00092     
-00093     //Complete database creation by commiting the store.
-00094     store->CommitL();
-00095     
-00096     
-00097     //Create a table definition.
-00098     CDbColSet* columns=CDbColSet::NewLC();
-00099     
-00100     //Add three columns each containing Int32 values. 
-00101     _LIT(KCol1, "Number1");
-00102     _LIT(KCol2, "Number2");
-00103     _LIT(KCol3, "Number3");   
-00104     columns->AddL(TDbCol(KCol1,EDbColInt32));
-00105     columns->AddL(TDbCol(KCol2,EDbColInt32));
-00106     columns->AddL(TDbCol(KCol3,EDbColInt32));
-00107     
-00108     
-00109     //Create the table, table name is "Numbers" and add the columns to it.
-00110     _LIT(KTable, "Numbers");
-00111     User::LeaveIfError(iDatabase.CreateTable(KTable,*columns));
-00112     
-00113     CDbKey* key=CDbKey::NewLC();
-00114     
-00115     //Add the key columns.
-00116     TDbKeyCol number1(KCol1);
-00117     key->AddL(number1);
-00118     TDbKeyCol number2(KCol2);
-00119     key->AddL(number2);
-00120     TDbKeyCol number3(KCol3);
-00121     key->AddL(number3);
-00122     User::LeaveIfError(iDatabase.CreateIndex(KTable,KTable,*key));
-00123     
-00124     iDatabase.Close();
-00125     //Cleanup the column set.  
-00126     CleanupStack::PopAndDestroy(key);
-00127     CleanupStack::PopAndDestroy(columns);
-00128     CleanupStack::PopAndDestroy(store);
-00129     }
-00130 
-00135 void CDatabase::WritetoDatabaseL()
-00136     {
-00137     iPeriodic->Start(0, KDelay, TCallBack(PeriodicWriteL, this));
-00138     CActiveScheduler::Start();
-00139     }
-00140 
-00145 TInt CDatabase::PeriodicWriteL(TAny* aPtr)
-00146     {
-00147     CDatabase* ptr = static_cast<CDatabase*> (aPtr);
-00148     //Invoke the RThread::Resume() function on the consumer thread repeatedly.
-00149     ptr->PeriodicWriteFuncL();
-00150     return KErrNone;
-00151     }
-00152 
-00157 void CDatabase::PeriodicWriteFuncL()
-00158     {
-00159     //Declare an integer which is used to fill numbers in the database. 
-00160     static int num = 0 ;  
-00161     
-00162      //Open the file store.
-00163     _LIT(KSQLStatement,"select Number1, Number2, Number3 from Numbers order by Number1,Number2,Number3");
-00164     CFileStore* store = CFileStore::OpenLC(iFsSession,iDbname,EFileRead|EFileWrite);
-00165     
-00166     
-00167     //Open the database from the root stream.
-00168     iDatabase.OpenL(store,store->Root());
-00169     
-00170     //Lock the database before use. 
-00171     iDatabase.Begin();
-00172     
-00173     //Create a view on the database view to read/write numbers into it. 
-00174     RDbView view;
-00175     User::LeaveIfError(view.Prepare(iDatabase,TDbQuery(KSQLStatement,EDbCompareNormal)));
-00176     User::LeaveIfError(view.EvaluateAll());
-00177 
-00178     
-00179     //Insert a new row at the end of the database. 
-00180     view.InsertL();
-00181 
-00182     //Fill three coloumns with numbers.
-00183     view.SetColL(1, num++);
-00184     view.SetColL(2, num++);
-00185     view.SetColL(3, num++);
-00186     view.PutL();
-00187     
-00188     //Close the view. 
-00189     view.Close();
-00190     
-00191     //Unlock the database after writing. 
-00192     iDatabase.Commit();
-00193     
-00194     // close the database.
-00195     iDatabase.Close();
-00196 
-00197     //Do not commit store: database has taken control of commit.
-00198     CleanupStack::PopAndDestroy(store);
-00199     
-00200     //Cancel the periodic function once 50 numbers have been written to the database.
-00201     if(num > KLastNum )
-00202         {
-00203         iPeriodic->Cancel();
-00204         CActiveScheduler::Stop();
-00205         }
-00206     
-00207     #ifdef USE_SEMAPHORE
-00208     /*Signal the semaphore and the PeriodicReadFunc() which was 
-00209       waiting on the semaphore is scheduled to run. 
-00210       */
-00211     iSemWrite.Signal();
-00212     #endif
-00213     }
-00214     
-00220 void CDatabase::ReadfromDatabaseL()
-00221     { 
-00222     _LIT(KTextConsoleTitle, "ReaderThread");
-00223     if(!iConsole)
-00224         {
-00225          iConsole = Console::NewL(KTextConsoleTitle, TSize(KConsFullScreen,KConsFullScreen)); 
-00226          _LIT(KReading, "Reading the database.\n");
-00227          iConsole->Printf(KReading);
-00228         }   
-00229     iPeriodic->Start(0, KDelay, TCallBack(PeriodicReadL,this));
-00230     CActiveScheduler::Start();
-00231     }
-00232 
-00237 TInt CDatabase::PeriodicReadL(TAny* aPtr)
-00238     {
-00239     CDatabase* ptr = static_cast<CDatabase*> (aPtr);
-00240     ptr->PeriodicReadFuncL();
-00241     return KErrNone;
-00242     }
-00243 
-00248 void CDatabase::PeriodicReadFuncL()
-00249     {
-00250     #ifdef USE_SEMAPHORE
-00251     //Semaphore waits till it gets a signal from the PeriodicWrite() function. 
-00252     iSemWrite.Wait();
-00253     #endif
-00254     
-00255     CFileStore* store = CFileStore::OpenLC(iFsSession,iDbname,EFileRead);  
-00256     
-00257     //Open the database from the root stream.
-00258     iDatabase.OpenL(store,store->Root());
-00259     
-00260     //Lock the database.
-00261     iDatabase.Begin();
-00262     
-00263     //Prepare an SQL query to read three numbers from the database. 
-00264     _LIT(KSQLStatement,"select Number1,Number2,Number3  from Numbers order by Number1,Number2, Number3");
-00265 
-00266     //Create a view on the database.
-00267     RDbView view; 
-00268     User::LeaveIfError(view.Prepare(iDatabase,TDbQuery(KSQLStatement,EDbCompareNormal)));
-00269     User::LeaveIfError(view.EvaluateAll());
-00270     
-00271     //Declare integers to iterate through the database rows. 
-00272     static int count = 0; 
-00273     TInt iter = 0; 
-00274     
-00275     /*Iterate through the database to read only the row which was most recently  
-00276       written by the PeriodicWriteFunc.
-00277       */
-00278     view.FirstL();
-00279     while( iter < count)
-00280         {
-00281         view.NextL();
-00282         iter++; 
-00283         }
-00284     count ++ ; 
-00285      
-00286     //Read the integers from the view and display in console. 
-00287     view.GetL();
-00288     TInt number1 = view.ColInt(1);
-00289     TInt number2 = view.ColInt(2);
-00290     TInt number3 = view.ColInt(3);
-00291     //Prepare a row formatter to print the numbers to the console. 
-00292     _LIT(KRowFormatter, "\n reading  %d \t%d\t%d");
-00293     
-00294     iConsole->Printf(KRowFormatter,number1,number2, number3);
-00295     
-00296     //Cancel the periodic function after it has read the last number in the database.  
-00297     if(number3 >= KLastNum)
-00298         {
-00299         iPeriodic->Cancel();
-00300         CActiveScheduler::Stop();
-00301         _LIT(KAllRead, "\nAll the numbers in the database have been read\n");
-00302         iConsole->Printf(KAllRead);
-00303         _LIT(KExit, "Press a key to exit\n");
-00304         iConsole->Printf(KExit);
-00305         iConsole->Getch();
-00306         }     
-00307     //Close the view. 
-00308     view.Close();
-00309     
-00310     //Unlock the database. 
-00311     iDatabase.Commit();
-00312     
-00313     iDatabase.Close();
-00314     CleanupStack::PopAndDestroy(store);
-00315     }
-