sqlite_dbengine.cpp

来自「Amarok是一款在LINUX或其他类UNIX操作系统中运行的音频播放器软件。 」· C++ 代码 · 共 228 行

// (c) 2004 Mark Kretschmann <[e-mail]>
// (c) 2004 Christian Muehlhaeuser <[e-mail]>
// (c) 2004 Sami Nieminen <[e-mail]>
// (c) 2005 Ian Monroe <[e-mail]>
// See COPYING file for licensing information.

#define DEBUG_PREFIX "SQLite-DBEngine"

#include "app.h"
#include "amarok.h"
#include "amarokconfig.h"
#include "debug.h"
#include "sqlite_dbengine.h"

#include <kapplication.h>

#include <qfile.h>
#include <qimage.h>
#include <qtimer.h>

#include <cmath>                 //DbConnection::sqlite_power()
#include <ctime>                 //query()
#include <unistd.h>              //usleep()

#include "sqlite/sqlite3.h"

AMAROK_EXPORT_PLUGIN( SqliteDbEngine )


//////////////////////////////////////////////////////////////////////////////////////////
// CLASS SqliteConnection
//////////////////////////////////////////////////////////////////////////////////////////

SqliteDbEngine::SqliteDbEngine()
    : DbConnection( new SqliteConfig( "collection.db" ) )
{
    const QCString path = QString(/*amaroK::saveLocation()+*/"collection.db").local8Bit();

    // Open database file and check for correctness
    m_initialized = false;
    QFile file( path );
    if ( file.open( IO_ReadOnly ) )
    {
        QString format;
        file.readLine( format, 50 );
        if ( !format.startsWith( "SQLite format 3" ) )
        {
            warning() << "Database versions incompatible. Removing and rebuilding database.\n";
        }
        else if ( sqlite3_open( path, &m_db ) != SQLITE_OK )
        {
            warning() << "Database file corrupt. Removing and rebuilding database.\n";
            sqlite3_close( m_db );
        }
        else
            m_initialized = true;
    }

    if ( !m_initialized )
    {
        // Remove old db file; create new
        QFile::remove( path );
        if ( sqlite3_open( path, &m_db ) == SQLITE_OK )
        {
            m_initialized = true;
        }
    }
    if ( m_initialized )
    {
        if( sqlite3_create_function(m_db, "rand", 0, SQLITE_UTF8, NULL, sqlite_rand, NULL, NULL) != SQLITE_OK )
            m_initialized = false;
        if( sqlite3_create_function(m_db, "power", 2, SQLITE_UTF8, NULL, sqlite_power, NULL, NULL) != SQLITE_OK )
            m_initialized = false;
    }

    //optimization for speeding up SQLite
    query( "PRAGMA default_synchronous = OFF;" );
}


SqliteDbEngine::~SqliteDbEngine()
{
    if ( m_db ) sqlite3_close( m_db );
}


QStringList SqliteDbEngine::query( const QString& statement )
{
    QStringList values;
    int error;
    const char* tail;
    sqlite3_stmt* stmt;

    //compile SQL program to virtual machine
    error = sqlite3_prepare( m_db, statement.utf8(), statement.length(), &stmt, &tail );

    if ( error != SQLITE_OK )
    {
        Debug::error() << k_funcinfo << " sqlite3_compile error:" << endl;
        Debug::error() << sqlite3_errmsg( m_db ) << endl;
        Debug::error() << "on query: " << statement << endl;
        values = QStringList();
    }
    else
    {
        int busyCnt = 0;
        int number = sqlite3_column_count( stmt );
        //execute virtual machine by iterating over rows
        while ( true )
        {
            error = sqlite3_step( stmt );

            if ( error == SQLITE_BUSY )
            {
                if ( busyCnt++ > 20 ) {
                    Debug::error() << "Busy-counter has reached maximum. Aborting this sql statement!\n";
                    break;
                }
                ::usleep( 100000 ); // Sleep 100 msec
                debug() << "sqlite3_step: BUSY counter: " << busyCnt << endl;
            }
            if ( error == SQLITE_MISUSE )
                debug() << "sqlite3_step: MISUSE" << endl;
            if ( error == SQLITE_DONE || error == SQLITE_ERROR )
                break;

            //iterate over columns
            for ( int i = 0; i < number; i++ )
            {
                values << QString::fromUtf8( (const char*) sqlite3_column_text( stmt, i ) );
            }
        }
        //deallocate vm resources
        sqlite3_finalize( stmt );

        if ( error != SQLITE_DONE )
        {
            Debug::error() << k_funcinfo << "sqlite_step error.\n";
            Debug::error() << sqlite3_errmsg( m_db ) << endl;
            Debug::error() << "on query: " << statement << endl;
            values = QStringList();
        }
    }

    return values;
}


int SqliteDbEngine::insert( const QString& statement, const QString& /* table */ )
{
    int error;
    const char* tail;
    sqlite3_stmt* stmt;

    //compile SQL program to virtual machine
    error = sqlite3_prepare( m_db, statement.utf8(), statement.length(), &stmt, &tail );

    if ( error != SQLITE_OK )
    {
        Debug::error() << k_funcinfo << " sqlite3_compile error:" << endl;
        Debug::error() << sqlite3_errmsg( m_db ) << endl;
        Debug::error() << "on insert: " << statement << endl;
    }
    else
    {
        int busyCnt = 0;
        //execute virtual machine by iterating over rows
        while ( true )
        {
            error = sqlite3_step( stmt );

            if ( error == SQLITE_BUSY )
            {
                if ( busyCnt++ > 20 ) {
                    Debug::error() << "Busy-counter has reached maximum. Aborting this sql statement!\n";
                    break;
                }
                ::usleep( 100000 ); // Sleep 100 msec
                debug() << "sqlite3_step: BUSY counter: " << busyCnt << endl;
            }
            if ( error == SQLITE_MISUSE )
                debug() << "sqlite3_step: MISUSE" << endl;
            if ( error == SQLITE_DONE || error == SQLITE_ERROR )
                break;
        }
        //deallocate vm resources
        sqlite3_finalize( stmt );

        if ( error != SQLITE_DONE )
        {
            Debug::error() << k_funcinfo << "sqlite_step error.\n";
            Debug::error() << sqlite3_errmsg( m_db ) << endl;
            Debug::error() << "on insert: " << statement << endl;
        }
    }
    return sqlite3_last_insert_rowid( m_db );
}


// this implements a RAND() function compatible with the MySQL RAND() (0-param-form without seed)
void SqliteDbEngine::sqlite_rand(sqlite3_context *context, int /*argc*/, sqlite3_value ** /*argv*/)
{
    //sqlite3_result_double( context, static_cast<double>(KApplication::random()) / (RAND_MAX+1.0) );
}

// this implements a POWER() function compatible with the MySQL POWER()
void SqliteDbEngine::sqlite_power(sqlite3_context *context, int argc, sqlite3_value **argv)
{
    Q_ASSERT( argc==2 );
    if( sqlite3_value_type(argv[0])==SQLITE_NULL || sqlite3_value_type(argv[1])==SQLITE_NULL ) {
        sqlite3_result_null(context);
        return;
    }
    double a = sqlite3_value_double(argv[0]);
    double b = sqlite3_value_double(argv[1]);
    sqlite3_result_double( context, pow(a,b) );
}


//////////////////////////////////////////////////////////////////////////////////////////
// CLASS SqliteConfig
//////////////////////////////////////////////////////////////////////////////////////////

SqliteConfig::SqliteConfig( const QString& dbfile )
    : m_dbfile( dbfile )
{}