* Use a separate database connection for each db-worker thread.

src/libtomahawk/database/Database.cpp

@@ -26,12 +26,7 @@
 #include "Source.h"
 
 #define DEFAULT_WORKER_THREADS 4
-
-#if ( QT_VERSION >= QT_VERSION_CHECK(4, 8, 2) )
-    #define MAX_WORKER_THREADS 1
-#else
-    #define MAX_WORKER_THREADS 16
-#endif
+#define MAX_WORKER_THREADS 16
 
 Database* Database::s_instance = 0;
 
@@ -47,7 +42,7 @@ Database::Database( const QString& dbname, QObject* parent )
     : QObject( parent )
     , m_ready( false )
     , m_impl( new DatabaseImpl( dbname, this ) )
-    , m_workerRW( new DatabaseWorker( m_impl, this, true ) )
+    , m_workerRW( new DatabaseWorker( this, true ) )
 {
     s_instance = this;
 
@@ -105,7 +100,7 @@ Database::enqueue( const QSharedPointer<DatabaseCommand>& lc )
         // create new thread if < WORKER_THREADS
         if ( m_workers.count() < m_maxConcurrentThreads )
         {
-            DatabaseWorker* worker = new DatabaseWorker( m_impl, this, false );
+            DatabaseWorker* worker = new DatabaseWorker( this, false );
             worker->start();
 
             m_workers << worker;

src/libtomahawk/database/Database.h

@@ -53,12 +53,13 @@ public:
     ~Database();
 
     QString dbid() const;
-    bool indexReady() const { return m_indexReady; }
 
     void loadIndex();
-
+    bool indexReady() const { return m_indexReady; }
     bool isReady() const { return m_ready; }
 
+    DatabaseImpl* impl() const { return m_impl; }
+
 signals:
     void indexReady(); // search index
     void ready();
@@ -74,8 +75,6 @@ private slots:
     void setIsReadyTrue() { m_ready = true; }
 
 private:
-    DatabaseImpl* impl() const { return m_impl; }
-
     bool m_ready;
     DatabaseImpl* m_impl;
     DatabaseWorker* m_workerRW;

src/libtomahawk/database/DatabaseImpl.cpp

@@ -46,9 +46,7 @@
 
 DatabaseImpl::DatabaseImpl( const QString& dbname, Database* parent )
     : QObject( (QObject*) parent )
-    , m_lastartid( 0 )
-    , m_lastalbid( 0 )
-    , m_lasttrkid( 0 )
+    , m_parent( parent )
 {
     QTime t;
     t.start();
@@ -67,13 +65,10 @@ DatabaseImpl::DatabaseImpl( const QString& dbname, Database* parent )
         m_dbid = uuid();
         query.exec( QString( "INSERT INTO settings(k,v) VALUES('dbid','%1')" ).arg( m_dbid ) );
     }
-    tLog() << "Database ID:" << m_dbid;
 
-     // make sqlite behave how we want:
-    query.exec( "PRAGMA auto_vacuum = FULL" );
-    query.exec( "PRAGMA synchronous  = ON" );
-    query.exec( "PRAGMA foreign_keys = ON" );
-    //query.exec( "PRAGMA temp_store = MEMORY" );
+    tLog() << "Database ID:" << m_dbid;
+    init();
+
     tDebug( LOGVERBOSE ) << "Tweaked db pragmas:" << t.elapsed();
 
     // in case of unclean shutdown last time:
@@ -84,7 +79,6 @@ DatabaseImpl::DatabaseImpl( const QString& dbname, Database* parent )
         QTimer::singleShot( 0, this, SLOT( updateIndex() ) );
 
     tDebug( LOGVERBOSE ) << "Loaded index:" << t.elapsed();
-
     if ( qApp->arguments().contains( "--dumpdb" ) )
     {
         dumpDatabase();
@@ -93,6 +87,30 @@ DatabaseImpl::DatabaseImpl( const QString& dbname, Database* parent )
 }
 
 
+DatabaseImpl::DatabaseImpl( Database* parent, const QString& dbname )
+    : QObject( (QObject*) QThread::currentThread() )
+    , m_parent( parent )
+{
+    openDatabase( dbname, false );
+    init();
+}
+
+
+void
+DatabaseImpl::init()
+{
+    m_lastartid = m_lastalbid = m_lasttrkid = 0;
+
+    TomahawkSqlQuery query = newquery();
+
+     // make sqlite behave how we want:
+    query.exec( "PRAGMA auto_vacuum = FULL" );
+    query.exec( "PRAGMA synchronous  = ON" );
+    query.exec( "PRAGMA foreign_keys = ON" );
+    //query.exec( "PRAGMA temp_store = MEMORY" );
+}
+
+
 DatabaseImpl::~DatabaseImpl()
 {
     delete m_fuzzyIndex;
@@ -115,6 +133,16 @@ DatabaseImpl::~DatabaseImpl()
 }
 
 
+DatabaseImpl*
+DatabaseImpl::clone() const
+{
+    DatabaseImpl* impl = new DatabaseImpl( m_parent, m_db.databaseName() );
+    impl->setDatabaseID( m_dbid );
+    impl->setFuzzyIndex( m_fuzzyIndex );
+    return impl;
+}
+
+
 void
 DatabaseImpl::dumpDatabase()
 {
@@ -681,27 +709,35 @@ DatabaseImpl::resultFromHint( const Tomahawk::query_ptr& origquery )
 
 
 bool
-DatabaseImpl::openDatabase( const QString& dbname )
+DatabaseImpl::openDatabase( const QString& dbname, bool checkSchema )
 {
+    const QStringList conns = QSqlDatabase::connectionNames();
+    const QString connName = QString( "tomahawk%1" ).arg( conns.count() ? QString::number( conns.count() ) : "" );
+
     bool schemaUpdated = false;
     int version = -1;
     {
-        QSqlDatabase db = QSqlDatabase::addDatabase( "QSQLITE", "tomahawk" );
+        QSqlDatabase db = QSqlDatabase::addDatabase( "QSQLITE", connName );
         db.setDatabaseName( dbname );
         if ( !db.open() )
         {
             tLog() << "Failed to open database" << dbname;
             throw "failed to open db"; // TODO
         }
-
-        QSqlQuery qry = QSqlQuery( db );
-        qry.exec( "SELECT v FROM settings WHERE k='schema_version'" );
-        if ( qry.next() )
+        
+        if ( checkSchema )
         {
-            version = qry.value( 0 ).toInt();
-            tLog() << "Database schema of" << dbname << "is" << version;
+            QSqlQuery qry = QSqlQuery( db );
+            qry.exec( "SELECT v FROM settings WHERE k='schema_version'" );
+            if ( qry.next() )
+            {
+                version = qry.value( 0 ).toInt();
+                tLog() << "Database schema of" << dbname << "is" << version;
+            }
         }
-
+        else
+            version = CURRENT_SCHEMA_VERSION;
+            
         if ( version < 0 || version == CURRENT_SCHEMA_VERSION )
             m_db = db;
     }

src/libtomahawk/database/DatabaseImpl.h

@@ -48,7 +48,7 @@ public:
     DatabaseImpl( const QString& dbname, Database* parent = 0 );
     ~DatabaseImpl();
 
-    bool openDatabase( const QString& dbname );
+    DatabaseImpl* clone() const;
 
     TomahawkSqlQuery newquery() { return TomahawkSqlQuery( m_db ); }
     QSqlDatabase& database() { return m_db; }
@@ -85,10 +85,17 @@ private slots:
     void updateIndex();
 
 private:
-    QString cleanSql( const QString& sql );
+    DatabaseImpl( Database* parent, const QString& dbname );
+    void setFuzzyIndex( FuzzyIndex* fi ) { m_fuzzyIndex = fi; }
+    void setDatabaseID( const QString& dbid ) { m_dbid = dbid; }
+
+    void init();
+    bool openDatabase( const QString& dbname, bool checkSchema = true );
     bool updateSchema( int oldVersion );
     void dumpDatabase();
+    QString cleanSql( const QString& sql );
 
+    Database* m_parent;
     bool m_ready;
     QSqlDatabase m_db;
 

src/libtomahawk/database/DatabaseWorker.cpp

@@ -34,9 +34,9 @@
     //#define DEBUG_TIMING TRUE
 #endif
 
-DatabaseWorker::DatabaseWorker( DatabaseImpl* lib, Database* db, bool mutates )
+DatabaseWorker::DatabaseWorker( Database* db, bool mutates )
     : QThread()
-    , m_dbimpl( lib )
+    , m_db( db )
     , m_outstanding( 0 )
 {
     Q_UNUSED( db );
@@ -68,6 +68,8 @@ DatabaseWorker::~DatabaseWorker()
 void
 DatabaseWorker::run()
 {
+    m_dbimpl = m_db->impl()->clone();
+    tDebug() << "New db connection with name:" << m_dbimpl->database().connectionName();
     exec();
     qDebug() << Q_FUNC_INFO << "DatabaseWorker finishing...";
 }

src/libtomahawk/database/DatabaseWorker.h

@@ -39,7 +39,7 @@ class DatabaseWorker : public QThread
 Q_OBJECT
 
 public:
-    DatabaseWorker( DatabaseImpl*, Database*, bool mutates );
+    DatabaseWorker( Database*, bool mutates );
     ~DatabaseWorker();
 
     bool busy() const { return m_outstanding > 0; }
@@ -59,6 +59,7 @@ private:
     void logOp( DatabaseCommandLoggable* command );
 
     QMutex m_mut;
+    Database* m_db;
     DatabaseImpl* m_dbimpl;
     QList< QSharedPointer<DatabaseCommand> > m_commands;
     int m_outstanding;