Adding notification feature to SQLite driver

This modification enables to use notification feature of SQLite with Qt
SQL driver, enables to subscribe for notifications and also to remove
notifications. close() is added to destructor to unregister
notifications in case it is used in multiple threads.

[ChangeLog][QtSql][SQLite] Adding notification feature to SQLite driver

Change-Id: I8b98787f5214a406357646a98711a8ff6045a0dd
Reviewed-by: Andy Shaw <andy.shaw@theqtcompany.com>

2 files changed, 84 insertions, 3 deletions

diff --git a/src/plugins/sqldrivers/sqlite/qsql_sqlite.cpp b/src/plugins/sqldrivers/sqlite/qsql_sqlite.cpp
index 2a45b73d14..ef4ef2e93c 100644
--- a/src/plugins/sqldrivers/sqlite/qsql_sqlite.cpp
+++ b/src/plugins/sqldrivers/sqlite/qsql_sqlite.cpp
@@ -59,6 +59,7 @@
 #endif
 
 #include <sqlite3.h>
+#include <functional>
 
 Q_DECLARE_OPAQUE_POINTER(sqlite3*)
 Q_DECLARE_METATYPE(sqlite3*)
@@ -140,6 +141,7 @@ public:
     inline QSQLiteDriverPrivate() : QSqlDriverPrivate(), access(0) { dbmsType = QSqlDriver::SQLite; }
     sqlite3 *access;
     QList <QSQLiteResult *> results;
+    QStringList notificationid;
 };
 
 
@@ -571,6 +573,7 @@ QSQLiteDriver::QSQLiteDriver(sqlite3 *connection, QObject *parent)
 
 QSQLiteDriver::~QSQLiteDriver()
 {
+    close();
 }
 
 bool QSQLiteDriver::hasFeature(DriverFeature f) const
@@ -585,11 +588,11 @@ bool QSQLiteDriver::hasFeature(DriverFeature f) const
     case SimpleLocking:
     case FinishQuery:
     case LowPrecisionNumbers:
+    case EventNotifications:
         return true;
     case QuerySize:
     case NamedPlaceholders:
     case BatchOperations:
-    case EventNotifications:
     case MultipleResultSets:
     case CancelQuery:
         return false;
@@ -664,9 +667,13 @@ void QSQLiteDriver::close()
         for (QSQLiteResult *result : qAsConst(d->results))
             result->d_func()->finalize();
 
+        if (d->access && (d->notificationid.count() > 0)) {
+            d->notificationid.clear();
+            sqlite3_update_hook(d->access, NULL, NULL);
+        }
+
         if (sqlite3_close(d->access) != SQLITE_OK)
-            setLastError(qMakeError(d->access, tr("Error closing database"),
-                                    QSqlError::ConnectionError));
+            setLastError(qMakeError(d->access, tr("Error closing database"), QSqlError::ConnectionError));
         d->access = 0;
         setOpen(false);
         setOpenError(false);
@@ -825,4 +832,72 @@ QString QSQLiteDriver::escapeIdentifier(const QString &identifier, IdentifierTyp
     return _q_escapeIdentifier(identifier);
 }
 
+static void handle_sqlite_callback(void *qobj,int aoperation, char const *adbname, char const *atablename,
+                                   sqlite3_int64 arowid)
+{
+    Q_UNUSED(aoperation);
+    Q_UNUSED(adbname);
+    QSQLiteDriver *driver = static_cast<QSQLiteDriver *>(qobj);
+    if (driver) {
+        QMetaObject::invokeMethod(driver, "handleNotification", Qt::QueuedConnection,
+                                  Q_ARG(QString, QString::fromUtf8(atablename)), Q_ARG(qint64, arowid));
+    }
+}
+
+bool QSQLiteDriver::subscribeToNotification(const QString &name)
+{
+    Q_D(QSQLiteDriver);
+    if (!isOpen()) {
+        qWarning("Database not open.");
+        return false;
+    }
+
+    if (d->notificationid.contains(name)) {
+        qWarning("Already subscribing to '%s'.", qPrintable(name));
+        return false;
+    }
+
+    //sqlite supports only one notification callback, so only the first is registered
+    d->notificationid << name;
+    if (d->notificationid.count() == 1)
+        sqlite3_update_hook(d->access, &handle_sqlite_callback, reinterpret_cast<void *> (this));
+
+    return true;
+}
+
+bool QSQLiteDriver::unsubscribeFromNotification(const QString &name)
+{
+    Q_D(QSQLiteDriver);
+    if (!isOpen()) {
+        qWarning("Database not open.");
+        return false;
+    }
+
+    if (!d->notificationid.contains(name)) {
+        qWarning("Not subscribed to '%s'.", qPrintable(name));
+        return false;
+    }
+
+    d->notificationid.removeAll(name);
+    if (d->notificationid.isEmpty())
+        sqlite3_update_hook(d->access, NULL, NULL);
+
+    return true;
+}
+
+QStringList QSQLiteDriver::subscribedToNotifications() const
+{
+    Q_D(const QSQLiteDriver);
+    return d->notificationid;
+}
+
+void QSQLiteDriver::handleNotification(const QString &tableName, qint64 rowid)
+{
+    Q_D(const QSQLiteDriver);
+    if (d->notificationid.contains(tableName)) {
+        emit notification(tableName);
+        emit notification(tableName, QSqlDriver::UnknownSource, QVariant(rowid));
+    }
+}
+
 QT_END_NAMESPACE
diff --git a/src/plugins/sqldrivers/sqlite/qsql_sqlite_p.h b/src/plugins/sqldrivers/sqlite/qsql_sqlite_p.h
index c9b7708698..ca969a4b53 100644
--- a/src/plugins/sqldrivers/sqlite/qsql_sqlite_p.h
+++ b/src/plugins/sqldrivers/sqlite/qsql_sqlite_p.h
@@ -93,6 +93,12 @@ public:
     QSqlIndex primaryIndex(const QString &table) const Q_DECL_OVERRIDE;
     QVariant handle() const Q_DECL_OVERRIDE;
     QString escapeIdentifier(const QString &identifier, IdentifierType) const Q_DECL_OVERRIDE;
+
+    bool subscribeToNotification(const QString &name) Q_DECL_OVERRIDE;
+    bool unsubscribeFromNotification(const QString &name) Q_DECL_OVERRIDE;
+    QStringList subscribedToNotifications() const Q_DECL_OVERRIDE;
+private Q_SLOTS:
+    void handleNotification(const QString &tableName, qint64 rowid);
 };
 
 QT_END_NAMESPACE