Fixed #70.

resources/text/CHANGELOG

@@ -2,6 +2,7 @@
 —————
 
 Added:
+▪ User now can select if DB transactions are enabled or not. (bug #70)
 ▪ MySQL database backend now requires at least version 5.5, DB encoding is now changed to utf8mb4 character set. (bug #74)
 ▪ Height if message attachment image is now configurable, defaults to 36. (issue #69)
 ▪ All textual contents of all messages are now locally saved in explicit UTF-8 encoding. This is partially because of MySQL backend. We need to keep encoding of data sent to DB and encoding of DB itself in parity.

src/gui/settings/settingsdatabase.cpp

@@ -32,6 +32,7 @@ SettingsDatabase::SettingsDatabase(Settings *settings, QWidget *parent)
   connect(m_ui->m_txtMysqlDatabase->lineEdit(), &QLineEdit::textChanged, this, &SettingsDatabase::dirtifySettings);
   connect(m_ui->m_txtMysqlHostname->lineEdit(), &QLineEdit::textChanged, this, &SettingsDatabase::dirtifySettings);
   connect(m_ui->m_txtMysqlPassword->lineEdit(), &QLineEdit::textChanged, this, &SettingsDatabase::dirtifySettings);
+  connect(m_ui->m_checkUseTransactions, &QCheckBox::toggled, this, &SettingsDatabase::dirtifySettings);
   connect(m_ui->m_txtMysqlUsername->lineEdit(), &QLineEdit::textChanged, this, &SettingsDatabase::dirtifySettings);
   connect(m_ui->m_spinMysqlPort, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged), this, &SettingsDatabase::dirtifySettings);
 
@@ -133,6 +134,7 @@ void SettingsDatabase::switchMysqlPasswordVisiblity(bool visible) {
 void SettingsDatabase::loadSettings() {
   onBeginLoadSettings();
 
+  m_ui->m_checkUseTransactions->setChecked(qApp->settings()->value(GROUP(Database), SETTING(Database::UseTransactions)).toBool());
   m_ui->m_lblMysqlTestResult->setStatus(WidgetWithStatus::Information,  tr("No connection test triggered so far."), tr("You did not executed any connection test yet."));
 
   // Load SQLite.
@@ -181,6 +183,8 @@ void SettingsDatabase::saveSettings() {
   const bool original_inmemory = settings()->value(GROUP(Database), SETTING(Database::UseInMemory)).toBool();
   const bool new_inmemory = m_ui->m_checkSqliteUseInMemoryDatabase->isChecked();
 
+  qApp->settings()->setValue(GROUP(Database), Database::UseTransactions, m_ui->m_checkUseTransactions->isChecked());
+
   // Save data storage settings.
   QString original_db_driver = settings()->value(GROUP(Database), SETTING(Database::ActiveDriver)).toString();
   QString selected_db_driver = m_ui->m_cmbDatabaseDriver->itemData(m_ui->m_cmbDatabaseDriver->currentIndex()).toString();

src/gui/settings/settingsdatabase.ui

@@ -7,7 +7,7 @@
     <x>0</x>
     <y>0</y>
     <width>558</width>
-    <height>282</height>
+    <height>356</height>
    </rect>
   </property>
   <layout class="QFormLayout" name="formLayout">
@@ -36,7 +36,20 @@
      </property>
     </widget>
    </item>
-   <item row="1" column="0">
+   <item row="2" column="0" colspan="2">
+    <widget class="QLabel" name="label_3">
+     <property name="text">
+      <string>Note that turning this option ON will make saving of new messages FASTER, but it might rarely cause some issues with messages saving.</string>
+     </property>
+     <property name="alignment">
+      <set>Qt::AlignHCenter|Qt::AlignTop</set>
+     </property>
+     <property name="wordWrap">
+      <bool>true</bool>
+     </property>
+    </widget>
+   </item>
+   <item row="3" column="0">
     <widget class="QLabel" name="m_lblDatabaseDriver">
      <property name="text">
       <string>Database driver</string>
@@ -46,10 +59,10 @@
      </property>
     </widget>
    </item>
-   <item row="1" column="1">
+   <item row="3" column="1">
     <widget class="QComboBox" name="m_cmbDatabaseDriver"/>
    </item>
-   <item row="2" column="0" colspan="2">
+   <item row="4" column="0" colspan="2">
     <widget class="QStackedWidget" name="m_stackedDatabaseDriver">
      <property name="currentIndex">
       <number>1</number>
@@ -267,6 +280,13 @@ Authors of this application are NOT responsible for lost data.</string>
      </widget>
     </widget>
    </item>
+   <item row="1" column="0">
+    <widget class="QCheckBox" name="m_checkUseTransactions">
+     <property name="text">
+      <string>Use DB transactions when storing downloaded messages</string>
+     </property>
+    </widget>
+   </item>
   </layout>
  </widget>
  <customwidgets>

src/miscellaneous/databasequeries.cpp

@@ -450,6 +450,8 @@ int DatabaseQueries::updateMessages(QSqlDatabase db,
     return 0;
   }
 
+  bool use_transactions = qApp->settings()->value(GROUP(Database), SETTING(Database::UseTransactions)).toBool();
+
   // Does not make any difference, since each feed now has
   // its own "custom ID" (standard feeds have their custom ID equal to primary key ID).
   int updated_messages = 0;
@@ -488,7 +490,7 @@ int DatabaseQueries::updateMessages(QSqlDatabase db,
                        "SET title = :title, is_read = :is_read, is_important = :is_important, url = :url, author = :author, date_created = :date_created, contents = :contents, enclosures = :enclosures "
                        "WHERE id = :id;");
 
-  if (!query_begin_transaction.exec(qApp->database()->obtainBeginTransactionSql())) {
+  if (use_transactions && !query_begin_transaction.exec(qApp->database()->obtainBeginTransactionSql())) {
     qCritical("Transaction start for message downloader failed: '%s'.", qPrintable(query_begin_transaction.lastError().text()));
     return updated_messages;
   }
@@ -624,7 +626,7 @@ int DatabaseQueries::updateMessages(QSqlDatabase db,
     qWarning("Failed to set custom ID for all messages: '%s'.", qPrintable(db.lastError().text()));
   }
 
-  if (!db.commit()) {
+  if (use_transactions && !db.commit()) {
     qCritical("Transaction commit for message downloader failed: '%s'.", qPrintable(db.lastError().text()));
     db.rollback();
 

src/miscellaneous/settings.cpp

@@ -216,6 +216,9 @@ DVALUE(int) Proxy::PortDef          = 80;
 // Database.
 DKEY Database::ID                       = "database";
 
+DKEY Database::UseTransactions              = "use_transactions";
+DVALUE(bool) Database::UseTransactionsDef   = false;
+
 DKEY Database::UseInMemory              = "use_in_memory_db";
 DVALUE(bool) Database::UseInMemoryDef   = false;
 

src/miscellaneous/settings.h

@@ -242,6 +242,9 @@ namespace Proxy {
 namespace Database {
   KEY ID;
 
+  KEY UseTransactions;
+  VALUE(bool) UseTransactionsDef;
+
   KEY UseInMemory;
   VALUE(bool) UseInMemoryDef;