Merge pull request #2918 from uklotzde/controlobject

ControlObject/ControlPrivateDouble: Various Fixes

12 files changed, 238 insertions, 227 deletions

diff --git a/src/control/control.cpp b/src/control/control.cpp
index d46fcb1d78..99f72ce37f 100644
--- a/src/control/control.cpp
+++ b/src/control/control.cpp
@@ -1,46 +1,38 @@
-#include <QtDebug>
-#include <QSharedPointer>
-
 #include "control/control.h"
 
+#include "control/controlobject.h"
 #include "util/stat.h"
 
-// Static member variable definition
+//static
 UserSettingsPointer ControlDoublePrivate::s_pUserConfig;
 
-QHash<ConfigKey, QWeakPointer<ControlDoublePrivate> > ControlDoublePrivate::s_qCOHash
-GUARDED_BY(ControlDoublePrivate::s_qCOHashMutex);
+//static
+QHash<ConfigKey, QWeakPointer<ControlDoublePrivate>> ControlDoublePrivate::s_qCOHash
+        GUARDED_BY(ControlDoublePrivate::s_qCOHashMutex);
 
+//static
 QHash<ConfigKey, ConfigKey> ControlDoublePrivate::s_qCOAliasHash
-GUARDED_BY(ControlDoublePrivate::s_qCOHashMutex);
+        GUARDED_BY(ControlDoublePrivate::s_qCOHashMutex);
 
+//static
 MMutex ControlDoublePrivate::s_qCOHashMutex;
 
-/*
-ControlDoublePrivate::ControlDoublePrivate()
-        : m_bIgnoreNops(true),
-          m_bTrack(false),
-          m_trackType(Stat::UNSPECIFIED),
-          m_trackFlags(Stat::COUNT | Stat::SUM | Stat::AVERAGE |
-                       Stat::SAMPLE_VARIANCE | Stat::MIN | Stat::MAX),
-          m_confirmRequired(false) {
-    initialize();
-}
-*/
-
-ControlDoublePrivate::ControlDoublePrivate(ConfigKey key,
-                                           ControlObject* pCreatorCO,
-                                           bool bIgnoreNops, bool bTrack,
-                                           bool bPersist, double defaultValue)
+ControlDoublePrivate::ControlDoublePrivate(
+        ConfigKey key,
+        ControlObject* pCreatorCO,
+        bool bIgnoreNops,
+        bool bTrack,
+        bool bPersist,
+        double defaultValue)
         : m_key(key),
+          m_pCreatorCO(pCreatorCO),
           m_bPersistInConfiguration(bPersist),
           m_bIgnoreNops(bIgnoreNops),
           m_bTrack(bTrack),
           m_trackType(Stat::UNSPECIFIED),
           m_trackFlags(Stat::COUNT | Stat::SUM | Stat::AVERAGE |
-                       Stat::SAMPLE_VARIANCE | Stat::MIN | Stat::MAX),
-          m_confirmRequired(false),
-          m_pCreatorCO(pCreatorCO) {
+                  Stat::SAMPLE_VARIANCE | Stat::MIN | Stat::MAX),
+          m_confirmRequired(false) {
     initialize(defaultValue);
 }
 
@@ -112,59 +104,88 @@ QSharedPointer<ControlDoublePrivate> ControlDoublePrivate::getControl(
     VERIFY_OR_DEBUG_ASSERT(!key.isEmpty()) {
         qWarning() << "ControlDoublePrivate::getControl returning NULL"
                    << "for empty ConfigKey.";
-        return QSharedPointer<ControlDoublePrivate>();
+        return nullptr;
     }
 
-    QSharedPointer<ControlDoublePrivate> pControl;
     // Scope for MMutexLocker.
     {
-        MMutexLocker locker(&s_qCOHashMutex);
-        auto it = s_qCOHash.constFind(key);
-        if (it != s_qCOHash.constEnd()) {
-            if (pCreatorCO) {
-                qWarning() << "ControlObject" << key.group << key.item << "already created";
-                DEBUG_ASSERT(!"ControlObject already created");
+        const MMutexLocker locker(&s_qCOHashMutex);
+        const auto it = s_qCOHash.find(key);
+        if (it != s_qCOHash.end()) {
+            auto pControl = it.value().lock();
+            if (pControl) {
+                // Control object already exists
+                VERIFY_OR_DEBUG_ASSERT(!pCreatorCO) {
+                    qWarning()
+                            << "ControlObject"
+                            << key.group << key.item
+                            << "already created";
+                    return nullptr;
+                }
+                return pControl;
             } else {
-                pControl = it.value();
+                // The weak pointer has become invalid and can be cleaned up
+                s_qCOHash.erase(it);
             }
         }
     }
 
-    if (pControl == NULL) {
-        if (pCreatorCO) {
-            pControl = QSharedPointer<ControlDoublePrivate>(
-                    new ControlDoublePrivate(key, pCreatorCO, bIgnoreNops,
-                                             bTrack, bPersist, defaultValue));
-            MMutexLocker locker(&s_qCOHashMutex);
-            //qDebug() << "ControlDoublePrivate::s_qCOHash.insert(" << key.group << "," << key.item << ")";
-            s_qCOHash.insert(key, pControl);
-        } else if (!flags.testFlag(ControlFlag::NoWarnIfMissing)) {
-            qWarning() << "ControlDoublePrivate::getControl returning NULL for ("
-                       << key.group << "," << key.item << ")";
-            DEBUG_ASSERT(flags.testFlag(ControlFlag::NoAssertIfMissing));
-        }
+    if (pCreatorCO) {
+        auto pControl = QSharedPointer<ControlDoublePrivate>(
+                new ControlDoublePrivate(key,
+                        pCreatorCO,
+                        bIgnoreNops,
+                        bTrack,
+                        bPersist,
+                        defaultValue));
+        const MMutexLocker locker(&s_qCOHashMutex);
+        //qDebug() << "ControlDoublePrivate::s_qCOHash.insert(" << key.group << "," << key.item << ")";
+        s_qCOHash.insert(key, pControl);
+        return pControl;
+    }
+
+    if (!flags.testFlag(ControlFlag::NoWarnIfMissing)) {
+        qWarning() << "ControlDoublePrivate::getControl returning NULL for ("
+                   << key.group << "," << key.item << ")";
+        DEBUG_ASSERT(flags.testFlag(ControlFlag::NoAssertIfMissing));
     }
-    return pControl;
+    return nullptr;
 }
 
 // static
-void ControlDoublePrivate::getControls(
-        QList<QSharedPointer<ControlDoublePrivate> >* pControlList) {
-    s_qCOHashMutex.lock();
-    pControlList->clear();
-    for (auto it = s_qCOHash.constBegin(); it != s_qCOHash.constEnd(); ++it) {
-        QSharedPointer<ControlDoublePrivate> pControl = it.value();
-        if (!pControl.isNull()) {
-            pControlList->push_back(pControl);
+QList<QSharedPointer<ControlDoublePrivate>> ControlDoublePrivate::getAllInstances() {
+    QList<QSharedPointer<ControlDoublePrivate>> result;
+    MMutexLocker locker(&s_qCOHashMutex);
+    result.reserve(s_qCOHash.size());
+    for (auto it = s_qCOHash.begin(); it != s_qCOHash.end(); ++it) {
+        auto pControl = it.value().lock();
+        if (pControl) {
+            result.append(std::move(pControl));
+        } else {
+            // The weak pointer has become invalid and can be cleaned up
+            s_qCOHash.erase(it);
         }
     }
-    s_qCOHashMutex.unlock();
+    return result;
 }
 
 // static
-QHash<ConfigKey, ConfigKey> ControlDoublePrivate::getControlAliases() {
+QList<QSharedPointer<ControlDoublePrivate>> ControlDoublePrivate::takeAllInstances() {
+    QList<QSharedPointer<ControlDoublePrivate>> result;
     MMutexLocker locker(&s_qCOHashMutex);
-    return s_qCOAliasHash;
+    result.reserve(s_qCOHash.size());
+    for (auto it = s_qCOHash.begin(); it != s_qCOHash.end(); ++it) {
+        auto pControl = it.value().lock();
+        if (pControl) {
+            result.append(std::move(pControl));
+        }
+    }
+    s_qCOHash.clear();
+    return result;
+}
+
+void ControlDoublePrivate::deleteCreatorCO() {
+    delete m_pCreatorCO.fetchAndStoreOrdered(nullptr);
 }
 
 void ControlDoublePrivate::reset() {
diff --git a/src/control/control.h b/src/control/control.h
index 56df7d5ae2..5ff49bcd4b 100644
--- a/src/control/control.h
+++ b/src/control/control.h
@@ -1,10 +1,10 @@
-#ifndef CONTROL_H
-#define CONTROL_H
+#pragma once
 
+#include <QAtomicPointer>
 #include <QHash>
-#include <QString>
 #include <QObject>
-#include <QAtomicPointer>
+#include <QSharedPointer>
+#include <QString>
 
 #include "control/controlbehavior.h"
 #include "control/controlvalue.h"
@@ -26,7 +26,7 @@ Q_DECLARE_OPERATORS_FOR_FLAGS(ControlFlags)
 class ControlDoublePrivate : public QObject {
     Q_OBJECT
   public:
-    virtual ~ControlDoublePrivate();
+    ~ControlDoublePrivate() override;
 
     // Used to implement control persistence. All controls that are marked
     // "persist in user config" get and set their value on creation/deletion
@@ -43,18 +43,24 @@ class ControlDoublePrivate : public QObject {
     // Gets the ControlDoublePrivate matching the given ConfigKey. If pCreatorCO
     // is non-NULL, allocates a new ControlDoublePrivate for the ConfigKey if
     // one does not exist.
-    static QSharedPointer<ControlDoublePrivate> getControl(const ConfigKey& key,
+    static QSharedPointer<ControlDoublePrivate> getControl(
+            const ConfigKey& key,
             ControlFlags flags = ControlFlag::None,
-            ControlObject* pCreatorCO = NULL,
+            ControlObject* pCreatorCO = nullptr,
             bool bIgnoreNops = true,
             bool bTrack = false,
             bool bPersist = false,
             double defaultValue = 0.0);
 
-    // Adds all ControlDoublePrivate that currently exist to pControlList
-    static void getControls(QList<QSharedPointer<ControlDoublePrivate> >* pControlsList);
+    // Returns a list of all existing instances.
+    static QList<QSharedPointer<ControlDoublePrivate>> getAllInstances();
+    // Clears all existing instances and returns them as a list.
+    static QList<QSharedPointer<ControlDoublePrivate>> takeAllInstances();
 
-    static QHash<ConfigKey, ConfigKey> getControlAliases();
+    static QHash<ConfigKey, ConfigKey> getControlAliases() {
+        // Implicitly shared classes can safely be copied across threads
+        return s_qCOAliasHash;
+    }
 
     const QString& name() const {
         return m_name;
@@ -78,7 +84,7 @@ class ControlDoublePrivate : public QObject {
     // ValueChangeRequest slot.
     void setAndConfirm(double value, QObject* pSender);
     // Gets the control value.
-    inline double get() const {
+    double get() const {
         return m_value.getValue();
     }
     // Resets the control value to its default.
@@ -86,8 +92,10 @@ class ControlDoublePrivate : public QObject {
 
     // Set the behavior to be used when setting values and translating between
     // parameter and value space. Returns the previously set behavior (if any).
-    // The caller must not delete the behavior at any time. The memory is managed
-    // by this function.
+    // Callers must allocate the passed behavior using new and ownership to this
+    // memory is passed with the function call!!
+    // TODO: Pass a std::unique_ptr instead of a plain pointer to ensure this
+    // transfer of ownership.
     void setBehavior(ControlNumericBehavior* pBehavior);
 
     void setParameter(double dParam, QObject* pSender);
@@ -98,27 +106,28 @@ class ControlDoublePrivate : public QObject {
     void setValueFromMidi(MidiOpCode opcode, double dParam);
     double getMidiParameter() const;
 
-    inline bool ignoreNops() const {
+    bool ignoreNops() const {
         return m_bIgnoreNops;
     }
 
-    inline void setDefaultValue(double dValue) {
+    void setDefaultValue(double dValue) {
         m_defaultValue.setValue(dValue);
     }
 
-    inline double defaultValue() const {
+    double defaultValue() const {
         return m_defaultValue.getValue();
     }
 
-    inline ControlObject* getCreatorCO() const {
-        return m_pCreatorCO;
+    ControlObject* getCreatorCO() const {
+        return m_pCreatorCO.loadAcquire();
     }
 
-    inline void removeCreatorCO() {
-        m_pCreatorCO = NULL;
+    bool resetCreatorCO(ControlObject* pCreatorCO) {
+        return m_pCreatorCO.testAndSetOrdered(pCreatorCO, nullptr);
     }
+    void deleteCreatorCO();
 
-    inline ConfigKey getKey() {
+    ConfigKey getKey() {
         return m_key;
     }
 
@@ -144,25 +153,30 @@ class ControlDoublePrivate : public QObject {
     void valueChangeRequest(double value);
 
   private:
-    ControlDoublePrivate(ConfigKey key, ControlObject* pCreatorCO,
-                         bool bIgnoreNops, bool bTrack, bool bPersist,
-                         double defaultValue);
+    ControlDoublePrivate(
+            ConfigKey key,
+            ControlObject* pCreatorCO,
+            bool bIgnoreNops,
+            bool bTrack,
+            bool bPersist,
+            double defaultValue);
+    ControlDoublePrivate(ControlDoublePrivate&&) = delete;
+    ControlDoublePrivate(const ControlDoublePrivate&) = delete;
+    ControlDoublePrivate& operator=(ControlDoublePrivate&&) = delete;
+    ControlDoublePrivate& operator=(const ControlDoublePrivate&) = delete;
+
     void initialize(double defaultValue);
     void setInner(double value, QObject* pSender);
 
-    ConfigKey m_key;
+    const ConfigKey m_key;
+
+    QAtomicPointer<ControlObject> m_pCreatorCO;
 
     // Whether the control should persist in the Mixxx user configuration. The
     // value is loaded from configuration when the control is created and
     // written to the configuration when the control is deleted.
     bool m_bPersistInConfiguration;
 
-    // User-visible, i18n name for what the control is.
-    QString m_name;
-
-    // User-visible, i18n description for what the control does.
-    QString m_description;
-
     // Whether to ignore sets which would have no effect.
     bool m_bIgnoreNops;
 
@@ -173,6 +187,12 @@ class ControlDoublePrivate : public QObject {
     int m_trackFlags;
     bool m_confirmRequired;
 
+    // User-visible, i18n name for what the control is.
+    QString m_name;
+
+    // User-visible, i18n description for what the control does.
+    QString m_description;
+
     // The control value.
     ControlValueAtomic<double> m_value;
     // The default control value.
@@ -180,8 +200,6 @@ class ControlDoublePrivate : public QObject {
 
     QSharedPointer<ControlNumericBehavior> m_pBehavior;
 
-    ControlObject* m_pCreatorCO;
-
     // Hack to implement persistent controls. This is a pointer to the current
     // user configuration object (if one exists). In general, we do not want the
     // user configuration to be a singleton -- objects that need access to it
@@ -191,7 +209,8 @@ class ControlDoublePrivate : public QObject {
     static UserSettingsPointer s_pUserConfig;
 
     // Hash of ControlDoublePrivate instantiations.
-    static QHash<ConfigKey, QWeakPointer<ControlDoublePrivate> > s_qCOHash;
+    static QHash<ConfigKey, QWeakPointer<ControlDoublePrivate>> s_qCOHash;
+
     // Hash of aliases between ConfigKeys. Solely used for looking up the first
     // alias associated with a key.
     static QHash<ConfigKey, ConfigKey> s_qCOAliasHash;
@@ -199,6 +218,3 @@ class ControlDoublePrivate : public QObject {
     // Mutex guarding access to s_qCOHash and s_qCOAliasHash.
     static MMutex s_qCOHashMutex;
 };
-
-
-#endif /* CONTROL_H */
diff --git a/src/control/controlobject.cpp b/src/control/controlobject.cpp
index 2de1c38683..988681cc50 100644
--- a/src/control/controlobject.cpp
+++ b/src/control/controlobject.cpp
@@ -54,7 +54,9 @@ ControlObject::ControlObject(ConfigKey key, bool bIgnoreNops, bool bTrack,
 
 ControlObject::~ControlObject() {
     if (m_pControl) {
-        m_pControl->removeCreatorCO();
+        const bool success = m_pControl->resetCreatorCO(this);
+        Q_UNUSED(success);
+        DEBUG_ASSERT(success);
     }
 }
 
diff --git a/src/control/controlobject.h b/src/control/controlobject.h
index 56af1aefd5..a3e247f846 100644
--- a/src/control/controlobject.h
+++ b/src/control/controlobject.h
@@ -180,6 +180,11 @@ class ControlObject : public QObject {
     void readOnlyHandler(double v);
 
   private:
+    ControlObject(ControlObject&&) = delete;
+    ControlObject(const ControlObject&) = delete;
+    ControlObject& operator=(ControlObject&&) = delete;
+    ControlObject& operator=(const ControlObject&) = delete;
+
     inline bool ignoreNops() const {
         return m_pControl ? m_pControl->ignoreNops() : true;
     }
diff --git a/src/dialog/dlgdevelopertools.cpp b/src/dialog/dlgdevelopertools.cpp
index 4642c649cc..9e5b462e1c 100644
--- a/src/dialog/dlgdevelopertools.cpp
+++ b/src/dialog/dlgdevelopertools.cpp
@@ -13,9 +13,9 @@ DlgDeveloperTools::DlgDeveloperTools(QWidget* pParent,
           m_pConfig(pConfig) {
     setupUi(this);
 
-    QList<QSharedPointer<ControlDoublePrivate> > controlsList;
-    ControlDoublePrivate::getControls(&controlsList);
-    QHash<ConfigKey, ConfigKey> controlAliases =
+    const QList<QSharedPointer<ControlDoublePrivate>> controlsList =
+            ControlDoublePrivate::getAllInstances();
+    const QHash<ConfigKey, ConfigKey> controlAliases =
             ControlDoublePrivate::getControlAliases();
 
     for (auto it = controlsList.constBegin();
@@ -144,8 +144,8 @@ void DlgDeveloperTools::slotControlDump() {
         return;
     }
 
-    QList<QSharedPointer<ControlDoublePrivate> > controlsList;
-    ControlDoublePrivate::getControls(&controlsList);
+    const QList<QSharedPointer<ControlDoublePrivate>> controlsList =
+            ControlDoublePrivate::getAllInstances();
     for (auto it = controlsList.constBegin(); it != controlsList.constEnd(); ++it) {
         const QSharedPointer<ControlDoublePrivate>& pControl = *it;
         if (pControl) {
diff --git a/src/mixxx.cpp b/src/mixxx.cpp
index 0fd9dde2a6..54b30bf3d2 100644
--- a/src/mixxx.cpp
+++ b/src/mixxx.cpp
@@ -142,7 +142,6 @@ const int MixxxMainWindow::kAuxiliaryCount = 4;
 MixxxMainWindow::MixxxMainWindow(QApplication* pApp, const CmdlineArgs& args)
         : m_pWidgetParent(nullptr),
           m_pLaunchImage(nullptr),
-          m_pSettingsManager(nullptr),
           m_pEffectsManager(nullptr),
           m_pEngine(nullptr),
           m_pSkinLoader(nullptr),
@@ -177,7 +176,7 @@ MixxxMainWindow::MixxxMainWindow(QApplication* pApp, const CmdlineArgs& args)
         StatsManager::createInstance();
     }
 
-    m_pSettingsManager = new SettingsManager(this, args.getSettingsPath());
+    m_pSettingsManager = std::make_unique<SettingsManager>(args.getSettingsPath());
 
     initializeKeyboard();
 
@@ -285,10 +284,10 @@ void MixxxMainWindow::initialize(QApplication* pApp, const CmdlineArgs& args) {
 
     m_pRecordingManager = new RecordingManager(pConfig, m_pEngine);
 
-
 #ifdef __BROADCAST__
-    m_pBroadcastManager = new BroadcastManager(m_pSettingsManager,
-                                               m_pSoundManager);
+    m_pBroadcastManager = new BroadcastManager(
+            m_pSettingsManager.get(),
+            m_pSoundManager);
 #endif
 
     launchProgress(11);
@@ -471,9 +470,17 @@ void MixxxMainWindow::initialize(QApplication* pApp, const CmdlineArgs& args) {
     }
 
     // Initialize preference dialog
-    m_pPrefDlg = new DlgPreferences(this, m_pSkinLoader, m_pSoundManager, m_pPlayerManager,
-                                    m_pControllerManager, m_pVCManager, pLV2Backend, m_pEffectsManager,
-                                    m_pSettingsManager, m_pLibrary);
+    m_pPrefDlg = new DlgPreferences(
+            this,
+            m_pSkinLoader,
+            m_pSoundManager,
+            m_pPlayerManager,
+            m_pControllerManager,
+            m_pVCManager,
+            pLV2Backend,
+            m_pEffectsManager,
+            m_pSettingsManager.get(),
+            m_pLibrary);
     m_pPrefDlg->setWindowIcon(QIcon(":/images/mixxx_icon.svg"));
     m_pPrefDlg->setHidden(true);
 
@@ -777,42 +784,6 @@ void MixxxMainWindow::finalize() {
     delete m_pGuiTick;
     delete m_pVisualsManager;
 
-    // Check for leaked ControlObjects and give warnings.
-    QList<QSharedPointer<ControlDoublePrivate> > leakedControls;
-    QList<ConfigKey> leakedConfigKeys;
-
-    ControlDoublePrivate::getControls(&leakedControls);
-
-    if (leakedControls.size() > 0) {
-        qDebug() << "WARNING: The following" << leakedControls.size()
-                 << "controls were leaked:";
-        foreach (QSharedPointer<ControlDoublePrivate> pCDP, leakedControls) {
-            if (pCDP.isNull()) {
-                continue;
-            }
-            ConfigKey key = pCDP->getKey();
-            qDebug() << key.group << key.item << pCDP->getCreatorCO();
-            leakedConfigKeys.append(key);
-        }
-
-        // Deleting leaked objects helps to satisfy valgrind.
-        // These delete calls could cause crashes if a destructor for a control
-        // we thought was leaked is triggered after this one exits.
-        // So, only delete so if developer mode is on.
-        if (CmdlineArgs::Instance().getDeveloper()) {
-            foreach (ConfigKey key, leakedConfigKeys) {
-                // A deletion early in the list may trigger a destructor
-                // for a control later in the list, so we check for a null
-                // pointer each time.
-                ControlObject* pCo = ControlObject::getControl(key, ControlFlag::NoAssertIfMissing);
-                if (pCo) {
-                    delete pCo;
-                }
-            }
-        }
-        leakedControls.clear();
-    }
-
     // Delete the track collections after all internal track pointers
     // in other components have been released by deleting those components
     // beforehand!
@@ -829,9 +800,34 @@ void MixxxMainWindow::finalize() {
     // at exit.
     m_pSettingsManager->save();
 
+    // Check for leaked ControlObjects and give warnings.
+    {
+        QList<QSharedPointer<ControlDoublePrivate>> leakedControls =
+                ControlDoublePrivate::takeAllInstances();
+        VERIFY_OR_DEBUG_ASSERT(leakedControls.isEmpty()) {
+            qWarning()
+                    << "The following"
+                    << leakedControls.size()
+                    << "controls were leaked:";
+            for (auto pCDP : leakedControls) {
+                ConfigKey key = pCDP->getKey();
+                qWarning() << key.group << key.item << pCDP->getCreatorCO();
+                // Deleting leaked objects helps to satisfy valgrind.
+                // These delete calls could cause crashes if a destructor for a control
+                // we thought was leaked is triggered after this one exits.
+                // So, only delete so if developer mode is on.
+                if (CmdlineArgs::Instance().getDeveloper()) {
+                    pCDP->deleteCreatorCO();
+                }
+            }
+        }
+        // Finally drop all shared pointers by exiting this scope
+    }
+
     Sandbox::shutdown();
 
     qDebug() << t.elapsed(false).debugMillisWithUnit() << "deleting SettingsManager";
+    m_pSettingsManager.reset();
 
     delete m_pKeyboard;
     delete m_pKbdConfig;
diff --git a/src/mixxx.h b/src/mixxx.h
index 765a7c065c..f34157f888 100644
--- a/src/mixxx.h
+++ b/src/mixxx.h
@@ -1,35 +1,19 @@
-/***************************************************************************
-                          mixxx.h  -  description
-                             -------------------
-    begin                : Mon Feb 18 09:48:17 CET 2002
-    copyright            : (C) 2002 by Tue and Ken Haste Andersen
-    email                :
- ***************************************************************************/
-
-/***************************************************************************
- *                                                                         *
- *   This program is free software; you can redistribute it and/or modify  *
- *   it under the terms of the GNU General Public License as published by  *
- *   the Free Software Foundation; either version 2 of the License, or     *
- *   (at your option) any later version.                                   *
- *                                                                         *
- ***************************************************************************/
-
-#ifndef MIXXX_H
-#define MIXXX_H
+#pragma once
 
 #include <QMainWindow>
 #include <QSharedPointer>
 #include <QString>
+#include <memory>
 
 #include "preferences/configobject.h"
-#include "preferences/usersettings.h"
 #include "preferences/constants.h"
+#include "preferences/usersettings.h"
+#include "soundio/sounddeviceerror.h"
 #include "track/track.h"
 #include "util/cmdlineargs.h"
-#include "util/timer.h"
 #include "util/db/dbconnectionpool.h"
-#include "soundio/sounddeviceerror.h"
+#include "util/parented_ptr.h"
+#include "util/timer.h"
 
 class ChannelHandleFactory;
 class ControlPushButton;
@@ -142,7 +126,7 @@ class MixxxMainWindow : public QMainWindow {
     QWidget* m_pWidgetParent;
     LaunchImage* m_pLaunchImage;
 
-    SettingsManager* m_pSettingsManager;
+    std::unique_ptr<SettingsManager> m_pSettingsManager;
 
     // The effects processing system
     EffectsManager* m_pEffectsManager;
@@ -203,5 +187,3 @@ class MixxxMainWindow : public QMainWindow {
     static const int kMicrophoneCount;
     static const int kAuxiliaryCount;
 };
-
-#endif
diff --git a/src/preferences/dialog/dlgprefdeck.cpp b/src/preferences/dialog/dlgprefdeck.cpp
index 9ce38c8158..79799bd4ad 100644
--- a/src/preferences/dialog/dlgprefdeck.cpp
+++ b/src/preferences/dialog/dlgprefdeck.cpp
@@ -34,22 +34,29 @@ constexpr int kDefaultRateRampSensitivity = 250;
 // to playermanager.cpp
 }
 
-DlgPrefDeck::DlgPrefDeck(QWidget * parent, MixxxMainWindow * mixxx,
-                         PlayerManager* pPlayerManager,
-                         UserSettingsPointer  pConfig)
-        :  DlgPreferencePage(parent),
-           m_pConfig(pConfig),
-           m_mixxx(mixxx),
-           m_pPlayerManager(pPlayerManager),
-           m_iNumConfiguredDecks(0),
-           m_iNumConfiguredSamplers(0) {
+DlgPrefDeck::DlgPrefDeck(QWidget* parent,
+        MixxxMainWindow* mixxx,
+        PlayerManager* pPlayerManager,
+        UserSettingsPointer pConfig)
+        : DlgPreferencePage(parent),
+          m_mixxx(mixxx),
+          m_pPlayerManager(pPlayerManager),
+          m_pConfig(pConfig),
+          m_pControlTrackTimeDisplay(std::make_unique<ControlObject>(
+                  ConfigKey("[Controls]", "ShowDurationRemaining"))),
+          m_pControlTrackTimeFormat(std::make_unique<ControlObject>(
+                  ConfigKey("[Controls]", "TimeFormat"))),
+          m_pNumDecks(
+                  make_parented<ControlProxy>("[Master]", "num_decks", this)),
+          m_pNumSamplers(make_parented<ControlProxy>(
+                  "[Master]", "num_samplers", this)),
+          m_iNumConfiguredDecks(0),
+          m_iNumConfiguredSamplers(0) {
     setupUi(this);
 
-    m_pNumDecks = new ControlProxy("[Master]", "num_decks", this);
     m_pNumDecks->connectValueChanged(this, [=](double value){slotNumDecksChanged(value);});
     slotNumDecksChanged(m_pNumDecks->get(), true);
 
-    m_pNumSamplers = new ControlProxy("[Master]", "num_samplers", this);
     m_pNumSamplers->connectValueChanged(this, [=](double value){slotNumSamplersChanged(value);});
     slotNumSamplersChanged(m_pNumSamplers->get(), true);
 
@@ -74,10 +81,10 @@ DlgPrefDeck::DlgPrefDeck(QWidget * parent, MixxxMainWindow * mixxx,
     connect(ComboBoxCueMode, SIGNAL(activated(int)), this, SLOT(slotCueModeCombobox(int)));
 
     // Track time display configuration
-    m_pControlTrackTimeDisplay = new ControlObject(
-            ConfigKey("[Controls]", "ShowDurationRemaining"));
-    connect(m_pControlTrackTimeDisplay, SIGNAL(valueChanged(double)),
-            this, SLOT(slotSetTrackTimeDisplay(double)));
+    connect(m_pControlTrackTimeDisplay.get(),
+            &ControlObject::valueChanged,
+            this,
+            QOverload<double>::of(&DlgPrefDeck::slotSetTrackTimeDisplay));
 
     double positionDisplayType = m_pConfig->getValue(
             ConfigKey("[Controls]", "PositionDisplay"),
@@ -101,10 +108,7 @@ DlgPrefDeck::DlgPrefDeck(QWidget * parent, MixxxMainWindow * mixxx,
             this, SLOT(slotSetTrackTimeDisplay(QAbstractButton *)));
 
     // display time format
-
-    m_pControlTrackTimeFormat = new ControlObject(
-            ConfigKey("[Controls]", "TimeFormat"));
-    connect(m_pControlTrackTimeFormat,
+    connect(m_pControlTrackTimeFormat.get(),
             &ControlObject::valueChanged,
             this,
             &DlgPrefDeck::slotTimeFormatChanged);
@@ -351,7 +355,6 @@ DlgPrefDeck::DlgPrefDeck(QWidget * parent, MixxxMainWindow * mixxx,
 }
 
 DlgPrefDeck::~DlgPrefDeck() {
-    delete m_pControlTrackTimeDisplay;
     qDeleteAll(m_rateControls);
     qDeleteAll(m_rateDirectionControls);
     qDeleteAll(m_cueControls);
diff --git a/src/preferences/dialog/dlgprefdeck.h b/src/preferences/dialog/dlgprefdeck.h
index 41788ab9cf..dde7bff85a 100644
--- a/src/preferences/dialog/dlgprefdeck.h
+++ b/src/preferences/dialog/dlgprefdeck.h
@@ -1,7 +1,7 @@
-#ifndef DLGPREFDECK_H
-#define DLGPREFDECK_H
+#pragma once
 
 #include <QWidget>
+#include <memory>
 
 #include "engine/controls/cuecontrol.h"
 #include "engine/controls/ratecontrol.h"
@@ -9,6 +9,7 @@
 #include "preferences/dialog/ui_dlgprefdeckdlg.h"
 #include "preferences/dlgpreferencepage.h"
 #include "preferences/usersettings.h"
+#include "util/parented_ptr.h"
 
 class ControlProxy;
 class ControlPotmeter;
@@ -58,7 +59,7 @@ class DlgPrefDeck : public DlgPreferencePage, public Ui::DlgPrefDeckDlg  {
     DlgPrefDeck(QWidget *parent, MixxxMainWindow *mixxx,
                     PlayerManager* pPlayerManager,
                     UserSettingsPointer pConfig);
-    virtual ~DlgPrefDeck();
+    ~DlgPrefDeck() override;
 
   public slots:
     void slotUpdate() override;
@@ -101,19 +102,22 @@ class DlgPrefDeck : public DlgPreferencePage, public Ui::DlgPrefDeckDlg  {
     void setRateRangeForAllDecks(int rangePercent);
     void setRateDirectionForAllDecks(bool inverted);
 
-    UserSettingsPointer m_pConfig;
-    ControlObject* m_pControlTrackTimeDisplay;
-    ControlObject* m_pControlTrackTimeFormat;
-    ControlProxy* m_pNumDecks;
-    ControlProxy* m_pNumSamplers;
+    MixxxMainWindow* const m_mixxx;
+    PlayerManager* const m_pPlayerManager;
+    const UserSettingsPointer m_pConfig;
+
+    const std::unique_ptr<ControlObject> m_pControlTrackTimeDisplay;
+    const std::unique_ptr<ControlObject> m_pControlTrackTimeFormat;
+
+    const parented_ptr<ControlProxy> m_pNumDecks;
+    const parented_ptr<ControlProxy> m_pNumSamplers;
+
     QList<ControlProxy*> m_cueControls;
     QList<ControlProxy*> m_rateControls;
     QList<ControlProxy*> m_rateDirectionControls;
     QList<ControlProxy*> m_rateRangeControls;
     QList<ControlProxy*> m_keylockModeControls;
     QList<ControlProxy*> m_keyunlockModeControls;
-    MixxxMainWindow *m_mixxx;
-    PlayerManager* m_pPlayerManager;
 
     int m_iNumConfiguredDecks;
     int m_iNumConfiguredSamplers;
@@ -143,5 +147,3 @@ class DlgPrefDeck : public DlgPreferencePage, public Ui::DlgPrefDeckDlg  {
     double m_dRatePermCoarse;
     double m_dRatePermFine;
 };
-
-#endif
diff --git a/src/preferences/settingsmanager.cpp b/src/preferences/settingsmanager.cpp
index f5bb8c680f..efae608981 100644
--- a/src/preferences/settingsmanager.cpp
+++ b/src/preferences/settingsmanager.cpp
@@ -6,10 +6,8 @@
 #include "preferences/upgrade.h"
 #include "util/assert.h"
 
-SettingsManager::SettingsManager(QObject* pParent,
-                                 const QString& settingsPath)
-        : QObject(pParent),
-          m_bShouldRescanLibrary(false) {
+SettingsManager::SettingsManager(const QString& settingsPath)
+        : m_bShouldRescanLibrary(false) {
     // First make sure the settings path exists. If we don't then other parts of
     // Mixxx (such as the library) will produce confusing errors.
     if (!QDir(settingsPath).exists()) {
diff --git a/src/preferences/settingsmanager.h b/src/preferences/settingsmanager.h
index d45ba67754..2f9dcd9dfb 100644
--- a/src/preferences/settingsmanager.h
+++ b/src/preferences/settingsmanager.h
@@ -1,17 +1,11 @@
-#ifndef PREFERENCES_SETTINGSMANAGER_H
-#define PREFERENCES_SETTINGSMANAGER_H
-
-#include <QObject>
-#include <QSharedPointer>
-#include <QString>
+#pragma once
 
 #include "preferences/broadcastsettings.h"
 #include "preferences/usersettings.h"
 
-class SettingsManager : public QObject {
-    Q_OBJECT
+class SettingsManager {
   public:
-    SettingsManager(QObject* pParent, const QString& settingsPath);
+    explicit SettingsManager(const QString& settingsPath);
     virtual ~SettingsManager();
 
     UserSettingsPointer settings() const {
@@ -37,5 +31,3 @@ class SettingsManager : public QObject {
     bool m_bShouldRescanLibrary;
     BroadcastSettingsPointer m_pBroadcastSettings;
 };
-
-#endif /* PREFERENCES_SETTINGSMANAGER_H */
diff --git a/src/test/mixxxtest.cpp b/src/test/mixxxtest.cpp
index f70495e225..a57debe7c7 100644
--- a/src/test/mixxxtest.cpp
+++ b/src/test/mixxxtest.cpp
@@ -45,13 +45,7 @@ MixxxTest::MixxxTest() {
 MixxxTest::~MixxxTest() {
     // Mixxx leaks a ton of COs normally. To make new tests not affected by