Cleanup: unify idiosyncratic singletons

The way we handle singletons in QML, QML insists on allocating the
objects. This leads to a very idiosyncratic way of handling
singletons: The global instance pointer is set in the constructor.

Unify all these by implementing a "SillySingleton" template. All
of the weird singleton-classes can derive from this template and
don't have to bother with reimplementing the instance() function
with all the safety-checks, etc.

This serves firstly as documentation but also improves debugging
as we will now see wanted and unwanted creation and destruction
of these weird singletons.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
This commit is contained in:
Berthold Stoeger 2019-09-22 14:33:33 +02:00 committed by Dirk Hohndel
parent f20d6187f0
commit 05200f9266
13 changed files with 86 additions and 89 deletions

View file

@ -15,7 +15,6 @@ extern QMap<QString, dc_descriptor_t *> descriptorLookup;
namespace {
QHash<QString, QBluetoothDeviceInfo> btDeviceInfo;
}
BTDiscovery *BTDiscovery::m_instance = NULL;
static dc_descriptor_t *getDeviceType(QString btName)
// central function to convert a BT name to a Subsurface known vendor/model pair
@ -139,11 +138,6 @@ BTDiscovery::BTDiscovery(QObject*) : m_btValid(false),
m_showNonDiveComputers(false),
discoveryAgent(nullptr)
{
if (m_instance) {
qDebug() << "trying to create an additional BTDiscovery object";
return;
}
m_instance = this;
#if defined(BT_SUPPORT)
QLoggingCategory::setFilterRules(QStringLiteral("qt.bluetooth* = true"));
BTDiscoveryReDiscover();
@ -202,19 +196,11 @@ void BTDiscovery::BTDiscoveryReDiscover()
BTDiscovery::~BTDiscovery()
{
m_instance = NULL;
#if defined(BT_SUPPORT)
delete discoveryAgent;
#endif
}
BTDiscovery *BTDiscovery::instance()
{
if (!m_instance)
m_instance = new BTDiscovery();
return m_instance;
}
#if defined(BT_SUPPORT)
extern void addBtUuid(QBluetoothUuid uuid);
extern QHash<QString, QStringList> productList;

View file

@ -10,6 +10,7 @@
#include <QBluetoothDeviceDiscoveryAgent>
#include <QBluetoothUuid>
#include "core/libdivecomputer.h"
#include "core/singleton.h"
#if defined(Q_OS_ANDROID)
#include <QAndroidJniObject>
@ -23,13 +24,12 @@ QString extractBluetoothAddress(const QString &address);
QString extractBluetoothNameAddress(const QString &address, QString &name);
QBluetoothDeviceInfo getBtDeviceInfo(const QString &devaddr);
class BTDiscovery : public QObject {
class BTDiscovery : public QObject, public SillySingleton<BTDiscovery> {
Q_OBJECT
public:
BTDiscovery(QObject *parent = NULL);
~BTDiscovery();
static BTDiscovery *instance();
struct btPairedDevice {
QString address;
@ -57,7 +57,6 @@ public:
void discoverAddress(QString address);
private:
static BTDiscovery *m_instance;
bool m_btValid;
bool m_showNonDiveComputers;

74
core/singleton.h Normal file
View file

@ -0,0 +1,74 @@
// SPDX-License-Identifier: GPL-2.0
/*
* We use singletons in numerous places. In combination with QML this gives
* us a very fundamental problem, because QML likes to allocate objects by
* itself. There are known workarounds, but currently we use idiosyncratic
* singleton classes, which initialize the global instance pointer in the
* constructor. Things get even more complicated if the same singleton is used
* on mobile and on desktop. The latter might want to simply use the classical
* instance() function without having to initialize the singleton first, as
* that would beat the purpose of the instance() method.
*
* The template defined here, SillySingleton, codifies all this. Simply derive
* a class from this template:
* class X : public SillySingleton<X> {
* ...
* };
* This will generate an instance() method. This will do the right thing for
* both methods: explicit construction of the singleton via new or implicit
* by calling the instance() method. It will also generate warnings if a
* singleton class is generated more than once (i.e. first instance() is called
* and _then_ new).
*
* In the long run we should get rid of all users of this class.
*/
#ifndef SINGLETON_H
#define SINGLETON_H
#include <typeinfo>
#include <QtGlobal>
// 1) Declaration
template<typename T>
class SillySingleton {
static T *self;
protected:
SillySingleton();
~SillySingleton();
public:
static T *instance();
};
template<typename T>
T *SillySingleton<T>::self = nullptr;
// 2) Implementation
template<typename T>
SillySingleton<T>::SillySingleton()
{
if (self)
qWarning("Generating second instance of singleton %s", typeid(T).name());
self = static_cast<T *>(this);
qDebug("Generated singleton %s", typeid(T).name());
}
template<typename T>
SillySingleton<T>::~SillySingleton()
{
if (self == this)
self = nullptr;
else
qWarning("Destroying unknown instance of singleton %s", typeid(T).name());
qDebug("Destroyed singleton %s", typeid(T).name());
}
template<typename T>
T *SillySingleton<T>::instance()
{
if (!self)
new T;
return self;
}
#endif

View file

@ -109,8 +109,6 @@ extern "C" int updateProgress(const char *text)
return progressDialogCanceled;
}
MainWindow *MainWindow::m_Instance = nullptr;
extern "C" void showErrorFromC(char *buf)
{
QString error(buf);
@ -128,8 +126,6 @@ MainWindow::MainWindow() : QMainWindow(),
survey(nullptr),
findMovedImagesDialog(nullptr)
{
Q_ASSERT_X(m_Instance == NULL, "MainWindow", "MainWindow recreated!");
m_Instance = this;
ui.setupUi(this);
read_hashes();
Command::init();
@ -357,7 +353,6 @@ MainWindow::MainWindow() : QMainWindow(),
MainWindow::~MainWindow()
{
write_hashes();
m_Instance = nullptr;
}
void MainWindow::setupSocialNetworkMenu()
@ -398,11 +393,6 @@ void MainWindow::setDefaultState()
ui.bottomLeft->currentWidget()->setEnabled(false);
}
MainWindow *MainWindow::instance()
{
return m_Instance;
}
// This gets called after one or more dives were added, edited or downloaded for a dive computer
void MainWindow::refreshDisplay(bool doRecreateDiveList)
{

View file

@ -21,6 +21,7 @@
#include "desktop-widgets/filterwidget2.h"
#include "core/applicationstate.h"
#include "core/gpslocation.h"
#include "core/singleton.h"
#define NUM_RECENT_FILES 4
@ -42,7 +43,7 @@ class LocationInformationWidget;
typedef std::pair<QByteArray, QVariant> WidgetProperty;
typedef QVector<WidgetProperty> PropertyList;
class MainWindow : public QMainWindow {
class MainWindow : public QMainWindow, public SillySingleton<MainWindow> {
Q_OBJECT
public:
enum {
@ -61,7 +62,6 @@ public:
MainWindow();
~MainWindow();
static MainWindow *instance();
void loadRecentFiles();
void updateRecentFiles();
void updateRecentFilesMenu();
@ -193,7 +193,6 @@ private:
QString filter_open();
QString filter_import();
QString filter_import_dive_sites();
static MainWindow *m_Instance;
QString displayedFilename(QString fullFilename);
bool askSaveChanges();
bool okToClose(QString message);

View file

@ -44,7 +44,6 @@
#include "core/settings/qPrefUnit.h"
#include "core/trip.h"
QMLManager *QMLManager::m_instance = NULL;
bool noCloudToCloud = false;
#define RED_FONT QLatin1Literal("<font color=\"red\">")
@ -150,7 +149,6 @@ QMLManager::QMLManager() : m_locationServiceEnabled(false),
m_showNonDiveComputers(false)
{
LOG_STP("qmlmgr starting");
m_instance = this;
m_lastDevicePixelRatio = qApp->devicePixelRatio();
timer.start();
connect(qobject_cast<QApplication *>(QApplication::instance()), &QApplication::applicationStateChanged, this, &QMLManager::applicationStateChanged);
@ -451,12 +449,6 @@ QMLManager::~QMLManager()
if (appLogFileOpen)
appLogFile.close();
#endif
m_instance = NULL;
}
QMLManager *QMLManager::instance()
{
return m_instance;
}
#define CLOUDURL QString(prefs.cloud_base_url)

View file

@ -13,13 +13,14 @@
#include "core/btdiscovery.h"
#include "core/gpslocation.h"
#include "core/downloadfromdcthread.h"
#include "core/singleton.h"
#include "qt-models/divelistmodel.h"
#include "qt-models/completionmodels.h"
#include "qt-models/divelocationmodel.h"
#define NOCLOUD_LOCALSTORAGE format_string("%s/cloudstorage/localrepo[master]", system_default_directory())
class QMLManager : public QObject {
class QMLManager : public QObject, public SillySingleton<QMLManager> {
Q_OBJECT
Q_PROPERTY(QString logText READ logText WRITE setLogText NOTIFY logTextChanged)
Q_PROPERTY(bool locationServiceEnabled MEMBER m_locationServiceEnabled WRITE setLocationServiceEnabled NOTIFY locationServiceEnabledChanged)
@ -89,7 +90,6 @@ public:
Q_INVOKABLE void setGitLocalOnly(const bool &value);
Q_INVOKABLE void setFilter(const QString filterText);
static QMLManager *instance();
Q_INVOKABLE void registerError(QString error);
QString consumeError();
@ -219,7 +219,6 @@ private:
bool m_verboseEnabled;
GpsLocation *locationProvider;
bool m_loadFromCloud;
static QMLManager *m_instance;
struct dive *deletedDive;
struct dive_trip *deletedTrip;
QString m_notificationText;

View file

@ -8,30 +8,13 @@
/*** Global and constructors ***/
QMLPrefs *QMLPrefs::m_instance = NULL;
QMLPrefs::QMLPrefs() :
m_credentialStatus(qPrefCloudStorage::CS_UNKNOWN),
m_oldStatus(qPrefCloudStorage::CS_UNKNOWN),
m_showPin(false)
{
// This strange construct is needed because QMLEngine calls new and that
// cannot be overwritten
if (!m_instance)
m_instance = this;
}
QMLPrefs::~QMLPrefs()
{
m_instance = NULL;
}
QMLPrefs *QMLPrefs::instance()
{
return m_instance;
}
/*** public functions ***/
const QString QMLPrefs::cloudPassword() const
{

View file

@ -5,9 +5,9 @@
#include <QObject>
#include "core/settings/qPrefCloudStorage.h"
#include "core/settings/qPrefDisplay.h"
#include "core/singleton.h"
class QMLPrefs : public QObject {
class QMLPrefs : public QObject, public SillySingleton<QMLPrefs> {
Q_OBJECT
Q_PROPERTY(QString cloudPassword
MEMBER m_cloudPassword
@ -35,9 +35,6 @@ class QMLPrefs : public QObject {
NOTIFY oldStatusChanged)
public:
QMLPrefs();
~QMLPrefs();
static QMLPrefs *instance();
const QString cloudPassword() const;
void setCloudPassword(const QString &cloudPassword);
@ -66,7 +63,6 @@ private:
QString m_cloudPin;
QString m_cloudUserName;
qPrefCloudStorage::cloud_status m_credentialStatus;
static QMLPrefs *m_instance;
qPrefCloudStorage::cloud_status m_oldStatus;
bool m_showPin;

View file

@ -134,11 +134,8 @@ QString DiveListSortModel::tripShortDate(const QString &section)
return QStringLiteral("%1\n'%2").arg(firstMonth,firstTime.toString("yy"));
}
DiveListModel *DiveListModel::m_instance = NULL;
DiveListModel::DiveListModel(QObject *parent) : QAbstractListModel(parent)
{
m_instance = this;
}
void DiveListModel::insertDive(int i)
@ -274,11 +271,6 @@ QString DiveListModel::startAddDive()
return QString::number(d->id);
}
DiveListModel *DiveListModel::instance()
{
return m_instance;
}
struct dive *DiveListModel::getDive(int i)
{
if (i < 0 || i >= dive_table.nr) {

View file

@ -6,6 +6,7 @@
#include <QSortFilterProxyModel>
#include "core/subsurface-qt/DiveObjectHelper.h"
#include "core/singleton.h"
class DiveListSortModel : public QSortFilterProxyModel
{
@ -28,7 +29,7 @@ private:
void updateFilterState();
};
class DiveListModel : public QAbstractListModel
class DiveListModel : public QAbstractListModel, public SillySingleton<DiveListModel>
{
Q_OBJECT
public:
@ -45,7 +46,6 @@ public:
DepthDurationRole,
};
static DiveListModel *instance();
DiveListModel(QObject *parent = 0);
void addDive(const QList<dive *> &listOfDives);
void addAllDives();
@ -63,8 +63,6 @@ public:
QString startAddDive();
void resetInternalData();
Q_INVOKABLE DiveObjectHelper at(int i);
private:
static DiveListModel *m_instance;
};
#endif // DIVELISTMODEL_H

View file

@ -3,11 +3,8 @@
#include "core/qthelper.h"
#include <QVector>
GpsListModel *GpsListModel::m_instance = NULL;
GpsListModel::GpsListModel(QObject *parent) : QAbstractListModel(parent)
{
m_instance = this;
}
void GpsListModel::update()
@ -62,9 +59,3 @@ QHash<int, QByteArray> GpsListModel::roleNames() const
roles[GpsLongitudeRole] = "longitude";
return roles;
}
GpsListModel *GpsListModel::instance()
{
return m_instance;
}

View file

@ -3,10 +3,10 @@
#define GPSLISTMODEL_H
#include "core/gpslocation.h"
#include <QObject>
#include "core/singleton.h"
#include <QAbstractListModel>
class GpsListModel : public QAbstractListModel
class GpsListModel : public QAbstractListModel, public SillySingleton<GpsListModel>
{
Q_OBJECT
public:
@ -19,7 +19,6 @@ public:
GpsWhenRole
};
static GpsListModel *instance();
GpsListModel(QObject *parent = 0);
void clear();
int rowCount(const QModelIndex &parent = QModelIndex()) const;
@ -28,7 +27,6 @@ public:
void update();
private:
QVector<gpsTracker> m_gpsFixes;
static GpsListModel *m_instance;
};
#endif // GPSLISTMODEL_H