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QCalendar: Delete registered calendar backends on program exit

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Add code to check if the calendar registry is destroyed to all
QCalendar methods that dereference QCalendarBackend pointer.

Pick-to: 6.2
Change-Id: I9b562355e2e0579396b52968f6065c6927cc9ca8
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
This commit is contained in:
Ievgenii Meshcheriakov 2021-07-22 17:44:36 +02:00
parent d0ae1ef33a
commit 84a93d94ac
2 changed files with 76 additions and 17 deletions
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86
src/corelib/time/qcalendar.cpp
View File

@ -118,7 +118,12 @@ class QCalendarRegistry
*/
QAtomicPointer<const QCalendarBackend> gregorianCalendar = nullptr;
enum : int { Unpopulated, Populated };
enum : int {
Unpopulated, // The standard backends may not yet be created
Populated, // All standard backends were created
IsBeingDestroyed, // The registry and the backends are being destroyed
};
/*
Fast way to check whether the standard calendars were populated.
@ -134,6 +139,10 @@ class QCalendarRegistry
public:
QCalendarRegistry() { byId.resize(int(QCalendar::System::Last) + 1); }
~QCalendarRegistry();
bool isBeingDestroyed() const { return status.loadRelaxed() == IsBeingDestroyed; }
void registerCustomBackend(QCalendarBackend *backend, const QStringList &names);
QStringList availableCalendars();
@ -168,6 +177,21 @@ public:
QStringList backendNames(const QCalendarBackend *backend);
};
/*!
Destroy the registry.
This destroys all registered backends. This destructor should only be called
in a single-threaded context at program exit.
*/
QCalendarRegistry::~QCalendarRegistry()
{
QWriteLocker locker(&lock);
status.storeRelaxed(IsBeingDestroyed);
qDeleteAll(byId);
}
/*!
Registers a custom backend.
@ -508,7 +532,7 @@ Q_GLOBAL_STATIC(QtPrivate::QCalendarRegistry, calendarRegistry);
Destroys the calendar backend.
Each calendar backend, once instantiated and successfully registered by ID,
shall exist for the lifetime of the program. Destroying a
shall exist until it is destroyed by the registry. Destroying a
successfully-registered backend otherwise may leave existing QCalendar
instances referencing the destroyed calendar, with undefined results.
@ -518,7 +542,8 @@ Q_GLOBAL_STATIC(QtPrivate::QCalendarRegistry, calendarRegistry);
*/
QCalendarBackend::~QCalendarBackend()
{
Q_ASSERT(!m_id.isValid());
Q_ASSERT(!m_id.isValid() || calendarRegistry.isDestroyed()
|| calendarRegistry->isBeingDestroyed());
}
/*!
@ -616,6 +641,15 @@ QCalendar::System QCalendarBackend::calendarSystem() const
return m_id.isInEnum() ? QCalendar::System(m_id.index()) : QCalendar::System::User;
}
/*
Create local variable d containing the backend associated with a QCalendar
instance unless the calendar registry is destroyed together with all backends,
then return nullptr.
This assumes that the registry is only destroyed in single threaded context.
*/
#define SAFE_D() const auto d = Q_UNLIKELY(calendarRegistry.isDestroyed()) ? nullptr : d_ptr
/*!
The primary name of this calendar.
@ -625,6 +659,7 @@ QCalendar::System QCalendarBackend::calendarSystem() const
*/
QString QCalendar::name() const
{
SAFE_D();
return d ? d->name() : QString();
}
@ -1141,17 +1176,16 @@ const QCalendarBackend *QCalendarBackend::gregorian()
*/
QCalendar::QCalendar()
: d(QCalendarBackend::gregorian())
: d_ptr(QCalendarBackend::gregorian())
{
Q_ASSERT(!d || d->calendarId().isValid());
Q_ASSERT(!d_ptr || d_ptr->calendarId().isValid());
}
QCalendar::QCalendar(QCalendar::System system)
: d(QCalendarBackend::fromEnum(system))
QCalendar::QCalendar(QCalendar::System system) : d_ptr(QCalendarBackend::fromEnum(system))
{
// If system is valid, we should get a valid d for that system.
Q_ASSERT(!d || (uint(system) > uint(QCalendar::System::Last))
|| (d->calendarId().index() == size_t(system)));
Q_ASSERT(!d_ptr || (uint(system) > uint(QCalendar::System::Last))
|| (d_ptr->calendarId().index() == size_t(system)));
}
/*!
@ -1166,21 +1200,21 @@ QCalendar::QCalendar(QCalendar::System system)
registered by name.
*/
QCalendar::QCalendar(QCalendar::SystemId id)
: d(QCalendarBackend::fromId(id))
: d_ptr(QCalendarBackend::fromId(id))
{
Q_ASSERT(!d || d->calendarId().index() == id.index());
Q_ASSERT(!d_ptr || d_ptr->calendarId().index() == id.index());
}
QCalendar::QCalendar(QLatin1String name)
: d(QCalendarBackend::fromName(name))
: d_ptr(QCalendarBackend::fromName(name))
{
Q_ASSERT(!d || d->calendarId().isValid());
Q_ASSERT(!d_ptr || d_ptr->calendarId().isValid());
}
QCalendar::QCalendar(QStringView name)
: d(QCalendarBackend::fromName(name))
: d_ptr(QCalendarBackend::fromName(name))
{
Q_ASSERT(!d || d->calendarId().isValid());
Q_ASSERT(!d_ptr || d_ptr->calendarId().isValid());
}
/*!
@ -1205,6 +1239,7 @@ QCalendar::QCalendar(QStringView name)
*/
int QCalendar::daysInMonth(int month, int year) const
{
SAFE_D();
return d ? d->daysInMonth(month, year) : 0;
}
@ -1215,6 +1250,7 @@ int QCalendar::daysInMonth(int month, int year) const
*/
int QCalendar::daysInYear(int year) const
{
SAFE_D();
return d ? d->daysInYear(year) : 0;
}
@ -1228,6 +1264,7 @@ int QCalendar::daysInYear(int year) const
*/
int QCalendar::monthsInYear(int year) const
{
SAFE_D();
return d ? year == Unspecified ? d->maximumMonthsInYear() : d->monthsInYear(year) : 0;
}
@ -1241,6 +1278,7 @@ int QCalendar::monthsInYear(int year) const
*/
bool QCalendar::isDateValid(int year, int month, int day) const
{
SAFE_D();
return d && d->isDateValid(year, month, day);
}
@ -1252,6 +1290,7 @@ bool QCalendar::isDateValid(int year, int month, int day) const
*/
bool QCalendar::isGregorian() const
{
SAFE_D();
return d && d->isGregorian();
}
@ -1266,6 +1305,7 @@ bool QCalendar::isGregorian() const
*/
bool QCalendar::isLeapYear(int year) const
{
SAFE_D();
return d && d->isLeapYear(year);
}
@ -1276,6 +1316,7 @@ bool QCalendar::isLeapYear(int year) const
*/
bool QCalendar::isLunar() const
{
SAFE_D();
return d && d->isLunar();
}
@ -1288,6 +1329,7 @@ bool QCalendar::isLunar() const
*/
bool QCalendar::isLuniSolar() const
{
SAFE_D();
return d && d->isLuniSolar();
}
@ -1299,6 +1341,7 @@ bool QCalendar::isLuniSolar() const
*/
bool QCalendar::isSolar() const
{
SAFE_D();
return d && d->isSolar();
}
@ -1313,6 +1356,7 @@ bool QCalendar::isSolar() const
*/
bool QCalendar::isProleptic() const
{
SAFE_D();
return d && d->isProleptic();
}
@ -1343,6 +1387,7 @@ bool QCalendar::isProleptic() const
*/
bool QCalendar::hasYearZero() const
{
SAFE_D();
return d && d->hasYearZero();
}
@ -1353,6 +1398,7 @@ bool QCalendar::hasYearZero() const
*/
int QCalendar::maximumDaysInMonth() const
{
SAFE_D();
return d ? d->maximumDaysInMonth() : 0;
}
@ -1363,6 +1409,7 @@ int QCalendar::maximumDaysInMonth() const
*/
int QCalendar::minimumDaysInMonth() const
{
SAFE_D();
return d ? d->minimumDaysInMonth() : 0;
}
@ -1373,6 +1420,7 @@ int QCalendar::minimumDaysInMonth() const
*/
int QCalendar::maximumMonthsInYear() const
{
SAFE_D();
return d ? d->maximumMonthsInYear() : 0;
}
@ -1394,6 +1442,7 @@ int QCalendar::maximumMonthsInYear() const
*/
QDate QCalendar::dateFromParts(int year, int month, int day) const
{
SAFE_D();
qint64 jd;
return d && d->dateToJulianDay(year, month, day, &jd)
? QDate::fromJulianDay(jd) : QDate();
@ -1415,6 +1464,7 @@ QDate QCalendar::dateFromParts(const QCalendar::YearMonthDay &parts) const
*/
QCalendar::YearMonthDay QCalendar::partsFromDate(QDate date) const
{
SAFE_D();
return d && date.isValid() ? d->julianDayToDate(date.toJulianDay()) : YearMonthDay();
}
@ -1429,6 +1479,7 @@ QCalendar::YearMonthDay QCalendar::partsFromDate(QDate date) const
*/
int QCalendar::dayOfWeek(QDate date) const
{
SAFE_D();
return d && date.isValid() ? d->dayOfWeek(date.toJulianDay()) : 0;
}
@ -1456,6 +1507,7 @@ int QCalendar::dayOfWeek(QDate date) const
QString QCalendar::monthName(const QLocale &locale, int month, int year,
QLocale::FormatType format) const
{
SAFE_D();
const int maxMonth = year == Unspecified ? maximumMonthsInYear() : monthsInYear(year);
if (!d || month < 1 || month > maxMonth)
return QString();
@ -1485,6 +1537,7 @@ QString QCalendar::monthName(const QLocale &locale, int month, int year,
QString QCalendar::standaloneMonthName(const QLocale &locale, int month, int year,
QLocale::FormatType format) const
{
SAFE_D();
const int maxMonth = year == Unspecified ? maximumMonthsInYear() : monthsInYear(year);
if (!d || month < 1 || month > maxMonth)
return QString();
@ -1509,6 +1562,7 @@ QString QCalendar::standaloneMonthName(const QLocale &locale, int month, int yea
QString QCalendar::weekDayName(const QLocale &locale, int day,
QLocale::FormatType format) const
{
SAFE_D();
return d ? d->weekDayName(locale, day, format) : QString();
}
@ -1531,6 +1585,7 @@ QString QCalendar::weekDayName(const QLocale &locale, int day,
QString QCalendar::standaloneWeekDayName(const QLocale &locale, int day,
QLocale::FormatType format) const
{
SAFE_D();
return d ? d->standaloneWeekDayName(locale, day, format) : QString();
}
@ -1557,6 +1612,7 @@ QString QCalendar::dateTimeToString(QStringView format, const QDateTime &datetim
QDate dateOnly, QTime timeOnly,
const QLocale &locale) const
{
SAFE_D();
return d ? d->dateTimeToString(format, datetime, dateOnly, timeOnly, locale) : QString();
}

7
src/corelib/time/qcalendar.h
View File

@ -153,7 +153,7 @@ public:
explicit QCalendar(SystemId id);
// QCalendar is a trivially copyable value type.
bool isValid() const { return d != nullptr; }
bool isValid() const { return d_ptr != nullptr; }
// Date queries:
int daysInMonth(int month, int year = Unspecified) const;
@ -201,7 +201,10 @@ public:
static QStringList availableCalendars();
private:
// Always supplied by QCalendarBackend and expected to be a singleton
const QCalendarBackend *d;
// Note that the calendar registry destroys all backends when it is itself
// destroyed. The code should check if the registry is destroyed before
// dereferencing this pointer.
const QCalendarBackend *d_ptr;
};
QT_END_NAMESPACE