AuroraMiddleware/qt5base-lts
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Allow QDateTime to shrink back to short data mode on copy

Browse Source 
We won't shrink on manipulation when we have memory allocated, but it's
a good idea to create a non-shared copy if we can. It's an unlikely
scenario, though, because it requires the QDateTime object to have been
set to a large state then manipulated back into a small state.

Change-Id: I06bae9392f534e45b3f1ffff144dfee755bafa01
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
This commit is contained in:
Thiago Macieira 2016-05-12 19:15:23 -07:00
parent d1395b76cf
commit 72393ac3b6
1 changed files with 30 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
src/corelib/tools/qdatetime.cpp
View File

@ -2482,6 +2482,11 @@ static qint64 localMSecsToEpochMSecs(qint64 localMsecs,
}
}
static inline bool specCanBeSmall(Qt::TimeSpec spec)
{
return spec == Qt::LocalTime || spec == Qt::UTC;
}
static Q_DECL_CONSTEXPR inline
QDateTimePrivate::StatusFlags mergeSpec(QDateTimePrivate::StatusFlags status, Qt::TimeSpec spec)
{
@ -2731,7 +2736,7 @@ static QPair<QDate, QTime> getDateTime(const QDateTimeData &d)
inline QDateTime::Data::Data(Qt::TimeSpec spec)
{
if (CanBeSmall && Q_LIKELY(spec == Qt::LocalTime || spec == Qt::UTC)) {
if (CanBeSmall && Q_LIKELY(specCanBeSmall(spec))) {
d = reinterpret_cast<QDateTimePrivate *>(int(mergeSpec(QDateTimePrivate::ShortData, spec)));
} else {
// the structure is too small, we need to detach
@ -2744,8 +2749,18 @@ inline QDateTime::Data::Data(Qt::TimeSpec spec)
inline QDateTime::Data::Data(const Data &other)
: d(other.d)
{
if (!isShort())
d->ref.ref();
if (!isShort()) {
// check if we could shrink
ShortData sd;
sd.msecs = qintptr(d->m_msecs);
if (CanBeSmall && specCanBeSmall(extractSpec(d->m_status)) && sd.msecs == d->m_msecs) {
sd.status = d->m_status | QDateTimePrivate::ShortData;
data = sd;
} else {
// no, have to keep it big
d->ref.ref();
}
}
}
inline QDateTime::Data &QDateTime::Data::operator=(const Data &other)
@ -2755,8 +2770,18 @@ inline QDateTime::Data &QDateTime::Data::operator=(const Data &other)
auto x = d;
d = other.d;
if (!other.isShort())
other.d->ref.ref();
if (!other.isShort()) {
// check if we could shrink
ShortData sd;
sd.msecs = qintptr(other.d->m_msecs);
if (CanBeSmall && specCanBeSmall(extractSpec(other.d->m_status)) && sd.msecs == other.d->m_msecs) {
sd.status = other.d->m_status | QDateTimePrivate::ShortData;
data = sd;
} else {
// no, have to keep it big
other.d->ref.ref();
}
}
if (!(CanBeSmall && quintptr(x) & QDateTimePrivate::ShortData) && !x->ref.deref())
delete x;