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QTimeZonePrivate: Reduce copying by not using QByteArray
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QByteArray creates copies of data, but we usually don't need the copy
and a view, for comparison or fetching substrings, is enough. So instead
we use QBAView and QLatin1String (when we need to go through
QStringTokenizer).

Change-Id: I12e0bd8777fc63f676b9371abfd345fab1046c44
Reviewed-by: Edward Welbourne <[email protected]>
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@Morten242
Morten242 committed Jun 14, 2021
1 parent b5da494 commit d325f63
Showing 1 changed file with 32 additions and 26 deletions.
58 changes: 32 additions & 26 deletions src/corelib/time/qtimezoneprivate.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -91,17 +91,12 @@ static QByteArray ianaId(const QWindowsData *windowsData)
}

// Return the IANA ID literal for a given QZoneData
static QByteArray ianaId(const QZoneData *zoneData)
static QByteArrayView ianaId(const QZoneData *zoneData)
{
return (ianaIdData + zoneData->ianaIdIndex);
}

static QByteArrayView ianaIdView(const QZoneData *zoneData)
{
return (ianaIdData + zoneData->ianaIdIndex);
}

static QByteArray utcId(const QUtcData *utcData)
static QByteArrayView utcId(const QUtcData *utcData)
{
return (ianaIdData + utcData->ianaIdIndex);
}
Expand Down Expand Up @@ -176,8 +171,7 @@ QLocale::Territory QTimeZonePrivate::territory() const
// Default fall-back mode, use the zoneTable to find Region of known Zones
for (int i = 0; i < zoneDataTableSize; ++i) {
const QZoneData *data = zoneData(i);
QByteArrayView idView = ianaIdView(data);
QLatin1String view(idView.data(), idView.size());
QLatin1String view(ianaId(data));
for (QLatin1String token : view.tokenize(QLatin1String(" "))) {
if (token == QLatin1String(m_id.data(), m_id.size()))
return QLocale::Territory(data->territory);
Expand Down Expand Up @@ -533,8 +527,11 @@ QList<QByteArray> QTimeZonePrivate::availableTimeZoneIds(QLocale::Territory terr

// First get all Zones in the Zones table belonging to the Region
for (int i = 0; i < zoneDataTableSize; ++i) {
if (zoneData(i)->territory == territory)
regions += ianaId(zoneData(i)).split(' ');
if (zoneData(i)->territory == territory) {
QLatin1String l1Id(ianaId(zoneData(i)));
for (auto l1 : l1Id.tokenize(QLatin1String(" ")))
regions << QByteArray(l1.data(), l1.size());
}
}

std::sort(regions.begin(), regions.end());
Expand All @@ -559,8 +556,11 @@ QList<QByteArray> QTimeZonePrivate::availableTimeZoneIds(int offsetFromUtc) cons
if (winData->offsetFromUtc == offsetFromUtc) {
for (int j = 0; j < zoneDataTableSize; ++j) {
const QZoneData *data = zoneData(j);
if (data->windowsIdKey == winData->windowsIdKey)
offsets += ianaId(data).split(' ');
if (data->windowsIdKey == winData->windowsIdKey) {
QLatin1String l1Id(ianaId(data));
for (auto l1 : l1Id.tokenize(QLatin1String(" ")))
offsets << QByteArray(l1.data(), l1.size());
}
}
}
}
Expand Down Expand Up @@ -717,13 +717,10 @@ QByteArray QTimeZonePrivate::ianaIdToWindowsId(const QByteArray &id)
{
for (int i = 0; i < zoneDataTableSize; ++i) {
const QZoneData *data = zoneData(i);
QByteArrayView idView = ianaIdView(data);
while (!idView.isEmpty()) {
qsizetype index = idView.indexOf(' ');
QByteArrayView next = index == -1 ? idView : idView.first(index);
if (next == id)
QLatin1String l1Id(ianaId(data));
for (auto l1 : l1Id.tokenize(QLatin1String(" "))) {
if (l1 == QByteArrayView(id))
return toWindowsIdLiteral(data->windowsIdKey);
idView = index == -1 ? QByteArrayView() : idView.sliced(index + 1);
}
}
return QByteArray();
Expand Down Expand Up @@ -757,8 +754,11 @@ QList<QByteArray> QTimeZonePrivate::windowsIdToIanaIds(const QByteArray &windows

for (int i = 0; i < zoneDataTableSize; ++i) {
const QZoneData *data = zoneData(i);
if (data->windowsIdKey == windowsIdKey)
list << ianaId(data).split(' ');
if (data->windowsIdKey == windowsIdKey) {
QLatin1String l1Id(ianaId(data));
for (auto l1 : l1Id.tokenize(QLatin1String(" ")))
list << QByteArray(l1.data(), l1.size());
}
}

// Return the full list in alpha order
Expand All @@ -773,8 +773,14 @@ QList<QByteArray> QTimeZonePrivate::windowsIdToIanaIds(const QByteArray &windows
for (int i = 0; i < zoneDataTableSize; ++i) {
const QZoneData *data = zoneData(i);
// Return the region matches in preference order
if (data->windowsIdKey == windowsIdKey && data->territory == static_cast<quint16>(territory))
return ianaId(data).split(' ');
if (data->windowsIdKey == windowsIdKey
&& data->territory == static_cast<quint16>(territory)) {
QLatin1String l1Id(ianaId(data));
QList<QByteArray> list;
for (auto l1 : l1Id.tokenize(QLatin1String(" ")))
list << QByteArray(l1.data(), l1.size());
return list;
}
}

return QList<QByteArray>();
Expand Down Expand Up @@ -804,7 +810,7 @@ QUtcTimeZonePrivate::QUtcTimeZonePrivate(const QByteArray &id)
// Look for the name in the UTC list, if found set the values
for (int i = 0; i < utcDataTableSize; ++i) {
const QUtcData *data = utcData(i);
const QByteArray uid = utcId(data);
const QByteArrayView uid = utcId(data);
if (uid == id) {
QString name = QString::fromUtf8(id);
init(id, data->offsetFromUtc, name, name, QLocale::AnyTerritory, name);
Expand Down Expand Up @@ -969,7 +975,7 @@ QList<QByteArray> QUtcTimeZonePrivate::availableTimeZoneIds() const
QList<QByteArray> result;
result.reserve(utcDataTableSize);
for (int i = 0; i < utcDataTableSize; ++i)
result << utcId(utcData(i));
result << utcId(utcData(i)).toByteArray();
// Not guaranteed to be sorted, so sort:
std::sort(result.begin(), result.end());
// ### assuming no duplicates
Expand All @@ -992,7 +998,7 @@ QList<QByteArray> QUtcTimeZonePrivate::availableTimeZoneIds(qint32 offsetSeconds
for (int i = 0; i < utcDataTableSize; ++i) {
const QUtcData *data = utcData(i);
if (data->offsetFromUtc == offsetSeconds)
result << utcId(data);
result << utcId(data).toByteArray();
}
// Not guaranteed to be sorted, so sort:
std::sort(result.begin(), result.end());
Expand Down

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