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QUuid: de-pessimize QDataStream operator

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Use a stack buffer instead of a QByteArray to hold the 16 bytes for
the QUuid serialisation, replacing toRfc4122() with toBytes() and a
memcpy().

As drive-bys, drop the needless cast from char* to uchar*
(qToLittleEndian() has void* arguments, so char* is fine) and drop {}
around single-line if body.

Change-Id: I6ffabcf07fc9a730a782e20e113999a0dcf15067
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
(cherry picked from commit 72d51f1c42b83c26d15cb626f1b22905fbbea474)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Marc Mutz 2023-09-06 14:53:15 +02:00 committed by Qt Cherry-pick Bot
parent c9cb83d212
commit 3d3837287a
1 changed files with 9 additions and 7 deletions
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16
src/corelib/plugin/quuid.cpp
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@ -745,13 +745,15 @@ QByteArray QUuid::toRfc4122() const
*/
QDataStream &operator<<(QDataStream &s, const QUuid &id)
{
QByteArray bytes;
constexpr int NumBytes = sizeof(QUuid);
static_assert(NumBytes == 16, "Change the serialization format when this ever hits");
char bytes[NumBytes];
if (s.byteOrder() == QDataStream::BigEndian) {
bytes = id.toRfc4122();
const auto id128 = id.toBytes();
static_assert(sizeof(id128) == NumBytes);
memcpy(bytes, &id128, NumBytes);
} else {
// we know how many bytes a UUID has, I hope :)
bytes = QByteArray(16, Qt::Uninitialized);
uchar *data = reinterpret_cast<uchar *>(bytes.data());
auto *data = bytes;
// for historical reasons, our little-endian serialization format
// stores each of the UUID fields in little endian, instead of storing
@ -769,9 +771,9 @@ QDataStream &operator<<(QDataStream &s, const QUuid &id)
}
}
if (s.writeRawData(bytes.data(), 16) != 16) {
if (s.writeRawData(bytes, NumBytes) != NumBytes)
s.setStatus(QDataStream::WriteFailed);
}
return s;
}