... you are too slow and QJson API is so ugly.
Now using this wonderful json lib:
https://github.com/nlohmann/json
Results in release mode (QJson tests are not shown but
QJson was even slower than string concat).
PASS : TestQgsJsonUtils::testExportAttributesJson(Use json)
RESULT : TestQgsJsonUtils::testExportAttributesJson():"Use json":
0.0022 msecs per iteration (total: 75, iterations: 32768)
PASS : TestQgsJsonUtils::testExportAttributesJson(Use old string concat)
RESULT : TestQgsJsonUtils::testExportAttributesJson():"Use old string concat":
0.0032 msecs per iteration (total: 54, iterations: 16384)
PASS : TestQgsJsonUtils::testExportFeatureJson(Use json)
RESULT : TestQgsJsonUtils::testExportFeatureJson():"Use json":
0.011 msecs per iteration (total: 96, iterations: 8192)
PASS : TestQgsJsonUtils::testExportFeatureJson(Use old string concat)
RESULT : TestQgsJsonUtils::testExportFeatureJson():"Use old string concat":
0.015 msecs per iteration (total: 64, iterations: 4096)
PASS : TestQgsJsonUtils::testExportGeomToJson(Use json)
RESULT : TestQgsJsonUtils::testExportGeomToJson():"Use json":
0.76 msecs per iteration (total: 98, iterations: 128)
PASS : TestQgsJsonUtils::testExportGeomToJson(Use old string concat)
RESULT : TestQgsJsonUtils::testExportGeomToJson():"Use old string concat":
0.85 msecs per iteration (total: 55, iterations: 64)
PASS : TestQgsJsonUtils::cleanupTestCase()
For non-point geometry subclasses (points are always valid!) we
now cache the results of a geometry validity check. Subsequent
checks utilise the cached result wherever possible.
Because QgsGeometry/QgsFeature objects are implicitly shared, this
means that we avoid a *lot* of duplicate validity checks as
features and geometries are thrown around during processing model
execution.
All your uses of toUtf8().data() actually just need a const char*
So use constData() that is semantically more correct, and documented
to be faster.
From http://doc.qt.io/qt-5/qbytearray.html#data
"For read-only access, constData() is faster because it never
causes a deep copy to occur."
