a11y: Do not cache classes that don't have a factory plugin

For Qt Widgets we thought it was a good idea to also store in the cache
if a class didn't have a factory plugin. This worked fine there, since
the number of QWidget classnames is quite limited (so the factory plugin
cache will soon reach a limit)

In QML however, classes are often suffixed with e.g. Button_QMLTYPE_123,
Button_QMLTYPE_124 etc.
This number suffix is just increased continuously. This could lead to that
the factory plugin cache will grow ad infinitum, which will cause
"memory leaks" in addition to a performance penalty.

Fixes: QTBUG-75106
Change-Id: I9ba189f989f0b90ab62a2c54a2e9230236a998d8
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 583668005d4d6399fc16d165dcb6a5af2b94323d)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Jan Arve Sæther 2021-01-13 14:33:55 +01:00 committed by Qt Cherry-pick Bot
parent 4b3417f0f4
commit e15d63baa3

View File

@ -695,15 +695,14 @@ QAccessibleInterface *QAccessible::queryAccessibleInterface(QObject *object)
// Find a QAccessiblePlugin (factory) for the class name. If there's
// no entry in the cache try to create it using the plugin loader.
if (!qAccessiblePlugins()->contains(cn)) {
QAccessiblePlugin *factory = nullptr; // 0 means "no plugin found". This is cached as well.
const int index = loader()->indexOf(cn);
if (index != -1)
factory = qobject_cast<QAccessiblePlugin *>(loader()->instance(index));
qAccessiblePlugins()->insert(cn, factory);
if (index != -1) {
QAccessiblePlugin *factory = qobject_cast<QAccessiblePlugin *>(loader()->instance(index));
qAccessiblePlugins()->insert(cn, factory);
}
}
// At this point the cache should contain a valid factory pointer or 0:
Q_ASSERT(qAccessiblePlugins()->contains(cn));
QAccessiblePlugin *factory = qAccessiblePlugins()->value(cn);
if (factory) {
QAccessibleInterface *result = factory->create(cn, object);