Cache QState's child states

This is the same type of optimization as that done for transitions in
commit 5d8dcd57cd13fdd9c8643fa3bdda9f197a4351ff. The idea is to avoid
calling qobject_cast() because it's very expensive.

Obtaining child states needs to be as fast as possible because it's in
the critical path of the state machine algorithm; it's called by a ton
of internal functions, like isCompound(), isAtomic(), isInFinalState().
It's also called heavily for parallel state groups.

Reviewed-by: Eskil Abrahamsen Blomfeldt

1 files changed, 2 insertions, 0 deletions

diff --git a/src/corelib/statemachine/qstate_p.h b/src/corelib/statemachine/qstate_p.h
index 3b5f416436..34c883831e 100644
--- a/src/corelib/statemachine/qstate_p.h
+++ b/src/corelib/statemachine/qstate_p.h
@@ -99,6 +99,8 @@ public:
     QAbstractState *errorState;
     QAbstractState *initialState;
     QState::ChildMode childMode;
+    mutable bool childStatesListNeedsRefresh;
+    mutable QList<QAbstractState*> childStatesList;
     mutable bool transitionsListNeedsRefresh;
     mutable QList<QAbstractTransition*> transitionsList;