Fix invalid access crash on exit in LimboHSM

Since #131, `LimboState::_exit()` became a source of potential crashes
if object references are used without a validity check. It's too easy
to miss this, which can lead to game crashing during runtime.

This fix reverts #131 change and proposes alternative approach of
re-activating root HSM upon tree entering if it was previously active.
Note that it's not an ideal solution, as some state will be lost upon
re-parenting: HSM exits and then re-activates and enters its initial state.
This commit is contained in:
Serhii Snitsaruk 2024-09-22 13:57:15 +02:00
parent 134bb3214a
commit 60142b191d
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GPG Key ID: A965EF8799FFEC2D
3 changed files with 16 additions and 5 deletions

View File

@ -263,6 +263,21 @@ void LimboHSM::_validate_property(PropertyInfo &p_property) const {
void LimboHSM::_notification(int p_what) {
switch (p_what) {
case NOTIFICATION_POST_ENTER_TREE: {
if (was_active && is_root()) {
// Re-activate the root HSM if it was previously active.
// Typically, this happens when the node is re-entered scene repeatedly (e.g., re-parenting, pooling).
set_active(true);
}
} break;
case NOTIFICATION_EXIT_TREE: {
if (is_root()) {
// Remember active status for re-parenting and exit state machine
// to release resources and signal connections if active.
was_active = active;
if (is_active()) {
_exit();
}
}
} break;
case NOTIFICATION_PROCESS: {
_update(get_process_delta_time());

View File

@ -55,6 +55,7 @@ private:
LimboState *previous_active;
LimboState *next_active;
bool updating = false;
bool was_active = false;
HashMap<TransitionKey, Transition, TransitionKeyHasher> transitions;

View File

@ -190,11 +190,6 @@ void LimboState::_notification(int p_what) {
_update_blackboard_plan();
}
} break;
case NOTIFICATION_PREDELETE: {
if (is_active()) {
_exit();
}
} break;
}
}