Ensure joy_connection_changed is emitted on the main thread
#80432
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| @@ -475,7 +475,7 @@ void Input::joy_connection_changed(int p_idx, bool p_connected, String p_name, S | |||
| } | |||
| joy_names[p_idx] = js; | |||
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| emit_signal(SNAME("joy_connection_changed"), p_idx, p_connected); | |||
| call_deferred("emit_signal", SNAME("joy_connection_changed"), p_idx, p_connected); | |||
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I'd add a comment to clarify, like "Defer to emit on the main thread." (IIUC).
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BTW I'm not good with multithreading, but would deferring the call to joy_connection_changed in the Linux input code solve the issue similarly?
If only some platforms do this in a thread, maybe they should be responsible for deferring to the main thread where needed?
Though this one claims to be thread-safe so I guess this helps provide this guarantee?
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Yeah, from what I've checked it seems only Linux runs on a thread, and I did try making this change there initially. But for some reason, it didn't work: on Godot 4, the signal stopped being emitted altogether; on Godot 3, the signal stopped being emitted when a joypad is disconnected, and every time I reconnected the joypad it registered a new device index.
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Thanks! |
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Cherry-picked for 3.6. |
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Cherry-picked for 3.5.3. |
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Cherry-picked for 4.1.2. |
Closes #78531 (once cherry-picked for
3.x)On Linux, the code for querying joypad status runs in a thread (
JoypadLinux::joypad_events_thread_run). Therefore, thejoy_connection_changedsignal is not emitted on the main thread, which depending on user code, can lead do a deadlock due to thread-unsafe API.